Details

Autor(en) / Beteiligte

• Balajthy, J.
• Brown, J.
• Brubaker, E.
• Cabrera-Palmer, B.
• Cates, J.
• Goldblum, B.L.
• Folsom, M.
• Hausladen, P.
• Keefe, K.
• Nattress, J.
• Negut, V.
• Nishimura, K.
• Steele, J.
• Ziock, K.

Titel

Characterization of a SiPM-based monolithic neutron scatter camera using dark counts

Ist Teil von

• Journal of instrumentation, 2024-06, Vol.19 (6), p.T06004

Ort / Verlag

Bristol: IOP Publishing

Erscheinungsjahr

2024

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The Single Volume Scatter Camera (SVSC) Collaboration aims to develop portable neutronimaging systems for a variety of applications in nuclear non-proliferation. Conventionaldouble-scatter neutron imagers are composed of several separate detector volumes organized in atleast two planes. A neutron must scatter in two of these detector volumes for its initialtrajectory to be reconstructed. As such, these systems typically have a large footprint and poorgeometric efficiency. We report on the design and characterization of a prototype monolithicneutron scatter camera that is intended to significantly improve upon the geometrical shortcomingsof conventional neutron cameras. The detector consists of a 50mm×56 mm× 60 mmmonolithic block of EJ-204 plastic scintillator instrumented on two faces with arrays of 64Hamamatsu S13360-6075PE silicon photomultipliers (SiPMs). The electronic crosstalk is limited to< 5% between adjacent channels and < 0.1% between all other channel pairs. SiPMs introduce a significantlyelevated dark count rate over PMTs, as well as correlated noise from after-pulsing and opticalcrosstalk. In this article, we characterize the dark count rate and optical crosstalk and presenta modified event reconstruction likelihood function that accounts for them. We find that theaverage dark count rate per SiPM is 4.3 MHz with a standarddeviation of 1.5 MHz among devices. The analysis method we employto measure internal optical crosstalk also naturally yields the mean and width of thesingle-electron pulse height. We calculate separate contributions to the width of thesingle-electron pulse-height from electronic noise and avalanche fluctuations. We demonstrate atiming resolution for a single-photon pulse to be (128 ± 4) ps. Finally, coincidence analysis is employed to measureexternal (pixel-to-pixel) optical crosstalk. We present a map of the average external crosstalkprobability between 2×4 groups of SiPMs, as well as the in-situ timing characteristicsextracted from the coincidence analysis. Further work is needed to characterize the performanceof the camera at reconstructing single- and double-site interactions, as well asimage reconstruction.