IOP Joint APP and HEPP Annual Conference 2026

8 Apr 2026, 09:00 → 10 Apr 2026, 19:00 Europe/London

John McIntyre Conference Centre

Cheryl Patrick, Victoria Martin (The University of Edinburgh (GB))

From 8-10 April 2026, the Institute of Physics will be bringing together the UK & Irish High Energy Particle Physics and Astroparticle Physics communities for a joint annual conference.

Registration is open until Wednesday 18th March through the IOP

Wednesday 8 April

09:45 Welcome Coffee

Plenary: Wednesday morning plenary

1 Welcome from LOC

Speakers: Cheryl Patrick, Victoria Martin (The University of Edinburgh (GB))

2 Welcome to Edinburgh

A welcome from Prof Philip Best, Head of the School of Physics and Astronomy at the University of Edinburgh.

Speaker: Prof. Philip Best

3 Welcome from IOP

4 Cosmic Questions, Human Answers

Speaker: Prof. Catherine Heymans

5 News from the Halo – Recent Developments in Dark Matter Searches

Speaker: Christian Wittweg (Universität Zürich)

6 An update from the Boulby Underground Laboratory

Speaker: Paul Scovell (STFC)

12:35 Lunch

Plenary: Wednesday afternoon plenary

7 CMB

Speaker: Blake Sherwin

8 Particle Physics Methods for Precision Gravitational Wave Physics

Speaker: Mao Zeng (University of Edinburgh)

9 Status and Recent Developments in Gravitational-wave Experiments

Speaker: Laura Nuttall (University of Portsmouth)

15:15 Afternoon Coffee

Parallel Talks: Wednesday 1 - dark matter

10 Projected Sensitivity of the XLZD Rare Event Observatory to New Physics via Low Energy Electron Recoils

LUX-ZEPLIN (LZ) and the next generation XLZD experiments are designed to search for dark matter using two-phase xenon time projection chambers. Apart from searching for Weakly Interacting Massive Particles (WIMPs), LZ is also looking for axion-like particles (ALPs), solar neutrino, mirror dark matter, and hidden photons. XLZD has already published or been researching on its projections to search for these particles. In this talk, I will show LZ’s most up-to-date results, and projected sensitivities for XLZD, to physics models expected to lead to increases in the observed rates of electron recoils in the detectors.

Speaker: Huan Zhang

11 Probing Light Dark Matter with Levitated Quantum Sensors

The nature of dark matter remains one of the pivotal questions in physics. To date, large-scale direct detection experiments have primarily focused on weakly interacting massive particles with masses above the GeV scale, leaving much of the eV–GeV mass range comparatively unexplored. This motivates the development of alternative detection strategies capable of probing sub-GeV dark matter, where qualitatively different experimental approaches are required. Optically levitated nanoparticles provide a promising platform for this purpose, offering ultra-low energy thresholds and a highly tunable mechanical response, enabling sensitivity to a wide range of potential dark matter interactions.
In this work, we present a phenomenological study of levitated optomechanical sensors operated at optimal sensitivity, and use this framework to project the reach of a table-top experiment based on a single levitated nanoparticle. By systematically accounting for the dominant noise sources: thermal decoherence, photon recoil, and quantum backaction, we identify the experimental configurations that maximise sensitivity using a newly developed computational framework.
We derive projected exclusion limits for several dark matter candidates, including standard spin-independent scattering as well as long-range Yukawa interactions relevant for composite and extended dark matter scenarios. We find that for spin-independent scattering, levitated sensors can achieve sensitivity competitive with existing constraints in the sub-GeV mass range and, for long-range Yukawa interactions, can achieve sensitivity beyond current experimental constraints. These results highlight the substantial and largely unexplored potential of levitated optomechanical systems as a versatile probe of sub-GeV dark matter phenomenology.

Speaker: Andrzej Gawdzik

12 Modelling the accidental coincidence background in LUX-ZEPLIN for a light dark matter search

Accidental coincidence events have emerged as the dominant background in low-energy rare event searches using dual-phase xenon time projection chambers. Interactions in the liquid xenon result in a primary scintillation signal (S1) and the release of electrons. These electrons then drift up under an electric field to the liquid surface where they are extracted and produce a secondary electroluminescence signal (S2) as they traverse the gaseous xenon. Accidental events arise when S1 and S2 pulses from separate energy depositions or instrumental effects are mistakenly paired and reconstructed as a single signal-like event. The rate of accidental coincidence events increases rapidly as the energy threshold is lowered, yet our ability to remove them with data quality cuts is reduced. This necessitates a robust accidental coincidence background model.
In this talk, I present a novel data-driven methodology for modelling these backgrounds in the LUX-ZEPLIN (LZ) detector. This approach crucially considers the time-varying nature of the isolated pulses that give rise to accidental coincidence events and their relation to the detector conditions. This model was successfully implemented in the most recent LZ analysis, enabling world-leading limits on spin-independent dark matter interactions for masses between 5 and 9 GeV/c$^2$, as well as the observation of boron-8 coherent elastic neutrino-nucleus scattering at 4.5𝜎 significance.

Speaker: Isabelle Darlington (UCL)

13 QUEST-DMC sensitivity across dark matter interaction types: linking direct detection, colliders, and freeze-out

The QUEST-DMC experiment utilises surface-based superfluid helium-3 bolometers to search for sub-GeV dark matter with ultra-low energy thresholds. This talk presents a study of how different dark matter interaction types impact QUEST-DMC's projected sensitivity. As a central component, we map the non-relativistic EFT operators onto the relativistic bilinear DM-nucleon interactions basis relevant at detector scales, and quantify QUEST-DMC sensitivity across interaction types. We show that QUEST-DMC provides a unique probe of dark matter interactions, with particular strength in previously unexplored parameter space for momentum- and velocity-dependent couplings, extending direct-detection coverage beyond traditional WIMP scenarios.

To connect this reach to collider constraints and cosmological targets in a consistent framework, we use a generalised BSM parton shower through Monte-Carlo event generation and developed two new UFO implementations corresponding to the canonical spin-independent and spin-dependent interactions. This enables sub-GeV dark matter event generation at hadron collider level, allowing collider cross-section limits to be derived in the sub-GeV mass range and compared directly to the corresponding thermal freeze-out targets. We confront these collider-based constraints with the QUEST-DMC reach, highlighting where QUEST-DMC offers uniquely strong coverage of currently unconstrained parameter space and where collider and cosmological considerations are complementary.

Speaker: Neda Darvishi (Royal Holloway University of London)

14 Searching for light dark matter with DarkSPHERE

DarkSPHERE is a next generation spherical proportional counter to explore light dark matter candidates in the 0.05 - 10 GeV mass range. To maximise radiopurity, the detector is planned to be fully electroformed underground at the Boulby Underground Laboratory. This approach opens up the potential to achieve sensitivity reaching the neutrino fog in the 1 GeV region. In this talk, current efforts towards DarkSPHERE will be discussed, including the preparation of a 30 cm in diameter version of DarkSPHERE that could probe new parameter space in this mass region.

Speaker: Dr Lachlan Milligan (University of Birmingham)

15 Prototype Validation Studies for the DarkSide-20k TPC

DarkSide-20k, currently under construction at LNGS, is a dark matter direct-detection experiment employing a dual-phase liquid argon TPC filled with more than 50 tonnes of underground argon. As the largest detector of its kind, it presents substantial technical and integration challenges.

To validate new technologies and reduce construction risk, an intermediate-scale prototype (the Mockup) was developed to bridge the transition from predecessors at the 50 kg (DarkSide-50) and 3.6 tonne (DEAP) stages. The Mockup design follows that of DarkSide-20k, featuring an octagonal PMMA TPC immersed in one tonne of liquid argon, with a wire extraction grid and field shaping provided by a conductive polymer coating (Clevios). The mockup programme enabled testing of novel components, assembly procedures, and system integration.

This talk presents the results of the Mockup programme, including QA/QC methods, HV and cryogenics and operations results, and discusses how these methods inform the integration and QA/QC strategy for the full-scale DarkSide-20k TPC.

Speaker: Angus Thompson (University of Oxford)

16 Spin-dependent dark matter sensitivity of DarkSide-20k

Darkside-20k is a direct dark matter detection experiment situated at LNGS, Italy, featuring a dual-phase liquid argon TPC with an active target mass of 50 tonnes. Due to the zero nuclear spin of argon, liquid argon detector data is typically interpreted only in terms of spin-independent dark matter interactions. However, in the non-relativistic effective field theory (NREFT) framework, liquid argon detector data does have sensitivity to spin-dependent interactions. We present a scan over the NREFT parameter space, considering all isospin-conserving couplings of dark matter to protons and neutrons in liquid argon in the DarkSide-50 data set, and produce sensitivity projections for DarkSide-20k. The results demonstrate that, contrary to previous expectations, large liquid argon detectors such as DarkSide-20k can indeed probe spin dependant dark matter models.

Speaker: Dr Ash Ritchie-Yates (The University of Manchester)

Parallel Talks: Wednesday 2 - collider

17 Run 3 measurement of tau identification performance in $t\bar{t}$ events with the GNtau algorithm in ATLAS

Precise modelling of hadronically decaying tau leptons is critical for many ATLAS measurements and searches, particularly in the top quark, electroweak, and Higgs sectors. The higher centre of mass energy and increased pile up conditions of Run~3 require updated, data driven calibrations of tau reconstruction and identification performance over an extended kinematic regime.

This talk presents a measurement of tau identification performance and data to simulation scale factors using proton proton collisions at $\sqrt{s}=13.6$ TeV recorded by ATLAS during 2022 to 2024. The study targets the GNtau algorithm, a graph neural network based identifier that exploits tracking, calorimeter, and substructure information to enhance discrimination between genuine hadronic taus and jets.

The measurement is performed in $t\bar{t}$ events with opposite sign $\tau_{\mathrm{lep}}\tau_{\mathrm{had}}$ final states, providing a high purity tau sample and coverage across transverse momenta from $20$ to $220$ GeV. Identification efficiencies are extracted using a simultaneous template likelihood fit in pass and fail regions, constraining signal and jet backgrounds in situ. Scale factors are derived as functions of $p_{\mathrm{T}}$, decay mode (1 prong and 3 prong), and identification working point within a unified fit combining the full 2022 to 2024 dataset to maximise statistical precision and ensure stability across detector and running conditions.

These results constitute a key component of the ATLAS Run-3 tau calibration programme and provide essential inputs for analyses with hadronic taus, while illustrating the performance gains enabled by modern graph neural network techniques.

Speaker: Sudev Pradhan (University of Sheffield (GB))

18 Constraining top-sector EFT effects with combined associated top-quark production measurements at ATLAS

A combined measurement of processes in which a top-quark is produced in association with additional particles using the full Run 2 dataset collected by the ATLAS experiment at the LHC is presented. The results are interpreted within the framework of the Standard Model Effective Field Theory (SMEFT), allowing constraints to be placed on dimension-six, top-sector operators.

ATLAS top-quark measurements provide uniquely powerful sensitivity to physics beyond the Standard Model due to the top-quark's unique position as the heaviest fundamental particle, the diverse set of final states, the exceptionally large dataset collected, and the high experimental precision achieved in Run 2. This analysis combines multiple top+X processes in a single, global fit, exploiting correlations and interplays between processes and SMEFT effects. All relevant SMEFT operators are included simultaneously, ensuring a consistent and comprehensive interpretation of the data. This approach aims to set competitive limits on top-sector SMEFT coefficients and highlights the importance of combining all available ATLAS top data to robustly probe new physics effects.

Speaker: Betsy Cunnett (University of Sussex (GB))

19 Gauge-Invariant Longitudinal Modes in Electroweak Parton Shower

Longitudinal electroweak gauge bosons are the most technically delicate ingredient of electroweak parton showers: in the broken Standard Model, the gauge component of a longitudinal polarisation does not cancel diagram by diagram, but is related by Ward identities to amplitudes with an insertion of the associated would-be Goldstone field. Building on the default \textsf{Herwig~7} treatment based on the Dawson-subtracted longitudinal current, we construct a gauge-invariant longitudinal scheme in which the Dawson remainder is retained as a well-defined contribution and completed by a Ward-identity-fixed Goldstone-matching term. We derive helicity-resolved building blocks and compact quasi-collinear splitting kernels for $q\to q'V$ and $V\to V'V''$ branchings, and implement the scheme in \textsf{Herwig~7} as a switchable alternative to the default longitudinal basis. The completion leaves the transverse sector unchanged and modifies only longitudinal entries through controlled symmetry-breaking terms, including Yukawa-sensitive contributions in massive-fermion channels. In shower-level studies, we find that the Dawson and gauge-invariant prescriptions coincide at high evolution scales, while differing at lower scales precisely in channels where symmetry breaking is active. Exclusive single-emission observables can moreover display non-monotonic scheme dependence once Sudakov suppression and kinematic constraints are accounted for. A first multi-emission LHC-like study confirms numerical stability and yields controlled, interpretable shifts in observables that probe propagating electroweak shower currents, whereas quantities dominated by promptly contracted, near on-shell vector-boson matrix elements remain largely unchanged.

Speaker: Aidin Masouminia (IPPP, Durham University)

20 Opposite-sign WW production with Run3 data in ATLAS

The $W^+W^−$ process is very interesting in that it can provide important tests of the electroweak gauge structure of the Standard Model. This contribution focuses on the opposite-sign opposite-charged $W^+W^-\to e\mu\nu\nu$ production, where a measurement with the partial Run3 dataset could provide insights on the CP nature of the anomalous triple gauge coupling.
In particular, this contribution will focus on unfolding. Unfolding refers to the procedure of removing all the detector effects (reconstruction inefficiency and acceptance) in order to obtain the "truth" distribution starting from the measured one, which is then used to measure the differential cross-section. In this contribution, I will present the unfolding performed on CP- and EFT-sensitive observables, both kinematic (ex. $\Delta\Phi (e,\mu)$) and NN-derived observables.
This analysis is aiming for publication by this Summer.

