UNO: Underground Nucleon Decay and Neutrino Observatory

Transcription

1 UNO: Underground Nucleon Decay and Neutrino Observatory Clark McGrew NESS, Jan 2002 NESS 2002 McGrew p. 1

2 The UNO Concept Build on well-established techniques Explore broad range of physics Provide a general purpose observatory Balance between physics and costs NESS 2002 McGrew p. 2

3 A Bigger Super-Kamiokande? Large Underground water Cherenkov Detectors have a remarkable success record Exclusion of minimal SU(5) Real-time directional measurement of solar neutrinos Observation of supernova 1987A Discovery of neutrino oscillations (and hence neutrino mass) Detected first long baseline neutrinos Best limits on nucleon decay What s left to be done? Wrong Question This is just the beginning NESS 2002 McGrew p. 3

4 Physics Opportunities Nucleon Decay Neutrino Mixing Neutrino Mass Astrophysical Observations UNO Addresses CPU Questions 1, 5, 7, 9, 10, 11 NESS 2002 McGrew p. 4

5 Experimentalist s Viewpoint Proton Decay Atmospheric Neutrinos Long Baseline Neutrinos Solar Neutrinos Supernova Neutrinos Relic Supernova Neutrinos Neutrino Astronomy NESS 2002 McGrew p. 5

6 UNO Baseline Design NESS 2002 McGrew p. 6

7 UNO Baseline Design Total Mass: Fiducial: NESS 2002 McGrew p. 6

8 UNO Baseline Design Total Mass: Fiducial: 60 m 60 m NESS 2002 McGrew p. 6

9 UNO Baseline Design Total Mass: Fiducial: 60 m 180 m 60 m NESS 2002 McGrew p. 6

10 UNO Baseline Design Total Mass: Fiducial: Optically Separate Modules NESS 2002 McGrew p. 6

11 UNO Baseline Design Total Mass: Fiducial: Optically Separate Modules Inner Coverage: 60, PMTs NESS 2002 McGrew p. 6

12 UNO Baseline Design Total Mass: Fiducial: Optically Separate Modules % Inner Coverage: 60, PMTs NESS 2002 McGrew p. 6

13 UNO Baseline Design Total Mass: Fiducial: Optically Separate Modules % % % Inner Coverage: 60, PMTs NESS 2002 McGrew p. 6

14 UNO Baseline Design Total Mass: Fiducial: Optically Separate Modules % % % NESS 2002 McGrew p. 6 Inner Coverage: 60, PMTs Outer Coverage: 15,000 8 PMTs

15 Size Comparison Parameters Kam-III IMB-3 SK UNO Total mass 4.5 kton 8 kton 50 kton 650 kton Fiducial mass proton decay 1.0 kton 3.3 kton 22 kton 440 kton solar 0.7 kton 22 kton 440 kton supernova 2.1 kton 6.8 kton 32 kton 580 kton Photocathode 20% 4% 40% 1/3 40% coverage 2/3 10% Depth NESS 2002 McGrew p. 7

16 UNO and Proton Decay Size Matters For exposure (no background) Want multi Background spoils the limit exposures Must be low background There are no sure thing decay modes UNO is sensitive to many modes NESS 2002 McGrew p. 8

17 Signature The Search in Super-Kamiokande Super-Kamiokande Preliminary days No events in signal region 1 Background: 2.2 event/ total invariant mass (MeV/c 2 ) NESS 2002 McGrew p. 9

18 Is Background Understood? Invariant mass of 2 e-like rings 19 1KT preliminary (~3x10 pot) events DATA MC Data from K2K Equivalent Exposure: Analyzed: Eventually: MeV/c 2 NESS 2002 McGrew p. 10

19 N : MC vs Data 1000 total momentum (MeV/c) KT DATA (Preliminary, ~3x10 pot) 1000 total momentum (MeV/c) KT MC (Preliminary, ~3x10 pot) total invariant mass (MeV/c 2 ) ν (~3Mtyr atm equiv.) total invariant mass (MeV/c 2 ) ν (~3Mtyr atm equiv.) µ µ Same interaction MC as SK NESS 2002 McGrew p. 11

20 Distance from Signal Box events distance "L" in mass vs. momentum plot (1KT preliminary, ~3x10 pot) DATA MC 19 total momentum (MeV/c) L (938,200) 10 2 total invariant mass (MeV/c ) L (arbitrary) NESS 2002 McGrew p. 12

