Series of Workshops Gran Sasso Nu Int 07

Series of Workshops Gran Sasso Nu. Int 07 3

Contents 1. 2. K 2 K実験とT 2 K実験 ニュートリノ・原子核反応断面積（K 2 K実験） 1. 2. 3. K 2 Kビームと前置ニュートリノ測定器 CC Quasi-Elastic反応 CC/NC-1 p反応 1. NC 1 p 0 2. CC-coherent p 4. Nuclear de-excitation g and NC elastic 5. Expected new results from K 2 K 3. T 2 K Near Detectors（T 2 K実験） 1. T 2 K n Beam 2. T 2 K ND 280 with New Technology 4. Summary 4

2. 1 K 2 Kビームと前置ニュートリノ測定器 Lead Glass or K 2 K n beam § K 2 K Beam § ~98% pure nm beam with <E>~1. 3 Ge. V § K 2 K Near Detectors § 4 detectors with H 2 O, HC and Fe targets. 8

2. 2 CC Quasi-Elastic反応の研究 -- ニュートリノエネルギー測定の主チャンネルーー § Scintillation Fiber planes and Water Target sandwich tracking detector § Pm > 600 Me. V/c § Pp > 600 Me. V/c § not always seen m p CC-QE candidate event 9

PRD 74(2006), 052002 § MA= 1. 20± 0. 12 Ge. V/c 2 § Largest systematic errors § Muon momentum scale: 0. 07 § neutrino beam flux: 0. 07 with One-track events. QQE 2 (Ge. V/c) 2 not used in fit (nuclear effect) Two-track QE events. (a proton with QE kinematics) QQE 2 (Ge. V/c) 2 11

Discussion w/ the past measurements s( 10 -38 cm 2) K 2 K result 0 0. 8 1 1. 2 MA (Ge. V/c 2) CC-QE cross section K 2 K 10 -1 s(nm n m- p) 1 10 Neutrino Energy (Ge. V) § We measured MA from the q 2 shape. § Systematic difference from the measurement of the total cross section? 12

2. 3 CC/NC-1 p 反応 (NC-1 p 0) NC: n+N→n+N’+p 0 § 1 KT Water Cherenkov Detector § Two Electron Ring Events. § Reconstruct gg inv. mass. NC-1 p 0 Not NC-1 p 0 13 Mgg (Me. V/c 2)

PLB 619(2005), 255 -262 ⇐ model prediction with NEUT: 0. 065 § An important channel to study ne appearance. § A further study is necessary! § Nuclear Effect § non NC-1 p 0 channel. NEUT 14

2. 3 CC/NC-1 p 反応 (CC coherent p+) § In K 2 K, there was a long-standing puzzle of the deficit of forward going m events. § 小さな CC coherent p 断面積が原因. n m < < N* N p N n Coherent p < < < CC 1 p (n+N m+N+p) ニュートリノが原子核と コヒーレントに反応して πを生成。 p* m p t~0 15

et rim lo ca er n CC-QE event candidate 3 m • ~15000 チェンネル Multi-anode • 短いトラックも見える (>8 cm) PMT (64 ch. ) • πと陽子をd. E/dxで識別 High track finding efficiency (>99%) Clear identification of ν interaction process 3 m Extruded • 抽出型シンチレータを波長変換ファイ scintillator バーで読み出す。 (15 t) • 2. 5 x 1. 3 x 300 cm 3 セルサイズ EM Sci. Bar Detector 1. 7 m Wave-length shifting fiber 16

Q 2 distribution in the CC-coherent p sample Signal Region (S/N ~ 1) CC coherent-p 事象は観測されなかった。 ⇐ model prediction with NEUT: 2. 667 10 -2 New and modified models are proposed to explain the small cross section. 17

Coherent p cross section PRL 95, 252301 (2006) 0. 65 x 10 -40 § How is the NC coherent p cross section at the low energy? 18

2. 4 Nuclear de-excitation g and NC elastic § NC: n + p → n + p Proton Decay: p→n. K+ 16 O n n 15 N* 16 O K+ n 15 N* g p g 19

p n. K+ Signal -- Prompt g tag is a very powerful tool. 2, 200 ns 20

First Observation of g rays from de-excitation of 1 KT Neutrino datainteractions. nuclei induced. Beam by neutrino l Good confirmation of prompt g-ray tag in the § Analyzed ~1/10 K 2 K data. proton decay search. Good NC samples for neutrino §l. Observation: 6504. 1 events. oscillation study. l ~60% NC-elastic § MC prediction: 5273 events. l ~80% NC interactions. l § Data/MC = 1. 23 ± 0. 04(stat. ) ± 0. 06(sys. ) MC 21 Nucl. Phys. Proc. Suppl. 159 (2006), 44 -49

2. 5 Expected New Results from K 2 K § 1 KT § CC 1 p 0 study for proton decay search BG § Sci. Bar § CC 1 p+ production cross section § CC p 0 production cross section § More? 22

3. T 2 K Near Detectors Off-axis Ground level Detector 2. 5 deg beam center 28. 5 m On-axis Detector Neutrino Profile & the beam center Neutrino Beam Flux & Spectrum Neutrino Interactions Magnet: 0. 2 T outer: 6. 1 m(H) x 5. 6 m(W) x 7. 6 m(L) 23 inner: 3. 6 m x 3. 5 m x 7. 0 m

