A large-acceptance proton scintillator detection system for electron scattering experiments

Two plastic scintillator arrays with fast read-out electronics have been constructed for proton detection in an electron scattering environment. The detectors, one consisting of 47 and the other of 53 scintillators, each subtend a 39 msr solid angle and cover dynamic ranges of 25–158 and 37–198 MeV, respectively. The segmentation of the detector allows detection at forward scattering angles (> 50°) at a luminosity of 8×1036 nucleons s−1 cm−2 (at about 1 MHz per element). The charge and time of arrival of each photomultiplier signal are digitized by two Flash ADCs. The read-out of background events is suppressed efficiently by a proper coincidence requirement in the first-level trigger. An unambiguous identification of protons and pions is obtained. The energy resolution amounts to 3.3 MeV for 87 MeV protons, while the intrinsic timing resolution is estimated at 0.6 ns.