The T2K long-baseline neutrino oscillation experiment is running in Japan. The primary goals of the T2K are measurement of the mixing angle  13, and precise measurements of the mixing angle  23 and of the mass difference  m2 23. The installation of the near detector complex was completed and first data were already registered. This article presents operation of the Side Muon Range Detector, a component of the Off-Axis near detector. Detector concept and implementation are presented, followed by a description of cosmic muon track reconstruction algorithm and finally current status

Aoki, S.

Brinson, J.

Błocki, J.

Danko, I.

Dziewiecki, M.

Dąbrowska, A.

Ellison, B.

Golan, T.

Golyshkin, L.

Gould, R.

Hara, T.

Hartfiel, B.

Holeczek, Jacek

Izmaylov, A.

Khabibullin, M.

Khotjantsev, A.

Kiełczewska, D.

Kisiel, Jan

Kozłowski, T.

Kudenko, Y.

Kulkarni, N.

Kurjata, R.

Kutter, T.

Liu, J.

Marzec, J.

Metcalf, W.

Mijakowski, P.

Mineev, O.

Naples, D.

Nauman, M.

Northacker, D.

Nowak, J.

Paolone, V.

Posiadała, M.

Przewłocki, P.

Reid, J.

Rondio, E.

Shabalin, E.

Smith, D.

Sobczyk, J.

Stodulski, M.

Straczek, A.

Sulej, R.

Suzuki, A.T.

Szeglowski, Tomasz

Szeptycka, M.

Warner, D.

Wąchała, T.

Yano, T.

Yershov, N.

Zalewska, A.

Zaremba, K.

Ziembicki, M.

Łagoda, J.

Świerblewski, J.

Żmuda, J.

