Construction and performance of 128-channel segmented pulsed μSR and μe detection system at Dai Omega

In order to perform μSR and μe measurements with an instantaneously intense pulsed 4-MeV muon beam currently available at Dai Omega, which is a large solid-angle-axial focusing superconducting surface muon channel at KEK-MSL, the detector segmentation in the conventional digital technique was improved to accept the predicted event rate of 2.0×104 muons/spill. A new detection system was designed to collect intense μe decay positrons with 128 two-fold coincidence detector elements. A major feature of the new detection system was an employment of multi-anode phototubes (MAPMT) to make the detection system be compact. We mitigated the problems related cross talks among channels by employing a special fiber holder. The performance of the detection system was confirmed by μSR and μe test experiments.