Speaker
Description
DarkSide-20k is a dark matter direct detection experiment operating a dual-phase liquid argon time projection chamber (TPC) at the Laboratori Nazionali del Gran Sasso (LNGS). To reach its design sensitivity, the experiment requires a cosmogenic background contribution of less than 0.01 events over a 200 ton-year exposure. This strict requirement needs precise characterization of prompt fast neutrons induced by high-energy atmospheric muons. Simulating this background is computationally challenging due to the thick rock overburden and the low probability of the photonuclear interactions required to generate penetrating neutrons.
In this work, we present a Monte Carlo simulation pipeline coupling the MUon inTensity codE (MUTE) with FLUKA. Using the high-resolution mountain topography of LNGS Hall C, MUTE calculates the surface-to-underground muon transport, preserving stochastic radiative energy losses. To interface these kinematics with FLUKA, we constructed a planar-weighted, joint 3D Cumulative Distribution Function (CDF) of the muon energy, zenith, and azimuthal angles. FLUKA samples this correlated phase space on-the-fly via a binary search algorithm. To improve computational efficiency, variance reduction techniques—including electromagnetic energy cutoffs and interaction length biasing—were applied in the rock overburden to accelerate fast neutron production while maintaining physical accuracy.
By simulating a live-time equivalent to several decades, we track the correlated energy depositions of cosmogenic events across the inner and outer veto systems. We evaluate the survival rate of isolated 1–2 MeV neutrons reaching the fiducial volume of TPC to estimate the prompt cosmogenic background budget for DarkSide-20k and assess the efficiency of the active veto strategy.
| Primary Abstract Topic | Experiment: Other Dark Matter |
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