Superbeams

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

2. 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 NOnA • Why Two Beams are better than one… • Far Term: Lots of other ideas… • Summary Deborah Harris, Superbeams, NuFact04

3. 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 n’s are there? • Mass Hierarchy? • Is CP Violated? • Are n’s their own antiparticles? Mena&Parke, hep-ph/0312131 Deborah Harris, Superbeams, NuFact04

4. Definition of Mixing Angles • Need to measure ne to nm transitions at Datm-scale baseline/energy Deborah Harris, Superbeams, NuFact04

5. What happens when ne’s pass through the earth? “Raises potential Energy for ne’s and Anti-ne’s separately” Wolfenstein, PRD (1978) electron density in the earth Deborah Harris, Superbeams, NuFact04

6. Designing a Neutrino Experiment • Currently: pin down or eliminate Dm2 • Next: look for ne /nm transitions at Dm2atm • CP violation in absence of matter effects • Matter effects in absence of Dmsol2 Deborah Harris, Superbeams, NuFact04

7. Making a Neutrino Beam • Conventional Beam • Beta Beam • Neutrino Factory Detector Needs Deborah Harris, Superbeams, NuFact04

8. Conventional Beam Challenges What is so hard about nm →ne • CHOOZ tells us it’s a small effect (<5%) • Unavoidable contamination of ne in beam • From m decays • At high enough p energies, K enters too! • KL→ p+ e –ne and KL→ p- e +ne • Can mistake p0, m or p± for e Deborah Harris, Superbeams, NuFact04

9. Two Approaches: Narrow and Broad • Narrow Band Beams • Lower backgrounds under peak from ne and NC • But flux is narrower than oscillation maximum! • Most sensitive limits per MW*kton • Examples: T2K, NOnA, CNGT • Broad Band Beams • Higher event rates • In some cases actually measure shape of oscillations • Higher ne backgrounds at any one energy • Examples: BNL LOI, FeHo, CERN SPL Deborah Harris, Superbeams, NuFact04

10. “Off Axis” Neutrino Beams • First Suggested by Brookhaven (BNL 889) • Take advantage of Lorentz Boost and 2-body decays • Concentrate nm flux at one energy • Lower NC and ne backgrounds at that energy (3-body decays) Deborah Harris, Superbeams, NuFact04

11. Detector Options • Water Cerenkov • Scintillator Calorimetry • Liquid Argon TPC Deborah Harris, Superbeams, NuFact04

12. Water Cerenkov • Excellent particle ID for single-ring events • Most massive n detector built to date • More problematic for multi-ring events • Multi-p events can fake single-ring events p0or e? SuperK event displays courtesy Mark Messier Being considered for higher and higher energies because of low energy capabilities… (see Strolin’s talk) Deborah Harris, Superbeams, NuFact04

13. Scintillator Calorimetry • Calorimeter with <X0 sampling can do • e/g separation by looking for gaps after event vertex • e/m 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 nm + A -> p +m- ne+A→p p+p- e- n + A -> p + 3p± + p0 + n Cooper, June 2004 PAC Deborah Harris, Superbeams, NuFact04

14. 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 D e+ B K+ C µ+ A Run 939 Event 46 AB Rubbia, NuINT04 K+ µ+ BC e-,15 GeV, pT=1.16 GeV/c Deborah Harris, Superbeams, NuFact04

15. In Praise of Near Detectors • To make precise measurements,need • Background cross sections • Signal (CC!) cross sections MINERnA event display g proton nA→mpA g Data compiled by G.Zeller, hep-ex/0312061 nN→mpN’ Need Dedicated Measurements in fine-grained detectors (see D.Casper’s talk on Friday) Deborah Harris, Superbeams, NuFact04

16. First Step: seeing if Q13 is non-zero • T2K Tokai to Kamioka • 295km, 1st osc. maximum • 50kton Water Cerenkov (SK) • New 0.8MW proton Source: J-PARC December, 2003 OAB2.0deg OAB2.5deg OAB3.0deg 12/2003 Exp’t approved 2008 Accelerator operating 2009 n Physics Running Deborah Harris, Superbeams, NuFact04

