Improving the Time Resolution of Large-Area LaBr3:Ce Detectors with SiPM Array Readout

Abstract

LaBr3:Ce crystals have good scintillation properties for X-ray spectroscopy. Initially, they were introduced for radiation imaging in medical physics with either a photomultiplier or SiPM readout, and they found extensive applications in homeland security and gamma-ray astronomy. We used 1 inch round LaBr3:Ce crystals to realize compact detectors with the SiPM array readout. The aim was a good energy resolution and a fast time response to detect low-energy X-rays around 100 keV. A natural application was found inside the FAMU experiment, at RIKEN RAL. Its aim is a precise measurement of the proton Zemach radius with impinging muons, to contribute to the solution to the so-called proton radius puzzle. Signals to be detected are characteristic X-rays around 130 KeV. A limit for this type of detector, as compared to the ones with a photomultiplier readout, is its poorer timing characteristics due to the large capacity of the SiPM arrays used. In particular, long signal falltimes are a problem in experiments such as FAMU, where a prompt background component must be separated from a delayed one (after 600 ns) in the signal X-rays to be detected. Dedicated studies were pursued to improve the timing characteristics of the used detectors, starting from hybrid ganging of SiPM cells; then developing a suitable zero pole circuit with a parallel ganging, where an increased overvoltage for the SiPM array was used to compensate for the signal decrease; and finally designing ad hoc electronics to split the 1 inch detector SiPM array into four quadrants, thus reducing the involved capacitances. The aim was to improve the detectors timing characteristics, especially falltime, while keeping a good FWHM energy resolution for low-energy X-ray detection.

References in corpus (7)

• Steps towards the hyperfine splitting measurement of the muonic hydrogen ground state: pulsed muon beam and detection system characterization
• Large-Area MPPC with Enhanced VUV Sensitivity for Liquid Xenon Scintillation Detector
• Theoretical and computational study of the energy dependence of the muon transfer rate from hydrogen to higher-Z gases
• Large area LaBr3:Ce crystals read by SiPM arrays with improved timing and temperature gain drift control
• Ce:LaBr${}_3$ crystals with SiPM array readout and temperature control for the FAMU experiment at RAL
• Online control of the gain drift with temperature of SiPM arrays used for the readout of LaB${}_3$:Ce crystals
• Detection of low-energy X-rays with 1/2 and 1 inch LaBr3:Ce crystals read by SIPM arrays

Cited by in corpus (3)

• Gamma-ray and high-energy X-ray detection with large area scintillating crystals: a hands-on review
• Status of the detector setup for the FAMU experiment at RIKEN-RAL for a precision measurement of the Zemach radius of the proton in muonic hydrogen
• The fast X-ray detector system of the FAMU experiment at RAL