arXiv subjects

Yutaro Sato

Publications and source records attributed to Yutaro Sato.

12 recordsLinked to original sources

arXiv2026

Hit-rate capability of a silicon strip detector module for decay positron detection in the J-PARC muon $g-2$/EDM experiment

In the J-PARC muon $g-2$/EDM experiment, a silicon strip detector will be used to detect positrons from muon decays. The detector consists of planes of detector modules arranged radially. The expected maximum hit rate reaches 1.4~MHz per sensor strip, and achieving high detection efficiency even under such hit-rate conditions is a key performance requirement. We have developed the smallest unit of the detector module, and its performance was evaluated using a muon beam at the J-PARC MLF H-line. The specifications of the detector module and the evaluated hit-rate capability are described in this article.

physics.ins-det↗

arXiv2024

The quality assurance test of the SliT ASIC for the J-PARC muon $g-2$/EDM experiment

The SliT ASIC is a readout chip for the silicon strip detector to be used at the J-PARC muon $g-2$/EDM experiment. The production version of SliT128D was designed and mass production was finished. A quality assurance test method for bare SliT128D chips was developed to provide a sufficient number of chips for the experiment. The quality assurance test of the SliT128D chips was performed and 5735 chips were inspected. No defect was observed in chips of 84.3%. Accepting a few channels with poor time walk performance out of 128 channels per chip, more than 90% yield can be achieved, which is sufficient to construct the whole detector.

physics.ins-det↗

arXiv2020

SliT: A Strip-sensor Readout Chip with Subnanosecond Time-walk for the J-PARC Muon $g-2$/EDM Experiment

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 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 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-cross architecture, which consists of a CR-RC filter followed by a CR circuit as a voltage differentiator. This architecture enables to generate hit signals with subnanosecond amplitude-independent time walk, which is the primary requirement for the experiment. The test results show the time walk of $0.38 \pm 0.16$ ns between 0.5 and 3 MIP signals. The equivalent noise charge is $1547 \pm 75 $ $e^{-}$ (rms) at $C_{\rm det} = 33$ pF as a strip-sensor capacitance. Other functionalities such as a strip-sensor readout chip have also been proven in the tests. The SliT128C satisfies all requirements of the J-PARC muon $g-2$/EDM experiment.

physics.ins-det↗

arXiv2019

Importance of Giant Impact Ejecta for Orbits of Planets Formed during the Giant Impact Era

Terrestrial planets are believed to be formed via giant impacts of Mars-sized protoplanets. Planets formed via giant impacts have highly eccentric orbits. A swarm of planetesimals around the planets may lead to eccentricity damping for the planets via the equipartition of random energies (dynamical friction). However, dynamical friction increases eccentricities of planetesimals, resulting in high velocity collisions between planetesimals. The collisional cascade grinds planetesimals to dust until dust grains are blown out due to radiation pressure. Therefore, the total mass of planetesimals decreases due to collisional fragmentation, which weakens dynamical friction. We investigate the orbital evolution of protoplanets in a planetesimal disk, taking into account collisional fragmentation of planetesimals. For 100 km-sized or smaller planetesimals, dynamical friction is insignificant for eccentricity damping of planets because of collisional fragmentation. On the other hand, giant impacts eject collisional fragments. Although the total mass of giant impact ejecta is 0.1-0.3 Earth masses, the largest impact ejecta are ~ 1,000 km in size. We also investigate the orbital evolution of single planets with initial eccentricities 0.1 in a swarm of such giant impact ejecta. Although the total mass of giant impact ejecta decreases by a factor of 3 in 30 Myrs, eccentricities of planets are damped down to the Earth level (~0.01) due to interaction with giant impact ejecta. Therefore, giant impact ejecta play an important role for determination of terrestrial planet orbits.

astro-ph.EP↗

arXiv2019

Prototype Front-end ASIC for Silicon-strip Detectors of J-PARC Muon g-2/EDM Experiment

We report on the development of a front-end ASIC for silicon-strip detectors of the J-PARC Muon g-2/EDM experiment. This experiment aims to measure the muon anomalous magnetic moment and electric dipole moment precisely to explore new physics beyond the Standard Model. Since the time and momentum of positrons from muon decay are key information in the experiment, a fast response with high granularity is demanded to silicon-strip detectors as the positron tracker. The readout ASIC is thus required to tolerate a high hit rate of 1.4 MHz per strip and to have deep memory for the period of 40 us with 5 ns time resolution. To satisfy the experimental requirements, an analog prototype ASIC was newly designed with the Silterra 180 nm CMOS technology. In the evaluation test, the time-walk was demonstrated to reach 0.8~ns with a sufficient dynamic range of 6~MIPs and pulse width of 45~ns for 1 MIP event. The design details and performance of the ASIC are discussed in this article.

