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

本研究是为了探索μ子轻子味被破坏的μ子-电子转换过程的实验而进行的研究与开发。特别是，我们专注于电子跟踪探测器（电子跟踪器）的发展，因为电子的动量测量是实验的关键。该电子跟踪器由聚酰亚胺吸管（25μm厚）制成，钨丝串在管的中心。它被称为“稻草毒气室”。带电粒子沿着阳极线的撞击位置由放置在管外部的铜带读取的感应电荷来评估。为了使这成为可能，吸管应该具有有限的阻力。我们为此开发了这样一种管。我们使用的吸管是日本开发的无缝吸管。我们成功地制作了30根吸管的吸管室。然后，我们在2002年5月对科索沃能源公司的电离室进行了束流测试。另外，我们还研制了一个300μm的可扩展光纤跟踪器。我们采用多阳极光电倍增管读出。2002年12月在科索沃能源公司进行了光束测试。跟踪器的空间分辨率和时间分辨率均满足要求，说明我们研制的μ子-电子转换实验跟踪器系统是可行的。

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.