arXiv subjects

Katsushige Kotera

Publications and source records attributed to Katsushige Kotera.

8 recordsLinked to original sources

arXiv2025

Proposal of the KOTO II experiment

The KOTO II experiment is proposed to measure the branching ratio of the decay $K_L\toπ^0ν\barν$ at J-PARC. With a beamline to extract long-lived neutral kaons at 5 degrees from a production target, the single event sensitivity of the decay is $8.5\times 10^{-13}$, which is much smaller than the Standard Model prediction $3\times 10^{-11}$. This allows searches for new physics beyond the Standard Model and the first discovery of the decay with a significance exceeding $5σ$. As the only experiment proposed in the world dedicated to rare kaon decays, KOTO II will be indispensable in the quest for a complete understanding of flavor dynamics in the quark sector. Moreover, by combining efforts from the kaon community worldwide, we plan to develop the KOTO II detector further and expand the physics reach of the experiment to include measurements of the branching ratio of the $K_L\toπ^0\ell^+\ell^-$ decays, studies of other $K_L$ decays, and searches for dark photons, axions, and axion-like particles. KOTO II will therefore obtain a comprehensive understanding of $K_L$ decays, providing further constraints on new physics scenarios with existing $K^+$ results.

hep-ex↗

arXiv2016

Describing the response of saturated SiPMs

We have developed a function which describes SiPM response in both small signal and highly saturated regimes. The function includes the reactivation of SiPM pixels during a single input light pulse, and results in an approximately linear increase of SiPM response in the highly saturated regime, as observed in real SiPMs. This article shows that the function can accurately describe the measured response of real SiPM devices over a wide range of signal intensities.

physics.ins-det↗

arXiv2016

Optimization of layer composition for ILD ECAL

International Large Detector (ILD) adopts Particle Flow Algorithm (PFA) for precise measurement of multiple jets. The electromagnetic calorimeter (ECAL) of ILD has two candidates sensor technologies for PFA, which are pixelized silicon sensors and scintillator-strips with silicon photomultipliers. Pixelized silicon sensors have higher granularity for PFA, however they have an issue of cost reduction. In contrast, scintillator-strips have an advantage of relatively low cost and a disadvantage of degradation of position resolution by ghost hits, which are generated by orthogonal arrangement. Hybrid ECAL using both candidates is proposed to supplement these disadvantages. In this paper, we report an optimization study of the hybrid ECAL using detector simulation.

physics.ins-det↗

arXiv2014

Extraction Method of Fine Granular Performance from Scintillator Strip Electromagnetic Calorimeter

We describe an algorithm which has been developed to extract fine granularity information from an electromagnetic calorimeter with strip-based readout. Such a calorimeter, based on scintillator strips, is being developed to apply particle flow reconstruction to future experiments in high energy physics. Tests of this algorithm in full detector simulations, using strips of size 45 x 5 mm^2 show that the performance is close to that of a calorimeter with true 5 x 5 mm^2 readout granularity. The performance can be further improved by the use of 10 x 10 mm^2 tile- shaped layers interspersed between strip layers.

physics.ins-det↗

arXiv2014

Scintillator Strip ECAL Optimization

The CALICE collaboration is developing a granular electromagnetic calorimeter using small scintillator strips for a future linear collider experiment. On developing of ~ 10^7 channel-ECAL in particle flow approach, CALICE is developing a technological prototype with 144 of 5 x 45 x (1 - 2) mm^3 strips on each 180 x 180 mm^2 base board unit in tandem with developing the design of scintillator strip and pixelated photon detector and their coupling after established the physics prototype which has required performance. A method of event reconstruction in such ECAL is also developed.

physics.ins-det↗

arXiv2012

Performance of the CALICE Scintillator-Based ECAL Depending on the Temperature

The CALICE collaboration is developing a granular electromagnetic calorimeter using (5-10) mm x 45 mm x 3 mm scintillator strips for a future linear collider experiment. Each scintillator strip is read out by using a Pixelated Photon Detector (PPD). A prototype module has been constructed and tested at Fermilab in 2008 and 2009. Since the sensitivity of the PPD is affected by temperature fluctuations, a temperature correction method has been established which performed such that the deviation of the measured response from a linear behavior is improved from greater than 10% to less than 1.5%.

physics.ins-det↗

arXiv2010

Status of Simulation Tools for the ILD ScECAL

The scintillator-strip electromagnetic calorimeter (ScECAL) is one of the calorimeter technic for the ILC. To achieve the fine granularity from the strip-segmented layers the strips in odd layers are orthogonal with respect to those in the even layers. In order to extract the best performance from such detector concept, a special reconstruction method and simulation tools are being developed in ILD collaboration. This manuscript repots the status of developing of those tools.

physics.ins-det↗

arXiv2004

Measurement of positron lifetime to probe the mixed molecular states of liquid water

Positron lifetime spectra were measured in liquid water at temperatures between 0c and 50c. The long lifetime of ortho-positronium atoms (o-Ps) determined by electron pick-off in molecular substances decreases smoothly by 10% as the temperature is raised. This lifetime temperature dependence can be explained by combining the Ps-bubble model and the mixture state model of liquid water.

cond-mat.other↗