21 Signature Years of Data 5 Mtyr exposure with tight cut eff.=17.4%, PDK=3, BG= Free protons invariant proton mass (MeV/c 2 ) NESS 2002 McGrew p. 13

22 Signature Years of Data 10 Mtyr exposure with tight cut eff.=17.4%, PDK=6, BG= Free protons invariant proton mass (MeV/c 2 ) NESS 2002 McGrew p. 14

23 Signature Years of Data 20 Mtyr exposure with tight cut eff.=17.4%, PDK=12, BG= Free protons invariant proton mass (MeV/c 2 ) NESS 2002 McGrew p. 15

24 Sensitivity p eπ 0 sensitivity (90 % CL) Partial Lifetime (years) Super Kamiokande eff = 44% SK BG = 2.2 ev/mtyr 6 SK eff = 17% BG = 0.15 ev/mtyr in 5 no bkgd small bkgd current status 79ktyr, 5.0 x yrs Exposure (Mton year) NESS 2002 McGrew p. 16

25 Sensitivity p νk + sensitivity (90% CL) Partial Lifetime (years) current limit 79.3ktyr 1.6 x yrs combined sensitivity π + π 0 prompt γ µ spectrum Limiting Bkgd: 1 event/ SK: 6 event/ in Exposure (kton year) This decay mode determines the PMT coverage requirement NESS 2002 McGrew p. 17

26 Nucleon Decay Sensitivity Super-Kamiokande UNO Mode Current 15 run 5 run 15 run Background estimation is important. The K2K experiment is currently collecting a equivalent exposure. NESS 2002 McGrew p. 18

27 UNO and Atmospheric Neutrinos Neutrino Oscillation Studies without a Neutrino Accelerator UNO is big Truly Colossal Atmospheric Neutrino Rate UNO: SK: Rate with Fully contain evt (165 evt events per year event (8.2 evt Water is a good Hadron Calorimeter ) ) NESS 2002 McGrew p. 19

28 Direct Observation of Ratio of oscillated to expected vs Log(L/E) Chi2 / ndf = / 18 Observed/Expected sstt = ± 1.003e-07 dms = ± 2.73e-07 decay rate = e-05 ± 6.893e-08 Log10(Resolution) = ± Log(L/E) (km/gev) A Laboratory for: Select good resolution events Only muon events ( ) Fully Contained Determine spectrum with down-going up- Measure going A clear test of neutrino oscillation Non-standard disappearance e.g. decay with NESS 2002 McGrew p. 20

29 UNO and Supernova Neutrinos A Supernova at 10 kpc Detector Method Mass Events UNO water Cherenkov 400 Super-Kamiokande water Cherenkov 22.5 OMNIS neutron capture several SNO water Cherenkov 1 KamLAND scintillation 1 Borexino scintillation 1 LVD scintillation 0.5 Estimate Supernova per century in our galaxy (Beacom et al. PRD63,073011) Supernova in Andromeda 10 events in UNO 140,000 9,000 2,000 1, NESS 2002 McGrew p. 21

30 Temperature of a Supernova T = 8 T = 6.3 3% of the events. Produces mono-energetic between Low Energy Threshold! NESS 2002 McGrew p. 22

31 Blackhole Formation Roughly half of Supernova may end in black hole formation. dn/dt [s 1 ] All Mid High m νe = 1.8 ev 200 Low t t BH [s] Formation is predicted during neutrino generation phase. Sensitive to collapse for tens of seconds. Direct evidence of blackhole formation. Can be used to measure neutrino kinematic mass. NESS 2002 McGrew p. 23

32 UNO and Relic Supernova Supernova Relic Search Event Rates Event Rate/year/22.5 kton/4 MeV Statistically limited Theory just below prediction Depth important spallation Energy (MeV) Possible the next observed astrophysical source NESS 2002 McGrew p. 24

33 Status Last year wrote and distributed a Whitepaper discussing the physics potential. Due to Super-Kamiokande accident, place proposal on hold Now understood so we will proceed Next collaboration meeting at BNL Oct 9, 10 Plans: Submit R&D proposal in 2003 Follow with LOI in 2004 NESS 2002 McGrew p. 25

34 Summary UNO is a General Purpose Detector Excellent Physics Opportunities Sensitive to a wide variety of proton decay modes to Atmospheric Neutrinos: several%, several% Sensitive to Supernova in Andromeda Will test supernova relic models. Builds on 20 Years of Continuous Water Cherenkov Detector Operation NESS 2002 McGrew p. 26