N. Yershov

The T2K Side Muon Range Detector (SMRD)

The T2K experiment is a long baseline neutrino oscillation experiment aiming to observe the appearance ofe in a �µ beam. The �µ beam is produced at the Japan Proton Accelerator Research Complex (J-PARC), observed with the 295 km distant Super- Kamiokande Detector and monitored by a suite of near detectors at 280m from the proton target. The near detectors include a magnetized off-axis detector (ND280) which measures the un-oscillated neutrino flux and neutrino cross sections. The present paper describes the outermost component of ND280 which is a side muon range detector (SMRD) composed of scintillation counters with embedded wavelength shifting fibers and Multi-Pixel Photon Counter read-out. The components, performance and response of the SMRD are presented.

Scintillator counters with multi-pixel avalanche photodiode readout for the ND280 detector of the T2K experiment

Abstract The Tokai-to-Kamioka (T2K) experiment is a second generation long baseline neutrino oscillation experiment which aims at a sensitive search for ν e appearance. The main design features of the T2K near neutrino detectors located at 280xa0m from the target are presented, and the scintillator counters are described. The counters are readout via WLS fibers embedded into S-shaped grooves in the scintillator from both ends by multi-pixel avalanche photodiodes operating in a limited Geiger mode. Operating principles and results of tests of photosensors with a sensitive area of 1 mm 2 are presented. A time resolution of 1.75xa0ns, a spatial resolution of 9.9 – 12.4 cm , and a detection efficiency for minimum ionizing particles of more than 99% were obtained for scintillator detectors in a beam test.

Multi-pixel Geiger-mode avalanche photodiode and wavelength-shifting fibre-optics readout of plastic scintillator counters for the EMMA underground experiment

The results of a development of a scintillator counter with wavelength shifting (WLS) fibre and a multi-pixel Geiger-mode avalanche photodiode readout are presented. The photodiode has a metal-resistor-semiconductor layered structure and operates in the limited Geiger mode. The scintillator counter has been developed for the EMMA underground cosmic ray experiment.

Test of exotic scalar and tensor interactions in K(e3) decay using stopped positive kaons

The form factors of the decay K+ → π0e+νe (Ke3) have been determined from the comparison of the experimental and Monte Carlo Dalitz distributions containing about 105Ke3 events. The following values of the parameters were obtained: λ+=0.0278±0.0017 (stat.)±0.0015 (syst.), |fS/f+(0)|=0.0040±0.0160 (stat.)±0.0067 (syst.), and |fT/f+(0)|=0.019±0.080 (stat.)±0.038 (syst.). Both scalar fS and tensor fT form factors are consistent with the Standard Model predictions of zero values.

New Limit on the T-Violating Transverse Muon Polarization in K^+ ¿ pi^0mu^+nu Decays

A search for T-violating transverse muon polarization (P(T)) in the K+-->pi(0)mu(+)nu decay was performed using kaon decays at rest. A new improved value P(T)=-0.0017+/-0.0023(stat)+/-0.0011(syst) was obtained giving an upper limit |P(T)|<0.0050. The T-violation parameter was determined to be Imxi=-0.0053+/-0.0071(stat)+/-0.0036(syst) giving an upper limit |Imxi|<0.016.

Background and muon counting rates in underground muon measurements with a plastic scintillator counter based on a wavelength shifting fibre and a multi-pixel avalanche photodiode readout

In this short note we present results of background measurements carried out with polystyrene based cast plastic 12.0×12.0×3.0 cm3 size scintillator counter with a wavelength shifting fibre and a multi-pixel Geiger mode avalanche photodiode readout in the Baksan underground laboratory at a depth of 200 metres of water equivalent. The total counting rate of the scintillator counter measured at this depth and at a threshold corresponding to ∼0.37 of a minimum ionizing particle is approximately 1.3 Hz.