17. T2K Detector Suite • Several jobs, • several detectors: • Verify n beam direction • Measure nm and ne fluxes with high statistics • Measure background and signal cross sections • Eventually, verify background rates in “identical” detector at 2km Hayato, n2004 Deborah Harris, Superbeams, NuFact04

18. T2K Physics Reach Hayato, n2004 Deborah Harris, Superbeams, NuFact04

19. NOnA • Use Existing NuMI beamline • New Detector 12km off axis • 820km shows best compromise between reach in q13 and matter effects • PAC recommendation “The Committee strongly endorses the physics case for the NOnA detector, and would like to see NOnA 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 Dm2=2.5x10-3eV2 Messier, n2004 Deborah Harris, Superbeams, NuFact04

20. NOnA Physics Reach Because of CP and matter effects, “reach” vs. sin2 2q13 will vary… 50kton baseline detector 50kton baseline detector Feldman, Aspen PAC 2004 Deborah Harris, Superbeams, NuFact04

21. Oscillation Probabilities P(nm→ne)=P1+P2+P3+P4 • 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? Minakata & Nunokawa JHEP 2001 Deborah Harris, Superbeams, NuFact04

22. 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 • NOnA 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 Deborah Harris, Superbeams, NuFact04

23. 4MW, 540kt 2yr for nm 6~7yr for nm CP Violation at T2Hyper-K CHOOZ excluded sin22q13<0.12@Dm312~3x10-3eV2 3s CP sensitivity : |d|>20o for sin22q13>0.01 with 2% syst. stat+2%syst. stat+5%syst. (signal+BG) stat only no BG signal stat only stat+10%syst. T2K 3s discovery Dm212=6.9x10-5eV2 Dm322=2.8x10-3eV2 q12=0.594 q23=p/4 T2K-I 90% Kobayashi, n2004 Deborah Harris, Superbeams, NuFact04

24. Next Steps depend on First Steps • LSND Confirmed by MiniBooNE? • Lots of new shorter baseline beamlines needed • CP violation in nm→ntbecomes more important • Both T2K and NOnA see no evidence for q13≠0? • Upgrade either (or both) to get most sensitive search • Either T2K or NOnA see a hint of q13≠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 Deborah Harris, Superbeams, NuFact04

25. Fermilab to Homestake ~8m • 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 30 mR maximum off axis ~200M ~4m 120 GeV protons 8 GeV protons Deborah Harris, Superbeams, NuFact04

26. Fermilab to Homestake Physics Reach ne Appearance Water Cerenkov nm Disappearance • Considering Different Detectors • 500kT Water Cerenkov (shown here) • Liquid Argon TPC • All-Scintillator Detector (NOnA) Water Cerenkov Michael, Snowmass 2004 Deborah Harris, Superbeams, NuFact04

27. 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 nm 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) Brett Viren Chiaki Yanagisawa Deborah Harris, Superbeams, NuFact04

28. But with both n and n running, CP precision much higher Brookhaven to Homestake Physics Reach Studies with agressive Detector MC: even with only n data, CP violation and mass hierarchy are visible in some regions of parameter space. Normal hierarchy Reversed hierarchy Diwan, 3/2004 APS study meeting Deborah Harris, Superbeams, NuFact04

29. Beta-Beam and SPL at CERN • 4MW 2.2GeV Superconducting Proton Linac (SPL) @ CERN • Low energy wide band (En~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 Schematic of Large detectors in Frejus tunnel (Mosca, CERN 2004) Beta beam uses known Isolde technology… Progress on design, and radiation shielding Deborah Harris, Superbeams, NuFact04

30. Beta-Beam and SPL Physics Reach 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… Burguet-Castel et al,hep-ph/0312068 Mezzetto, NuFact03 Deborah Harris, Superbeams, NuFact04

31. Summary • Two complementary steps right around the corner • T2K • NOnA • 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 (MINERnA,K2K Scibar) • Next superbeam to build depends on what the first superbeams find Deborah Harris, Superbeams, NuFact04