arXiv subjects

S. Narita

Publications and source records attributed to S. Narita.

8 recordsLinked to original sources

arXiv2025

Status of the International Linear Collider

This paper is not a proposal for a CERN future project but provides information on the International Linear Collider (ILC) considered for Japan in order to facilitate the European Strategy discussion in a global context. It describes progress to date, ongoing engineering studies, updated cost estimate for the machine at $\sqrt{s}=250~\rm GeV$ and the situation in Japan. The physics of the ILC is not presented here, but jointly for all Linear Collider projects in a separate document ``A Linear Collider Vision for the Future of Particle Physics'' submitted for the forthcoming European Strategy deliberations.

hep-ex↗

arXiv2022

A novel technique for the measurement of the avalanche fluctuations of a GEM stack using a gating foil

We have developed a novel technique for the measurement of the size of avalanche fluctuations of gaseous detectors using a gating device (gating foil) prepared for the time projection chamber in the international linear collider experiment (ILD-TPC). In addition to the gating function, the gating foil is capable of controlling the average fraction of drift electrons detected after gas amplification. The signal charge width and shape (skewness) for electron-ion pairs created by a pulsed UV laser as a function of the transmission rate of the gating foil can be used to determine the relative variance of gas gain for single electrons. We present the measurement principle and the result obtained using a stack of gas electron multipliers (GEMs) operated in a gas mixture of Ar-CF$_4$(3%)-isobutane(2%) at atmospheric pressure. Also discussed is the influence of the avalanche fluctuations on the spatial resolution of the ILD-TPC.

physics.ins-det↗

arXiv2020

LTARS: Analog Readout Front-end ASIC for Versatile TPC-applications

We designed a versatile analog front-end chip, called LTARS, for TPC-applications, primarily targeted at dual-phase liquid Ar-TPCs for neutrino experiments and negative-ion $μ$-TPCs for directional dark matter searches. Low-noise performance and wide dynamic range are two requirements for reading out the signals induced on the TPC readout channels. One of the development objectives is to establish the analog processing circuits under low temperature operation, which are designed on function block basis as reusable IPs (Intellectual Properties). The newly developed ASIC was implemented in the Silterra 180~nm CMOS technology and has 16 readout channels. We carried out the performance test at room temperature and the results showed an equivalent noise charge of 2695$\pm$71~e$^-$ (rms) with a detector capacitance of 300~pF. The dynamic range was measured to be 20--100~fC in the low-gain mode and 200--1600~fC in the high-gain mode within 10\% integral nonlinearity at room temperature. We also tested the performance at the liquid-Ar temperature and found a deterioration of the noise level with a longer shaper time. Based on these results, we also discuss a unique simulation methodology for future cold-electronics development. This method can be applicable to design the electronics used at low temperature.

physics.ins-det↗

arXiv2019

Measurement of the electron transmission rate of the gating foil for the TPC of the ILC experiment

We have developed a gating foil for the time projection chamber envisaged as a central tracker for the international linear collider experiment. It has a structure similar to the Gas Electron Multiplier (GEM) with a higher optical aperture ratio and functions as an ion gate without gas amplification. The transmission rate for electrons was measured in a counting mode for a wide range of the voltages applied across the foil using an $^{55}$Fe source and a laser in the absence of a magnetic field. The blocking power of the foil against positive ions was estimated from the electron transmissions.

physics.ins-det↗

arXiv2014

The LBNO long-baseline oscillation sensitivities with two conventional neutrino beams at different baselines

The proposed Long Baseline Neutrino Observatory (LBNO) initially consists of $\sim 20$ kton liquid double phase TPC complemented by a magnetised iron calorimeter, to be installed at the Pyhäsalmi mine, at a distance of 2300 km from CERN. The conventional neutrino beam is produced by 400 GeV protons accelerated at the SPS accelerator delivering 700 kW of power. The long baseline provides a unique opportunity to study neutrino flavour oscillations over their 1st and 2nd oscillation maxima exploring the $L/E$ behaviour, and distinguishing effects arising from $δ_{CP}$ and matter. In this paper we show how this comprehensive physics case can be further enhanced and complemented if a neutrino beam produced at the Protvino IHEP accelerator complex, at a distance of 1160 km, and with modest power of 450 kW is aimed towards the same far detectors. We show that the coupling of two independent sub-MW conventional neutrino and antineutrino beams at different baselines from CERN and Protvino will allow to measure CP violation in the leptonic sector at a confidence level of at least $3σ$ for 50\% of the true values of $δ_{CP}$ with a 20 kton detector. With a far detector of 70 kton, the combination allows a $3σ$ sensitivity for 75\% of the true values of $δ_{CP}$ after 10 years of running. Running two independent neutrino beams, each at a power below 1 MW, is more within today's state of the art than the long-term operation of a new single high-energy multi-MW facility, which has several technical challenges and will likely require a learning curve.

hep-ph↗

arXiv2014

Optimised sensitivity to leptonic CP violation from spectral information: the LBNO case at 2300 km baseline

One of the main goals of the Long Baseline Neutrino Observatory (LBNO) is to study the $L/E$ behaviour (spectral information) of the electron neutrino and antineutrino appearance probabilities, in order to determine the unknown CP-violation phase $δ_{CP}$ and discover CP-violation in the leptonic sector. The result is based on the measurement of the appearance probabilities in a broad range of energies, covering t he 1st and 2nd oscillation maxima, at a very long baseline of 2300 km. The sensitivity of the experiment can be maximised by optimising the energy spectra of the neutrino and anti-neutrino fluxes. Such an optimisation requires exploring an extended range of parameters describing in details the geometries and properties of the primary protons, hadron target and focusing elements in the neutrino beam line. In this paper we present a numerical solution that leads to an optimised energy spectra and study its impact on the sensitivity of LBNO to discover leptonic CP violation. In the optimised flux both 1st and 2nd oscillation maxima play an important role in the CP sensitivity. The studies also show that this configuration is less sensitive to systematic errors (e.g. on the total event rates) than an experiment which mainly relies on the neutrino-antineutrino asymmetry at the 1st maximum to determine the existence of CP-violation.

hep-ph↗

arXiv2012

Performance of a 250L liquid Argon TPC for sub-GeV charged particle identification

We have constructed a liquid Argon TPC detector with fiducial mass of 150 kg as a part of the R&D program of the next generation neutrino and nucleon decay detector. This paper describes a study of particle identification performance of the detector using well-defined charged particles (pions, kaons, and protons) with momentum of ~800 MeV/$c$ obtained at J-PARC K1.1BR beamline.

physics.ins-det↗

arXiv2011

A tagged low-momentum kaon test-beam exposure with a 250L LAr TPC (J-PARC T32)

At the beginning of 2010, we presented at the J-PARC PAC an R$&$D program towards large (100 kton scale) liquid argon TPCs, suitable to investigate, in conjunction with the J-PARC neutrino beam, the possibility of CP violation in the neutrino sector and to search for nucleon decay. As a first step we proposed a test experiment to identify and measure charged kaons, including their decays, in liquid argon. The detector, a 250L LAr TPC, is exposed to charged kaons, in a momentum range of 540-800 MeV/c, in the K1.1BR beamline of the J-PARC slow extraction facility. This is especially important to estimate efficiency and background for nucleon decay searches in the charged kaon mode ($p \rightarrow \barν K^+$, etc.), where the kaon momentum is expected to be in the few hundred MeV/c range. A prototype setup has been exposed in the K1.1BR beamline in the fall of 2010. This paper describes the capabilities of the beamline, the construction and setting up of the detector prototype, along with some preliminary results.

physics.ins-det↗