LSND/MiniBooNE Follow-up Experiment with DAEdALUS

1. LSND/MiniBooNE Follow-up Experiment with DAEdALUS W.C. Louis Los Alamos National Laboratory August 6, 2010

2. Outline • LSND & MiniBooNE nm -> ne Oscillation Results • 3+1 Fit to World Antineutrino Data • Testing the LSND/MiniBooNE Signals with DAEdALUS • Conclusions

3. LSND Signal • LSND experiment • Stopped pion beamp+ -> m+ nmm+ -> e+nm ne • Excess of ne in nm beam • ne signature: Cherenkov light from e+ with delayed g from n-capture • Excess=87.9 ± 22.4 ± 6 (3.8s)

4. 2 mass LSND Signal • Assuming two neutrino oscillations • Can't reconcile LSND result with atmospheric and solar neutrino using only 3 Standard Model neutrinos – only two independent mass splitings

5. 2 mass Sterile Neutrinos • 3+N models • N>1 allows CP violation • nm -> ne ≠nm -> ne n5 Dm452 ~ 0.1 – 100 eV2 n4 Dm342 ~ 0.1 – 100 eV2 n3 n2 n1

6. MiniBooNE Neutrino ResultPRL 102, 101802 (2009) • 6.5e20 POT • No excess of events in signal region (E>475 MeV) • Ruled out simple 2n oscillations as LSND explanation (assuming no CP or CPT violation) SIGNAL REGION Phys. Rev. Lett. 98, 231801 (2007)

7. MiniBooNE Neutrino ResultPRL 102, 101802 (2009) • Excess of events observed at low energy:128.8 ± 20.4 ± 38.3 (3.0σ)‏ • Shape not consistent with simple 2n oscillations • Magnitude consistent with LSND • Anomaly Mediated Neutrino-Photon Interactions at Finite Baryon Density: Jeffrey A. Harvey, Christopher T. Hill, & Richard J. Hill, arXiv:0708.1281 • CP-Violation 3+2 Model: Maltoni & Schwetz, arXiv:0705.0107; T. Goldman, G. J. Stephenson Jr., B. H. J. McKellar, Phys. Rev. D75 (2007) 091301. • Extra Dimensions 3+1 Model: Pas, Pakvasa, & Weiler, Phys. Rev. D72 (2005) 095017 • Lorentz Violation: Katori, Kostelecky, & Tayloe, Phys. Rev. D74 (2006) 105009 • CPT Violation 3+1 Model: Barger, Marfatia, & Whisnant, Phys. Lett. B576 (2003) 303 • New Gauge Boson with Sterile Neutrinos: Ann E. Nelson & Jonathan Walsh, arXiv:0711.1363

8. MiniBooNE Antineutrino Result • 5.66e20 POT • arXiv:1007.1150

9. MiniBooNE Antineutrino Null Probability • Absolute c2 probability of null point (background only) - model independent • Frequentist approach

10. MiniBooNE Oscillation Fit E>475 • 5.66E20 POT • E>475 is signal region for LSND type osc. • Oscillations favored over background only hypotheses at 99.4% CL (model dependent) • Best fit (sin22q, Dm2) = (0.9584, 0.064 eV2) c2/ND = 16.4/12.6; Prob. = 20.5%c2/ND = 8.0/4; Prob. = 8.7% (475-1250 MeV)

11. E>475 MeV MiniBooNE nm->ne oscillation results appear to confirm the LSND evidence for antineutrino oscillations, although more data are needed

13. LSND/MiniBooNE Data Compared to 3+N Global Fits (fits from Karagiorgi et al.) 3+1 3+2

14. 3+1 Global Fit to World Antineutrino Data (with old MiniBooNE data set) G. Karagiorgi et al., PRD80, 073001 (2009) Best 3+1 Fit: Dm412 = 0.915 eV2 sin22qme = 0.0043 c2 = 87.9/103 DOF Prob. = 86% Predicts nm &ne disappearance of sin22qmm ~ 35% and sin22qee ~ 4.3%

15. 3+N Models Requires Large nm Disappearance! In general, P(nm -> ne) < ¼ P(nm -> nx) P(ne -> nx) Reactor Experiments: P(ne -> nx) < 5% LSND/MiniBooNE: P(nm -> ne) ~ 0.25% Therefore: P(nm -> nx) > 20%

16. MiniBooNE Neutrino & Antineutrino Disappearance Limits A.A. Aguilar-Arevalo et al.,PRL 103, 061802 (2009) Global best fit * * Improved results soon from MiniBooNE/SciBooNE Joint Analysis!

17. Future Experiments • MicroBooNE • CD1 approved • Address MB low energy n excess • Statistics too low for antineutrinos • Few ideas under consideration: • Move or build a MiniBooNE like detector at 200m (LOI arXiv:0910.2698) • A new search for anomalous neutrino oscillations at the CERN-PS (arxiv:0909.0355v3) • Redoing a stopped pion source at ORNL (OscSNS - http://physics.calumet.purdue.edu/~oscsns/) or DAEdALUS!

