1. 1 Super muon-neutrino beam Takashi Kobayashi IPNS, KEK Fact02 July 1, 2002 Imperial College London Contents 1.Introduction 2.“Super-beam” long baseline experiments 3.Physics sensitivity 4.Summary

2. 2 Next goals of LBL experiments  Establish 3 flavor framework (or find something new)  Discovery of e appearance (  13 >0?)  At the same  m 2 as  disapp.  Firm evidence of 3gen. mix.  Open possibility to search for CPV  Confirmation of     Appearance  NC measurement  Precision measurements of ocs. params.   m 23,  23 /  m 13,  13  Test exotic models (decay, extra dimensions, ….)  Sign of  m 2  Search for CPV in lepton sector  Give hint on Matter/Anti-matter asymmetry in the universe

3. 3 What ’ s super muon-neutrino beam? Proton Beam Target Focusing Devices Decay Pipe Beam Dump  ,K,K   Pure  beam ( ≳ 99%)  e ( ≲ 1%) from     e chain and K decay(K e3 )   /  can be switched by flipping polarity of focusing device “Conventional” neutrino beam production with MW-class proton beam For high precision LBL experiments

4. 4 “ Super beam LBL experiments ” ≈ “ 2 nd generation LBL experiments w/ high intensity conventional beam ”  High statistics  Beam intensity ≲ 100kW  ≳ MW (super beam)  AND/OR detector mass ~10kt  100~1,000kt  Designed and optimized after the knowledge of Super- Kamiokande/K2K results  Primary goal: e app.  CPV, sign of  m 2  Japan: JHF(off-axis)  SK/HK  FNAL: Off-axis NuMI, Proton driver upgrade,  BNL: Super AGS(off-axis)  ?  CERN: SPL  Furejus, Off-axis CNGS

5. 5 Next critical path   e appearance Signal Single EM shower Backgroud  e 1.Beam intrinsic e contamination Identical signature w/ signal Different energy distribution 2.NC  0 production 3.NC multi pion production x 00  x x   

6. 6 Key for e appearance experiment  High statistics  Small background contamination (beam)  intrinsic e  short decay pipe, …  off-axis, …  less high energy tail  less inelastic  Background rejection (beam+detector)  event topology (e ⇔  0 )  narrow spectrum beam w/ neutrino energy reconstruction  additional kinematical constraint  Small systematic error on background estimation  near/far spectrum difference  cross section  detector response

7. 7 High intensity narrow band beam -- Off-axis (OA) beam -- (ref.: BNL-E889 Proposal)  Target Horns Decay Pipe Far Det. Decay Kinematics  Increase statistics @ osc. max.  Decrease background from HE tail 1/~1/~ E  (GeV) E (GeV) 5 1 2  flux

8. 8 Charged current cross sections CCqe (  + n   + p ) Inelastic  NC  0  multi   …. CCqe dominate ≲ 1GeV Inelastic dominate ≳ 1GeV Backgroud

9. 9 Background rejection  Event topology   0 : for example,  additional EM activity?  vertex displacement (  flight)  angular distribution  intrinsic beam e : no way  E distribution  Signal peaked at osc. max.  Fake “ e ” event by  0 &beam e broad OA2deg@JHF  e Typical OA spectrum

10. 10 E reconstruction  ≲ 1GeV  2-body kinematics of dominant CCqe  Water Ch. works well  ≳ 1GeV  Inelastics (nuclear resonances) dominate  (Fine grain) sampling calorimeter. Resolution?  Full reconstruction of secondary particles?

11. 11  reconstruction ≲ 1GeV region CC quasi elastic reaction  + n →  + p -- p ( E , p  )   + n →  + p +  -- p ( E , p  )  CCqe  Inelastic (BG)  CCqe inelastic  ~80MeV(10%) limited by Femi motion Small BG SK Full Det. Sim.

12. 12 Syst. error: far/near spectrum diff. Typical OA beam(80mDV) 280m 295km K2K case (MC) FD(300m) (xL SK 2 /L FD 2 ) SK Important not only for  disappearance, but also for sig/BG estimation for e search Large(~x2) effect around peak!!