Speaker: Alberto Plebani (University of Cambridge (GB))

21 Search for Di-Higgs Pair Production in the bbtautau decay channel using Run2+Run3 Data with the ATLAS Detector at the LHC.

HH->bbtautau lies in the sweetspot for the study of di-Higgs owing to its relatively low background and significant branching ratio, making it the most sensitive channel according to the ATLAS Run2 results for the study of Higgs self-coupling. Using Run2+Run3 data collected by the ATLAS Experiment, a significant improvement is expected in the sensitivity to the signal strength. This is an overview of the current status and plans, with particular focus on my work on the study of top and Z-boson background modelling and associated uncertainties.

Speaker: Bhupesh Dixit (University of Liverpool (GB))

22 Searching for BSM Higgs bosons in the bbWW final state at the ATLAS detector

Two-Higgs-Doublet-Models are theoretical extensions of the standard model that are able to account for some of its unanswered questions, for example the source of the matter/antimatter asymmetry in the Universe. They predict 5 bosons, the scalar/pseudoscalar H/A and the charged H+ and H-, alongside the h (the standard model Higgs boson). This talk will present the (currently blind) search for the decay of A/H → H+W- → btw- → bbWW (+charge conjugate) at the ATLAS detector, a decay mode which has never previously been searched for. The analysis is in a mature state, with the search covering the mass ranges 300 < mA < 1000 GeV and 200 < mH+ < 800 GeV. The recent tensions at 400 GeV between the ATLAS and CMS results in A→ tt searches therefore also motivate this search. This talk will cover the theory and motivations behind the search, and the current status of the analysis.

Speaker: Rachel Ashby Pickering (University of Warwick (GB))

23 Analysis of Λb → Λ h+h- decays at LHCb in Run 3

Following the recent first observation of baryonic CP violation in $\Lambda_b \rightarrow p K^- \pi^+ \pi^+$ with the Run 1 and 2 dataset, it is vital to study the pattern of CP asymmetries and branching fractions in a wide range of baryonic decay modes. These measurements form important inputs to theoretical approaches such as QCD factorisation.

The upgraded LHCb detector operates at an instantaneous luminosity five times higher than in Runs 1 and 2 and has transitioned from a hardware-based first-level trigger to a fully software trigger. This is particularly advantageous for fully hadronic final state decays, where the efficiency of the previous hardware trigger would quickly saturate at higher luminosities.

During 2024 and 2025, LHCb recorded integrated luminosities of 9.56 fb$^{-1}$ and 11.81 fb$^{-1}$ respectively, more than twice the total dataset collected in Runs 1 and 2 combined. This unprecedented dataset opens new opportunities for precision flavour-physics measurements.

We present ongoing work towards a measurement of the branching fractions of $\Lambda_b \rightarrow \Lambda h^+ h^- (h = \pi, K)$ decays with 2024 data, laying the foundations for a CP violation study using the full Run 3 dataset.

Speaker: George Hallett (University of Warwick (GB))

Parallel Talks: Wednesday 3 - neutrino

24 Improving Uncertainty Estimates from Final State Interactions using the NEUT Event Generator

Modern neutrino experiments use highly flexible neutrino event generators to determine systematic uncertainties which can arise due to model dependence. Final state interactions (FSI), which are modelled using intranuclear cascade models, are a dominant source of uncertainty in these experiments. As experimental improvements both decrease statistical uncertainty and allow lower nucleon momenta to be probed, the systematic uncertainty due to FSI modelling will be exacerbated.
This talk will discuss how adaptations to the existing cascade, together with the implementation of new cascade models in the event generator NEUT can improve estimates of FSI-related uncertainties in future neutrino experiments.
Firstly, the implementation of an FSI Pauli Blocking strength reweight parameter within the event generator NEUT will be discussed. The effects of variation of this parameter will be shown and compared to recent neutrino data, highlighting how this can improve estimations of uncertainty arising due to FSI modelling.
Secondly, preliminary results of the implementation of the new intranuclear cascade model liege (INCL++) model into NEUT will be presented and compared to previous results from another generator, NuWro, for CCQE and NEUT’s original cascade, showing how improvements to our FSI modelling may widen our scope to unexplored areas of neutrino-nucleus interactions in the future.

Speaker: Tom Peacock (University of Sheffield)

25 Searches for Beyond the Standard Model physics with e+e- signatures in MicroBooNE

The MicroBooNE experiment is a liquid argon time projection chamber (LArTPC) that operated for six years at Fermilab, located on-axis of the Booster Neutrino Beam (BNB) target, and 8° off-axis to the Neutrinos from the Main Injector (NuMI) beam. In this talk, I will present searches for Beyond the Standard Model physics producing electron-positron final states using data from both the BNB and NuMI beams. These analyses include recent constraints on dark neutrino models and Higgs-portal scalars, as well as ongoing work. Electromagnetic shower reconstruction is essential for MicroBooNE’s physics program, and the granularity and calorimetry of the detector enables electron and photon-induced showers to be distinguished.

Speaker: Joseph Bateman

26 Measuring Electron Diffusion in the Short-Baseline Near Detector

The Short-Baseline Near Detector (SBND) serves as the near detector for Fermilab's Short-Baseline Neutrino (SBN) programme. It is a 112-ton Liquid Argon Time Projection Chamber (LArTPC) designed to search for new physics phenomena such as sterile neutrinos and study neutrino-argon interactions. Situated only 110 meters from the Booster Neutrino Beam (BNB), SBND has completed its first physics run, recording the world’s most extensive dataset of neutrino–argon interactions. SBND’s TPC subsystem hosts two drift volumes, each of which consists of three charge-sensing wire planes that detect ionisation electrons drifting from charged particles traversing the detector. A detailed understanding of electron transport within a LArTPC is crucial, as it directly influences how the recorded signal waveforms are translated into precise 3D reconstructions of neutrino interactions. One key transport property is diffusion, the gradual spreading of the ionisation cloud over drift time. Longitudinal diffusion, which occurs along the drift direction, directly affects the timing resolution and reconstruction precision. I will present studies of longitudinal diffusion in SBND at electric field strengths of 500, 400, 325, and 275 V/cm.

Speaker: Bethany McCusker (Lancaster University)

27 Neutron detection using the T2K ND280 Electromagnetic Calorimeters

Tokai to Kamioka is a long baseline neutrino oscillation experiment in Japan. The primary goal of the T2K experiment is to investigate neutrino oscillations and CP-violation using neutrino and antineutrino beams. To make precision measurements of these oscillations, the un-oscillated beam is characterised using the off-axis near detector, ND280, at the Japan Proton Accelerator Research Complex (J-PARC). The beam is then characterised again after travelling 295 km at the far detector. Recent Gd doping of the T2K far detector, Super-Kamiokande, has increased ability to tag antineutrinos through the presence of a final state neutron. In this talk, the importance of an ND280 neutron sample will be discussed and the first results of a charged current sample in ND280 with neutrons tagged using the Electromagnetic Calorimeters is presented. The treatment of additional systematics will be discussed as well as motivation to extend the signal definition using the ND280 Super Fine Grained Detector.

Speaker: Hannah Alarakia-Charles (Lancaster University)

28 The NOvA Test Beam Program

The NOvA (NuMI Off-Axis electron neutrino Appearance) Experiment is a long-baseline neutrino oscillation experiment composed of two functionally identical detectors, a 300 ton Near Detector, and a 14 kton Far Detector separated by 809 km and placed 14 mrad off the axis of the NuMI neutrino beam created at Fermilab. This configuration enables NOvA's rich neutrino physics program, which includes measuring neutrino mixing parameters, determining the neutrino mass hierarchy, and probing CP violation in the leptonic sector. The NOvA Test Beam experiment deployed at Fermilab between 2018 and 2022 used a scaled-down 30 ton detector to analyse tagged beamline particles. The beamline selected and identified electrons, muons, pions, kaons, and protons with momenta ranging from 0.4 to 1.8 GeV/c, as understanding how the detector responds to these particles found in the final state of neutrino interactions is crucial. In this talk, we will describe the highlights and challenges of the NOvA Test Beam program, and present preliminary results from studies of particle response in the NOvA Test Beam detector.

Speaker: Emerson Bannister (University of Sussex)

29 The NEXT experiment: Results from the NEXT-100 detector

The NEXT collaboration is focused on the development of high-pressure gaseous xenon time projection chambers to investigate the Majorana nature of the neutrino via the search for neutrinoless double beta decay (0νββ). The previous NEXT-WHITE detector demonstrated the technology's excellent capabilities with respect to energy resolution (sub-1%), topological discrimination, and a good understanding of background; allowing for novel methods to search for the challenging 0νββ signal.

The latest detector within the NEXT programme is NEXT-100; operating at the Laboratorio Subterráneo de Canfranc. NEXT-100 is designed to run with ∼100kg of enriched Xe-136 at 15 bar for 3 years to achieve a competitive 0νββ decay half-life sensitivity . The detector has completed commissioning, calibration and low background runs at ~4 bar with further data taking planned to begin shortly at ~10 bar. Initial results have shown very promising prospects for the scalability of NEXT technology for future tonne-scale detectors.

In this talk I will discuss the recent results from the NEXT-100 detector, its current status, and ongoing research.

Speaker: John Waiton (University of Manchester)

Parallel Talks: Wednesday 4 - detectors

30 The Beam Momentum Spectrometer Stations for the MUonE experiment

There has been a long-standing discrepancy between theoretical predictions and experimental measurements in the evaluation of the muon anomalous magnetic moment a_μ. The leading order hadronic contribution to a_μ, a_μ^HLO , represents the dominant source of uncertainty in the Standard Model evaluation. The MUonE experiment aims to determine a_μ^HLO with high precision using a novel experimental approach. MUonE will take place in CERN’s north area, using the M2 beamline that produces 160GeV muons that will be scattered on a low Z target. The experiment has a modular structure composed of multiple 1m long tracking stations that have individual targets. a_μ^HLO can be evaluated by the extraction of the effective electromagnetic coupling from the shape of the differential cross section of the µ - e elastic scattering. Upstream of the tracking stations there are the beam momentum spectrometer (BMS) stations. The role of the BMS is to measure the momentum of individual incoming muons to a few per mille accuracy. For the 2025 test run dedicated stations were designed for the BMS stations with a new support structure made out of a carbon fibre composite called M55J, and were equipped with silicon strip sensors (2S modules) that were developed for the CMS phase 2 upgrade. The development of the new support structure and preliminary results on the performance of the BMS from the 2025 test run will be presented.

Speaker: Giorgia Cacciola (University of Liverpool (GB))

31 A Novel Cherenkov Radiator for Particle Identification

High performance particle identification has traditionally employed Cerenkov detectors due to their accuracy and elegance.
All current Cerenkov detectors in use today at LHC experiments rely on fluorocarbons as their radiating material.
However, the environmental impacts of fluorocarbon gasses prompts a search for a replacement.

This talk presents a novel glass radiator for use in high energy particle identification detectors.
The design and recent sample measurements in a testbeam is presented, along with a discussion on the advantages brought about by a new radiator.

Speaker: Henry James Linton (Imperial College (GB))

32 Phase-2 CMS ECAL APD Spike Rejection Studies Using 2021 and 2025 Test Beam Data

The High-Luminosity LHC (2030+) will operate at unprecedented intensities and radiation levels, with up to 200 overlapping proton-proton collisions per LHC bunch crossing, requiring significant upgrades to the CMS detector to maintain its physics performance. As part of the Phase-2 upgrade of CMS, the electromagnetic calorimeter (ECAL) readout electronics will be upgraded, providing a 160 MHz sampling rate that enables improved timing reconstruction and enhanced Level-1 Trigger capabilities. These upgrades also allow for greatly improved rejection of unwanted ECAL signals from APD spikes, which arise from highly ionising particles directly striking the avalanche photodiodes used for the light readout.

APD spikes can mimic high-energy electromagnetic deposits and, if not effectively suppressed, may saturate the Level-1 trigger bandwidth. This work focuses on the study of two spike-tagging algorithms for Phase-2 operation of CMS ECAL using test beam data from electron and pion beams provided by the CERN SPS.

Preliminary performance results are presented using datasets from ECAL Phase-2 test beam campaigns collected in 2021 and 2025. These studies assess the spike-tagging performance in detector configurations representative of the upgraded ECAL, providing input to the development of robust spike-mitigation strategies for HL-LHC conditions.

Speaker: Jakub Andrzej Gajownik (Science and Technology Facilities Council STFC (GB))

33 Materials screening at Boulby Underground Laboratory

The Boulby UnderGround Screening (BUGS) facility is a world-class materials screening lab based at the Boulby Underground Laboratory in North Yorkshire. The facility has been, and continues to be, used for screening a wide variety of parts and materials prior to their use in low background experiments in the UK and worldwide. The BUGS facility is continuously improving and currently houses a range of detectors capable of assessing samples of various shapes and sizes through gamma spectroscopy, surface alpha counting, radon emanation measurements, and mass spectrometry. In this talk I will give an overview of the BUGS facility, and discuss recent and ongoing upgrades to the systems.

Speaker: Alice Hamer

34 Inter-Channel Timing Variations in RICH MAPMTs

The ring-imaging Cherenkov (RICH) detectors of the LHCb experiment provide charged-particle identification by reconstructing characteristic Cherenkov rings of photons produced when particles traversing gaseous radiators ($C_{4}F_{10}$, $CF_{4}$) exceed the phase velocity of light. These photons are detected by planes of multi-anode photomultiplier tubes (MAPMTs), where precise timing is essential to suppress backgrounds, directly impacting particle identification performance.
Accurate characterisation of the MAPMT time resolution is therefore critical. Previous studies indicate that the time resolution is not uniform across individual channels, implying that photons incident on different regions of a single pixel may be measured with different precision.
This analysis presents a detailed spatial study of the performance of the 2-inch MAPMTs, including inter-channel timing-resolution maps and full-sensor occupancy imaging, together with an investigation of unexpected spatial structures observed in the data.

