Application of Hamamatsu MPPC to T2K Neutrino Detectors

A special type of Hamamatsu MPPC, with a sensitive area of 1.3x1.3mm^2 containing 667 pixels with 50x50um^2 each, has been developed for the near neutrino detector in the T2K long baseline neutrino experiment. About 60 000 MPPCs will be used in total to read out the plastic scintillator detectors with wavelength shifting fibers. We report on the basic performance of MPPCs produced for T2K.Comment: Contribution to the proceedings of NDIP 2008, Aix-les-Bains, France, June 15-20, 200

Performance of Multi-Pixel Photon Counters for the T2K near detectors

We have developed a Multi-Pixel Photon Counter (MPPC) for the neutrino detectors of T2K experiment. About 64,000 MPPCs have been produced and tested in about a year. In order to characterize a large number of MPPCs, we have developed a system that simultaneously measures 64 MPPCs with various bias voltage and temperature. The performance of MPPCs are found to satisfy the requirement of T2K experiment. In this paper, we present the performance of 17,686 MPPCs measured at Kyoto University.Comment: 15 pages, 14 figure

Mass production test of Hamamatsu MPPC for T2K neutrino oscillation experiment

In the T2K near neutrino detectors, about 60 000 Hamamatsu Multi-Pixel Photon Counters (MPPCs) will be used. The mass production of MPPC has started in February 2008.In order to perform quality assurance and to characterize each device, we have developed an MPPC test system. For each MPPC, gain, breakdown voltage, noise rate, photo detection efficiency, and cross-talk and after-pulse rate are measured as functions of the bias voltage and temperature. The design of the test system and the measurement procedure are described.Comment: Contribution to the proceedings of NDIP 2008, Aix-les-Bains, France, June 15-20, 200

Drift field generation with Cockcroft-Walton voltage multiplier in xenon gas for AXEL 0vββ search detector

16th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2019) 9-13 September 2019, Toyama, JapanFor noble gas Time Projection Chambers (TPCs) in the field of rare event searches, operation of high voltage to generate an electric field is a key point. We designed a new structure of electrodes to shape a strong and uniform drift field without electric discharge, in which electrodes of two different radius are used. We also developed Cockcroft-Walton voltage multiplier as a high voltage generator inside a pressure vessel. We achieved −30.0 kV output and examined such kind of voltage generator is feasible as a high voltage supplier in a TPC

Design and performance of a high-pressure xenon gas TPC as a prototype for a large-scale neutrinoless double-beta decay search

A high-pressure xenon gas time projection chamber, with a unique cellular readout structure based on electroluminescence, has been developed for a large-scale neutrinoless double-beta decay search. In order to evaluate the detector performance and validate its design, a 180~L size prototype is being constructed and its commissioning with partial detector has been performed. The obtained energy resolution at 4.0~bar is 1.73 $\pm$ 0.07% (FWHM) at 511 keV. The energy resolution at the $^{136}$Xe neutrinoless double-beta decay Q-value is estimated to be between 0.79 and 1.52% (FWHM) by extrapolation. Reconstructed event topologies show patterns peculiar to track end-point which can be used to distinguish $0\nu\beta\beta$ signals from gamma-ray backgrounds.Comment: 24 pages, 25 figures, 1 table. Preprint paper for PTE

Search for nucleon decay via modes favored by supersymmetric grand unification models in Super-Kamiokande-I

We report the results for nucleon decay searches via modes favored by supersymmetric grand unified models in Super-Kamiokande. Using 1489 days of full Super-Kamiokande-I data, we searched for $p \to \bar{\nu} K^+$, $n \to \bar{\nu} K^0$, $p \to \mu^+ K^0$ and $p \to e^+ K^0$ modes. We found no evidence for nucleon decay in any of these modes. We set lower limits of partial nucleon lifetime 2.3$\times10^{33}$, 1.3$\times10^{32}$, 1.3$\times10^{33}$ and 1.0$\times10^{33}$ years at 90% confidence level for $p \to \bar{\nu} K^+$, $n \to \bar{\nu} K^0$, $p \to \mu^+ K^0$ and $p \to e^+ K^0$ modes, respectively. These results give a strong constraint on supersymmetric grand unification models.Comment: 14 pages, 13 figure

Measurement of negatively charged pion spectra in inelastic p+p interactions at plabp_{lab} = 20, 31, 40, 80 and 158 GeV/c

We present experimental results on inclusive spectra and mean multiplicities of negatively charged pions produced in inelastic p+p interactions at incident projectile momenta of 20, 31, 40, 80 and 158 GeV/c ($\sqrt{s} =$ 6.3, 7.7, 8.8, 12.3 and 17.3 GeV, respectively). The measurements were performed using the large acceptance NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. Two-dimensional spectra are determined in terms of rapidity and transverse momentum. Their properties such as the width of rapidity distributions and the inverse slope parameter of transverse mass spectra are extracted and their collision energy dependences are presented. The results on inelastic p+p interactions are compared with the corresponding data on central Pb+Pb collisions measured by the NA49 experiment at the CERN SPS. The results presented in this paper are part of the NA61/SHINE ion program devoted to the study of the properties of the onset of deconfinement and search for the critical point of strongly interacting matter. They are required for interpretation of results on nucleus-nucleus and proton-nucleus collisions.Comment: Numerical results available at: https://edms.cern.ch/document/1314605 Updates in v3: Updated version, as accepted for publicatio

NA61/SHINE facility at the CERN SPS: beams and detector system

NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) is a multi-purpose experimental facility to study hadron production in hadron-proton, hadron-nucleus and nucleus-nucleus collisions at the CERN Super Proton Synchrotron. It recorded the first physics data with hadron beams in 2009 and with ion beams (secondary 7Be beams) in 2011. NA61/SHINE has greatly profited from the long development of the CERN proton and ion sources and the accelerator chain as well as the H2 beamline of the CERN North Area. The latter has recently been modified to also serve as a fragment separator as needed to produce the Be beams for NA61/SHINE. Numerous components of the NA61/SHINE set-up were inherited from its predecessors, in particular, the last one, the NA49 experiment. Important new detectors and upgrades of the legacy equipment were introduced by the NA61/SHINE Collaboration. This paper describes the state of the NA61/SHINE facility - the beams and the detector system - before the CERN Long Shutdown I, which started in March 2013

Pion emission from the T2K replica target: method, results and application

The T2K long-baseline neutrino oscillation experiment in Japan needs precise predictions of the initial neutrino flux. The highest precision can be reached based on detailed measurements of hadron emission from the same target as used by T2K exposed to a proton beam of the same kinetic energy of 30 GeV. The corresponding data were recorded in 2007-2010 by the NA61/SHINE experiment at the CERN SPS using a replica of the T2K graphite target. In this paper details of the experiment, data taking, data analysis method and results from the 2007 pilot run are presented. Furthermore, the application of the NA61/SHINE measurements to the predictions of the T2K initial neutrino flux is described and discussed.Comment: updated version as published by NIM