13. 13 (“super-beam”) LBL experiments E p (GeV) Power (MW) Beam 〈 E 〉 (GeV) L (km) M det (kt)  CC (/yr) e @peak K2K120.005WB1.325022.5~50~1% MINOS(LE)1200.41WB3.57305.4~2,5001.2% CNGS4000.3WB18732~2~5,0000.8% JHF-SK500.75OA0.729522.5~3,0000.2% JHF-HK504OA0.72951,000~600,0000.2% OA-NuMI1200.3OA~2730?20kt?~1,000?0.5% OA-NuMI21201.2OA~2730?20kt?~4,000?0.5% AGS  ??281.3WB/OA~12,500?1,000?~1,000? SPL-Furejus2.24WB0.2613040(400)650(0)0.4% OA-CNGS4000.3OA0.8~12001,000?~4000.2% The plans are in very different phases. Most are in optimization phase. JHF-SK most advanced  budget request submitted  EXISITING real detector

14. 14 JHF-Kamioka Neutrino Project ~1GeV beam Kamioka JAERI (Tokaimura) 0.77MW 50 GeV PS ( conventional beam) Super-K: 22.5 kt 4MW 50 GeV PS Hyper-K: 1000 kt Phase-I (0.77MW + Super-Kamiokande) Phase-II (4MW+Hyper-K) ~ Phase-I  200 Plan to start in 2007 (hep-ex/0106019)

15. 15 Principle of JHF-Kamioka project  Intense Narrow Band Beam by “ off-axis ”.  Beam energy is at the oscillation maximum.  High sensitivity, less background  ~1 GeV beam for Quasi-elastic interaction. E (reconstruct) – E (True) (MeV)  =80MeV E (reconstruct) E (True)  events

16. 16 JHF Facility Construction 2001 ～ 2006 (approved) JAERI@Tokai-mura (60km N.E. of KEK) Super Conducting magnet for beam line Near detectors @280m and @~2km 10 21 POT(130day)≡ “1 year” (0.77MW) Budget Request of the  beam line submitted

17. 17 Expected spectrum e contamination 0.21% K-decay  -decay Very small e /  @  peak ~4500 tot int/22.5kt/yr ~3000 CC int/22.5kt/yr  OA3° OA2° OA1° Osc. Prob.= sin 2 (1.27  m 2 L/E )  m 2 =3x10 -3 eV 2 L=295km osc.max.

18. 18 Detectors at near site  Muon monitors @ ~140m  Behind the beam dump  Fast (spill-by-spill) monitoring of beam direction/intensity  First Front detector “ Neutrino monitor ” @280m  Intensity/direction  Neutrino interactions  Second Front Detector @ ~2km  Almost same E spectrum as for SK  Absolute neutrino spectrum  Precise estimation of background  Investigating possible sites 1.5km 295km 0.28km Neutrino spectra at diff. dist 280m

19. 19 Far Detectors 48m × 50m ×500m, Total mass = 1 Mton ４０ｍ ４１．４ｍ 1 st Phase (2007~, ≥5yrs) Super-Kamiokande(22.5kt) 2 nd Phase (201x~?) Hyper-Kamiokande(~1Mt)

20. 20 USA: FNAL and BNL plan  BNL: Super AGS (1.3MW, LOI submitted)  FNAL: Super NUMI (1.6 MW) or the new proton driver. Off-axis beams + 2 detectors 100km FNAL BNL Soudan Homestake WIPP (hep-ex/0205040,0204037,hep-ph/0204208)

21. 21 OA-NuMI A. Para, M. Szleper, hep- ex/0110032 Osc. max. @ 730km 1.8GeV (  m 2 =3x10 -3 eV 2 ) K decay 0.78deg Features  Nuclear resonance region  Inelastic background  Energy reconstruction?  Too large angle  Kaon peak  Beam goes 3.5deg downward  hard to place 2 nd near det.  Far/near ratio? Para/Szleper’s prescription using Matrix (hep-ex/0110001)

22. 22 Europe: SPL  Furejus Geneve Italy 130km 40kt  400kt CERN SPL @ CERN 2.2GeV, 50Hz, 2.3x10 14 p /pulse  4MW Now under R&D phase

23. 23 Detectors UNO (400kton Water Cherenkov) Liquid Ar TPC (~100kton)

24. 24 Physics Sensitivity

25. 25  e appearance in JHF-Kamioka (phase 1) e 00 1.8 events 9.3 events 11.1 events 123.2 events @ sin 2 2  13 =0.1,  m 2 =3×10 -3 eV 2 Backgrounds Signal (5 years running)

26. 26 e appearance (continue) e appearance (continue) sin 2 2   e =0.05 (sin 2 2   e  0.5sin 2 2  13 ) 3×10 -3 ×20 improvement CHOOZ sin 2 2   e =1/2  sin 2 2  13 m2m2 sin 2 2  13 <0.006 (90% C.L.)