Speaker: Callum James White (University of Cambridge (GB))

35 Commissioning of the CMS Phase-2 Tracker Cosmic Test Stand

The High-Luminosity LHC (HL-LHC) will operate with up to 200 simultaneous proton–proton interactions per bunch crossing, requiring upgraded detector readout, triggering, and data acquisition systems. The Phase-2 CMS Outer Tracker introduces new detector modules and a trigger architecture designed to contribute to online trigger decisions within 12.5 $\mu$s. Demonstrating the performance and operational behaviour of this system prior to HL-LHC data taking is an important step toward operational readiness.

A CMS Tracker Phase-2 Cosmic Rack setup has been assembled, consisting of a vertical array of Outer Tracker ladders, each instrumented with twelve Outer Tracker modules. The system is integrated using a readout and processing architecture based on ATCA electronics and prerequisite firmware and software. The rack is operated with cosmic-ray muons, with the ability for self-triggering in addition to the provision of an independent trigger based on scintillator tiles instrumented with photomultiplier tubes.

The primary goals of this system are to exercise the integration of a full trigger and DAQ chain and to develop and validate commissioning procedures for CMS operation at the HL-LHC. The setup also provides a platform for detector backend system development, studying detector synchronisation, online control and offline reconstruction. The status and performance of these components within the integrated system will be presented.

Speaker: Andrew Mastronikolis (Imperial College (GB))

36 Performance studies of the ePIC Barrel Tracking Detector for the Electron-Ion Collider

The Electron-Ion Collider is a future facility that will provide unprecedented insight into the structure of matter by colliding polarised electrons with polarised protons/light ions and unpolarised heavy ions. The project detector, ePIC, is being developed to enable precision measurements of the internal dynamics of quarks and gluons.

The tracking detector is the innermost subdetector of ePIC, and the UK'S contribution towards it is the Outer Barrel.

As the engineering design develops, a detailed understanding of the performance impact is required. I will present a series of simulation studies used to evaluate the performance of the barrel tracking detector over the course of its development. Performance will be evaluated in terms of its ability to reconstruct the momentum and Distance of Closest Approach (DCA) of charged particle tracks to the vertex.

Speaker: Athavan Ramalingam

Parallel Talks: Wednesday 5 - collider

37 Quantum correlated D mesons in LHCb Run 3 data

Quantum correlations in pairs of neutral $D$ mesons are induced by charge-conjugation symmetry in the decay of charmonia and charmonia-like states such as the $C=-1$ $\psi(3770)$ charmonium state decaying to $D\overline{D}$. Such systems are currently used to measure $D$ decay strong phases, which serve as an input to measurements of $D^{0}-\overline{D}^{0}$ mixing as well as measurements of the CKM angle $\gamma$. Additionally, correlated pairs of $D$ mesons could also potentially enable direct measurements of $T$ and $CPT$ symmetries in the neutral charm system, and constrain the properties of observed resonances in spectroscopy studies.

To date, all studies involving quantum-correlated $D\overline{D}$ pairs have been carried out at $e^{+}e^{-}$ experiments, with the most notable examples being BESIII and CLEO-c. Prompt production of correlated $D\overline{D}$ pairs from the decays of charmonia and charmonia-like states, including the $\chi_{c1}(3872)$ exotic hadron, with its subsequent decay to the $D\overline{D}\pi^{0}$ and $D\overline{D}\gamma$ final states, provides us with an opportunity to study such systems at a hadron collider for the first time. The presence of boosted $D$ mesons at LHCb also presents a unique opportunity for time-dependent measurements of $T$ and $CPT$ symmetries.

This talk presents work on an ongoing analysis to make the first confirmation of quantum-correlated $D\overline{D}$ pairs at a hadron collider, using $16.8\ \mbox{fb}^{-1}$ of $pp$ collision data collected in 2024 and 2025 by the LHCb experiment at CERN. $C$-even and $C$-odd $D\overline{D}$ contributions from the $\chi_{c1}(3872)$ decay are studied with the goal of measuring the branching fraction of the non-resonant $\chi_{c1}(3872) \to D^{0}\overline{D}^{0}\pi^{0}$ relative to the $\chi_{c1}(3872) \to D^{0}\overline{D}^{*0}$ decay and the relative strong phase $\delta^{D}_{K\pi}$ between the $D^{0} \to K^{-}\pi^{+}$ and $\overline{D}^{0} \to K^{+}\pi^{-}$ decays.

Speaker: Ho Sang Lee (University of Liverpool (GB))

38 2l+MET signature from two-component dark matter at the LHC

The talk will cover an exploration on the dilepton plus missing transverse energy (MET) signature from the LHC to search for two-component scalar Dark Matter (DM). The model discussed in this work is a 3-Higgs Doublet Model (3HDM) where two of the doublets are inert and the other one is active and also the SM Higgs doublet, hence a I(2+1)HDM. Each inert doublet will provide a scalar DM particle with a discrete symmetry of Z2xZ2’ applying on the doublets, and therefore the model will provide two-component DM. The work studies the model parameter space connected to the masses of two DM particles and the mass differences between the DMs and the next-to-lightest neutral states in each inert doublet. Despite the numerical analysis is performed within the I(2+1)HDM for illustrative purposes, this approach makes it essentially largely model-independent and thus suitable for interpretations in other two-component scalar DM scenarios giving rise to the dilepton plus MET signature.

Speaker: Shu Chen (University of Southampton)

39 Simplified Template Cross Section measurements of Higgs Boson production in the diphoton decay channel at CMS

Precision measurements of Higgs boson production are essential for testing the Standard Model and searching for new physics. This talk presents progress towards measuring Higgs boson production cross sections in the diphoton decay channel at CMS using the Simplified Template Cross Section (STXS) framework. We leverage the first part of the Run 3 dataset collected at $\sqrt{s} = 13.6\,\text{TeV}$ since 2022, improving over the previous analysis via simplified analysis strategy with a global view to event classification. Initial validation using 2022 and 2023 data shows promising results, with extension to the 2024 dataset underway.

To address computational challenges arising from the large datasets in Run 3 and beyond, we explore recent developments in automatic differentiation support within the RooFit framework, which promises order-of-magnitude speedups in likelihood evaluation for complex analyses. This development is crucial for enabling increasingly granular measurements and combinations thereof as the dataset grows.

The anticipated two-fold increase in statistical precision from Run 3 - combined with our refined analysis techniques and computational advances - provides enhanced sensitivity to potential deviations from Standard Model predictions in Higgs boson production.

Speaker: Tom Runting (Imperial College (GB))

40 ATLAS Muon Spectrometer Displaced Vertex Searches

Many BSM models predict the existence of neutrally-charged long-lived particles (LLPs) with macroscopic lifetimes. When these LLPs decay back into SM particles, they leave a striking detector signature in the form of displaced vertices (DVs). Due to its large size and shielding provided by more inward detector systems, the ATLAS muon spectrometer (MS) is a powerful tool for such DV searches.

This talk will introduce the strategies used in reconstructing and selecting vertices from long-lived particles decaying into hadronic jets in the MS with displacements between 3 m and 14 m from the primary interaction vertex. World-leading exclusion limits obtained from Run 2 proton-proton collision data are highlighted, and the current developments for the Run 3 iteration are summarised. Further, an outlook on work regarding overhauling the vertexing algorithm is presented.

Speaker: Julian Friedrich Wack (University of Cambridge (GB))

41 Search for new physics in final states with semi-visible jets or anomalous signatures using the ATLAS detector

We present here a search for semi-visible jets (SVJs) arising from a QCD-like dark sector in ATLAS data. The signal model used predicts a heavy leptophobic Z' mediator and we consider a resonant production via an s-channel. The Z' promptly decays to two dark quarks, which hadronise into both standard model and dark matter particles generating SVJs in our final states. The search for SVJs is conducted using neural networks that create event representations of observables from jet associated tracks to identify the underlying differences between standard model and dark matter hadronisation. The resonant search is performed by fitting the transverse mass distribution. No significant excess was observed, results are presented as limits on the cross section of the Z’ mediator, where signals are parameterised by the mass of the Z’ and the relative amount of dark and visible final state matter in the jets.

Speaker: Saashiv Valjee (University of London (GB))

42 Impact of Hadronic Transport on Identified Particle Production in Pb–Pb Collisions at $\sqrt{s_{NN}}$ = 5.02 TeV\\

Identified charged-hadron production ($\pi^{\pm}$, $K^{\pm}$, and $p(\bar{p})$) in Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV is investigated within the EPOS4 framework to study the role of late-stage hadronic interactions. Simulations are performed both with and without the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) hadronic afterburner, enabling a quantitative assessment of hadronic phase effects. Key observables, including charged-particle multiplicity ($dN_{\mathrm{ch}}/d\eta$), transverse momentum ($p_{\mathrm{T}}$) spectra, and both $p_{\mathrm{T}}$-differential and integrated particle ratios ($K/\pi$ and $p/\pi$), are analyzed. The results indicate that the low-$p_{\mathrm{T}}$ region is strongly influenced by hadronic rescattering and strangeness enhancement, reflected in a centrality-dependent increase of the $K/\pi$ ratio. At intermediate $p_{\mathrm{T}}$, an enhanced baryon-to-meson ratio ($p/\pi$) is observed, consistent with the effects of radial flow and quark recombination. The inclusion of UrQMD leads to improved agreement with ALICE measurements, particularly in reproducing the spectral shapes and mass-dependent collective behavior. Hadronic processes such as baryon--antibaryon annihilation and resonance decays significantly modify the final particle distributions, highlighting the importance of the hadronic phase. Overall, EPOS4 coupled with UrQMD provides a consistent description of the centrality and mass dependence of charged-particle production, emphasizing the essential role of late-stage hadronic dynamics in shaping final-state observables.

Speaker: Anju Bhasin (University of Liverpool)

43 Dimuon decay of Higgs Boson through VH

This contribution presents the search for the dimuon decay of the Standard Model Higgs boson ($H\rightarrow\mu\mu$) in the vector boson associated production (VH) mode using 2022–2024 ATLAS Run 3 pp collision data at $\sqrt{s}=13.6$ TeV. The $H\rightarrow\mu\mu$ channel probes the Higgs coupling to second-generation fermions despite its small branching ratio and challenging signal-to-background ratio. Multivariate techniques, including Boosted Decision Trees (BDTs) implemented with XGBoost, are used for event categorisation and signal discrimination. The VH categories form part of a combined analysis with earlier run 2 ATLAS data, which led to evidence for $H\rightarrow\mu\mu$ with an observed (expected) significance of $3.42\sigma$ ($2.46\sigma$) at $m_H = 125.09$ GeV. This contribution will also discuss potential improvements targeting the forthcoming analysis using the full ATLAS Run 3 dataset.

Speaker: Mr Arnav Sunil Avad (University of London (GB))

Poster Evening: Posters

44 Quantum-Limited Instrumentation for Axion Dark Matter Detection

Axions remain one of the most compelling dark matter candidates, arising from the Peccei–Quinn solution to the strong CP problem. Detecting them requires sensitivity to microwave signals with power levels below
10^−22W.

Haloscope experiments search for photons generated through axion–photon conversion in resonant cavities embedded in strong magnetic fields. Achieving the required sensitivity demands cryogenic operation at millikelvin temperatures, ultra-low-noise amplification, and quantum-aware measurement strategies.

The Quantum Sensors of the Hidden Sector (QSHS) group at the University of Sheffield is commissioning a new axion haloscope that integrates advanced microwave engineering, dilution refrigeration, and quantum-limited detection to extend the search for axion dark matter.

Speaker: Annora Sundararajan

45 Spin Dependent Sensitivity Projection for QUEST-DMC

QUEST-DMC is a dark matter direct detection experiment aiming for world-leading sensitivity to interactions with sub-GeV mass dark matter. The experiment is comprised of a superfluid helium-3 bolometer equipped with a NEMS acting as our detector and a SQUID readout system. A Geant4 model of the detector and surrounding cryostat has been developed to simulate the background energy deposits in the detector volume. These simulations are normalised using ambient gamma spectra measured in situ with a NaI(Tl) detector, along with additional material assay data provided by the Boulby Underground Laboratory. This poster outlines the Geant4 modelling and Monte Carlo simulation of background within this bolometer system and the surrounding cryostat, and discusses the use of this background simulation along with sub mK prototype bolometer data to identify the current sensitivity limit for QUEST-DMC.

Speaker: Lizzie Bloomfield (University of Oxford)

46 From Cavern to Classroom - Outreach at Boulby Underground Laboratory

Delivering high-quality public engagement and outreach from 1.1km underground introduces a unique set of challenges. Restricted access to site, an unfamiliar and extreme environment, and a wide range of science that cuts across disciplines make the Boulby Underground Laboratory science programme difficult to convey to a varied audience. This poster covers the goals of the laboratory's outreach and describes the strategies we use to communicate the breadth and depth of our science programme in schools, in public, and with our science users, noting our analysis and review process for the efficacy of our outreach projects.

Speaker: Jonathan Gutteridge (Boulby Underground Laboratory)

47 Time calibration of SuperNEMO calorimeter

The SuperNEMO Demonstrator is a double-beta-decay detector currently taking physics data at the LSM, France. It has a unique ability to measure the full topology of decay events, providing strong background rejection for $\beta\beta$ decay searches. However, extremely rare backgrounds from high-energy beta emitters can mimic $\beta\beta$-like signatures via secondary interactions. An important example is $^{208}$Tl ($Q_{\beta}$ $\simeq$ 5 MeV), which can contribute to the background in the $^{82}$Se region of interest ($Q_{\beta\beta}$ $\simeq$ 3 MeV). We constrain this by measuring the rate of the dominant $^{208}$Tl topology, 1e1$\gamma$ events, with a common vertex. This requires an accurate understanding of the calorimeter response to electrons and $\gamma$ rays in both energy and timing. Using $^{207}$Bi sources, which have well-known electron and $\gamma$ spectra, we calibrate the energy and timing response using selected 1e1$\gamma$ decays. This data-driven calibration supports the $\sim$ 200 ps timing target and improves the robustness of the $^{208}$Tl background estimate for SuperNEMO.

