New Intiative on Search for Muon Lepton Flavor Violation with Highly Intense Muon Source

2002 Fiscal Year Final Research Report Summary

• Project/Area Number: 13304019
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 素粒子・核・宇宙線
• Research Institution: Osaka University
• Principal Investigator: KUNO Yoshitaka Osaka University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (30170020)
• Co-Investigator(Kenkyū-buntansha): SUGAYA Yorihito Osaka University, Graduate School of Science, Research Associate, 大学院・理学研究科, 助手 (80324747) ; AOKI Masaharu Osaka University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (80290849) ; NOUMACHI Masaharu Osaka University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (90208299) ; MORI Yoshiharu OSAKA UNIV. KEK, Accelerator, Professor, 加速器研究施設, 教授 (30124176) ; NAKANO Takashi OSAKA UNIV. RCNP, Professor, 核物理研究センター, 教授 (80212091)
• Project Period (FY): 2001 – 2002
• Keywords: Muon / lepton flavor / polyimide / straw gas chamber / seamless straw / cathode strip / scintillating fiber / multi-anode photomultiplier

Research Abstract

This research is to carry out R&D for an experiment searching for the muon-electron conversion process, in which the muon lepton flavor is violated. Especially, we focused on development of an electron tracking detector (electron tracker), since the measurement of electron's momentum is critical for the experiment. This electron tracker is made of pelyimide straw tubes (25μm thickness) with a Tungsten wire strung at the center of the tube. It is called a "straw gas chamber". The hit position of charged particles along the anode wire is evaluated from induced charges read by copper strips placed exterior of the tube. To make this possible, a straw tube should have finite resistance. We developed such a tube for our purpose. The straw tube we used was a seamless one that was developed in Japan. We succeeded to fabricate straw tube chambers with 30 straw tubes. Then, we performed a beam test of the chambers at KEK in May 2002. We confirmed that the spatial resolution of the chamber is sufficient enough for our purpose.
In addition, we also developed a scintillating fiber tracker with 300μm fiber. We employed multi-anode photomultipliers for readout. The beam test was performed at KEK in December 2002. Both the spatial and time resolutions of the tracker were found to meet the requirements.
From those studies, we conclude that our development of the tracker system for the muon-electron conversion experiment is feasible.