Acta Physica Polonica B

English

Repozytorium Uniwersytetu Śląskiego RE-BUŚ

             Title: The SMRD subdetector at the T2K near detector station  Author: M. Ziembicki, R. Sulej, S. Aoki, J. Błocki, J. Brinson, A. Dąbrowska, Jacek Holeczek, Jan Kisiel, Tomasz Szeglowski i in.  Citation style: Ziembicki M., Sulej R., Aoki S., Błocki J., Brinson J., Dąbrowska A., Holeczek Jacek, Kisiel Jan, Szeglowski Tomasz i in. (2010). The SMRD subdetector at the T2K near detector station. "Acta Physica Polonica B" (Vol. 41, no. 7 (2010), s. 1579-1584).  Vol. 41 (2010) ACTA PHYSICA POLONICA B No 7THE SMRD SUBDETECTOR AT THE T2KNEAR DETECTOR STATION∗M. Ziembickig, R. Suleji, S. Aokie, J. Błockih, J. BrinsonaA. Dąbrowskah, I. Dankoc, M. Dziewieckig, B. EllisonaT. Golank L. Golyshkind, R. Goulda, T. Harae, B. HartfielaJ. Holeczekj, A. Izmaylovd, M. Khabibullind, A. KhotjantsevdD. Kiełczewskaf , J. Kisielj, T. Kozłowskii, Y. KudenkodN. Kulkarnia, R. Kurjatag, T. Kuttera, J. Łagodai, J. LiuaJ. Marzecg, W. Metcalfa, P. Mijakowskii, O. MineevdD. Naplesc, M. Naumana, D. Northackerc, J. NowakaV. Paolonec, M. Posiadałaf , P. Przewłockii, J. Reida, E. RondioiE. Shabalind, D. Smitha, J. Sobczykk, M. StodulskihA. Straczekh, A.T. Suzukie, J. Świerblewskih, T. SzeglowskijM. Szeptyckai, T. Wąchałah, D. Warnerb, T. YanoeN. Yershovd, A. Zalewskah, K. Zarembag, J. ŻmudakaDepartment of Physics and Astronomy, Louisiana State University, USAbDepartment of Physics, Colorado State University, USAcDepartment of Astronomy and Physics, University of Pittsburgh, USAdInstitute for Nuclear Research, Moscow, RussiaeKobe University, JapanfInstitute of Experimental Physics, University of Warsaw, PolandgInstitute of Radioelectronics, Warsaw University of Technology, PolandhThe H. Niewodniczański Institute of Nuclear Physics PAN, PolandiThe A. Sołtan Institute of Nuclear Studies, PolandjInstitute of Physics, University of Silesia, PolandkInstitute of Theoretical Physics, Wrocław University, Poland(Received May 27, 2010)The T2K long-baseline neutrino oscillation experiment is running inJapan.The primary goals of the T2K are measurement of the mixing angleθ13, and precise measurements of the mixing angle θ23 and of the mass dif-ference ∆m223. The installation of the near detector complex was completedand first data were already registered. This article presents operation of theSide Muon Range Detector, a component of the Off-Axis near detector. De-tector concept and implementation are presented, followed by a descriptionof cosmic muon track reconstruction algorithm and finally current status.PACS numbers: 29.40.Mc, 85.60.Gz∗ Presented at the Cracow Epiphany Conference on Physics in UndergroundLaboratories and Its Connection with LHC, Cracow, Poland, January 5–8, 2010.(1579)1580 M. Ziembicki et al.1. IntroductionThe T2K (Tokai to Kamioka) experiment [1, 2] is a second generationlong-baseline neutrino oscillation experiment located in Japan. The goals ofthe T2K are measurement of the neutrino mixing angle θ13 (sensitivity forsin2 2θ13 > 0.006) and precise measurement of the mixing angle θ23 and ofthe mass difference ∆m223 (δ(sin2 2θ23) = 0.01 and δ(∆m223) = 10−4 eV2).The T2K Off-Axis νµ beam is generated with the 30GeV proton synchrotronat the J-PARC facility (Japan Proton Accelerator Research Complex). Thebeam direction is inclined 2.5 degree with respect to the direction of the fardetector — Super-Kamiokande (SK), located 295 km away. This beam allowsthe measurement of the oscillation parameters with the neutrino energies of500÷ 700MeV, which gives the oscillation maximum at the SK.The near detector complex, ND280 [3, 4], is designed to measure theproperty and interaction cross-sections of the ν beam before its oscillation.It is located 280m downstream from the hadron production target. TheND280 consists of two parts:• The On-Axis detector (INGRID), placed on the beam axis, allowingdirect measurement of the direction and of the profile of the ν beam.• The Off-Axis detectors (Fig. 1), placed on the direction to SK, forthe measurement of the neutrino beam flux, energy spectrum, flavorcontents and neutrino cross-sections. These detectors are placed insidethe UA1 magnet, which provides horizontal uniform magnetic field of0.2T for the Off-Axis detectors.Fig. 1. ND280 Off-Axis detector.The SMRD Subdetector at the T2K Near Detector Station 15812. Side muon range detector2.1. Detector concept and implementationThe side muon range detector (SMRD) is one of the components of theOff-Axis detector. The goals of SMRD are:1. Energy measurement of muons generated in charged current neutrinointeractions;2. Identification of backgrounds from beam neutrino interactions in themagnet yokes and in the walls of the experimental hall;3. Generation of cosmic ray trigger signals for the calibration of innerdetectors.The SMRD is designed as a multi layered structure made of plastic scin-tillation counters and iron yokes of the UA1 magnet. Each magnet yokeis made of sixteen 48mm iron plates with 17mm air gaps between them(Fig. 2(a)). The scintillation counters (Fig. 2(b)), grouped into modulesusing aluminum H-profiles (Fig. 2(c)), are placed inside the gaps and fixedusing phosphorus-bronze springs1 (Fig. 2(a)). The number of counters forthe horizontal modules is four and for the vertical ones is five. Each mod-ule is equipped with two temperature sensors2, placed on opposite sides.There are 3 layers of the scintillators per magnet yoke, with the 3 down-stream yokes equipped with 1 to 3 additional vertical layers (making a totalof 4 to 6 vertical layers).Fig. 2. (a) Module fixing inside the magnet yokes; (b) SMRD counter with