3. 1 T 2 K n Beam § Conventional nm beam: § p + Graphite target p’s § p+ or p- is focused selectively by 3 electromagnetic horns. p+ m+ + nm or p- m- + nm § Off-Axis technique: (OA = 2 ~ 2. 5 ) § Tune n energy at oscillation max. § Reduce the high energy neutrinos. Extraction point Target &horn Oscillation Prob. @ L=295 km Dm 2=2. 5 10 -3, 3. 0 10 -3[e. V 2] n energy spectrum (flux Cross Section) OA 0 OA 2. 5 OA 3 Decay Volume 280 m Beam dump m-monitor OA n Near Detector SK 24

3. 2 T 2 K ND 280 -offaxis § Spectrometer in the magnet. § Finer-Grained target Detector (FGD) § 1 1 cm 2 segmentation (Sci. Bar: 2. 5 1. 3 cm 2) § Large TPC (2. 5 1 m 3 3) § EM calorimeter and Muon Catcher surrounds § p 0 dedicated detector (P 0 D) Reuse of UA 1 magnet ~0. 1 events/ton/spill Physics purpose § Measure n-flux in SK direction : Fn. ND(En). § Measure nm, nm and ne+ne fluxes. § Neutrino energy w/ CC-QE. § Cross sections of n interactions § CC-1 p : BG for En reconstruction § NC-1 p 0: BG for ne detection 25

ND 280 and New Technology P 0 D Dedicated p 0 Detector w/ Micromegas 8 mm UA 1/NOMAD magnet w/ 0. 2 T (3. 5 3. 6 7 m 3) 2 FGD + 3 TPC for nm FGD scintillator w/ Water Target Muon Range Detector CPTA MRS-APD § New photo-sensor (Multi-pixel Si 1 mm APDs) for all scintillator detectors: P 0 D, FGD, ECAL, SMRD 10 mm ECAL for p 0 ne HPK MPPC 1 mm 26

Micromegas for TPC (copy from http: //cbernet. home. cern. ch/cbernet/Micromegas) 27

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Neutrino Interactions at ND 280 CCQE Pp 0 1 2 (Ge. V/c) CCQE qm Pm 30 0 1 2 3 4 (Ge. V/c) 0 40 80 120 160 (degree)

Backup 33

NON NC-1 p 0 fraction 34

Q 2 distribution in the CC-coherent p sample Signal Region (S/N ~ 1) In the Signal Region, § Observation: 113 § BG estimate: 111. 4 10. 6(stat. ) § Signal prediction by the Rein&Sehgal model: 99 No Evidence of CC-coherent p process at low energy 35

Upper limit on σ(CC-coherent p)/σ(nm. CC) ⇔ Rein & Sehgal : 2. 667 x 10 -2 Main Systematic uncertainties Nuclear effect and neutrino interaction (+0. 273, -0. 253) p absorption in the nucleus BG estimation from CC-1 p +0. 171, -0. 08 +0. 144, * 36

A Novel Idea: Prompt g tag Nucl. Phys. Proc. Suppl. 159: 44 -49, 2006 K+ 16 O n 15 N* g § A proton in 16 O decays (or disappears) ➾ 41% 6. 3 Me. V g-ray generates This propmt g events will be measured at K 2 K by NC elastic scattering 16 15 * 37

§ § § 1 -ring m-like 215 pm 260 Me. V/c 1 Decay electron No proton ring 7 Nghit 60 (prompt g) Efficiency = 8. 6% Nghit tp/BR(p n. K+) > 1. 1 x 1033 years (90% CL) w/ 0. 7 expected Background events 38

J-PARC schedule w/ beam power estimation 0. 75 MW Hardware upgrade is necessary for 1 MW. 39 Target date for new RF system installation.

On-Axis Neutrino Monitor (INGRID) - Extruded Scintillators - Photo-Sensor (MPPC/Si. PM) 14 Iron/Sci sandwich trackers are placed with a “cross shape” around the beam axis Each tracker consists of 10 iron plates and 11 scintillator strip planes Design-A x & y views OR 10 cm Design-B + veto planes around each tracker 10 cm 40

FGD i. Plastic FGD: 15 XY modules (30 layers) i. Water FGD: 7 XY modules with 6 water layers (2. 5 cm/layer) 365 mm 2300 mm i. Nominal scnitillator bar: 1 cmx 185 cm 2 K 2 K-Sci. Bar Scinitillation counter: 1 cm ( better segmentation then K 2 K) 41

TPC § § Measure the momenta of all charged particles: m, e, p , . . Particle ID for e versus m. 1 m § Gas amplification devise: Micromegas § § 12 modules on each TPC end plate (Module: 34 cm x 36 cm) 72 modules in total 3 42

ECAL § Measure the EM component (e, g) from P 0 D and FGD, and veto background particles coming outside. § Measure the EM cluster position and energy. § Perform Particle ID. scintillator bar (4 cm (width) x 1 cm (depth)) with 0. 03 X 0 Pb Barrel ECAL module fiber Photo-sensor 43

P 0 D i. A dedicated NC p 0 detector. Pb(0. 6 mm) + scintillator (17 mm thick) + Water 44

SMRD i. Muon Range detector to catch the muon going out of the TPC acceptance. i. Momentum measurement by the range of muon whose momentum is not measured by TPC. i. Scintillator modules are instrumented in the Fe gap (4 cm) 1 unit: 4 scntillator slab 45

Summary of the detector technology No. of channels Detector Technology INGRID Fe+Scinti+WLS+MPPC/MR S-APD 9, 000 FGD Scinti+WLS+MPPC/MRSAPD (+Water) 8, 500 TPC Micromegas 124, 000 ECAL Pb+Scinti+WLS+MPPC/MR S-APD 22, 000 P 0 D Pb+Scinti+WLS+MPPC/MR S-APD (+Water) 11, 000 Scinti+WLS+MPPC/MRSAPD 10, 000 SMRD 46

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