current interactions on iron in the NINJA experiment Contents Toho - PowerPoint PPT Presentation

Study of neutrino charged current interactions on iron in the NINJA experiment Contents Toho Univ. , Nagoya Univ., Kobe Univ., ・ Introduction Nihon Univ., Kyoto Univ., Yokohama national Univ. ICRR and Univ. of Tokyo ・ NINJA experiment ・ Detector construction H. Oshima , H. Shibuya, S. Ogawa, ・ν event analysis T. Matsuo, Y. Morimoto, K. Mizuno, ・ Outcomes H. Takagi, Y. Kosakai, ・ Summary & Prospect for NINJA Collaboration 7416001o@nc.toho-u.ac.jp Monday 9th September 2019 The 16 st Topics in Astroparticle and Underground Physics (TAUP2019)

Introduction : Neutrino Interactions ・ hard to detect the low energy protons. ・ pions can be re- scattered, charge exchanged or absorbed in nucleus. E ν reconstruction (CCQE) T. Kikawa : Shin-gakujutsu Workshop(2018) Residual of Neutrino Energy(MC) CCQE Number of events (a.u.) Hard to separate interaction modes. NEUT 5.4.0 CCRES Iron int. → Neutrino energy reconstruction can 2p2h be mistaken. → This is a major systematic uncertainty E rec – E true in neutrino oscillation experiments. (GeV) 1

Introduction : What we can measure What we can measure to solve this problem : ・ the number of charged hadrons ・ their emission angles and momenta with wide angle acceptance and low energy threshold. We use an emulsion-based detector, Emulsion Cloud Chamber(ECC), which has sub-micron position resolution with wide angle acceptance. We can measure charged hadron final states with low energy threshold. 2

NINJA experiment (J-PARC T60 / T66 / T68 / E71) Neutrino no Intera racti tion on rese sear arch ch with th Nuclea ear r emuls lsion on and J-PAR ARC C Accele lera rator tor The NINJA collaboration aims to study neutrino-nucleus interactions in the energy range of hundreds of MeV to a few GeV by using emulsion-based detector. → We can study ν– nucleus interactions with sub-micron accuracy. → We can use various target (Fe, H 2 O, C, etc. ) NINJA Run so far A) Detector test run with emulsion shifter → published PTEP. 063C02(2017), PTEP. 063H02 (2017) B-1) 65kg iron target run (2016) → analysis on-going This talk B-2) 3kg water target run (2017-2018) → analysis on-going A. Hiramoto (oral, TAUP2019, 09/09) C) Physics run (75kg water, 130kg iron, CH 15kg target) → under preparation J - PARC Materials and Life Science Hadron Beam Facility Experimental Facility Nuclear Transmutation Neutrino to Kamiokande 3 Gev Rapid-Cycling 50 Gev Main Ring 3 Synchrotron, RCS Linac(330m) Synchrotron (0.75MW) (25 Hz, 1MW)

NINJA iron target run in 2016 : Detector construction Detector ： Overall view Side view ECC Shifter INGRID μ range detector (T2K near detector) (no magnet) ECC1 2 3 4 muon ID select CC int. ECC (Emulsion Cloud Chamber) analyze a Neutrino - Fe interaction Emulsion multi-stage Emulsion Film ＋ Iron PL stacked chamber Shifter Total ： 12 ECC (264 Iron PLs, 65kg) Size of Iron Plate (Film) : 25cm × 25cm × 0.05 (0.03) cm Add Metal plate timestamp Emulsion film for event tracks from ν event ν int. microscope picture Metal plate Emulsion film 4 Emulsion have no dead time, but do not have time resolution.

An example of ν – iron interaction (NINJA iron target run in 2016) Emulsion layer image by microscope system (FTS @ Toho Univ.) ν 281.6 um ν IronPL 500um This layer emulsion 60um base 180um 60um 5 354.6 um

Expected Neutrino Flux @ ECCs Beam Exposure @ SS floor, Feb. – May 2016 Neutrino Beam Mode Anti-Neutrino Beam Mode ー ν 𝜈 ー ν 𝜈 ー ത ー ത ν 𝜈 ν 𝜈 0.40 × 10 20 POT 3.53 × 10 20 POT Neutrino no Beam Mode Anti-Ne Neutr utrino no Beam Mode 95.9 % 7.8 % ν 𝜈 4.1 % 92.2 % ν 𝜈 ത POT 0.40 × 10 20 3.53 × 10 20 𝐹 ν average ν : 1.49 GeV / anti - ν : 1.52 GeV ν : 2.12 GeV / anti - ν : 1.30 GeV 𝐹 ν peak ν : 0.90 GeV / anti - ν : 0.70GeV ν : 0.90 GeV / anti - ν : 0.90 GeV 6

Expected CC Events in ECCs NEUT 5.4.0, Iron CC int. (tuned flux) Anti-Neutrino Beam Mode Neutrino Beam Mode QE QE Number of events 2p2h 2p2h COH COH RES RES DIS DIS DFR DFR Other Other ν 𝜈 ത ν 𝜈 𝐹 ν [𝐻𝑓𝑊] 𝐹 ν [𝐻𝑓𝑊] Neutrino no Beam Mode Anti-Ne Neutr utrino no Beam Mode POT Normalize factor : 0.40 × 10 20 3.53 × 10 20 ・ POT ν 𝜈 CC int. 98.6 % 28.2 % ・ target mass ν 𝜈 CC int. 1.4 % 71.8 % ത We can get the high purity ν – iron CC interactions by selecting ν beam mode events. => In this talk, we analyze these ν CC interactions . 7