27. 27  disappearance 1ring FC  -like Non-QE (log)  m 2 =3×10 -3 sin 2 2  =1.0 ~3% m2m2 sin 2 2   sin 2 2     m  2    eV 2 Oscillation with  m 2 =3×10 -3 sin 2 2  =1.0 Reconstructed E (MeV)  (sin 2 2  ) OAB-2degree 0.01 True  m 2  sin 2 2  3  10 -3

28. 28 Sensitivity(3  ) to CPV(2 nd phase) Chooz excluded @  m 31 ~3x10 -3 eV 2  >~27deg  >~14deg Preliminary 4MW,1Mt 2yr for  6.8yr for  JHF1 3  discovery

29. 29 US Super beam They are studying the physics potential of several options, which are competitive to JHF-Kamioka project. CHOOZ NUMI-offaxis |U e3 | 2 =1/4  sin 2 2  13 0.003

30. 30 Possibility to discriminate sign of  m 2 (Matter effect)  Small matter effect in JHF- SK (~1GeV-295km)  Other longer baseline projects could play complementary role OA-NuMI MC study  m 23 2 true =+ hep-ex/0206025 33 For example, ~5yrs of OA-NuMIx20kt (w/ proton driver) Running time  :  ~1:3 (cross sec. diff)

31. 31 Summary  Exciting topics in 2 nd generation LBL experiments.  ne appearance  CPV, sign of  m 2, ……  Several “ super-beam ” experiments are under consideration  US, Europe and Japan  They are in very different stages.  Earliest beam is expected in 2007 at JHF- Kamioka project  Accelerator construction started in 2001.  Budget request for  facility submitted this year.

32. 32 Summary (II)  Physics sensitivity of JHF-Kamioka project  sin 2  13 ≤0.006 (90%CL)   (  m 2 ) ≲ 3%,  (sin 2  23 )~1%  can discover CPV if  ≳ 20 o (in 2 nd phase)  Experiments are complementary each other  JHF-Kamioka hard to see matter effect   Longer baseline/higher energy experiments  Fact will come after the (at least) 1st round of super- beam experiments (10~20yrs)  If sin 2  13 ≲ 0.01, JHF-SK may not see, but JHF-HK may.  But sensitivity to CPV in JHF-HK reduces   CPV in Fact?

33. 33 Future Prospect JHF1 sin 2 2  13 >0.018? JHF2 CPV precision meas.  13 Proton decay JHF2 Search  13 <10 -3 Proton decay 2007 201x 2002 : JHFn budget request&approval 2003 : start construction 2005 : K2K final results Future SuperBeam, VLBL, -fact for very small  13, CPV, sign of  m 2 20xx 3  discovery Hint?

34. 34 (Super) Neutrino Beams (GeV)L(km)#CC /kt/yr/kt/yr L/L osci.* f( e ) @peak K2K1.325020.47~1% NuMi (High E) 1573031000.120.6% NuMi (Low E) 3.57304690.511.2% CNGS17.773224480.100.8% JHF-I0.72951331.020.2% Numi off-axis 2.0730~800.890.5% JHF-II0.72956911.020.2% SPL0.2613016.31.210.4%

35. 35 FNAL, BNL to Soudan  Water Cherenkov like Super-K Events/0.1GeV/5years/100kTon Events/0.1GeV/5years/10kTon 1  off-axis x

36. 36 Far/near spectrum ratio 0.28km 0.5km 1.0km1.5km2.0km 0 1 3 5 (GeV) Decay pipe len. L DV =80m want near det. @ ≳ 10 x L DV

37. 37 Sensitivity for Mixing Angle sin 2 2   e sensitivity ~JHF2-HK 1yr

38. 38   →  confirmation w/ NC interaction   →  confirmation w/ NC interaction NC  0 interaction ( + N → + N +  0 )    e CC + NC(~0.5CC) ~0 (sin 2 2   e ~0)  CC + NC(~0.5CC) ~0 (maximum oscillation)   NC #  0 is sensitive to  flux. Limit on s (  f( s )~0.1)      s  =390±44 #  0 + #e-like  m 23 2 3.5  10 -3      CC NC

39. 39 (High Intensity) Proton Accelerators Power (MW) Energy (GeV) Intensity (10 12 ppp) Rep. rate (Hz) KEK-PS0.0051260.45 AGS0.1424600.6 FNAL-MI0.41120400.53 SPS0.3400350.16 JHF-I0.77503300.29 Super-AGS1.3281202.5 FNAL-proton driver-I 1.2163015 SPL42.223050 JHF-II450 Not the construcion stage yet, but R&D stage.

40. 40 Some ideas for OA-NuMI detector (under consideration) 1m Plastic pellets +RPC (A.Para) 70ton/plane 20m SOMINOS(Fe+Sci) Szleper+Velasco 5kt, 12m dia., 875planes

41. 41 Super Proton Linac (SPL) @ CERN Under R&D phase Reuse some parts from LEP