1. Measurements of neutrino charged current scattering in K2K Fine-Grained Detector Introduction Introduction K2K Near Detector K2K Near Detector CC interactions (p  Q 2 ) CC interactions (p  Q 2 ) Summary Summary M.Hasegawa Kyoto University for the K2K collaboration for the K2K collaboration

2. Charged Current Scattering Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. Charged Current Quasi-Elastic (CCQE) Scattering - Dominant process around 1GeV (~40% of CC) p  - E can be reconstructed from (p  ) Charged Current non Quasi-Elastic (nonQE) Scattering - single  production (CC1  ) (~38% of CC) - multi  production (CCm   (~18% of CC) - Coherent  production (~2% of CC)   Coherent  production

3. K2K Charged Current Analysis Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. … … 1kt data (for example)   (deg.) p  (MeV/c) 0 20 40 60 5001000 Data (P ,   ) = F(i) * [  CCQE + R nQE/QE *  nQE ] F(i) : Neutrino flux (i =1~7) R nQE/QE : NonQE to QE ratio Main motivation is to determine E spectrum @near site Latest result in Maesaka’s(Kyoto)talk (WG1 in this morning)

4. CC Analysis - cont’d Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. Another Motivation is to study the int. in a few GeV region.  CCQE, CC1  Form factors   CC1  ) /  CCQE),  CC multi  ) /  CCQE)  LowQ 2 (CC1 , Coherent  (Important to understand Background for CCQE) K2K measures (On-Going Work) B.G. from non-QE E (near vs Far)

5. K2K Near Detectors Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ.  1kt Water Cherencov detector (1kt)  Scintillating Fiber Detector (Scifi)  Scintillator Bar Detector (SciBar) (2003-)  Muon Range Detector (MRD) K2K Near Detectors Neutrino beam properties at production. Neutrino interactions ~ 1.3GeV K2K-II Detectors (2003-)  Study int.

6. Scifi Detector Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. SciFi Scintillating Fiber sheet / Water Sandwich detector Track Finding Efficiency ~93% (single track) Tracking threshold 3layer(>12cm) (=Proton 0.60GeV/c) 260cm 173cm 260cm Possible to identify CCQE events by using Proton track

7. SciBar Detector Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. Extruded scintillator (15t) Multi-anode PMT (64 ch) Wave-length shifting fiber EM calorimeter 1.7m 3m Neutrino target is scintillator itself 2.5 x 1.3 x 300 cm 3 cell (15000ch) (Fairly) large volume (10000 int. / month) Just constructed in last summer! Fine segmented, Full Active SciBar Scintillator-Bar Tracker Tracking Threshold : 8cm (=0.4GeV/c Proton) Track-finding efficiency >99% (Single Track) Excellent p/  using dE/dx misID(   P) = 1.7% @ P Eff =90%  High 2-track CC-QE efficiency  Identify ν interaction mode clearly Preliminary

8. SciBar Shot ! Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ.  p CCQE candidate 1 2 3 CCnQE candidate

9. FGD Charged Current Analysis Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. Vertex MRD (Iron plates and drift tubes) SciBar  Selection Use events which have more than 1 track connected with MRD ( CC fraction ~100%(Scifi), ~ 98% (SciBar) ) ScifiSciBarMRD

10. Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. QE/nQE QEnonQE DATA CC QE CC 1  CC coherent-  CC multi-  pp (deg) (1) 1 Track 60% QE (2) 2 Track QE enriched 60%(SF) / 70%(SB) QE (3) 2 Track nonQE enriched 85% nQE  Expected proton direction assuming CCQE pp Observed second track SciBar  p Use proton track direction to enhance CCQE / non QE

11. SciBar 1Track Sample Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. pp DATA CC QE CC 1  CC coherent-  CC multi-   q 2 (rec) Agreement is good except for lowQ 2 (forward) region. MC (NEUT4.5) Nucl.Phys.Proc.112,171 - M A (QE) = M A (1  ) = 1.1GeV/c 2 - Marteau model (coherent  ) - Bodek/Yang (DIS)

