Performance evaluation of a silicon strip detector for positrons/electrons from a pulsed a muon beam

Abstract

Many experiments to study fundamental physics using this high-intensity muon beam are proposed. An experiment to measure the muon magnetic moment anomaly (g − 2) and the muon electric dipole moment (EDM) is one of these experiments and it requires a tracking detector for positrons from muon decay. Fine segmentation is required in a detector to tolerate the high rate of positrons. The time resolution is required to be much better than the muon anomalous spin precession period while a buffer depth of a front-end electronics needs to be much longer than the accelerated muon lifetime. Requirements of this detector also meet requirements of a measurement of the muonium hyperfine structure interval at the J-PARC and another experiment to measure the proton charge radius at Tohoku University. We have developed a single-sided silicon strip sensor with a 190 µm pitch, a front-end electronics with a sampling rate of 200 MHz and a buffer memory depth of 8192, and a data acquisition system based on DAQ-Middleware for the J-PARC muon g − 2/EDM experiment. We have fabricated detector modules consisting of this sensor and the front-end electronics. Performance of fabricated detector modules was evaluated at a laboratory and a beam test using the positron beam at Tohoku University. The detector is confirmed to satisfy all requirements of the experiments except for the time walk, which will be solved by the next version of a front-end electronics.

Present Status of Spectroscopy of the Hyperfine Structure and Repolarization of Muonic Helium Atoms at J-PARC

“…With the detector used in our measurements, one cannot ignore the effects of pileup at high event rates of the H-line. To reduce systematic uncertainty caused by pile-up, we plan to refine the segmentation of the detector and use high-rate capability silicon strip sensors that are being developed for the J-PARC muon g − 2/EDM experiment [31,32]. Since fluctuations in the magnetic field mean fluctuations in the resonance frequency, measurements at high magnetic fields can introduce significant systematic uncertainties due to the lack of uniformity in the magnetic field.…”

SliT: A Strip-Sensor Readout Chip With Subnanosecond Time Walk for the J-PARC Muon g − 2/EDM Experiment

“…In the previous studies, we started from a small-scale analog prototype in Silterra 180-nm CMOS technology. Then we fabricated module-prototype chips named "SliT128A" [8] and "SliT128B" [9]. The module-prototype ASICs included 128 readout channels, buffer memories, and other digital processing circuits to store and cope with timing information from the strip sensors.…”

Rabi-oscillation spectroscopy of the hyperfine structure of muonium atoms

“…In our recent experiment [17], a polarized muon beam was injected into a krypton gas target, resulting in the formation of muonium. The muon spin-flip signal induced by the microwave was measured with downstream positron detectors that use a silicon strip sensor [18]. The sensor was optimized to the pulsed beam experiment and exhibited a high-rate capability to reduce inefficiency due to pile-up events.…”