The LaBr3(Ce) based detection system for the FAMU experiment

Abstract

The FAMU experiment is devoted to the high precision measurement of the hyperfine splitting of the muonic-hydrogen atom ground state using a pulsed and intense muon beam; it requires careful technological choices both in the construction of the gas target and of the detectors. In the last three years, the cryogenic gas target was developed and used for experimental measurement sessions, with the low energy pulsed muon beam (55–65 MeV), at the RIKEN-RAL (U.K.) muon facility. At the same time, eight LaBr3(Ce) based detectors have been developed to be accommodated in a circular support surrounding the target. The readout for each detector consists of a photomultiplier tube (PMT) equipped with an improved fully active high voltage divider and a Digital Pulse Processor (DPP) performing noise reduction with an optimal (triangular) filter. The active voltage divider, together with the DPP, allow to operate at high speed while retaining all the spectrometric properties of the LaBr3(Ce) scintillator. In this paper, the development of this innovative high-performance detection system is presented.