12. SciBar 2Track QE sample Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. DATA CC QE CC 1  CC coherent-  CC multi-  pp  Good Agreement (No deficit can be found) q 2 (rec)

13. SciBar 2Track nQE sample Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. DATA CC QE CC 1  CC coherent-  CC multi-  pp  Agreement is good except for lowQ 2 (forward) region. Clear deficit can be seen. q 2 (rec)

14. 1Kt, Scifi Q 2 distribution Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. 1 Kt 1ring muon-like event (GeV 2 ) From SciBar (&Scifi) result, source is nonQE. (CC1  or coherent  cross section is suspicious ) Scifi 2track nonQE enriched event DATA CC QE CC 1  CC coherent-  CC multi-  Three detectors see the same effect.  This cannot be explained by detector systematics.

15. CC1  suppressing vs No coherent  Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. LowQ 2 suppression in CC1   Q   Q   No coherent  Currently, we don’t judge which is source of low Q 2 deficit.

16. SB Coherent  Analysis (On- going) Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ.     N CC1  Coherent   No activity around Vertex (Full Active)  Hadron track is Pion ( PID ) SciBar can separate them effectively. And just working now Difference between coherent  and CC1  In the case of coherent 

17. Summary Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. K2K Charged Current Analysis provide K2K Charged Current Analysis provide Neutrino Flux & Knowledge of  int (~1.3GeV). Neutrino Flux & Knowledge of  int (~1.3GeV). New near detector ‘SciBar’ was installed in New near detector ‘SciBar’ was installed in last summer and works stably and shows last summer and works stably and shows good performance as expected. good performance as expected. Muon distributions (p  Q 2 ) agreed with MC Muon distributions (p  Q 2 ) agreed with MC except for lowQ 2 region. (Origin is CC1  except for lowQ 2 region. (Origin is CC1  or coherent  or Both. Currently we doesn’t judge.) or coherent  or Both. Currently we doesn’t judge.) SciBar Analysis will answer this question soon. SciBar Analysis will answer this question soon. stay tuned! stay tuned!

18. Supplement

19. A A=0.10 +/– 0.03  CC1  q 2 /0.10 (Data–MC)/MC Agree quite well By using SciBar 2track-nonQE and fitted flux, I looked for the best value of CC1  suppression. Suppression factor q 2 /A (q 2 >A) Scan A value and calculate  2 of  distribution. Calculate  2 SciBar 2track nonQE CC1  suppression factor tuning

20. Basic Performance (Tracking) Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. Track Finding Efficiency (Single Track) Efficiency : 99.2% (>4layer ~ 10cm) in coming  10cm SciBar Track Finding Efficiency (2nd Track) True Length Detected ! Efficiency:76.7% (>8Hits) Main contribution on ineff. Is overlapping  will be improved to > 90% soon Confirmed w/ eye Systematic error : +0.2 / -2.5 %

21. Basic Performance (PID) Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. Mu-like(purity ~ 99.6%) Proton-like(purity 90%) Range in SciBar (cm) Total dE (MIPs) Range vs Total deposit energy DATA (2track QE sample) Non Muon-Like  sample proton  sample Proton Efficiency Muon mis-ID Preliminary Preliminary Excellent p/  using dE/dx When 90% proton eff. is required, Muon Miss ID probability is 1.7% Muon C.L.

22. Basic Performance (Energy Response) Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. Top view Side view   High Accuracy gain monitoring SystEm (HASE moni) (HASE moni) +5% -5% We use a penetrating muon (cosmic  as a (strip to strip) relative energy calib. source. All PMT channel’s (~15000ch) gain are monitored by LED based system. - Relative energy scale is calibrated at 1.5% precision - response for dE/dx is stable within 1.0% for 4months

23. Basic Performance (Stability) Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. Event rate Date Event rate (/10 18 POT) Efficiency 0.748  Overall  int. detection efficiency : ~75% (MC) (w/ >30cm Track)  Event rate is stable for 4 months.

