arXiv subjects

N. Teshima

Publications and source records attributed to N. Teshima.

5 recordsLinked to original sources

arXiv2019

Status of the DeeMe Experiment, an Experimental Search for $\mu$-$e$ Conversion at J-PARC MLF

The DeeMe experiment is planned to search for muon-to-electron conversion at J-PARC MLF. Our goal is to measure the process with a single event sensitivity of $1 \times 10^{-13}$ or $2 \times 10^{-14}$ for a graphite or silicon carbide target. That is one or two orders of magnitude better than the current upper limits, $7 \times 10^{-13}$ for a gold target by the SINDRUM-II experiment at PSI and $4.6 \times 10^{-12}$ for a titanium target by the experiment at TRIUMF. We are in the middle of preparation for the experiment. The construction of the secondary beamline, H Line, is now in progress. Four tracking detectors have been manufactured in 2017, and the optimization study of the filling gas is ongoing to improve the performance. After getting the better hit efficiency, we measured the momentum spectrum of electrons produced through muon-decay-in-orbit from a carbon target at J-PARC MLF D2 Area in March, 2019. In this paper, the preparation status of the DeeMe experiment will be presented.

physics.ins-det↗

arXiv2019

Development of a multiwire proportional chamber with good tolerance to burst hits

The DeeMe experiment to search for muon-to-electron conversions with a sensitivity 10--100 times better than those achieved by previous experiments is in preparation at the Japan Proton Accelerator Research Complex. The magnetic spectrometer used by the DeeMe experiment consists of an electromagnet and four multiwire proportional chambers (MWPCs). The newly developed MWPCs are operated with a high voltage (HV) switching technique and have good burst-hit tolerance. In this article, the final designs of the MWPCs, amplifiers for readout, and HV switching modules are described. Additionally, some results of MWPC performance evaluation are presented.

physics.ins-det↗

arXiv2018

Development of the detectors for the DeeMe experiment

In the DeeMe experiment, approximately $70\ \mathrm{GHz/mm^{2}}$ prompt-charged particles will hit the multi-wire proportional chambers (MWPCs) before signal electrons come. To avoid the space charge effect, we developed fast HV-switching MWPCs in order to control the gas gain dynamically. All four of the MWPCs were manufactured. Last year, the circuit of readout amplifiers is slightly modified to further improve the efficiency of the detector, and we also started to investigate other possible choices of the gas mixture. In this article, the development of the detectors and results of performance tests will be presented.

physics.ins-det↗

arXiv2018

$μ$-$e$ conversion experiments at J-PARC

There are two plans of experiments to search for muon to electron ($μ$-$e$) conversion at J-PARC, which are called DeeMe and COMET. The $μ$-$e$ conversion is one of the charged lepton flavor violation processes. The processes are forbidden in the Standard Model, but some theories beyond the Standard Model predict relatively large branching ratios at orders of $10^{-12}$ to $10^{-17}$. DeeMe will be conducted with a sensitivity of $1\times10^{-13}$ using a carbon target for 1 year, and COMET will be done with that of $3\times10^{-15}$ in Phase-I. In this article, the current status of these two experiments will be presented.

physics.ins-det↗

arXiv2016

A Fast High-Voltage Switching Multiwire Proportional Chamber

A new experiment, called DeeMe, which is designed to search for $μ$-e conversions with a sensitivity of $\mathcal{O}(10^{-14})$, is in preparation at the Japan Proton Accelerator Research Complex (J-PARC). It utilizes a high-quality pulsed proton beam from the Rapid Cycling Synchrotron at J-PARC. The detector for DeeMe must tolerate large pulses of prompt charged particles whose instantaneous hit rate is as large as 70 GHz/mm$^2$ in a time width of 200 ns and detect a single electron that arrives with delayed timing on the order of microseconds. A special wire chamber has been developed with a new dynamic gain control technique that reduces space charge effects. In this paper, we detail the novel detector scheme and operation verification.

physics.ins-det↗