Feb.28,2011 機構シンポ J-PARCニュートリノ の 将来計画 Takashi Kobayashi IPNS/KEK 1 目次 素粒子物理道路計画の中のニュートリノ道路 現在位置と目標地点の確認 道路計画：幹線 道路計画：支線 θ13の決定(T2K)CP非保存（＋陽子崩壊）探索 ニュートリノの性質の徹底解明驚き？ まとめ 2 Neutrino in particle physics Neutrinos have still lots of mystery, for example Extremely small (&unknown) mass not yet understood Flavor relations Not yet fully known Looks very much different from quark structure? Why? May contain some hint to unification? CP is violated also in lepton sector? One promising scenario: See-Saw mechanism (Yanagida 1974) Existence of very large mass Majorana neutrino may explain small neutrino mass Neutrino may be window to see very high energy scale physics? Could provide clue to the mystery of matter dominated universe Big expectation to find breakthrough to answer the fundamental questions in particle physics, such as, what is the unified theory?, origin of mass?, origin of matter in the universe? by attacking and exploring the mystery of the neutrino one by one 3 大雑把にいうと 加速器ニュートリノ物理は～１０％効果を探す(測 る) 山師的時代から～１％の高感度精密測定の 時代へ。 そのために欠くべからざる要素は 大強度ビーム O(100kW)の物理は長年BNL,FNAL,CERNで散々やられ てきた 高性能検出器 4 現在位置と目標地点の確認 5 ニュートリノの３世代混合 フレーバー固有状態 νe νµ ντ U PMNS ν e ユニタリー行列 ν 1 ν µ = U PMNSν 2 ν ν τ 3 0 1 = 0 + c23 0 − s 23 大気、加速器 0 + c13 + s23 0 + c23 − s13eiδ m1 質量固有状態 m2 m3 0 + s13e − iδ + c12 1 0 − s12 0 + c13 0 (大気)、加速器 + s12 + c12 0 0 0 1 太陽、原子炉 ニュートリノ振動をつかさどる６個のパラメータ θ12, θ23, θ13, δ ∆m122, ∆m232, ∆m132 c ij = cos(θ ij ), s ij = sin(θ ij ) 6 What’s are known & unknown? Sol&Reactor •θ12~34o •∆m122~0.00008eV2 Atm+Acc •θ23~45o •∆m232~0.0024eV2 Unknown •θ13<10o • (∆m132~∆m232)? •δ ??? νe?? ν3 ν2 OR ν1 どっち？？ 7 •クォークにくらべまだまだ大雑把 •クォークと大きく異なる構造(大きな混合) 青：PMNS 赤：CKM 1.20±0.80 (7%) 0.201±0.011 (5%) (90%CL) 2.38±0.06 (2.5%) •θ13, δ未知 <10.5° ???????????????????????????? 34.4±1.0 (3%) 13.04±0.05 (0.4%) Angles in mixing matrix (CKM,PMNS) PDG, Concha Gonzalez-Garcia(NOW2010) 8 Unkonwn in neutrinos The last unknown mixing θ13. 3 flavor mixing picture? First indispensable step to go CPV search T2K experiment Reactor experiments CP is violated in lepton sector? Could provide hint for matter-anti-matter asymmetry in the unverse Future Acclerator neutrino experiments Mass hierarchy Future Acclerator neutrino experiments Absolute mass Precision measurement of Tritium beta decay spectrum Neutrino-less double beta decay Neutrino is Majorana ? Dirac? Majorana neutrino: Neutrino = Anti-Neutrino Neutrino-less double beta decay 9 道路計画：幹線 θ13の決定(T2K)CP非保存（＋陽子崩壊）探索 10 Next most important step: θ13. Why? CPV & sign(∆m2) will be probed thru νe appearance in accel LBL Leading CP-odd δ−δ, a-a for ν µ → ν e + other terms.. CP-odd term ∝ sin δ ⋅ s12 ⋅ s23 ⋅ s13 ρ E ⋅ 3 [g cm ] [GeV] Matter eff.: a = 7.56 ×10 −5 [eV 2 ] ⋅ (where sinθ12~0.5, sinθ23~0.7, sinθ13<0.2) The size of θ13 Decide future dir.! 1999日本(戸塚＋西川)が 世界で初めて着目T2K提案 Takashi Kobayashi (KEK), PAC07 11 T2K (Tokai to Kamioka) experiment High intensity νµ beam from J-PARC MR to SuperKamiokande @ 295km Discovery of νe appearance Determine θ13 Precise meas. of νµ disappearance θ23, ∆m232 Near ν detectors 12 Data taking status 135kW(9x1013ppp) 125kW 2010a 100kW 50kW 3.7x1013ppp 2010b Stable data taking started in Jan. 2010 ~135kW stable operation achieved (Feb 14, 2011~) 1.2x1020p’s (59kWx107s) delivered (Feb.21, 2011) We thank CONTINUOUS GREAT EFFORT of accelerator team 13 Mid term goal By summer 2014 1000[kWx1E7s] 速やかな大強度化必須 Now 0.014 1000[kWx1E7s] 14 Quest for the Origin of Matter Dominated Universe One of the Main Subject of the KEK Roadmap T2K (2009~) Discovery of the νe Appearance Neutrino Intensity Improvement Huge Detector R&D Establish Huge Detector Construction of Huge Detector Technology v Water Cherenkov Liquid Ar TPC Discovery of Lepton CP Violation Proton Decay Scenario 1 J-PARC to Okinoshima P32 proposal (Lar TPC R&D) Recommended by J-PARC PAC (Jan 2010), arXiv:0804.2111 Scenario 1 J-PARC to Okinoshima P32 proposal (Lar TPC R&D) Recommended