24. On-Going Analysis Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. M A Analysis(QE) (Scifi) Coherent  search (mainly SciBar) This is the first measurement of M A with water target. This is the first search in a few GeV region. Preliminary 7.03.0 Observed.(CC) (Nuint04 Minerva) One Candidate of Origin of LowQ 2 (forward)Deficit (Nuint04 R.Gran) K2K

25. SciBar Detector Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. Extruded scintillator (15t) Multi-anode PMT (64 ch) Wave-length shifting fiber EM calorimeter 1.7m 3m Extruded scintillator with WLS fiber readout Neutrino target is scintillator itself 2.5 x 1.3 x 300 cm 3 cell ~15000 channels Detect from less than 10cm track Distinguish proton from pion by using dE/dx (fairly) large volume  High 2-track CC-QE efficiency  Identify ν interaction mode clearly Just constructed in last summer!

26. SciBar Charged Current Analysis Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. Vertex MRD (Iron plates and drift tubes) SciBar  Selection  Vertex SciBar-MRD 3D Track Matching ( p μ >0.5GeV/c) - 35% of All interaction ( CCQE fraction ~  SciBar-MRD 1L Stopping Event ( p μ >0.3GeV/c) - 9% of All interaction ( CCQE fraction ~ 

27. Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. CC quasi elastic (CCQE) –Smith and Moniz with M A =1.1GeV CC (resonance) single  (CC-1  ) –Rein and Sehgal’s with M A =1.1GeV DIS –GRV94 + JETSET with Bodek and Yang correction. CC coherent  –Rein&Sehgal with the cross section rescale by J. Marteau NC + Nuclear Effects  /E (10 -38 cm 2 /GeV) E (GeV) NEUT: K2K Neutrino interaction MC

28. Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. P  1trk P  2trk QE P  2trk non-QE   1trk   2trk QE   2trk non-QE 02(GeV/c)040(degree) flux measurement 10 SciFi (K2K-IIa with measured spectrum)

29. P  1trk P  2trk QE P  2trk nQE   1trk   2trk QE   2trk nQE flux measurement 10 SciBar (with measured flux) Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ.

30. K2K Charged Current Analysis Main motivation is to determine E spectrum @near site Latest result in Maesaka’s(Kyoto)talk (WG1 in this morning) Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ.

31. K2K Charged Current Analysis Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ. … … 1kt data (for example)   (deg.) p  (MeV/c) 0 20 40 60 5001000 Data (P ,   ) = F(i) * [  CCQE + R nQE/QE *  nQE ] F(i) : Neutrino flux (i =1~7) R nQE/QE : NonQE to QE ratio Main motivation is to determine E spectrum @near site Latest result in Maesaka’s(Kyoto)talk (WG1 in this morning)

32. SB Coherent  Analysis (On- going) Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1, 2004 Osaka Univ.   Neutrino scatters coherently from the entire nucleus with small energy transfer.   N CC1  Coherent   No activity around Vertex (Full Active)  Hadron track is Pion ( PID ) SciBar can separate them effectively.

33. SciBar non-QE Events K2K observed forward  deficit. –A source is non-QE events. –For CC-1 , Suppression of ~q 2 /0.1[GeV 2 ] at q 2 <0.1[GeV 2 ] may exist. –For CC-coherent , The coherent  may not exist. We do not identify which process causes the effect. The MC CC-1  (coherent  ) model is corrected phenomenologically. Oscillation analysis is insensitive to the choice. q 2 rec (Data-MC)/MC DATA CC 1  CC coherent-  Preliminary q 2 rec (GeV/c) 2 CC1  suppression