Speaker: Penghui Li (university of edinburgh)

48 Spin-dependent dark matter sensitivity within the non-relativistic effective field theory framework

Direct detection experiment data is typically interpreted in terms of a single non-relativistic effective theory (NREFT) operator, for instance liquid argon detector data is historically interpreted only in terms of spin-independent dark matter interactions due to the zero nuclear spin of argon. However, in the NREFT framework multiple operators contribute. While the contribution of the canonical SD operator O4 vanishes for argon, additional operators involving the dark matter spin remain non-zero. For sufficiently large target masses, the sum of these surviving contributions can be large enough to produce observable nuclear recoil signals.

We perform a scan over the NREFT parameter space, considering all isospin-conserving couplings of dark matter to protons and neutrons in liquid argon and liquid xenon. We then produce sensitivity projections for DarkSide-20k and LZ and show maximal enhancement and suppression arising from the additional NREFT operator contributions. The results demonstrate that, contrary to expectations, large liquid argon detectors such as DarkSide-20k can indeed probe SD dark matter models, highlighting the importance of operator-level analyses in future direct detection searches.

Speaker: Saule Piguleviciute (University of Manchester)

49 Neutrino-Less Double Beta Decay Searches with the LUX-ZEPLIN Experiment

The LUX-ZEPLIN experiment is a low-background 7-tonne dual-phase xenon time projection chamber based at Sanford Underground Research Facility in South Dakota, USA. While the primary physics motivation is the search for WIMP dark matter interactions, investigations of other rare physics processes such as neutrinoless double beta decay are also being pursued.

If observed, neutrinoless double beta decay would prove that the neutrino is a Majorana particle and possibly explain the matter-antimatter imbalance in the universe. This poster will introduce the LUX-ZEPLIN experiment and the status of the searches for this rare process within the detector

Speaker: Robyn Evren (university of sheffield)

50 Production Modelling of the ATLAS ITk Strip Detector Using the ITk Project Production Simulation

The High-Luminosity LHC upgrade of the ATLAS detector requires the large-scale, distributed production of the Inner Tracker (ITk), posing significant challenges in scheduling, logistics, yield management, and risk mitigation. To support this effort, the ITk Project Production Simulation (IPPS) has been developed as a flexible, process-based discrete-event simulation framework that models the end-to-end production flow of ITk components.

This contribution focuses on recent work within the IPPS framework related to the Strip detector production. The simulation uses human-readable configuration files to describe detector components, production activities, sites, transport links, and expected yields, enabling rapid scenario testing and transparent communication with subsystem experts. The model produces detailed production reports, process flow diagrams, and time-evolution visualisations that can be used for monitoring progress and identifying potential bottlenecks.

Current developments include validation of Strip production workflows, refinement of activity definitions and rates, and exploration of alternative production scenarios to assess sensitivity to delays and yield variations. These studies aim to improve the realism of the production model and enhance its usefulness as a planning and decision-support tool for the ITk collaboration.

This poster presents an overview of the IPPS framework and its application to the current status of ITk production, with a particular focus on the Strip detector. It summarises the system design, the implemented production workflows, and recent studies used to understand production behaviour and potential bottlenecks. The poster also outlines ongoing validation efforts and future directions as the ITk project progresses towards large-scale construction.

Speaker: Fawaz Mutllaq S. Alhawiti (University of Sheffield (GB))

51 Electron and Photon Reconstruction Performance in High Pile-Up Conditions for ATLAS Run-4 Using the Topo-Clustering Algorithm

The reconstruction of electrons and photons in ATLAS, produced from proton-proton collisions at the Large Hadron Collider (LHC), is based on the performance of the Topo-Clustering algorithm developed for electron and photon reconstruction in Run-4. To extract the signal, the algorithm reconstructs three-dimensional energy deposits in the calorimeter by grouping neighbouring cells with signal significance exceeding a noise threshold that depends on the number of pile-up interactions in the event. This approach retains cells with signals near the noise level while maintaining effective noise suppression. The resulting topo-clusters provide information on the shape and location of the energy deposits. Electrons are matched to the topo-clusters from the inner detector tracks and are corrected for the energy lost as they pass through the detector. For a photon, the conversion vertex (where they convert into an electron-positron pair) is matched to the topo-clusters. As a result, the electron and photon objects are reconstructed with their energies calibrated and initial positions corrected.  This research investigates the impact of increased pile-up levels of up to 200 simultaneous interactions on the performance of the clustering algorithms, and consequently on electron and photon reconstruction performance.

Speaker: Holly Lea Rose Davies (University of Sheffield (GB))

52 Spin-Independent and Spin-Dependent Dark Matter Scattering in a Many-Body Superfluid $^3$He Target

We present a calculation from first-principles of the dark matter scattering rates in a superfluid $^3$He target, for both spin-independent and spin-dependent dark matter interactions. This study develops a complementary approach to studying the dark matter signal, accounting for the many-body physics of the target using the dynamic structure function. We find this both validates previous determinations of the QUEST-DMC experiment’s current reach, and provides the methods required to produce accurate signals for near-future experiments. Accounting for the many-body physics of $^3$He and its quantum statistics changes the kinematics of the scattering. The correction to the signal projects an improved reach to dark matter in the MeV mass region for future, lower-temperature, experiments.

Speaker: Adam Ting (Royal Holloway, University of London)

53 Semi-inclusive hadron+jet spectra in central Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV with ALICE using mixed events

The ALICE experiment at the LHC studies the quark-gluon plasma (QGP), a state of matter formed at extreme temperatures/densities with partonic degrees of freedom produced in ultra-relativistic heavy-ion collisions. Jets, generated in the initial hard scatterings, are valuable for probing QGP properties. As they traverse through the QGP medium, their energy and structure are modified by medium interactions.
This presentation shows the measurement of jets recoiling from a high-$p_T$ trigger hadron (h+jets) in central Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV. Jet measurements in heavy-ion collisions are challenging due to the large uncorrelated background, particularly at low transverse momentum ($p_T$). To address this, a novel mixed-event technique is applied, where artificial events with uncorrelated tracks are constructed from real events. Jet reconstruction is performed using the anti-$k_T$ algorithm with varying jet radii and a trigger of $20\,\text{GeV/c}<p_T^{trig}<50\,\text{GeV/c}$. For both real and mixed events, the same analysis is performed, and the jet $p_T$ distribution obtained from the mixed events is used to correct the background yield in real event jet spectra. Finally, an unfolding procedure corrects detector and background effects. This work presents first results of hadron-triggered recoil-jet transverse momentum spectra using the mixed-event technique in ALICE.

Speaker: Nicola Wilson (University of Liverpool, GSI Darmstadt)

54 Ultra-Trace Radioassay of U-238 and Th-232 using ICP-MS at Boulby Underground Laboratory

The Boulby Underground Laboratory provides a world class material screening suite for the radioassay of materials for rare-event particle research. This poster will present the Inductively Coupled Plasma Mass Spectrometer which is one of four instruments used at Boulby for the quantification of long-lived naturally occurring radionuclides Uranium-238 and Thorium-232 to high sensitivities. Using ion counting, the concentration of U-238 and Th-232 can be measured to provide a snapshot of a materials radio-purity. This is critical for next-generation rare-event experiments in dark matter and neutrinoless double-beta decay, helping to ensure that their background goals can be met.

In our purpose built ISO-6 cleanroom, we assay materials for collaborations such as XLZD and LEGEND, varying materials from metals to polymers which all require different digestion processes and careful ultra-clean preparation.

At Boulby Underground Laboratory, we aim to push our standard detection limits towards a radiopurity of 0.01 ppt (100ppq), and to be able to measure ultra-trace sensitivities of 10 parts-per-quadrillion (ppq).

Speaker: Ms Kayleigh Johnson (STFC - Boulby Underground Laboratory)

55 DarkSide-20k Low-Mass Sensitivity and Implications for 5σ Discovery Prospects of Future Detectors

DarkSide-20k is a direct dark-matter detection experiment which is under construction underground at LNGS. It deploys a 50 tonne dual-phase liquid-argon TPC designed for nearly instrumental background-free operation. DarkSide-20k is projected to probe spin-independent dark matter-nucleon scattering down to 7.4 x 10-48 cm2 for a 1 TeV/c2 dark matter candidate, approaching the neutrino floor. This talk focuses on the low-mass regime, where sensitivity reach is governed by detector thresholds and by the high-velocity tail of the local dark-matter phase-space distribution. Within an ionisation-only (S2-only) analysis framework, we quantify the impact of an LMC (Large Magellanic Cloud)-perturbed halo model on DarkSide-20k sensitivity, demonstrating that changes to the high-speed tail can affect projections in threshold-limited regions. Nuclear-recoil induced atomic ionisation (the Migdal effect) is incorporated as an additional electronic channel, to extend sensitivity below the conventional nuclear-recoil threshold and into the sub-GeV mass range.
Given the resulting enhanced sensitivity, an extended DarkSide-20k null result would imply exceptionally strong exclusions. We therefore perform a complementary, decision-relevant study: conditioning on a DarkSide-20k null, we assess the probability that next-generation detectors beyond achieve a 5σ discovery. We construct a likelihood-based inference that maps DarkSide-20k outcomes to a posterior over particle-physics parameters, and propagate this posterior through forward models of future experiments to evaluate their conditional discovery probabilities. This provides a quantitative metric for whether additional detector generations are expected to retain meaningful discovery potential once DarkSide-20k constraints are taken into account.

Speaker: Haoxiang Zhan

56 Commissioning of the CMS Phase-2 Tracker Cosmic Test Stand

The High-Luminosity LHC (HL-LHC) will operate with up to 200 simultaneous proton–proton interactions per bunch crossing, requiring upgraded detector readout, triggering, and data acquisition systems. The Phase-2 CMS Outer Tracker introduces new detector modules and a trigger architecture designed to contribute to online trigger decisions within 12.5 $\mu$s. Demonstrating the performance and operational behaviour of this system prior to HL-LHC data taking is an important step toward operational readiness.

A CMS Tracker Phase-2 Cosmic Rack setup has been assembled, consisting of a vertical array of Outer Tracker ladders, each instrumented with twelve Outer Tracker modules. The system is integrated using a readout and processing architecture based on ATCA electronics and prerequisite firmware and software. The rack is operated with cosmic-ray muons, with the ability for self-triggering in addition to the provision of an independent trigger based on scintillator tiles instrumented with photomultiplier tubes.

The primary goals of this system are to exercise the integration of a full trigger and DAQ chain and to develop and validate commissioning procedures for CMS operation at the HL-LHC. The setup also provides a platform for detector backend system development, studying detector synchronisation, online control and offline reconstruction. The status and performance of these components within the integrated system will be presented.

Speaker: Andrew Mastronikolis (Imperial College (GB))

57 MicroBooNE NuMI Muon Neutrino and Muon Antineutrino Charged-Current Separation Using BDT

Many current forefront precision neutrino experiments are studying neutrinos and their properties, including the MicroBooNE experiment. The MicroBooNE detector employs a liquid argon time projection chamber (LArTPC), a detector technology at the forefront of the field due to its excellent capabilities in tracking, calorimetry, and particle identification. However, like most LArTPCs, the MicroBooNE detector lacks a magnetic field and therefore a straightforward method to distinguish charged particles from their antiparticles. Measurements of muon antineutrino charged-current ($\bar{\nu}_\mu \text{CC}$) interactions are important to CP-violation searches as the observation of CP violation relies on comparisons between neutrino and antineutrino oscillation probabilities. Furthermore, measuring the $\bar{\nu}_\mu \text{CC}$ cross section at MicroBooNE can aid the interaction modeling in such CP violation searches. This analysis provides a method to isolate the $\bar{\nu}_\mu \text{CC}$ and $\nu_\mu \text{CC}$ distribution despite the absence of a magnetic field by employing machine-learning techniques, specifically boosted decision trees, to separate $\nu_\mu \text{CC}$ and $\bar{\nu}_\mu \text{CC}$ interaction events using kinematic differences between them. Once the separation is achieved, this approach will enable the extraction of the individual total $\nu_\mu$ and $\bar{\nu}_\mu$ CC cross sections on argon. This will allow us to measure the $\bar{\nu}_\mu \text{CC}$ total cross section on argon in MicroBooNE. This poster presents the current status of the simulation studies performed using MicroBooNE NuMI Run 3 reversed horn current samples and outlines progress toward the extraction of the individual total cross sections.

Speaker: William Wang (The University of Edinburgh)

58 Germanium Detectors in the Boulby Underground Screening Facility

Boulby Underground screening facility is our work class assay suite. This poster will contain a description of the different Ultra Low Background Germanium detectors at Boulby Underground laboratory, how they work and their properties. It will also explain the contributions our Germanium detectors make to world class science and the different projects we collaborate with on a global scale. Our detectors include BeGe, Coax, Well detectors, and our twin detector setup

Speaker: Beth Green (Boulby Underground Laboratory)

59 CaloTrilogy: One Step, End-to-End Shower Generation for Calorimeter

High precision calorimeter simulation is essential for particle reconstruction, and precision measurements at the LHC and its High-Luminosity LHC upgrade. In precision channels such as H→γγ, accurate photon shower modeling directly impacts the diphoton mass resolution and signal sensitivity. Achieving the required precision demands very large Monte Carlo samples to constraint systematic uncertainties and backgrounds. As detector granularity and event complexity increase, full simulation with Geant4 becomes a major computational bottleneck, limiting the Monte Carlo statistics required for precision Standard Model studies and rare process searches.
We present a fast simulation framework designed to preserve key physics features of calorimeter showers with accurate energy response, realistic longitudinal and transverse development, and inter-layer correlations while dramatically reducing inference cost. The method combines: (i) an average velocity field integrator enabling sampling in one or a few evaluations; (ii) a data-driven generative prior constructed in shower space; and (iii) physics-guided loss terms that impose inductive biases on observables such as energy conservation and shower shape moments. These constraints act only during training, preserving strictly end-to-end generation at inference.
With one or a few evaluations, the model achieves shower quality competitive with state-of-the-art flow and diffusion approaches on public high granularity calorimeter datasets, providing a computationally efficient solution for large scale collider simulation workflows.