18. MiniDAEdALUS • Build MiniBooNE-like detector ~300’ (~90m) below cyclotron; (or use large WC detector filled with Gd!) • Copy MiniBooNE detector design except for higher PMT coverage (10%->20%) and addition of ~0.031 g/l of b-PBD; cost ~$10-15M • Poor cyclotron duty factor compensated by 300’ overburden (cosmic muon rate reduced by factor of ~100) • Assume ~ 1 year of data at ~1MW • Well understood neutrino fluxes and cross sections • Many advantages over LSND: (1) x5 larger detector; (2) x4 higher n flux; (2) x100 lower cosmic-muon rate; (3) negligible DIF background; (4) run 12 months per year (instead of 3); (5) larger distance for Dm2<1 eV2 implies lower n backgrounds;

19. MiniDAEdALUS For OscSNS & not MiniDAEdALUS nm -> neD(L/E) ~ 3% ; ne p -> e+ n (2.2 MeV g) • nm -> neD(L/E) < 1% ; Monoenergetic nm!; ne C -> e- Ngs (17.3 MeV e+) nm -> nsD(L/E) < 1% ; Monoenergetic nm!; nm C -> nm C* (15.11 MeV g) • nm -> ns; nm C -> nm C* (15.11 MeV g) MiniDaedalus would be capable of making precision measurements of ne appearance & nm disappearance and proving, for example, the existence of sterile neutrinos! (see Phys. Rev. D72, 092001 (2005)).

20. Search for Sterile Neutrinos with MiniDAEdALUS (or WC) Via Measurement of NC Reaction: nm C -> nm C*(15.11) Garvey et al., Phys. Rev. D72 (2005) 092001

21. MiniDAEdALUS • ne appearance (left) and nm disappearance sensitivity (right) for 1 year of running (for 60m!) LSND Best Fit LSND Best Fit

22. Conclusions • The MiniBooNE data are consistent with nm -> ne oscillations at • Dm2 ~ 1 eV2 and consistent with the evidence for antineutrino • oscillations from LSND. • The MiniBooNE nm -> ne oscillation allowed region appears to be • different from the nm -> ne oscillation allowed region. • The world antineutrino data fit well to a 3+1 oscillation model with • Dm2 ~ 1 eV2. All 3+N models predict large nm disappearance! • A MiniBooNE-like detector (MiniDAEdALUS) located ~300’ below the • DAEdALUS cyclotron could measure neutrino oscillations with high • significance (>>5s) and prove that sterile neutrinos exist!

23. Backup

24. E>200MeV • 5.66E20 POT • Oscillations favored over background only hypotheses at 99.6% CL (model dependent) • No assumption made about low energy excess • Best fit (sin22q, Dm2) = (0.0066, 4.42 eV2)c2/NDF = 20.4/15.3; Prob.=17.1%

25. E>200MeV • Subtract excess produced by neutrinos in n mode (11.6 events) • E<475MeV: • Large background • Not relevant for LSND type osc. • Big systematics • Null c2=32.8; p=1.7% Best fit (sin22q, Dm2) = (0.0061, 4.42 eV2)c2/NDF = 21.6/15.3; Prob.=13.7%

26. Future sensitivity E>475MeV fit • MiniBooNE approved for a total of 1e21 POT • Potential exclusion of null point assuming best fit signal Protons on Target

27. BooNE 6.5e20 Far + 1e20 Near POT • MiniBooNE like detector at 200m • Flux, cross section and optical model errors cancel in 200m/500m ratio analysis • Present neutrino low energy excess is 6 sigma statistical; 3 sigma when include systematics • Study L/E dependence • Gain statistics quickly, already have far detector data Near/Far 4  sensitivity similar to single detector 90% CL Sensitivity (Neutrino mode)

28. BooNE • Better sensitivity to nm (nm) disappearance • Look for CPT violation (nm  nm≠ nm nm) 1e21 Far/1e20 Near POT 6.5e20 Far/1e20 Near POT

29. Reminders of some analysis choices • Data bins chosen to be variable width to minimize N bins without sacrificing shape information • Technical limitation on N bins used in building syst error covariance matrices with limited statistics MC • First step in unblinding revealed a poor chi2 for oscillation fits extending below 475 MeV • Region below 475 MeV not important for LSND-like signal -> chose to cut it out and proceed

30. Reminders of some pre-unblinding choices • Why is the 300-475 MeV region unimportant? • Large backgrounds from mis-ids reduce S/B • Many systematics grow at lower energies • Most importantly, small S/B so not a good L/E region to look for LSND type oscillations 475 333 1250 Energy in MB [MeV]

31. E>475 MeV • 1 sigma contour includes 0.003<sin22q<1

32. Initial MINOSnmDisappearance Results Expect nm disappearance above 10 GeV for LSND neutrino oscillations.

33. OscSNS • Spallation neutron source at ORNL • 1GeV protons on Hg target (1.4MW) • Free source of neutrinos • Well understood flux of neutrinos • Physics reach would be similar with DARDaedalus