by J-PARC PAC (Jan 2010), arXiv:0804.2111 J-PARC to Okinoshima •Cover 1st and 2nd Maximum •Neutrino Run Only 5Years×1.66MW •100kt Liq. Ar TPC -Good Energy resolution/reconstruction ability -Good e/π０discrimination •Keeping Reasonable Statistics νeSpectrum sin22θ13=0.03,Normal Hierarchy δ=0° δ=90° δ=180° δ=270° CP Measurement Potential 3σ Beam νe Background Okinoshima 658km 0.8deg. almost On-axis P32 proposal (LAr TPC R&D) Encouraged by J-PARC PAC (Jan 2010), NP08, arXiv:0804.2111 Liquid Argon TPC R&D (T32) 250L TPC beam exposure in Oct/Nov, 2010 ETHZ Iwate KEK Waseda Largest K and π samples ever accumulated for Liquid Argon TPC Results will be presented in PAC in July 2011 19 J-PARC-Okinoshima feasibility studies (Some examples) Site visit Potential LiqAr supply 20 実現のためには。 大強度(>1MW)達成 着実な検出器開発継続 21 道路計画：支線 ニュートリノの性質の徹底解明驚き？ 22 Other important physics in LBL experiment (J-PARC SK) Precision measurement of numu disappearance Precise measurement of spectrum shape T2K proposal (3750kWx1E7sec) T2K proposal (3750kWx1E7sec) δ(∆m232)~1x10-4eV2, δ(sin22θ23)~1% Sterile neutrino search Really (only) oscillation??? No other exotic mode???? O(100) neutral current enhanced sample Anti-neutrino measurement (appearance and disappearance) Precision measurement of θ13 23 Precision measurement of numu Disappearance Really follow oscillation pattern?? Mixing really maximal??? Same for anti-nu??? T2K proposal (3750kWx1E7sec) δ(∆m232)~1x10-4eV2, δ(sin22θ23)~1% Need Power!!! 24 Sterile neutrino search in T2K 100% νµ νs disfavored by SK Probe small mixing to sterile Select NC enhanced sample From T2K proposal 2 e-like ring, no decay electron Nevt = 255 vs 104 with “750kWx5yr” From T2K proposal Need Power!!! 25 νe appearance search/measurement in anti-neutrino mode Once finite θ13 is firmly established, move to antineutrino If no signal is observed in neutrino mode (θ13 is small), we need to move to antineutrino at some optimized timing. Some early hint on CPV?? 26 νµ/νµ # of CC int. (Very old sim(2001) w/ 50GeV) νµ beam 1021pot/yr ~800kWx107sec Need Power!!! νµ beam right sign wrong sign # of int. for νµ is factor ~3 smaller than νµ due to cross section. 大強度 (Over several 100kW) 実現不可欠 28 Existing puzzles = Yet another physics opportunities Example LSND/MiniBooNE anomaly 2 2 Sterile neutrino at ∆m ~2eV ?? (Weinberg angle?) 29 Another (sterile) neutrino at large ∆m2 ??? 30 Another (sterile) neutrino at large ∆m2 ??? Need to be concluded! ∆m2~eV2, sin22θ~10-3 L(m)/E(MeV) ~ 1.2 740m @ 600MeV High statistics high sensitivity short baseline νe appearance experiment Suited at J-PARC To decisively conclude High PID performance detector LiqAr? Liq Scin? Energy spectrum measurement Precise normalization 31 Reactor anomaly ?? Recently reactor flux calculation is refined Flux prediction slightly increased Results in almost all experiment observation more smaller than prediction Other disappearance from anti-νe to sterile neutrino? ∆m2~2eV2 To conclude in accelerator experiment Short baseline ne disappearance experiment ~17% deficit expected Very high PID performance required (because nm interaction dominate) High intensity needed! (νe is ~1% of νµ) Precise normalization of νe prediction needed! Near/far configuration?? Dichromatic beam?? 32 The Reactor Antineutrino Anomaly Best fit: ∆m2=2.35±0.1eV2 sin22θ=0.165±0.04 arXiv:submit/0179257 [hep-ex] 14 Jan 2011 33 大強度 実現不可欠 34 Summary Big goal Search for CPV and proton decay w/ >MW beam power machine Huge/high sensitivity detector To realize, need Discovery of non-zero θ13 Accelerator power upgrade step-by-step sure R&D of detector Because neutrino has many unknowns, various EXCITING physics exists along the road toward realizing the big goal 100kt LiqAr TPC at Okinoshima is seriously being investigated Gold may be buried??? All these can only be realized with HIGH POWER JPARC (& GOOD IDEA!) 35
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