Speaker: Cheng Jiang (University of Edinburgh)

60 The FastRICH ASIC for a time resolved LHCb RICH

Speaker: George Ramsey (The University of Edinburgh (GB))

61 Underwater Characterisation of a BUTTON Optical Module

The Boulby Underground Technology Testbed for Observing Neutrinos (BUTTON-30) is a technology demonstrator installed in the Boulby Underground Laboratory (BUL) in the north-east of England. Situated at a depth of 1070 m in a polyhalite mine, BUL provides an ideal low-background environment for studying neutrinos and searching for dark matter. BUTTON-30 will study the performance of novel hybrid fill media, such as Water-based Liquid Scintillator (WbLS) and gadolinium (Gd)-loaded media. The use of these novel media has the potential to be transformative for neutrino detection. The optical detector system consists of ninety-six 10-inch Hamamatsu R7081-100 photomultiplier tubes (PMTs) with low-radioactivity glass. To allow operation in WbLs and other novel fill media, the PMTs are encapsulated in custom-built watertight acrylic housings. One of the modules is being tested underwater at the surface level within a mini-tank setup in Edinburgh.

Here, we report the design and assembly of the optical modules, leading up to their installation at Boulby, and the characterisation of one of the modules at the mini-tank setup in Edinburgh.

Speaker: Deb Sankar Bhattacharya (The University of Edinburgh (GB))

Thursday 9 April

Plenary: Thursday morning plenary

62 Precision measurements

Speaker: Rebecca Chislett

63 Science in Society: Prizewinner's talk

Speaker: Gediminas Sarpis (University of Edinburgh)

64 Particle Physics Action Group

10:30 Morning coffee

Parallel Talks: Thursday 1 - detectors

65 The FastRICH ASIC for a time resolved LHCb RICH

The FastRICH is a novel ASIC central to the implementation of a time resolved readout chain for the two ring-imaging Cherenkov (RICH) detectors in LHCb. The upgraded electronics will be installed during Long Shutdown Three (LS3) to retain RICH's excellent particle identification (PID) performance after transition to the high multiplicity environment provided by the High Luminosity LHC (HL-LHC). This contribution will present preliminary results from the FastRICH characterisation with radiation tolerance measurements, and verification of the FastRICH while coupled to the MaPMTs currently installed in RICH through lab and beam test measurements. Upcoming beam tests in 2026 will aim to instrument a full column before installation in the RICH detectors, as well as integrate the readout with the candidate Upgrade II (LS4) photodetector technologies: micro channel plate photomutipliers (MCP-PMT) and cryogenic silicon photomultiplier (SiPM) detectors.

Speaker: George Ramsey (The University of Edinburgh (GB))

66 Pulse Shape Analysis for Low Radioactivity Material Screeening

Detection for extremely rare events such as 0nbb requires great background modelling. In this research, I work with Boulby Underground Laboratory and apply pulse shape analysis methods developed by LEGEND experiment to improve their material screening efficiency.

Speaker: Difei Xu (UCL)

67 The LHCb Mighty Tracker pixel sensor characterisation and multi-module serial powering prototyping

As the LHCb experiment transitions to the conditions imposed by the High-Luminosity LHC, the performance requirements for it's detectors will increase significantly. To meet these demands, all detectors in LHCb will undergo an upgrade during long shutdown 4 in 2035, collectively called Upgrade II. One of the most significant design changes will be applied to the SciFi tracking detector which will be upgraded to the Mighty Tracker, consisting of an outer region instrumented with the existing SciFi scintillating fibres, and an inner region instrumented with pixelated silicon tracking detectors. This contribution will present the lab characterisation of the LF-MightyPix, a prototype MightyPix High-Voltage CMOS (HV-CMOS) silicon pixel sensor. The final MightyPix design is a candidate for installation in MightyTracker. Also presented are results from a HV-CMOS serial powering prototype, developing a feature vital for the final detector.

Speaker: Daniel Foulds-Holt (University of Edinburgh (GB))

68 Preparing for DarkSide-20k veto photodetector installation

DarkSide-20k is a direct dark matter detection experiment employing a dual-phase liquid argon time projection chamber (TPC) to search for rare dark matter interactions. DarkSide-20k is instrumented with silicon photomultiplier (SiPM) array photon detectors, termed Photo-Detector Units (PDUs). This talk focuses on installation metrology and QA/QC, inheriting from methods developed during the neutron veto PDU production.

With veto PDU production complete, focus has shifted to veto PDU transport to, and installation at, LNGS in Italy. Installation on the optical planes viewing the TPC requires custom handling equipment and careful procedures to avoid mechanical damage. For this reason, comprehensive pre- and post-installation testing is essential to evaluate the PDU integrity throughout.

This talk presents the data used to assess veto PDU integrity, preliminary results from reception testing of veto PDUs upon arrival at LNGS, and the planned post-installation testing using a custom data acquisition system.

Speaker: Isobel Sargeant (Science and Technology Facilities Council)

69 RadPix: A High-Voltage CMOS Sensor for the LHCb Upgrade

RadPix is a High-Voltage CMOS (HV-CMOS) pixel sensor developed collaboratively by the Large Hadron Collider Beauty (LHCb) experiment, and the DRD3 collaboration for Solid State Detector R&D. It represents the first monolithic pixel sensor capable of operating in the high radiation environment of the High Luminosity LHC. Building on the RD50-MPW chip series (led by Liverpool/UK) — established to push the limits of HV-CMOS technology — RadPix uniquely brings DRD3 developments to the application level. It is designed to address the requirements of both the LHCb Mighty-Tracker and Upstream trackers within a single sensor die, offering a strategic solution for the current financial climate.

RadPix1 is a small sensor chip prototype currently in development to meet LHCb requirements of good timing and spatial resolution, high data rate, and low power. Fabrication submission is planned for early 2026 as part of a DRD3-organized engineering run with LFoundry. As a UK-led initiative, RadPix is a leading candidate for deployment in LHCb Upgrade II.

This paper outlines the features of RadPix1, with particular emphasis on radiation hardness and serial powering capabilities—essential for physics performance. The digital design has been specifically tailored to interface with the experiment's electronics framework. An integrated, system-level approach is pursued for the end-to-end chain from sensor to backend DAQ. Extensive simulation and verification tools have been employed to mitigate risks prior to fabrication. Furthermore, the paper presents the roadmap for RadPix2, which builds from the testing outcomes of its predecessor. The active area will be scaled to full-size chip dimensions, and complete the feature set for full LHCb coverage.

Speaker: Karol Hennessy (University of Liverpool (GB))

Parallel Talks: Thursday 2 - precision measurements

70 Precision Measurement of the Two-Pion Contribution to the Hadronic Vacuum Polarization with KLOE

The KLOE detector at the DA$\Phi$NE electron–positron collider has delivered some of the most precise measurements of the two-pion contribution to the hadronic vacuum polarization (HVP) term in the Standard Model prediction of the muon anomalous magnetic moment, $a_{\mu}$. A precise determination of the HVP term is essential to clarify the longstanding tension between the theoretical prediction and experimental measurements.
A key component of the ongoing KLOE analysis (KLOE-NXT) is a stringent QED validation of the $e^+e^- \to \mu^+ \mu^- \gamma$ process, which provides an important cross-check. Reaching the required level of precision demands an improved determination of the integrated luminosity and a careful reassessment of the systematic uncertainties.
This talk will present the ongoing KLOE-NXT analysis, based on a previously unexplored dataset with significantly higher statistics than those used in earlier KLOE measurements, and will report preliminary results from the dedicated luminosity study.

Speaker: Niels Vestergaard (University of Liverpool)

71 Differential cross-section measurement of $t\bar{t}t\bar{t}$ production with ATLAS using 2022-2024 data

The production of four top quarks ($t\bar{t}t\bar{t}$) was observed by the ATLAS and CMS experiments in 2023 and the cross section was measured to be slightly higher than the prediction from the Standard Model. This is an important process as it has sesntivity to the top quark yukawa coupling and new physics signals. Since the start of the LHC Run-3 in 2022 and until the end of 2024, the ATLAS detector has recorded $165fb^{-1}$ of data at an energy of 13.6TeV. The increased statistics and the higher centre-of-mass energy compared to the dataset used for the observation of the $t\bar{t}t\bar{t}$ process opens the possibility for differential measurements of this rare process. The talk will present work towards the first ATLAS differential measurement of $t\bar{t}t\bar{t}$ production, including reconstruction of the kinematics of the $t\bar{t}t\bar{t}$ system.

Speaker: Fani Nathalie E. Henry (University of Glasgow (GB))

72 The MUonE Experiment and First Results from the 2025 Test run

The MUonE experiment at CERN aims to determine the leading-order hadronic vacuum polarization contribution to the Standard Model prediction of the muon anomalous magnetic moment $a_{µ}$, which plays a central role in the present differences among theoretical determinations and in the comparison with experimental measurements. MUonE follows an innovative approach based on a precise measurement of the shape of the differential cross section for elastic scattering of 160 GeV muons on atomic electrons in a low-Z target, providing direct sensitivity to the hadronic contribution to the running of the electromagnetic coupling $\alpha$ in the space-like region. A test run was carried out in 2025 with a reduced detector configuration. An overview of the experiment will be given, and first preliminary results from the 2025 data taking will be presented.

Speaker: Clement Loic Devanne (University of Liverpool (GB))

73 Analysis of the CP Structure of the Tau Lepton Yukawa Coupling at the CMS Experiment

Despite the many successes of the Standard Model (SM), it is known to be incomplete, for instance, it does not provide an explanation for the observed baryon asymmetry of the universe. One of the necessary conditions to generate this asymmetry is charge-parity (CP) violation on a scale many orders of magnitude larger than SM predictions. An intriguing possibility is new sources of CP violation in the Higgs sector, for example in the Yukawa couplings to fermions. I will present the latest measurement of the CP structure of the Higgs to tau lepton coupling by CMS, using proton-proton collision data collected at a centre of mass energy of 13.6 TeV, corresponding to an integrated luminosity of 62.4/fb. Angular correlations between the decay products of tau leptons produced in Higgs to TauTau decays are exploited to constrain the effective CP mixing angle alpha. The sensitivity achieved is comparable to the CMS result at 13 TeV, despite using less than half the amount of data. The result is then combined with the previous measurement, and represents the most sensitive measurement to date of the CP properties of the Higgs boson coupling to tau leptons.

Speaker: Lucas Russell (Imperial College (GB))

74 Towards Precise Determination of the CKM angle $\gamma$

Precision measurements of the CKM angle $\gamma$ provide a theoretically clean test of the unitarity of the CKM matrix and are therefore a powerful probe for physics beyond the Standard Model. Despite significant experimental progress, $\gamma$ remains one of the least precisely determined CKM parameters, with current measurements dominated by statistical uncertainties. This makes $\gamma$ measurements particularly sensitive to both increased data samples and improvements in analysis techniques.

In this talk, I will present the first measurement of $\gamma$ and related CP observables using $B^{\pm}\!\to D(\to K^0_S h^{\prime+} h^{\prime-})\,h^{\pm}$ decays with data collected during Run~3 of the LHC using the upgraded LHCb detector. The higher instantaneous luminosity and the software-only trigger of the LHCb Upgrade significantly enhance the efficiency for such hadronic final states, enabling this single year of data-taking alone to provide one of the dominant inputs to the global $\gamma$ combination.

Looking to future measurements, I will present recent developments in the optimisation of Dalitz-plot binning schemes used in model-independent $\gamma$ measurements. A revised optimisation metric, directly related to the statistical precision on $\gamma$, is introduced, together with improvements that account for realistic experimental effects such as backgrounds and binning-dependent systematic uncertainties. Sensitivity studies demonstrate an improvement of approximately $5\%$ in the expected precision on $\gamma$ in $B^{\pm}\!\to D(\rightarrow K_S^0\pi^+\pi^-)K^{\pm}$ decays compared to the previously used binning scheme.

In addition, the optimisation framework is extended to measurements of CP violation in charm mixing using $D\to K^0_S\pi^+\pi^-$ decays, where a dedicated optimal binning scheme is derived for the first time. Sensitivity studies show a substantial improvement of approximately $25\%$ relative to the equal-phase binning currently in use.

Speaker: Marcelo Bovill (University of Oxford)

Parallel Talks: Thursday 3 - neutrinos

75 The helium recycling system for SuperNEMO

The SuperNEMO Demonstrator is a double-beta-decay detector, currently taking physics data at LSM, France. It has a unique ability to measure the full topology of decay events, thanks to a tracking detector filled with a carefully-controlled gas mixture consisting of 95$\%$ ultra-pure helium, 4$\%$ ethanol, and 1$\%$ argon. To achieve SuperNEMO's ambitious radiopurity target of 0.15mBq/m3, fresh gas is constantly flowed through a bespoke radon trap, and subsequently through the SuperNEMO detector.\
In response to the recent helium shortage, decision was made to recycle helium from SuperNEMO's exhaust. This is particularly challenging as due to the design of the radon trap, all traces of ethanol must be removed from the SuperNEMO exhaust before it can be recirculated. In this talk, I will presents our innovative helium-recycling system, which uses a novel combination of cryogenic and adsorption techniques to reduce ethanol levels to below 1ppm. It explains how, through a bespoke control and monitoring system, it runs semiautomatically, maintaining our controlled gas composition, and dramatically reducing SuperNEMO's helium consumption.