awavelength shifting fiber; (c) Vertical SMRD module.The counters3 are made from Polystyrene based scintillator, with a re-flective coating made by etching the outer surface using chemical agent andsubsequent fixing of the diffuse film [5]. The dimensions of individual coun-1 Phosphorus content is 0.3%.2 DS18B20, 1-Wire bus, manufactured by Maxim-Dallas Semiconductor.3 Produced by extrusion at Uniplast company in Vladimir, Russia and assembled atINR RAS.1582 M. Ziembicki et al.ters are 875 × 175 × 7mm3 and 875 × 167 × 7mm3 for vertical and hori-zontal ones, respectively. A total of 2008 counters have been installed. Theoptical signal is extracted from the scintillator slab using Kuraray Y11 [6]wavelength shifting fiber (1mm diameter), placed in an S-shaped groove(Fig. 2(b)). The readout is performed with two 667 pixel, 1.3 × 1.3 mm2Hamamatsu MPPCs, [7,8] attached to both ends of the fiber and working incoincidence mode. The light yield was found to be 25 to 50 p.e./MIP, result-ing in MIP detection efficiency better than 99% [9]. The spatial resolutionwas measured as 6.1±0.8 cm, derived from signal timing [10]. Due to the factthat the photosensors used are relatively new and, to date, have not beenused on such a large scale, an extensive testing has been performed4, whichrevealed good sensor quality. A description of one of these tests can be foundin [11]. A system for on-line monitoring has also been developed, allowing forrealtime data analysis — currently only MPPC gain and dark count rate arechecked, based on channel histograms, but the work is on-going to extendthe system to allow readout of temperature data, displaying per-channelhistory, threshold calculation and monitoring the quality of physics data.2.2. Cosmic muon track reconstructionFirst level of the track reconstruction is the estimation of the actualhit times and positions in the scintillator slabs. Photosensor signals areconsidered as hits if they are in the time coincidence (23 ns time window)and above the amplitude threshold of 4.5 p.e. Actual hit position along theWLS fiber direction is calculated from the time difference dt of the signalson both ends of the slab. Bayesian estimate is used with the followingassumptions:1. uniform prior distribution of the hit positions in the scintillator slab;2. Gaussian likelihood of measured dt, based on scintillator slab tests per-formed before the installation. Actual hit time is calculated accordingto the estimated hit position.Simple reconstruction was proposed for cosmic muon data. Straight lineis fitted to the hits reconstructed in the first stage; PCA (Principal Com-ponent Analysis) technique is used. Example of reconstructed muon trackis shown in Fig. 3(a). The distribution of the zenithal angle of the recon-structed cosmic muon tracks was compared to the Monte Carlo simulation.A very good agreement was achieved as shown in Fig. 3(b).4 The sensors have been measured independently at INR Moscow, Luisiana State Uni-versity and Warsaw University of Technology.The SMRD Subdetector at the T2K Near Detector Station 1583Fig. 3. (a) Example of the cosmic muon event — fired scintillators and track fit areshown. (b) Comparison of the distributions of the zenithal angle for cosmic muons:one curve shows the angle of the muon entering the magnet (no reconstruction pro-cedures are applied) for the simulated data, the other one shows the reconstructedtrack angle for the real data.2.3. Current statusThe detector has been installed in July 2009 and fully commissioned.Only few broken channels were found (some of them already repaired) andmore than 99.8% of all 4016 channels function correctly. Data acquisitionworks and first cosmic muon tracks were already reconstructed. Currently,main efforts concentrate on detector calibrations, development of an on-linemonitoring system and a cosmic muon trigger — both simulation and settingup the trigger itself. Preliminary data show that the cosmic trigger simula-tion and real data agree well. Also, different reconstruction approaches arebeing pursued for beam events.3. SummaryT2K long-baseline neutrino oscillation experiment is currently runningin Japan. The description and current status of one of the components ofthe Off-Axis near detector — the Side Muon Range Detector has been pre-sented. The detector is fully operational and first cosmic muon tracks werealready registered and reconstructed. Current efforts concentrate arounddetector calibrations, an on-line monitoring system, a cosmic trigger andreconstruction of muon tracks (both cosmic and beam related).This work is partially supported by the Polish Ministry of Science andHigher Education, grant number 35/N-T2K/2007/0.1584 M. Ziembicki et al.REFERENCES[1] Y. Itow et al., hep-ex/0106019.[2] D. Kiełczewska, Acta Phys. Pol. B 41, 1565 (2010), this issue.[3] Yu. Kudenko, arXiv:0805.0411.[4] T2K ND280 Conceptual Design Report, T2K Internal Documents.[5] Yu. Kudenko et al., Nucl. Instrum. Methods A469, 340 (2001).[6] Kuraray Co., Ltd, Kuraray Technical Information, Scintillation Materials,Nihonbashi, Chuo-ku, Tokzo 103-8254, Japan.[7] http://www.hamamatsu.com.[8] M. Yokoyama et al., arXiv:0807.3145.[9] A. Izmaylov et al., arXiv:physics/0904.4545v1.[10] T. Yano et al., Proceedings of the XXIX Physics in Collision, Kobe, Japan,Aug. 30–Sept. 2, 2009.[11] M. Dziewiecki et al., PoS PD09 016.

The SMRD subdetector at the T2K near detector station

https://rebus.us.edu.pl/bitstream/20.500.12128/7180/1/Ziembicki_The_SMRD_subdetector.pdf

The SMRD subdetector at the T2K near detector station

Abstract

Similar works

Full text

Available Versions

Repozytorium Uniwersytetu Śląskiego RE-BUŚ