The new experiment WAGASCI for water to hydrocarbon neutrino cross section measurement using the J-PARC beam

The T2K (Tokai-to-Kamioka) is a long baseline neutrino experiment designed to study various parameters that rule neutrino oscillations, with an intense beam of muon neutrinos. A near detector complex (ND280) is used to constrain non-oscillated flux and hence to predict the expected number of events in the far detector (Super-Kamiokande). The difference in the target material between the far (water) and near (scintillator, hydrocarbon) detectors leads to the main non-canceling systematic uncertainty for the oscillation analysis. In order to reduce this uncertainty a new water grid and scintillator detector, WAGASCI, has been proposed. The detector will be operated at the J-PARC neutrino beam line with the main physics goal to measure the charged current neutrino cross section ratio between water and hydrocarbon with a few percent accuracy. Further physics program may include high-precision measurements of different charged current neutrino interaction channels. The concept of the new detector will be covered together with the actual construction plan.

Performance test of new MPPC for a new neutrino detector WAGASCI

F. Hosomi∗,1 N. Chikuma,1 A. Izmaylov,1 T. Koga,1 M. Yokoyama,1 M. Antonova,2 M. Khabibullin,2 A. Khotjantsev,2 Y. Kudenko,2 A. Mefodiev,2 O. Mineev,2 T. Ovsiannikova,2 S. Suvorov,2 N. Yershov,2 A. Bonnemaison,3 R. Cornat,3 O. Drapier,3 O. Ferreira,3 F. Gastaldi,3 M. Gonin,3 Th. A. Mueller,3 A. Blondel,4 F. Cadoux,4 Y. Favre,4 E. Noah,4 M. Rayner,4 T. Hayashino,5 A. K. Ichikawa,5 A. Minamino,5 K. Nakamura,5 T. Nakaya,5 B. Quilain,5 J. Harada,6 K. Kin,6 Y. Seiya,6 K. Yamamoto,6 Y. Hayato7 1The University of Tokyo, Department of Physics, Tokyo, Japan 2Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia 3Ecole Polytechnique, IN2P3-CNRS, Laboratoire Leprince-Ringuet, Palaiseau, France 4University of Geneva, Section de Physique, DPNC, Geneva, Switzerland 5Kyoto University, Department of Physics, Kyoto, Japan 6Osaka City University, Department of Physics, Osaka, Japan 7The University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan

A Spiral Fiber Tracker for the J-PARC E36 experiment

A Spiral Fiber Tracker (SFT) has been developed for use in the E36 experiment at the Japan Proton Accelerator Research Complex (J-PARC). The SFT is designed for conducting high-precision momentum measurement of charge particles from kaon decays and consists of four layers of flat ribbons made of 1 mm diameter plastic scintillating fibers. The ribbons are spirally wound around the kaon stopping target at the center of the detector setup, a single ribbon per layer. A total of 64 fibers are read out by 128 HAMAMATSU MPPCs connected to the scintillating fibers at both ends by clear fiber extensions. The SFT started to collect beam data in the spring of 2015.

Development of electronics and data acquisition system for the J-PARC T59 (WAGASCI) experiment

WAGASCI is a new experiment at J-PARC neutrino beamline, to measure the cross section ratio of charged current neutrino interaction on nucleus between water target and plastic target with the accuracy of a few percent. The detector adopts three-dimensional grid structure of 3-mm-thick scintillator bars around water and plastic targets, to obtain large angular acceptance. As a photodetector a 32-channel arrayed MPPC has been developed for the WAGASCI detector, and the total number of channels is 1280 for each module. Our front-end electronics is SPIROC2D, a product of Omega, which is an auto-triggered, bi-gain, 36-channel ASIC, allowing to measure the charge from one to 2000 photoelectron and the time with 100ps step. It contains a 16-deep analog memory array, which allows to store 16 hits in an acquisition gate. The back-end boards control the data output from the front-end ASIC and reception of trigger signals for neutrino beam. The module construction has been completed and the data acquisition system has almost been completed, to be ready for the neutrino beam measurement from October 2017.