Scintillating-fiber-block detector for studying double-strangeness nuclei

Abstract Scintillating-fiber-block detectors have been constructed using 0.5 mm square fibers for the KEK-PS E373 experiment, which searches for double-strangeness nuclei. The main aim of the detector is to measure the energies of protons and pions produced from decay of double- or single-hypernuclei using their ranges. It is also used to detect Λ hyperons or the H -dibaryon, and to make event selection. The performance of the detectors was studied with low-energy proton and pion beams as well as minimum-ionizing particles. The energy resolution determined by the range measurements was 0.86 MeV for 37 MeV π − 's and 1.4 MeV for 47 MeV protons. The excellent capability of π/p separation has been also demonstrated.