Speaker: Penghui Li (university of edinburgh)

76 Detector and background modelling for neutrinoless double beta decay searches in LEGEND

The discovery of neutrinoless double beta decay ($0\nu\beta\beta$) would have a profound impact on particle physics. This would show Lepton number is not conserved and neutrinos are Majorana particles. Unfortunately for us, the expected rate of this decay is vanishingly small. This creates an extremely large experimental challenge, the largest of which is to control the rate of background events to just a few per 10 years of data taking. The LEGEND collaboration is searching for $0\nu\beta\beta$ with HPGe detectors, enriched in $^{76}$Ge, operated in LAr using a phased approach. The first phase LEGEND-200 is currently taking data in LNGS, Italy. In this talk we will review the status of LEGEND-200 and the first $0\nu\beta\beta$ search. We will particularly focus on recent efforts to model the experimental data and background sources, both before and after our analysis cuts.

Speaker: Toby Dixon (UCL)

77 Efficient sampling for the precision era of neutrino experiments

The upcoming next-generation neutrino experiments, notably the Deep Underground Neutrino Experiment (DUNE), and the joint analysis of existing experiments, such as that of T2K and NOvA, bring long-baseline neutrino experiments into the precision era. Performing $5\sigma$ measurements of neutrino properties using Bayesian analysis typically requires hundreds of billions of Markov-Chain Monte Carlo (MCMC) steps, straining existing computational resources. Efficient sampling techniques, such as adaptive MCMC, can meaningfully reduce these requirements and hence enable high-significance measurements to be made within reasonable resource constraints. I present the application of adaptive MCMC to DUNE and report a reduction in the number of MCMC steps by a factor of 50, cutting person-power and computation time from months to days.

Speaker: Hank Hua (Imperial College (GB))

78 Latest collider neutrino measurements with the FASER detector

FASER is a compact, purpose-built experiment at the LHC, investigating long-lived BSM particles and collider neutrinos, located approximately 480m from the ATLAS interaction point. As the first experiment to directly measure collider neutrinos, it continues to probe the previously unexplored energy gap between neutrinos from man-made sources and astrophysical processes. Its latest results use only the electronic components of the detector and a dataset of 177fb-1 collected during the first 3 years of LHC Run 3, to further understand the behaviour of neutrinos at TeV energies. This talk will present the latest studies from FASER on measurements of high-energy neutrino cross sections, focusing on the electron neutrinos, and further interpretation of the results in the beyond SM frameworks.

Speaker: Sinead Eley (University of Liverpool (GB))

79 Maximising MicroBooNE's sensitivity to Heavy Neutral Leptons produced in the NuMI beam

The MicroBooNE experiment is an 85-tonne liquid argon time-projection chamber (LArTPC) that operated at Fermilab from 2015 to 2021, exposed to both the Booster Neutrino Beamline (BNB) and the Main Injector Neutrino Beamline (NuMI). Uniquely positioned, MicroBooNE sits off-axis to the NuMI beam and upstream of the NuMI hadron absorber, providing strong sensitivity to heavy, long-lived beyond-the-Standard-Model particles produced in meson decays. I will present our latest search for Heavy Neutral Leptons, and will show how new analysis techniques including high-precision timing and improved event reconstruction are allowing us to maximise the sensitivities from our full dataset.

Speaker: Magnus Handley (University of Cambridge)

Parallel Talks: Thursday 4 - detectors

80 Single-Electron Gas Characterisation for Dark Matter Searches using Spherical Proportional Counters

The spherical proportional counter, a novel gaseous detector, has been employed in direct, low-mass particle dark matter (DM) searches thanks to its radiopure material construction, single-electron energy threshold, and flexibility to operate with a range of gases. Gases containing low-mass nuclei such as hydrogen, carbon, and neon are used in the detector to provide good kinematic matching to sub-GeV particle DM. The design of a proposed future experiment, DarkSPHERE, which could be operated in the Boulby Underground Laboratory, is well underway. Gas mixtures containing combinations of He, Ne, CH4, and i-C4H10, intended for use in DarkSPHERE, require characterisation in the detector, for example, measuring electron drift times and gas gains. Measurements of these properties using a UV laser calibration system will be presented, along with comparison to Monte Carlo simulations.

Speaker: Peter Walters

81 Novel Mass Measurement Methods using the LHCb RICH Detectors

Two Ring Imaging Cherenkov (RICH) detectors enable LHCb to identify charged hadrons between 2-100 GeV with unprecedented Cherenkov angle resolution. While primarily designed for particle identification, novel developments enable direct mass inference using reconstructed Cherenkov photons, paving the way for new precision mass measurements of charged hadrons.
This work presents the practical implementation, developmental steps taken and challenges encountered so far. Highlighted are two complementary approaches. One performs a mass fit by minimising a global likelihood constructed from reconstructed Cherenkov information. The other directly reconstructs a mass value at the per-photon and per-track level. The structure of the global fit, treatment of angular offsets, and construction of fit inputs are described.
A feasibility study probing the precision of such measurements alongside toy studies which model the Cherenkov response within the RICH are presented. Sample selection methods are also presented, which kinematically isolate kaons, pions and protons independently of any particle identification capability. Monte Carlo samples generated using these selections are used to evaluate the performance of each methodology and are included in the study.

Speaker: Michael James Kane (University of Edinburgh (GB))

82 Cryogenic characterization of the DarkSide-20k veto photo-detector units

DarkSide-20k is a direct detection dark matter experiment currently under construction at LNGS in Italy. The central detector is a time projection chamber (TPC) filled with 50 tonnes of liquid low-radioactivity underground argon (UAr). The TPC is surrounded by an additional 32 tonnes of UAr which acts as a neutron veto. The neutron veto plays a vital part in ensuring that DarkSide-20k achieves its goal of being instrumental background free in 200 tonne-years of exposure, by tagging neutrons that interact only once within the central detector. The neutron veto is instrumented with 120 veto photo-detector units (vPDUs) which are custom built 20cm x 20cm arrays containing 384 SiPMs split between 16 tiles that are assembled in the UK and tested in both the UK and Poland. DarkSide-20k is operated at 87K, thus during the production of the vPDUs it was essential to test them at cryogenic temperature.

This talk will focus on the characterization of the DarkSide-20k vPDUs in liquid nitrogen to ensure that they passed photon detection QA/QC standards before they were shipped to LNGS for installation. The three cryogenic test facilities in Edinburgh, Liverpool and AstroCeNT (Poland) conduct these tests for each vPDU and compare to the required standard for the DarkSide-20k neutron veto.

Speaker: Emma Ellingwood (University of Edinburgh)

83 Ultra-pure copper electroforming at Boulby deep underground laboratory

Rare-event search experiments, for example those looking for dark matter and neutrinoless double beta decay, require increasingly sensitive detectors. A critical aspect of this is the reduction of backgrounds from detector materials, especially those in contact with the sensitive volume. High-grade copper is an attractive construction choice, due to its commercial availability and lack of long-lived radioisotopes. Despite this, copper can still represent a dominant background, with impurities from the ore, implanted during manufacture or from cosmogenic activation. Underground additive-free electroforming provides a method to produce ultra-pure copper parts with orders of magnitude reduction in background. This contribution will describe a copper electrodeposition facility constructed at Boulby, the UK’s deep underground laboratory, and show first results of electroformed copper which is critical for several future experiments. One such experiment DarkSPHERE, a large diameter spherical proportional counter, will be presented along with the near-term plan to electroform a 30cm spherical proportional counter as the first step towards its construction.

Speaker: Giovanni Rogers (University of Birmingham (UK), STFC - Boulby Underground Laboratory)

84 Tyvek reflectance study for the outer detector of the Hyper-Kamiokande experiment.

Hyper-Kamiokande is a state-of-the-art water Cherenkov neutrino detector, currently under construction in Japan. In its capacity as the far detector within a long baseline program, Hyper-K aims to make high precision measurements of key neutrino oscillation parameters and has the ability to observe exotic phenomena such as proton decay and other BSM physics. One of the main backgrounds to such studies come from cosmic ray muons. To veto these muons, an outer detector region is instrumented with 3600 PMTs with wavelength shifters and the whole region is outfitted with a highly reflective material known as Tyvek to maximise light collection. This talk presents the measurement programme developed to measure the reflectivity of various Tyvek material samples in both air and water to inform the selection of final products for Hyper-K OD.

Speaker: Sania Lewis (King's College London)

Parallel Talks: Thursday 5 - astroparticle

85 High Frequency Axion Searches at the University of Manchester

Axions are now one of the best motivated candidates for physics beyond the standard model. Cavity haloscopes search for these particles by converting them into microwaves in strong laboratory magnetic fields. I will give an overview of cavity searches for the QCD axion taking place at the University of Manchester in 26 - 40 GHz. I will also describe recently demonstrated quantum-noise limited amplifiers and outline our future plans for upscaling the detector to boost sensitivity.

Speaker: Jamie McDonald (University of Manchester)

86 When Supernova Neutrinos met Liquid Argon: using muons decaying-at-rest to look for MeV-scale electron neutrinos in SBND

In just under a ten-second period, a supernova explosion ejects debris and photons, while up to 99% of its entire explosive energy is carried away by neutrinos, the smallest known weakly-interacting fundamental particles. The explosion emits all neutrino flavours at tens-of-MeV energies, but the electron neutrino charged-current interaction (CCI) is the only way to infer the neutrino type and allows for direct probing of the supernova exploding mechanism and the intrinsic properties of neutrinos. The cross section of this interaction is small, but its faint visible signal in liquid argon (LAr) can be taken advantage of in experiments that utilise LAr as their detector medium. Theoretical predictions of CCI vary greatly depending on the model and there is no experimental data at present, so I will be presenting how the Short Baseline Near Detector (SBND), based at the Fermilab National Laboratory near Chicago in the U.S., is aiming to be the first to perform this measurement. After just one year of operation, this experiment currently holds the record of the world’s largest dataset of neutrino-argon interactions, achieved by bombarding SBND’s active volume with neutrinos from the Booster Neutrino Beam (BNB). A subset of these neutrinos are produced by muons Decaying At Rest (DAR) within the beam pipe. This enormous flux of electron neutrinos, with tens-of-MeV energies, mimic those from a supernova explosion. To perform this measurement, beam flux and systematic uncertainty simulation, system trigger and reconstruction algorithms need to be re-examined and adapted to this lower energy range. I will summarise how SBND is addressing these challenges towards obtaining the first measurement of the charged-current electron neutrino cross section on argon at energies below 50 MeV, establishing the first experimental constraints of supernova neutrino detection in LAr.

Speaker: Lucy Kotsiopoulou (University of Edinburgh)

87 Are dark showers observables visible for us?

In the study of dark matter detection at colliders, novel candidates have emerged to bridge between experimental data and theoretical models. Dark Showers (DS) are being studied as an extension of the Standard Model (SM), containing both invisible and visible particles that allow us to predict scenarios involving collider observables. Among these, Semi-Visible Jets (SVJs), represent a novel promising new signature, particularly those mediated by a massive $Z^{\prime}$ boson that enables the production of heavy dark hadrons. In such a scenario, jets enclose visible SM particles and invisible dark matter components, having more Missing Transverse Energy $E_{T}^{miss}$ (MET).
The complexity is further heightened since the poorly constrained nature of the dark sector; factors such as the dark confinement scale, dark meson masses and the fraction of the invisible DM hadrons. Our study considers different topologies, including a resonant heavy gauge boson $Z^\prime$, resulting in different approaches to study the kinematic features of the produced SVJs compared to those of the QCD ones, we are looking at correlations between the MET respect to their jet axes, alongside the EMD, Energy Correlation Functions and the Lund Jet Plane with the purpose of classifying SVJs from QCD jets and characterising them by finding a right description for a Machine Learning (ML) model to work with. For it, we are looking at a transformer-based NN to not only classify between SVJs and QCD jets but also, create pseudo-labels to cluster the data between invisible and/or visible particles.

Speaker: Mr Miguel Angel Avendano Bernal (University of Southampton)

88 How Sensitive is Cosmic Inflation to Quantum Corrections?

A lot. In this talk, I will present a non-perturbative framework that allows to track the dynamics of slow-roll inflation while consistently incorporating quantum corrections, based on an alternative functional renormalisation group (RG) approach. I will guide you through the derivation of a set of coupled Friedmann-RG flow equations governing the joint evolution of spacetime, the inflaton field, and its effective potential. Applying this formalism to α-attractor E-models, I will show that the RG flow induces a dynamical destabilisation of the inflationary trajectory, leading to a premature termination of slow roll. Remarkably, the resulting predictions bring α-attractors into full agreement with the latest ACT data without introducing new physics beyond a consistent quantum-corrected treatment of the inflaton dynamics.

Speaker: Lucien Heurtier (King's College London)

89 The Anatomy of a P-ONE Optical Module

The Pacific Ocean Neutrino Experiment (P-ONE) is a planned cubic-kilometre-scale Cherenkov neutrino telescope to be deployed off the west coast of Canada, designed to detect high-energy neutrinos, from TeV to PeV energy scales, from astrophysical sources. The first string will be deployed later this year, with the full detector planned to be operational within the decade. P-ONE will join a growing network of neutrino telescopes scattered across the world, pushing us into a new era of high-energy neutrino astronomy. This talk presents the design and novel hardware of the P-ONE optical modules, with context on the broader physics case and deployment status. The ocean setting of the experiment necessitates precise calibration systems, including acoustic positioning system and optical calibration units, which these optical modules allow us to do, along with detection of Cherenkov light.