Flow of event reconstruction Overall view of detector (NINJA iron target run in 2016) Detector preparation @Nagoya Univ. , Toho Univ. Beam exposure @J-PARC SS floor Development, Swelling Track scanning @Nihon Univ. Track Scanning(HTS) @ Nagoya Univ. ν event FTS picture Track & Event reconstruction @ Toho Univ., Nagoya Univ. Event eye check （ FTS)@ Toho Univ. 8

Extract ν CC interaction events by ScanBack method Data ： 12 ECCs （ Target mass 65 kg (fiducial mass 43 kg) ） ECC Muon ID track ： 47,901 tracks Muon ID t track # of Tracks 13,621 tracks FV out 3,2962 tracks Wall (sand- μ, π, p) 1,318 tracks ν + ത ν CC Event candidate Trace back to vertex in ECC from INGRID via shifter. ν + ത ν int.(CC+NC) + cosmic-ray ν CC int. μ cand. ν CC int. events ECC tracks ν CC int. selection with shifter + INGRID ： Event reconstruction ： Timestamp + Muon ID Attaching track search 9

Extract ν CC interaction events by ScanBack method Data ： 12 ECCs （ Target mass 65 kg (fiducial mass 43 kg) ） ECC Muon ID track ： 47,901 tracks Muon ID t track # of Tracks 13,621 tracks FV out 3,2962 tracks Wall (sand- μ, π, p) 1,318 tracks ν + ത ν CC Event candidate (preliminary) ν beam event selection efficiency : ~ 27 % (NEUT 5.4.0 ν - iron int., Normalization : POT, Target mass) We are analyzing the ν CC interactions. ν beam : 221 events. The res esul ults s on the he foll llowing owing slid ides s are re Iron n int. t. : 194 even ents. s. Emulsion int. : 13 events. based on these 194 ν -iron iron Char arge ged d Current rrent Base int. : 14 events. int nteracti eraction ons. s. ν beam : 1,097 events. → Analysis on-going. ത 10 10

dE/dx & momentum measurments in iron ECC Volume Pulse Height (VPH) VPH distribution (Iron ECC tracks) VPH is a measure of dE/dx. The number of tracks μ, p, π Base layer (180um) Emulsion layer (60um) track VPH T. Toshito Nucl. Instr. Heavily ionizing particles A, 556(2006) 482-489 MIP VPH is the sum of the number of hit pixels in all 16 layers. Momentum measurements in iron ECC Measure momentum in three ways and use the best method for each track. Range – energy relation for a short track (P μ err. ~ 16%, P p/π err. ~ 5%) Measurement of Multiple Coulomb Scattering ・ Coordinate method (1/pβ error sys. ~10%, stat. < ~45%) ・ Angular method (Nucl. Instrum. Meth. A574 (2007) 192-198.) (1/pβ error sys. ~20%, stat. < ~50%) 11 11

P roton and π ± PID in ECC The number of tracks ←μ ± / π ± (mip) like Likelihood function −(𝑊𝑄𝐼−𝜈 𝑞𝛾,𝑏𝑜𝑕𝑚𝑓 ) 2 1 L = 2𝜌𝜏 𝑞𝛾,𝑏𝑜𝑕𝑚𝑓 exp[ ] 2 2𝜏 𝑞𝛾,𝑏𝑜𝑕𝑚𝑓 Likelihood Ratio ↓ proton like σ mip σ p 𝑀 𝑛𝑗𝑞 𝑚𝑗𝑙𝑓 LR = VPH μ p μ mip 𝑀 𝑛𝑗𝑞 𝑚𝑗𝑙𝑓 +𝑀 𝑞𝑠𝑝𝑢𝑝𝑜 𝑚𝑗𝑙𝑓 Likelihood Ratio (NEUT 5.4.0, ν -Iron CC int.) VPH vs. Pβ (Real data) VPH Pβ < 0.6 GeV/c ・ muon cand. preliminary # of tracks (INGRID matching) Proton : eff. 94%, purity 98% ・ pion like Pion : eff. 94%, purity 82% ・ proton like pion ID proton ID LR Pβ(GeV/c) → p / π ± separation by using VPH and pβ is good. 12 12 Previous study Y. Morimoto (Toho Univ.), O. Sato (Nagoya Univ.), T. Toshito Nucl. Instr. A, 556(2006) 482-489.

Setup of Monte Carlo simulation Event Generator : NEUT 5.4.0 Used in Super-Kamiokande, T2K and the various experiments. NEUT covers a wide energy range of neutrino from several tens of MeV to hundreds of TeV. Y. Hayato, Nucl. Phys. B, Proc. Suppl. 112, 171 (2002), Y. Hayato, Acta Phys. Pol. B 40, 2477 (2009). Normalization : POT & target mass of NINJA 65kg iron target run in 2016. Considered particle : Muon, charged pion, proton Detector response : Angle … no smeared Momentum … MCS 1/Pβ err. = 50% Range P μ err. = 16% (using ECC and INGRID iron plates(65mm)) P p/π err. = 5% (using ECC iron plates(0.5mm)) 13 13

Muon angle & momentum distribution Detection condition Nplane(Number of INGRID iron layers) ≧ 2 ⇒ P μ > ~300 MeV/c | tanθx | ≦ 1.7, | tanθy | ≦ 1.7, Muon angle Muon momentum Number of events ☩ ： Real data ☩ ： Real data Histogram ： MC Histogram ： MC Preliminary Preliminary Pμ (GeV/c) θμ (deg.) ・ Angular distribution is limited to the forward direction because muon ID is performed by matching with ECC-Shifter-INGRID. ・ Real Data and MC agree well. 14