Language：English   Publishing type：Research paper (scientific journal)  

A new silicon-strip readout chip named “SliT” has been developed for the measurement of the muon anomalous magnetic moment and electric dipole moment at J-PARC. The SliT chip is designed in the Silterra 180 nm CMOS technology with mixed-signal integrated circuits. An analog circuit incorporates a conventional charge-sensitive amplifier, shaping amplifiers, and two distinct discriminators for each of the 128 identical channels. A digital part includes storage memories, an event building block, a serializer, and LVDS drivers. A distinct feature of the SliT is utilization of the zero-crossing architecture, which consists of a CR-RC filter followed by a CR circuit as a voltage differentiator. This architecture allows generating hit signals with subnanosecond amplitude-independent time walk, which is the primary requirement for the experiment. The test results show a time walk of 0.38 +/- 0.16 ns between 0.5 and 3 MIP signals. The equivalent noise charge is 1547 +/- 75 e- (rms) at Cdet = 33 pF as a strip-sensor capacitance. The SliT128C satisfies all requirements of the J-PARC muon g-2/EDM experiment.

DOI： 10.1109/TNS.2020.3012924

Other Link： https://ieeexplore.ieee.org/abstract/document/9153019

Language：English   Publishing type：Research paper (scientific journal)  

A high-intensity pulsed muon beam is becoming available at the at the Japan Proton Accelerator Research Complex (J-PARC). 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 um 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 DAQMiddleware 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.

DOI： 10.1088/1748-0221/15/04/P04027

Other Link： https://iopscience.iop.org/article/10.1088/1748-0221/15/04/P04027

Language：English   Publishing type：Research paper (scientific journal)  

This paper introduces a new approach to measure the muon magnetic moment anomaly aμ = (g − 2)/2 and the muon electric dipole moment (EDM) dμ at the J-PARC muon facility. The goal of our experiment is to measure aμ and dμ using an independent method with a factor of 10 lower muon momentum, and a factor of 20 smaller diameter storage-ring solenoid compared with previous and ongoing muon g − 2 experiments with unprecedented quality of the storage magnetic field. Additional significant differences from the present experimental method include a factor of 1000 smaller transverse emittance of the muon beam (reaccelerated thermal muon beam), its efficient vertical injection into the solenoid, and tracking each decay positron from muon decay to obtain its momentum vector. The precision goal for aμ is a statistical uncertainty
of 450 parts per billion (ppb), similar to the present experimental uncertainty, and a systematic uncertainty less than 70 ppb. The goal for EDM is a sensitivity of 1.5 × 10^−21 e · cm.

DOI： 10.1093/ptep/ptz030

Language：English   Publishing type：Research paper (scientific journal)  

A search for the supersymmetric partners of quarks and gluons (squarks and gluinos) in final states containing hadronic jets and missing transverse momentum, but no electrons or muons, is presented. The data used in this search were recorded in 2015 and 2016 by the ATLAS experiment in √s=13 TeV proton-proton collisions at the Large Hadron Collider, corresponding to an integrated luminosity of 36.1 fb^−1. The results are interpreted in the context of various models where squarks and gluinos are pair
produced and the neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 2.03 TeV for a simplified model incorporating only a gluino and the lightest neutralino, assuming the lightest neutralino is massless. For a simplified model involving the strong production of mass-degenerate first- and second-generation squarks, squark masses below 1.55 TeV are excluded if the lightest neutralino is massless. These limits substantially extend the region of supersymmetric parameter space previously excluded by searches with the ATLAS detector.

DOI： 10.1103/PhysRevD.97.112001

Language：English   Publishing type：Research paper (scientific journal)  

A search for squarks and gluinos in final states containing hadronic jets, missing transverse momentum but no electrons or muons is presented. The data were recorded in 2015 by the ATLAS experiment in √s= 13 TeV proton--proton collisions at the Large Hadron Collider. No excess above the Standard Model background expectation was observed in 3.2 fb^−1 of analyzed data. Results are interpreted within simplified models that assume R-parity is conserved and the neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1.51 TeV for a simplified model incorporating only a gluino octet and the lightest neutralino, assuming the lightest neutralino is massless. For a simplified model involving the strong production of mass-degenerate first- and second-generation squarks, squark masses below 1.03 TeV are excluded for a massless lightest neutralino. These limits substantially extend the region of supersymmetric parameter space excluded by previous measurements with the ATLAS detector.

DOI： 10.1140/epjc/s10052-016-4184-8

Other Link： https://link.springer.com/article/10.1140%2Fepjc%2Fs10052-016-4184-8

Event date： 2020.9 - 2020.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Status and prospect of the g-2 experiment in J-PARC

Event date： 2019.4

Language：English   Presentation type：Oral presentation (general)  

Venue：Daejeon   Country：Korea, Republic of  

A new precise muon g-2/EDM measurement is planned at J-PARC. The recent experiment at BNL measured muon g-2 at 0.54 ppm but there is a discrepancy from the Standard Model expectation by more than three standard deviations. The experiment at J-PARC aims to measure muon g-2 with a different method from BNL or another experiment ongoing at FNAL and also to improve a sensitivity to muon EDM. We use a novel technique of muon beam thermalization, accelerate muons to 300 MeV/c, inject and store them in high precision MRI-type magnet with the storage orbit diameter of 66 cm and 3 T field and focuses with weak magnetic field. Positron tracks from muon decays are reconstructed by the silicon strip detector. By using different approaches from BNL and FNAL, J-PARC experiment will provide a independent measurement. The overall design and its preparation status will be presented.

Event date： 2019.2

Language：English  

Venue：Vienna   Country：Austria  

Event date： 2018.1

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya   Country：Japan  

A new precise muon g-2/EDM measurement is planned at J-PARC. The recent experiment at BNL measured muon g-2 at 0.5 ppm but there is a discrepancy from the standard model expectation by three standard deviation. The experiment at J-PARC uses a novel technique of ultra-cold muon beam, accelerates muons to 300 MeV/c, injects and stores them in ultra-high precision MRI-type magnet with 66 cm diameter and 3 T field and focuses with weak magnetic field. Positron tracks from muon decays are reconstructed by the silicon strip detector. By using different approaches from BNL and another experiment ongoing at FNL, J-PARC experiment will provide a independent measurement. The overall design and its preparation status will be reported.

Other Link： http://inst.cyric.tohoku.ac.jp/fpua2018/

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

ミュオニックヘリウム原子の超微細構造の測定による負ミュオン質量の高精度化を目指した実験がJ-PARCで進められており、このためには磁場を印加した際に分離する2つの超微細構造遷移周波数を測定する必要がある。本グループで開発したラビ振動分光という手法を用いることで共鳴周波数を走査することなく遷移周波数の決定が可能となるが、ミュオニックヘリウム原子の場合には2つの遷移周波数の同時測定を行う方法を新たに考案した。本講演ではこの方法と実験の準備状況について報告する。

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：50

Type：Competition, symposium, etc. 

Number of participants：50