1. Superbeams Deborah Harris Fermilab July 26, 2004 NuFact’04 Osaka University

2. 26 July 2004Deborah Harris, Superbeams, NuFact042 Outline of this Talk Goals for the Next Steps Why Superbeams are a Challenge Beamline Strategies Detector Strategies (see Strolin tomorrow!) Prospects –Near Term: T2K and NO A –Why Two Beams are better than one… –Far Term: Lots of other ideas… Summary

3. 26 July 2004Deborah Harris, Superbeams, NuFact043 What do we want to know? Known: –Two large mixing angles, maybe one small –3 independent mass splittings, one is positive –Absolute neutrino mass limits Unknown: –Absolute Mass Scale –How many ’s are there? –Mass Hierarchy? –Is CP Violated? –Are ’s their own antiparticles? Mena&Parke, hep-ph/0312131

4. 26 July 2004Deborah Harris, Superbeams, NuFact044 Definition of Mixing Angles Need to measure e to  transitions at  atm -scale baseline/energy

5. 26 July 2004Deborah Harris, Superbeams, NuFact045 What happens when e ’s pass through the earth? “Raises potential Energy for e ’s and Anti- e ’s separately” electron density in the earth Wolfenstein, PRD (1978)

6. 26 July 2004Deborah Harris, Superbeams, NuFact046 Designing a Neutrino Experiment Currently: pin down or eliminate  m 2 Next: look for e /  transitions at  m 2 atm –CP violation in absence of matter effects –Matter effects in absence of  m sol 2

7. 26 July 2004Deborah Harris, Superbeams, NuFact047 Making a Neutrino Beam Conventional Beam Beta Beam Neutrino Factory Detector Needs

8. 26 July 2004Deborah Harris, Superbeams, NuFact048 Conventional Beam Challenges CHOOZ tells us it’s a small effect (<5%) Unavoidable contamination of e in beam –From  decays –At high enough p energies, K enters too! K L →   e – e and K L →   e + e Can mistake  0,  or  ± for e What is so hard about  → e

9. 26 July 2004Deborah Harris, Superbeams, NuFact049 Two Approaches: Narrow and Broad Narrow Band Beams –Lower backgrounds under peak from e and NC –But flux is narrower than oscillation maximum! –Most sensitive limits per MW*kton –Examples: T2K, NO A, CNGT Broad Band Beams –Higher event rates –In some cases actually measure shape of oscillations –Higher e backgrounds at any one energy –Examples: BNL LOI, FeHo, CERN SPL

10. 26 July 2004Deborah Harris, Superbeams, NuFact0410 “Off Axis” Neutrino Beams First Suggested by Brookhaven (BNL 889) Take advantage of Lorentz Boost and 2-body decays Concentrate  flux at one energy Lower NC and e backgrounds at that energy (3-body decays)

11. 26 July 2004Deborah Harris, Superbeams, NuFact0411 Detector Options Water Cerenkov Scintillator Calorimetry Liquid Argon TPC

12. 26 July 2004Deborah Harris, Superbeams, NuFact0412 Water Cerenkov Excellent particle ID for single-ring events Most massive detector built to date More problematic for multi-ring events Multi-  events can fake single-ring events Being considered for higher and higher energies because of low energy capabilities… (see Strolin’s talk)  0 or e? SuperK event displays courtesy Mark Messier

13. 26 July 2004Deborah Harris, Superbeams, NuFact0413 Scintillator Calorimetry Calorimeter with <X 0 sampling can do – e/  separation by looking for gaps after event vertex –e/  separation from track characteristics Can see all particles, good energy reconstruction at all energies Events at right: all scintillator, 1 cell equals: –4.9 cm horizontal axis –4.0 cm vertical axis + A -> p + 3  ± +  0 + e +A→p  +  - e -  + A -> p +  - Cooper, June 2004 PAC