physics.ins-det↗

arXiv2017

A Challenge to Lepton Universality in B Meson Decays

One of the key assumptions of the Standard Model of fundamental particles is that the interactions of the charged leptons, namely electrons, muons, and taus, differ only because of their different masses. While precision tests comparing processes involving electrons and muons have not revealed any significant violation of this assumption, recent studies involving the higher-mass tau lepton have resulted in observations that challenge lepton universality at the level of four standard deviations. A confirmation of these results would point to new particles or interactions, and could have profound implications for our understanding of particle physics.

hep-ex↗

arXiv2014

Inclusive $B$ decays and exclusive radiative decays by Belle

The $b \rightarrow s γ$, $b \rightarrow d γ$ and $b \rightarrow s \ell^+ \ell^-$ processes are allowed at higher order via the electroweak loop or box diagrams in the Standard model. It is sensitive probe to search for new physics beyond the Standard model because new particles might enter in the loop. We present preliminary results of branching fraction of the $\bar{B} \rightarrow X_s γ$, $CP$ asymmetry in the $\bar{B} \rightarrow X_{s+d} γ$, and the forward-backward asymmetry in the $\bar{B} \rightarrow X_s \ell^+ \ell^-$. The results are based on a data sample containing $772 \times 10^6 B\bar{B}$ pairs recorded at the $Υ(4S)$ resonance with the Belle detector at the KEKB $e^+ e^-$ collider.

hep-ex↗

arXiv2010

Forward Instrumentation for ILC Detectors

Two special calorimeters are foreseen for the instrumentation of the very forward region of the ILC detector, a luminometer designed to measure the rate of low angle Bhabha scattering events with a precision better than 10-3 and a low polar angle calorimeter, adjacent to the beam-pipe. The latter will be hit by a large amount of beamstrahlung remnants. The amount and shape of these depositions will allow a fast luminosity estimate and the determination of beam parameters. The sensors of this calorimeter must be radiation hard. Both devices will improve the hermeticity of the detector in the search for new particles. Finely segmented and very compact calorimeters will match the requirements. Due to the high occupancy fast front-end electronics is needed. The design of the calorimeters developed and optimised with Monte Carlo simulations is presented. Sensors and readout electronics ASICs have been designed and prototypes are available. Results on the performance of these major components are summarised.

physics.ins-det↗

arXiv2010

Irradiation test on FD-SOI Readout ASIC of Pair-monitor

We fabricated a readout ASIC with the fully depleted silicon-on-insulator (FD-SOI) technology for the pair-monitor. The pair-monitor is a silicon pixel device that measures the beam profile of the international linear collider. It utilizes the directional distribution of a large number of electron-positron pairs created by collision of bunches, and is required to tolerate radiation dose of about a few Mrad/year. The irradiation might cause the buried oxide layer of SOI to accumulate charges which interfere with intended functions. We thus performed extensive irradiation tests on the prototype ASIC, and the results are described in this paper.

physics.ins-det↗

arXiv2009

Beam Size Measurement with Pair Monitor and BeamCal

At the International Linear Collider (ILC), measurement of the beam profile at the interaction point (IP) is a key issue to achieve high luminosity. We studied the beam size measurement by combination of Pair Monitor and BeamCal. We obtained measurement accuracies of 2.7%, and 6.6% for the horizontal, and vertical beam sizes, respectively, for 50 bunch crossings.

physics.ins-det↗

arXiv2009

Study of Beam Profile Measurement at Interaction Point in International Linear Collider

At the international linear collider, measurement of the beam profile at the interaction point is a key issue to achieve high luminosity. We report a simulation study on a new beam profile monitor, called the pair monitor, which uses the hit distribution of the electron-positron pairs generated at the interaction point. We obtained measurement accuracies of 5.1%, 10.0%, and 4.0% for the horizontal, vertical, and longitudinal beam size, respectively, for 50 bunch crossings.

physics.ins-det↗

arXiv2009

Development of Pair Monitor

The pair monitor is a beam profile monitor at interaction point (IP) for the international linear collider (ILC). We have designed and developed the pair monitor as a silicon pixel sensor which is located at about 400 cm from IP. As the first step to develop the pair monitor, the readout ASIC was developed. In this paper, test results of the readout ASIC and the future plan are reported.

physics.ins-det↗