Speaker: Alexia Alexander Wight (UCL)

12:30 Lunch

Plenary: Thursday afternoon plenary

90 LHCb

Speaker: Harry Victor Cliff (University of Cambridge (GB))

91 Early-career researchers report

Speaker: Harriet Watson (The University of Edinburgh (GB))

STFC Town Meeting: Early afternoon

15:45 Coffee

STFC Town Meeting: Late afternoon

Dinner & Ceilidh

Friday 10 April

Plenary: Friday morning plenary

92 Collider physics results

Speaker: Holly Pacey (University of Oxford (GB))

93 Opening Particle Physics: Outreach & Communication, Inclusion and Participation

Speaker: Dr Kate Shaw (University of Sussex (GB))

10:30 Coffee

Parallel Talks: Friday 1 - dark matter

94 First Measurements of the Effectiveness of Radon Removal in Liquid Xenon via Charcoal Chromatography

LUX-ZEPLIN (LZ) is a dual phase xenon time projection chamber, searching for WIMP dark matter, and other rare phenomena. Decays from the $^{222}$Rn chain pose a dominant background in LZ, requiring multiple mitigation strategies targeting either $^{222}$Rn or its daughters. One method utilised by LZ is an inline radon removal system, separating radon from gaseous xenon using a charcoal chromatography column. Continued progress in the search for dark matter will require more sensitive experiments with more stringent radiogenic background controls. An alternative approach to radon removal is therefore necessary for the next-generation of experiments. This talk presents the first measurements of the effectiveness of radon removal with a charcoal chromatography column in the liquid phase, performed at SLAC, USA. We find an adsorption coefficient in liquid 3 orders of magnitude lower than in the gas phase, rendering charcoal chromatography an ineffective method for liquid-phase radon removal.

Speaker: Simran Dave

95 Using Computer Vision to Reject Instrumental Background in LUX-ZEPLIN and Multi-Vertex Inelastic Dark Matter Signal Searches

The LUX-ZEPLIN (LZ) experiment is a dual-phase xenon time projection chamber designed to search for weakly interacting massive particle (WIMP) dark matter via nuclear recoils within a 7-tonne active target. In addition to its primary WIMP search programme, LZ is sensitive to a wide range of other dark matter signatures.
In this talk, I describe a computer-vision-based technique to identify and mitigate transient, spatially localised electron emission from the electrode grids, known as “hotspots”. By treating the distribution of pulses at a given time in the detector as images, regions of anomalously high activity are identified and dynamically excluded in space and time. This approach, which is sensitive to weaker grid emission and removes less exposure than more traditional time-based exclusions, has enabled us to further cut our observed hotspot backgrounds with minimal loss of exposure.
I will also outline plans for a magnetic inelastic dark matter (MiDM) signal search in LZ. These interactions - characterised by a WIMP scattering within the target, entering an excited mass state, and then emitting a gamma-ray equal in energy to the mass splitting - lead to a distinctive, background-light, two scatter topology which we can reconstruct within LZ’s large active volume.

Speaker: Catherine Lawes (King's College London)

96 Probing low mass dark matter with superfluid helium

Dark matter direct detection experiments have historically focused on searches for GeV-TeV/c$^2$ mass WIMP dark matter, undergoing spin-independent scattering interactions with a target. However, there are well motivated models at lower masses including those with spin-dependent interactions. This parameter space remains significantly less constrained due to the challenge of achieving lower energy thresholds and the limited number of target nuclei with non-zero nuclear spin for spin-dependent interactions.

The QUEST-DMC experiment addresses these challenges using a gram scale superfluid helium-3 bolometer, with $10^{-7}$ eV superfluid gap, instrumented with nanowire resonators. Low noise quantum sensor readout enables low threshold detection, probing new parameter space. Recent work on development of this readout scheme to optimise energy threshold will be presented, along with first data and comparison to simulations.

A subsequent experimental run is now underway, reaching new lowest temperatures of 130 $\mu K$. Initial measurements and energy calibration techniques will be shown, with developments underway to establish complementary measurements of the energy scale. The dark matter search has potential to reach unprobed parameter space and further plans to extend the reach of this globally unique experiment will be discussed.

Speaker: Elizabeth Leason

97 Construction Progress of the DarkSide-20k Dark Matter Search Experiment

DarkSide-20k is a global direct dark matter detection experiment in the construction phase at LNGS (in Italy). The core of the detector is a dual-phase Time Projection Chamber (TPC) filled with 50 tonnes of low-radioactivity liquid argon. The entire TPC wall is surrounded by a pure polymethylmethacrylate (PMMA) of 15 cm, which acts as a neutron veto, immersed in a second low-radioactivity liquid argon bath enclosed in a stainless steel vessel. The entire detector is enclosed in a protoDUNE-like cryostat filled with 600 tons of atmospheric argon. DarkSide-20k is designed to deploy several major novel technologies: (i) underground argon at the >100 tonne scale (integrated over the central time projection chamber and inner veto volumes); (ii) large-area cryogenic SiPM array detectors at the scale of 26 m2; and, (iii) a TPC fully formed in acrylic. This talk presents the progress of the overall experiment construction, and its flagship dark matter search sensitivity based on radioassay of the experiment component materials.

Speaker: Daria Santone

98 Production of 26 m2 of SiPM Detectors for DarkSide-20k

Darkside-20k is a global direct dark matter detection experiment situated underground at LNGS (in Italy), designed to reach a total exposure of 200 tonne-years, nearly free from instrumental backgrounds. The core of the detector is a dual-phase Time Projection Chamber (TPC) filled with 50 tonnes of low-radioactivity liquid argon. This is surrounded by inner and outer active veto volumes. Both TPC and vetoes are instrumented with large-area light detectors utilising a custom Silicon Photo-Multiplier (SiPM) technology optimised for high optical photon detection efficiency and low noise at liquid argon temperatures.
SiPMs are arranged in Photo-Detector Units (PDUs), which is a compact design meant to minimise the material (and hence the radioactive budget) used for the active electronics, cables and connectors. Each PDU has 20$\times$20 cm$^2$ of active area, comprising 384 SiPMs. The TPC is equipped with 518 PDUs and the inner veto with another 120, for an unprecedented cryogenic SiPM area of 26 m$^2$.
The talk will focus on the production of the TPC and Veto PDUs, illustrating the assembly chain in Italy and the UK institutes, and in particular describing the completion of the Veto production in the UK. Mechanical, electrical, cleanliness and noise tests have been extensively performed at every stage of the production, in order to meet the stringent requirements for the DarkSide-20k photosensors.

Speaker: Dr Paolo Franchini (University of Oxford)

Parallel Talks: Friday 2 - Collider

99 Everything Quantum

Both the ATLAS Collaboration and the CMS Collaboration have recently observed quantum entanglement in top-quark pairs using Run 2 data; the highest energy scale at which quantum phenomena have ever been probed. I will present new measurements of quantum discord and related quantum observables in ttbar events, focusing on both the dileptonic and single-lepton decay channels. I will discuss the analysis strategy, reconstruction techniques, and the impact of Run 3 data, as well as the implications for future measurements at HL-LHC, highlighting the potential of collider experiments to probe quantum information concepts in novel and experimentally accessible ways.

Speaker: Ivo Young (University of Glasgow (GB))

100 A Search for Z' Dilepton Resonances Using the ATLAS Detector in Run 3 at the LHC

Heavy Z' gauge bosons are predicted to exist by a number of promising theories of physics beyond the Standard Model, including GUTs. Many Z' models predict decay into a pair of oppositely charged electrons or muons. These decay channels offer clear, low-background signatures with fully reconstructed final states - ideal for discovery by a general purpose collider experiment like ATLAS. A summary of the search for dilepton resonances over a Standard Model background, based on a partial ATLAS Run 3 dataset, is presented. The analysis, currently at an advanced stage, aims to improve on the mass and cross-section exclusion limits, set by ATLAS and CMS in Run 2, on a number of Z' models as well as on Randall-Sundrum gravitons, to which the search is also sensitive.

Speaker: Tom Elliot (Royal Holloway, University of London (GB))

101 Measuring the Binned CP Asymmetry in B to K mu mu

Precision measurements of rare decays of b-mesons are excellent probes for indirect new physics searches. They are greatly suppressed in the standard model and thus are highly sensitive to contributions from new physics. Many observables serve as targets for these studies, allowing for a wide range of tests of the standard model (SM). For example, charge-parity (CP) asymmetries allow to test for contributions from CP-violating new physics. In the case of the $B \rightarrow K \mu \mu$ decay, such contributions would manifest as a deviation from the SM prediction of negligible CP-violation. This talk presents an ongoing analysis of LHCb run 1, 2 and 3 data that will measure the CP-asymmetry in this decay in bins of the invariant mass of the muon pair ($q^2$). The aim is to improve upon the precision of the previous run 1 [[1]] only measurement and adapt the binning scheme to maximise the sensitivity to CP-violation.

Speaker: Juan Jose Juan Castella (University of Cambridge (GB))

102 A search for displaced tau production from long-lived particles at the ATLAS experiment

Searches for new BSM physics at the ATLAS experiment typically target particles that decay promptly, very close to the collision point. New physics has so far evaded these searches. Multiple BSM models predict new long-lived particles (LLPs) with decay lengths ranging from millimetres to kilometres. In new physics scenarios where LLPs couple preferentially to heavy particles or to leptons, tau lepton final states would offer high experimental sensitivity.

A search for displaced tau decays within the ATLAS Inner Detector is presented, using a partial ATLAS Run 2 dataset. The search targets final states with two taus, where one or both taus decay hadronically. The fully leptonic scenario is experimentally covered by other ATLAS searches. A machine learning-based identification model was developed to identify displaced tau jets, reducing the dominant background contribution from QCD-induced jets mis-reconstructed as tau jets. The analysis design is model-independent, allowing for both the placement of model-independent and model-dependent exclusion limits. Future searches are planned using the ATLAS Run 3 datasets, and Run 3-specific developments of the identification model will be presented.

Speaker: Alex Veltman (The University of Edinburgh (GB))

Parallel Talks: Friday 3 - Neutrino

103 Searches for Light Dark Matter and Evidence of Coherent Elastic Neutrino-Nucleus Scattering of Solar Neutrinos with the LUX-ZEPLIN (LZ) Experiment

The LUX-ZEPLIN (LZ) dark matter experiment is located at a depth of about 4850 feet at Sanford Underground Research Facility (South Dakota, USA). The LZ detector constitutes a dual-phase time projection chamber with a 7-tonne liquid xenon target. Weakly Interacting Massive Particles (WIMPs), well motivated dark matter candidates, are expected to produce nuclear recoils while interacting with the target medium, giving a detectable signal. Although no evidence of WIMPs has yet been found, LZ has been able to set world leading limits on the interaction cross-section of such a particle over a wide range of masses. In this talk, I will present the results of the recent LZ search for light dark matter and our 4.5𝜎 detection of solar B8 neutrinos, the first >3𝜎 detection of the neutrino fog.

Speaker: Leah Wolf

104 Simulation studies for the nuSTORM facility

nuSTORM (neutrinos from STORed Muons) is a future-generation accelerator-based neutrino facility that is currently being designed to have %-level flux uncertainty. This facility produces neutrinos from the decay of muons circulating in a storage ring. nuSTORM will be able to measure ν-nucleus cross-section with great precision for both electron and muon neutrinos. The storage ring will store muons with a momentum range of 1–6 GeV/c covering the energy range of major future experiments such as DUNE and Hyper-K. Beyond standard model sensitivity can also be expected. Additionally, nuSTORM can pioneer accelerator technologies such as being a testbed for muon colliders, magnet technologies, and beam monitoring. This talk will cover updates on the simulation of the storage ring and the studies of the emerging neutrino beams.

Speaker: WONJONG CHANG (University of Warwick/STFC RAL)

105 β Backgrounds Using the 1-Electron Channel in SuperNEMO

The SuperNEMO Demonstrator is a double-beta-decay experiment with a unique capability to reconstruct the full topology of decay events. The ability to identify and measure the energy and trajectory of individual particles enables sophisticated background rejection, as well as the ability to search for not only neutrinoless double-beta decay, but also exotic decays and nuclear effects on the standard model double-beta decay.
Ultra-low backgrounds are key when studying rare processes like double-beta decay. In particular, β-emitting contaminants in detector materials - especially the ββ-decay source - can, through secondary interactions, mimic ββ events. This is particularly problematic when studying low-energy effects on the standard-model 2νββ spectrum, where 210Bi, 234mPa, and 40K contribute to the background.

To constrain this effect, we study the 1-electron channel, to fit and quantify the level of background from these isotopes.

Speaker: Gill Turnbull (University of Edinburgh)

106 Latest developments in near detector analyses at T2K

The Tokai-to-Kamioka (T2K) experiment is a long-baseline neutrino oscillation experiment, providing world-leading measurements of oscillation parameters and CP violation using the Super-Kamiokande (SK) water cherenkov detector, 295km downstream of a neutrino beam created at the Japan Proton Accelerator Research Complex (J-PARC). These measurements benefit from neutrino cross-section and beam flux constraint provided by ND280, a near detector positioned 280m from the J-PARC beam target.

In this talk, we present the latest developments to the T2K near detector fit, based on results and studies from previous iterations of this analysis. Using newly available time-of-flight information, ND280 particle track reconstruction has been updated to include backwards-going tracks, bringing ND280 efficiencies closer to that of SK. In addition, the neutrino cross section model has been updated, allowing for additional freedom in the low energy transfer region dominated by nuclear effects.

The performance of this updated T2K near detector analysis is compared to previous iterations, showcasing a similarly effective post-fit constraint using a more robust cross section model, with potential to propagate these improvements to the T2K oscillation analysis using SK. ND280 efficiency is expected to further improve with inclusion of data and systematics from the detector upgrade.