14. 26 July 2004Deborah Harris, Superbeams, NuFact0414 Liquid Argon TPC Electronic Bubble Chamber Lots of recent progress with event reconstruction Test runs at Pavia and CERN producing lots of pretty events Looking forward to seeing how detector measures CNGS beam Looking to “industrialize” design ABAB BC K+ µ+ Run 939 Event 46 A B C D K+ µ+ e+ e -, 15 GeV, p T =1.16 GeV/c Rubbia, NuINT04

15. 26 July 2004Deborah Harris, Superbeams, NuFact0415 In Praise of Near Detectors To make precise measurements,need –Background cross sections –Signal (CC!) cross sections MINER A event display Need Dedicated Measurements in fine-grained detectors (see D.Casper’s talk on Friday) Data compiled by G.Zeller, hep-ex/0312061 proton   A→  A N→  pN’

16. 26 July 2004Deborah Harris, Superbeams, NuFact0416 First Step: seeing if  13 is non-zero T2K Tokai to Kamioka –295km, 1 st osc. maximum –50kton Water Cerenkov (SK) –New 0.8MW proton Source: J-PARC OAB2.0deg OAB2.5deg OAB3.0deg December, 2003 12/2003 Exp’t approved 2008 Accelerator operating 2009 Physics Running

17. 26 July 2004Deborah Harris, Superbeams, NuFact0417 T2K Detector Suite Several jobs, several detectors: 1.Verify beam direction 2.Measure  and e fluxes with high statistics 3.Measure background and signal cross sections 4.Eventually, verify background rates in “identical” detector at 2km Hayato, 2004

18. 26 July 2004Deborah Harris, Superbeams, NuFact0418 T2K Physics Reach Hayato, 2004

19. 26 July 2004Deborah Harris, Superbeams, NuFact0419 NO A Use Existing NuMI beamline New Detector 12km off axis 820km shows best compromise between reach in  13 and matter effects PAC recommendation “The Committee strongly endorses the physics case for the NO A detector, and would like to see NO A proceed on a fast track that maximizes its physics impact.” Beam ready first—start taking data with fraction of the detector New Studies show all scintillator has better reach per dollar Assuming  m 2 =2.5x10 -3 eV 2 Messier, 2004

20. 26 July 2004Deborah Harris, Superbeams, NuFact0420 NO A Physics Reach 50kton baseline detector 50kton baseline detector Because of CP and matter effects, “reach” vs. sin 2 2  13 will vary… Feldman, Aspen PAC 2004

21. 26 July 2004Deborah Harris, Superbeams, NuFact0421 Oscillation Probabilities For any one energy and baseline, you don’t get the whole story… Need two energies, or two baselines, and at least one baseline needs to be long enough to see matter effects First question: what do you get if you add more protons and detector to first generation experiments? P(  → e )=P 1 +P 2 +P 3 +P 4 Minakata & Nunokawa JHEP 2001

22. 26 July 2004Deborah Harris, Superbeams, NuFact0422 What does 2 get you that 1 doesn’t? J-PARC Upgrade:  0.7 to 4MW proton source  Beamline preparations now  50kton to 500kton (Hyper-K)  Study new light collection technology NO A Upgrade:  0.25 to 2MW proton source  Proton Driver CD-0 Machine and Physics Study  Possible second detector at 710km, 30km off axis Feldman, Aspen 2004

23. 26 July 2004Deborah Harris, Superbeams, NuFact0423 CP Violation at T2Hyper-K no BG signal stat only (signal+BG) stat only stat+2%syst. stat+5%syst. stat+10%syst. CHOOZ excluded sin 2 2  13 <0.12@  m 31 2 ~3x10 -3 eV 2 T2K 3  discovery 3  CP sensitivity : |  |>20 o for sin 2 2  13 >0.01 with 2% syst. 4MW, 540kt 2yr for  6~7yr for   m 21 2 =6.9x10 -5 eV 2  m 32 2 =2.8x10 -3 eV 2  12 =0.594  23 =  /4 T2K-I 90% Kobayashi, 2004

