Scintillator counters with multi-pixel avalanche photodiode readout for the ND280 detector of the T2K experiment

摘要

The Tokai-to-Kamioka (T2K) experiment is a second generation long baselineneutrino oscillation experiment which aims at a sensitive search for the nu_eappearance. The main design features of the T2K near detectors located at 280 mfrom the target are presented. Scintillator counters developed for the T2K neardetectors are described. Readout of the counters is provided via WLS fibersembedded into S-shape grooves in a scintillator and viewed from both ends bymulti-pixel avalanche photodiodes operating in a limited Geiger mode. Adesription, operational principles and the results of tests of photosensorswith a sensitive area of 1.1 mm^2 are presented. A time resolution of 1.5 ns, aspatial resolution of 9.9-12.4 cm, and a MIP detection efficiency of more than99% were obtained for scintillator detectors in a beam test.