Development of a Cylindrical Drift Chamber for the COMET Phase-I Experiment

Yohei Nakatsugawa,Yoshitaka Kuno,Hideyuki Sakamoto,Ming-Liang Wong,Ting-Sam Wong,Hisataka Yoshida,Saki Ohta,Yao Zhang,Xiao-Shan Jiang,Akira Sato,Yu Nakazawa,Ye Yuan,Jie Zhang,Manabu Moritsu,Chen Wu,Hai-Bo Li

doi:10.7566/jpscp.33.011123

Abstract

A search for \(\mu \)–e conversion, the COMET experiment, will be conducted at J-PARC. The experiment has two phases. Phase-I aims to measure the background directly and search for \(\mu \)–e conversion with a sensitivity of 10^−15. Phase-II will use the information gained in Phase-I and utilize a much more intense muon beam to achieve a sensitivity of 10^−17. The main detector of the COMET Phase-I experiment is a cylindrical drift chamber (CDC). The COMET CDC will be installed in a solenoidal magnetic field, surrounding the muon stopping targets. It was designed to efficiently detect signal electrons of \(\mu \)–e conversion (105 MeV/c) emitted from the targets with momentum resolution of 200 keV/c. The COMET CDC has already been constructed and the performance test using cosmic ray is in progress. The details of the CDC design and the analysis results of the cosmic ray test is reported.

Highlights

The Standard Model (SM) of particle physics successfully explains the experimental observations so far, many questions are left unanswered
It is believed that the SM is not the full story and many intensive studies have been dedicated to exploring new physics beyond the SM
Lepton Flavor Violation is one of the processes forbidden in the original SM

Summary

Introduction

The Standard Model (SM) of particle physics successfully explains the experimental observations so far, many questions are left unanswered. Muon to electron conversion in the nuclear field (μ− N → e− N). Sizable branching ratios of muon to electron conversion are predicted by various theoretical models [3,4,5,6]. The signal electrons of μ - e conversion in the muonic atoms will be emitted from the stopping targets and measured by the detector systems. The momentum resolution of 200 keV/c is required to distinguish the signal electrons from the background electrons coming from the high energy tail of the muon Decay-In-Orbit (DIO) in the muonic atoms.

Number of wires

Summary