24. 26 July 2004Deborah Harris, Superbeams, NuFact0424 Next Steps depend on First Steps LSND Confirmed by MiniBooNE? –Lots of new shorter baseline beamlines needed –CP violation in  →  becomes more important Both T2K and NO A see no evidence for  13 ≠0? –Upgrade either (or both) to get most sensitive search Either T2K or NO A see a hint of  13 ≠0? –Lots of new ideas, depends on who sees what Is signal in neutrinos or antineutrinos? Does one see it but not the other? No matter what we know we will need: –Need protons and targets that can accept them –Need better background rejection with high efficiency

25. 26 July 2004Deborah Harris, Superbeams, NuFact0425 Fermilab to Homestake Based on 2MW at 120GeV, +2MW at 8GeV Several off axis beams + 1 on axis beam to give broad spectrum May be easiest way to get to 4MW of proton power Very preliminary, more of a show of flexibility given enough protons ~200M ~8m ~4m 30 mR maximum off axis 120 GeV protons 8 GeV protons

26. 26 July 2004Deborah Harris, Superbeams, NuFact0426 Fermilab to Homestake Physics Reach Considering Different Detectors 1.500kT Water Cerenkov (shown here) 2.Liquid Argon TPC 3.All-Scintillator Detector (NO A ) Michael, Snowmass 2004 Water Cerenkov  Disappearance e Appearance Water Cerenkov

27. 26 July 2004Deborah Harris, Superbeams, NuFact0427 Brookhaven to Homestake 28GeV AGS upgrade to 1MW (2MW) cf current 0.1MW Wide band beam (0.5~6GeV) L=2,540km Mton UNO (alternative option: Liquid Argon TPC) ~13,000   CC/year/500kt Cover higher osc. maxima Recent Progress AGS Upgrade path solidified Civil Construction Developed Targeting R&D Better WC simulations— investigating ways to overcome backgrounds (1 degree off-axis capability) Chiaki Yanagisawa Brett Viren

28. 26 July 2004Deborah Harris, Superbeams, NuFact0428 Brookhaven to Homestake Physics Reach Studies with agressive Detector MC: even with only data, CP violation and mass hierarchy are visible in some regions of parameter space. Normal hierarchyReversed hierarchy But with both and running, CP precision much higher Diwan, 3/2004 APS study meeting

29. 26 July 2004Deborah Harris, Superbeams, NuFact0429 Beta-Beam and SPL at CERN 4MW 2.2GeV Superconducting Proton Linac (SPL) @ CERN Low energy wide band (E ~0.3GeV) L=130km Water Cerenkov (400kt) or LAr TPC ~18,000 nm CC/year/400kt SPL in R&D, UNO in conceptual design Clear overlap between SPL target and neutrino factory target Beta beam uses known Isolde technology… Progress on design, and radiation shielding Schematic of Large detectors in Frejus tunnel (Mosca, CERN 2004)

30. 26 July 2004Deborah Harris, Superbeams, NuFact0430 Beta-Beam and SPL Physics Reach Burguet-Castel et al,hep-ph/0312068  L(km)E (GeV) 60/1001300.23/0.37 350/5807301.4/2.2 1500/250030005.8/9.4 Results below for combining Conventional and beta-beams But also physics study has been done To look at higher energy beta-beams As well—feasibility studies to follow… Mezzetto, NuFact03

31. 26 July 2004Deborah Harris, Superbeams, NuFact0431 Summary Two complementary steps right around the corner –T2K –NO A After that, we know we need more protons—many proton driver upgrade paths –Fermilab –J-PARC –Brookhaven –CERN SPL Plenty of important measurements to make along the way –Cross Sections (MINER A,K2K Scibar) Next superbeam to build depends on what the first superbeams find