Speaker
Description
The FAMU experiment at RIKEN-RAL has been devised to measure with high precision (better than 1%) the proton Zemach radius in muonic hydrogen, produced from a 55 MeV/c muon beam impinging on a target containing a mixture of H2 and O2 (1.5% in weight). The innovative method is based on a custom MIR laser (working at ~6800 nm) and a fast X-ray detector system. The X-ray detector system in the 2023-2024 data taking is based on LaBr3:Ce crystals with a conventional PMT readout or a SiPM array readout. It is used to detect signal X-rays in the region around 130 keV. To discriminate the delayed X-rays signal from the prompt background a fast timing is needed. To this aim an innovative custom electronics has been developed for the SiPM arrays readout, reducing both signal's falltime (risetime) by a factor three (two). A 8-channels NIM custom module, based on the CAEN A7585D chip, has been developed to correct online the SiPM gain drift with temperature. The presence of detectors with both PMT's and SiPM array's readout in the same experimental setup has allowed useful comparisons. FWHM energy resolutions better than 3% (8%) has been obtained at the CS137 (Co57) peak for the SiPM array readout. This compares with the best results obtained with a conventional PMT readout scheme. Results on both laboratory tests and beam performances of our innovative readout scheme with SiPM arrays will be reported.
| Primary experiment | FAMU |
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