Fast and Efficient Detection of 511 keV Photons using Cherenkov Light in PbF$_2$ Crystal coupled to a MCP-PMT and SAMPIC Digitization Module

TL;DR

This paper demonstrates a fast, efficient method for detecting 511 keV photons using Cherenkov light in PbF2 crystals coupled with MCP-PMTs and SAMPIC digitization, achieving high timing resolution suitable for TOF-PET.

Contribution

The study introduces a novel detection module combining PbF2 crystals, MCP-PMTs, and SAMPIC digitization, with detailed calibration and analysis of timing characteristics for improved PET imaging.

Findings

Achieved 24% detection efficiency for 511 keV photons.

Measured a coincidence resolving time of 280 ps.

Developed a calibration system for PMT timing response.

Abstract

We study the possibility to use the Cherenkov light for the efficient detection of 511 keV photons with the goal to use it in TOF-PET. We designed and tested two detection modules consisting of PbF$_2$ crystals attached to Planacon MCP-PMT XP85012. Amplified PMT signals are digitized by the SAMPIC module with high readout rate, up to $10^5$ events/s, and a negligible contribution to the time resolution, below 20 ps (FWHM). We developed a fast 2D scanning system to calibrate the PMT time response and studied in details the timing characteristics of the Planacon PMT. Using a radioactive $^{22}$Na source we measured a detection efficiency of 24% for 511 keV photons in a 10 mm thick crystal and a coincidence resolving time of 280 ps. We analyzed the main factors limiting the time resolution of the large-surface detection module and proposed solutions to improve it, which will be tested in our future project.