Speaker: Dominic Langridge (Royal Holloway University of London)

Parallel Talks: Friday 4 - Detectors

107 The LHCb Mighty Tracker: Thermo-mechanical design and prototype testing.

The LHCb experiment at the Large Hadron Collider will undergo a major
high-luminosity upgrade during Long Shutdown 4, targeting instantaneous luminosities
up to 1.5×1034 cm−2 s−1, representing a tenfold increase over previous
operations. This will lead to a significant rise in recorded data, from 50 fb−1 to
300 fb−1, and poses challenges for the current tracking system due to increased
occupancy, harsh radiation, and strict material budget constraints.
To address these challenges, the downstream tracker will be replaced with the
Mighty Tracker, a hybrid detector combining monolithic High Voltage CMOS
(HV-CMOS) silicon pixel sensors in the inner region and scintillating fibres in
the outer region. The silicon pixel modules are based on HV-CMOS pixel sensor
technologies currently under development, with MightyPix as a leading candidate.
These sensors provide efficient charge collection, nanosecond-level timing
resolution (∼ 3 ns), and excellent radiation tolerance, making them suitable for
operation under the high-luminosity conditions of the LHCb Upgrade II. Thinning
the sensors to 150 μm minimises inactive volume while keeping the material
budget low. The outer scintillating fibre region preserves coverage in the peripheral
detector acceptance. The silicon sensors are mounted on a lightweight
composite support structure, ensuring both mechanical stability and efficient
thermal management under extreme hit rates (18MHz/cm2) and high radiation
fluence (∼ 6×1014 MeV neq/cm2). This contribution presents the ongoing R&D
efforts and summarises the performance results from thermo-mechanical design
and prototype testing.

Speaker: Mr Bilal Ganie (University of Manchester)

108 Testing stitched devices for the upcoming ALICE ITS3: results of babyMOSS chip characterisation at a test beam

During the LHC Long Shutdown 3 (2026-2030), the ALICE Inner Tracking System (ITS) upgrade to ITS3 will see the replacement of the innermost 3 layers (also referred to as Inner Barrel, or IB) of the current ITS2 with 6 large-area (26 cm long), flexible, stitched 65 nm CMOS sensors. The ITS3 sensors will be air cooled, with integrated power and signal transmission, and for the first time in a High Energy Physics experiment, they will be bent into a truly half-cylindrical shape, with no more than lightweight carbon fibre foam supports to hold the structure in place. The greatest advantage brought by the new ITS3 detector will be the expected low material budget of 0.09% X$_{0}$ per layer on average, compared with the current 0.36% X$_{0}$ per ITS2 IB layer. This will improve ITS tracking and vertexing capabilities, especially at low momenta.

In the complex ITS3 R&D process, stitched test devices such as the MOnolithic Stiched Sensors (MOSS) and their smaller variants (babyMOSS) were developed to evaluate the wafer yields and assess stitched sensor performances. The babyMOSS is a ~14×30 mm$^{2}$ chip, including 8 digitally read out pixel matrices (regions) arranged in 2 rows, or half-units. This design replicates that of one of the 10 MOSS repeated sensor units, in a more compact and easier to handle version. The babyMOSS performance has been extensively characterised in terms of detection efficiency, spatial resolution and fake-hit rate in charged particle beams at the CERN Proton Sychotron and ELSA facilities.

In this contribution, we will present results for babyMOSS sensors irradiated to various fluences. We will show that, consistent with full MOSS devices, babyMOSS sensors can achieve a detection efficiency higher than 99%, a fake-hit rate lower than 10$^{-6}$ hits per pixel and event, and a spatial resolution finer than 5 μm. We also show that the babyMOSS sensor maintains this performance up to the expected ITS3 radiation level of 4·10$^{12}$ 1 MeV n$_{\mathrm{eq}}$ cm$^{-2}$ NIEL (Non-Ionising Energy Loss) + 4 kGy TID (Total Ionising Dose), in full compliance with the ITS3 sensor requirements.

Speaker: Alessandro Sturniolo (University of Liverpool (GB))

109 Benchmarking SRO Performance of CAEN Digitizers

The CAEN x2740/x2745, x2730, and x2751 digitizers belong to the Digitizer 2.0 family and are designed to meet the high data rate requirements of modern nuclear and particle physics experiments, medical imaging systems, and large-scale detector readouts. These platforms support both triggered acquisition and continuous streaming readout, integrating high-speed Flash ADCs, FPGA-based real-time processing, large DDR4 buffers, and native USB 3.1, 1 GbE TCP, and 10 GbE UDP connectivity. This work provides a performance evaluation of the readouts architectures. Hardware benchmarks were performed employing triggered and streaming readout firmware in order to investigate saturation behavior and identify throughput limitations. In triggered readout with raw waveform transmission over 10 GbE UDP, data rates close to 1.1 GB/s were achieved with no packet loss. In list-mode streaming readout with onboard processing, the maximum event rate is limited by internal FPGA event-sorting algorithm rather than by network bandwidth. Software benchmarks using CAEN FELib and the CoMPASS DAQ software highlight additional decoding and processing bottlenecks.

Speaker: Mr Yuri Venturini (CAEN S.p.A.)

110 Physics studies for the Muon Collider target system.

Muon colliders are one of the next-generation accelerators being proposed for the future of particle physics but their development faces limitations throughout the system, with new innovations required to achieve the desired performance. The focus here is on the target system which needs to withstand multi-MW pulsed proton beams in order to produce the muons through pion decay. Because of this, the target system must have long-term reliability while being able to provide the required particle yield, with performance depending on factors such as its capability to sustain high thermal and radiation loads.

Several target concepts have been proposed for the facility, including graphite, liquid-metal jets, and, in this case, a tungsten powder jet. The tungsten-powder option is desirable for a 2 - 4 MW scenario, as it combines tungsten's high density and melting point, allowing it to survive in the intense beam environment. The granular nature provides improved thermal dissipation, reduced cavitation, and enables self-replenishing behaviour. The aim of the study is to optimise the pion-to-muon production yields and investigate radiation-induced heat loads for the novel tungsten powder target system using simulation software such as FLUKA, Geant4 and BDSIM, which will help determine the optimal target design for use within the collider.

Speaker: William Bishop (University of Warwick/RAL)

111 Flexible Organic Semiconductor Radiation Sensors for use in Industry and Particle Physics

Nuclear decommissioning requires a thorough understanding of the radiological hazards present, typically achieved through a combination of in-situ detection and complementary radiochemical analysis. A major
challenge with in-situ detection arises from the diverse functions at nuclear installations, which impose constraints on detector geometry, precision, and the chemical and environmental resilience of the characterisation technology used. These challenges often necessitate customised solutions.

In this context, we explore the use of organic (polymer, oligomer, and small molecule) semiconductors deposited on flexible substrates as a conformable and tuneable solution. Organic semiconductors have gained prominence in consumer electronics, such as OLED displays, IR photodiodes, and flexible photovoltaics. Over the past two decades, they have also been studied as cost-effective alternatives to inorganic materials in radiation detection, with applications spanning medical dosimetry, nuclear security, and high-energy physics. Our focus is on fabricating flexible alpha particle sensors for in-situ characterisation of buried structures (e.g: pipelines and scaffolding) on Nuclear Decommissioning Authority (NDA) sites. The characterisation objectives in this setting include:

1. Identifying contamination location.

2. Measuring radioactivity levels.

3. Determining radioisotope identity.

We are investigating the alpha detection capabilities of these organic diode-style sensors under laboratory conditions, using 241-Am sources. Our initial goal is to assess the detection performance of the sensor
elements, focusing on minimum detectable activity and sensitivity to particle energy. Ultimately, we aim to apply this technology to an NDA site.

Speaker: Albanik Gashi (Queen Mary University of London)

Parallel Talks: Friday 5 - machine learning / reconstruction

112 Particle-Based Representation Learning for Anomaly Detection in the CMS High-Level Trigger

Anomaly detection at the LHC aims to identify events that deviate from dominant Standard Model (SM) processes while minimizing assumptions inherent to predefined trigger selections, enabling model-agnostic searches for new physics. The CMS experiment employs a two-stage trigger system that reduces the LHC bunch-crossing rate of up to 40 MHz to an output rate of approximately 9 kHz for offline processing in Run 3.

This work explores a proposed additional anomaly-detection layer at the High-Level Trigger (HLT), complementing the AXOL1TL system deployed at Level-1. The approach uses self-supervised representation learning to construct a physics-informed latent space in which the main SM processes populate well-separated regions, while anomalous or previously unmodeled event topologies tend to occupy distinct areas.
The model ingests the full set of reconstructed particles and their features, processes them with an attention-based architecture, and produces a compact fixed-size event representation. Preliminary results demonstrate the potential of this strategy to preferentially highlight anomalous events and to achieve rate reduction while improving sensitivity to a broad range of signal scenarios relative to dominant SM backgrounds.

Speaker: Mehrnoosh Moallemi (Science and Technology Facilities Council STFC (GB))

113 ML based Jet Calibration for HL-LHC

The High-Luminosity LHC (HL-LHC) will push the ATLAS experiment into an unprecedented regime of pile-up, data volume, and analysis complexity. In this environment, traditional calibration paradigms, while robust, face increasing pressure in terms of scalability and development effort.

For small-radius jets, the current Monte Carlo (MC) Jet Energy Scale (JES) calibration proceeds through sequential stages: pile-up corrections, MC JES calibration, and Global Sequential Corrections (GSC), including its deep-learning extension (GNNC). Although this structured approach has delivered excellent performance, it relies on multiple independently developed components, each requiring significant time and expert manpower.
We investigate a next-generation calibration strategy based on machine learning that unifies these stages into a single, end-to-end framework. By embedding pile-up mitigation, response correction, and global jet property information into one coherent model, this approach rethinks calibration as a holistic learning problem rather than a sequence of isolated corrections. Such a paradigm shift has the potential to enhance performance, improve robustness under extreme HL-LHC conditions, and substantially reduce development overhead.
This work represents a step toward a more integrated, scalable, and future-ready JES calibration strategy for ATLAS.

Speaker: Snigdho Chakraborty (University of Warwick (GB))

114 Boosted Top Jet Tagging Based on LundNet

This study investigates the enhancement of boosted top quark tagging at the ATLAS detector by integrating jet substructure features, captured through the Lund Jet Plane (LJP) and the LundNet Graph Neural Network, with b-tagging information from the GN3X transformer model. The study demonstrates that combining these orthogonal data sources improves background rejection compared to using individual taggers, revealing that the inclusion of b-tagging information (secondary vertices) is a dominant factor in improving discrimination power. Despite the challenges of mass sculpting, where the networks learn the top quark mass as a primary discriminator, the results provide a preliminary validation for using multi-tagger workflows to optimize signal purity for future analyses, such as charm quark direction reconstruction in $W \to cq$ decays

Speaker: Yuanda Zhu (UCL)

115 Quantum Computing for Particle Physics: Simulation and Machine Learning

Quantum computing is a rapidly emerging technology with potential applications in particle physics. From the direct simulation of quantum field theories on quantum hardware to the acceleration of computationally demanding components of data analysis, the interface between quantum information science and high-energy physics has become an active and expanding area of research. Potential applications include the quantum simulation of lattice gauge theories and real-time quantum dynamics, as well as hybrid quantum–classical algorithms for optimisation, sampling, and data-driven analysis in collider and phenomenological studies. Although current devices remain in the noisy intermediate-scale quantum (NISQ) era and are limited in scale and noise resilience, this period provides an important testing ground for developing algorithms for future large-scale quantum machines.
This talk will provide a high-level and accessible introduction to quantum computing, with particular emphasis on quantum machine learning. I will discuss two complementary perspectives. First, the use of parameterised quantum circuits as trainable machine learning models, with potential applications to data analysis; and second, the use of classical machine learning techniques to design and control quantum systems, for example, through quantum optimal control methods aimed at improving quantum simulation. I will outline potential advantages, discuss current limitations and realistic near-term expectations, and highlight recent contributions from our group in these areas.

Speaker: Callum Duffy (University College London)

116 A Hadronic Tau Preselection in the ATLAS detectors High Level Trigger

At the Large Hadron Collider, the ATLAS detector experiences a collision rate of about 1 billion proton-proton collisions per second. This rate of collisions is far too large for us to store all observed events, so only interesting events are stored. The ATLAS trigger system reduces this input rate to a manageable 3 kHz via the use of the hardware-based Level 1 trigger and the software-based high level trigger (HLT). Neural networks classifiers have previously been used in the identification of b-quark initiated jets in order to further reduce the rate within the HLT. Here, a similarly structured classifier has been used for hadronically decaying tau leptons. A first iteration of this classifier has been active since early 2024, achieving a rate reduction of 32% for a 𝑏 + 𝜏 trigger chain used in the 𝐻𝐻 → 𝑏𝑏𝜏𝜏 analysis. Further development of this hadronic tau classifier has yielded an additional 46% rate reduction.

Speaker: Joel Davidson (University of Warwick (GB))

12:30 Lunch

Plenary: Friday afternoon plenaries

117 Energy correlators for collider phenomenology

Speaker: Jack Holguin

118 Neutrinos

Speaker: Rhiannon Susan Jones (University of Sheffield (GB))

119 AI for theory

Speaker: Jack Y. Araz (Stony Brook University)

120 LHC Upgrades

Speaker: Dr Silvia Gambetta

121 Closeout

Public Event: Particles with Purpose - How Fundamental Physics Benefits Society: Outreach Event

Open to the public - friends and family welcome!

With ...
Robin Ince (chair)
Dr Harry Cliff (Cambridge)
Dr Kirsty Duffy (Oxford)
Prof Jenni Smilie (Edinburgh)
Dr Matjaz Vidmar (Edinburgh)
Dr Estifa'a Zaid (Liverpool)