Time resolution limits in particle detection with modern SiPMs and scintillators

by Stefan Gundacker (Rheinisch Westfaelische Tech. Hoch. (DE))

Tuesday 21 May 2024, 11:00 → 12:00 Europe/Vienna

Library (HEPHY)

The precise measurement of the time of arrival of optical and high-energy photons has received a lot of attention in the past years as many applications require fast timing performance. Examples include detectors in high-energy physics (HEP) experiments and medical imaging applications, e.g. tagging of high-energetic particles, ultraviolet, optical and infrared photons, time-of-flight positron emission tomography (TOF-PET) and photon-counting computed tomography (PCCT). In the field of scintillator-based detectors, there have been remarkable improvements in timing performance over the last two decades. For instance, in HEP, scintillator-based detectors have been shown to achieve time resolutions below 10ps sigma, which was the starting point for their use in the CMS timing layer to mitigate pile-up effects expected by the high-luminosity upgrade of the LHC at CERN. Whereas in medical applications, TOF-PET had almost no time-of-flight capability in the late 2000s, with time resolutions around 500ps, nowadays clinical systems achieve 200ps FWHM. New technologies and materials deployed in advanced laboratories even make it possible to detect annihilation photon pairs with a time resolution of 30-50ps FWHM. These advances have been made possible by developments in all aspects of the detector, i.e. the scintillation material, the scintillation light transport, the photodetectors and the readout electronics.

To understand and improve the time resolution, always, the entire detection chain has to be considered. This talk will give an overview of the theory of scintillation and the timing limits in terms of the photo-statistics and light transport. In almost all applications, these scintillation photons are detected by silicon photomultipliers (SiPMs), making the SiPM the standard device for many time-critical photon detection tasks. Therefore, state-of-the-art measurements of important SiPM parameters will be discussed and their impact on timing will be examined (e.g. the photon detection efficiency, single photon time resolution and noise sources). Furthermore, with many new developments in scintillation and photodetection, fast readout electronics are essential. The impact of electronic front-end designs to the overall time resolution will be presented and different strategies for amplification and processing the signals from the SiPM-detector will be elaborated. Emerging high-frequency readout has been shown to overcome the limitations of the electronics, but is difficult to integrate into larger systems, for which a roadmap will be given. This talk will conclude on various experimental and theoretical evaluations of state-of-the-art SiPMs and scintillators, allowing to fully understand their timing limits.

Gundacker_Hephy_21052024_VF.pdf