The Physics and Status of MiniBooNE

1. The Physics and Status of MiniBooNE Jonathan Link Columbia University Fermilab Annual Users Meeting June 10-11, 2002 Jonathan Link, Columbia Fermilab Users Meeting

2. A Little Neutrino Phenomenology If neutrinos have mass then they may oscillate between flavors with the following probability Lis the distance that the neutrino travels (the baseline) Eis the neutrino energy sin22qis the oscillation mixing angle Dm2is the mass difference squared between neutrino mass eigenstates Jonathan Link, Columbia Fermilab Users Meeting

3. LSND - Uncorroborated Atmospheric Neutrinos - Super-K, IMB, Kamiokande, etc. Solar Neutrinos - Recently nailed down by SNO Plenty of Evidence for Neutrino Mass Jonathan Link, Columbia Fermilab Users Meeting

4. The LSND Experiment LSND took data from 1993-98 The full dataset represents nearly 49,000 Coulombs of protons on target. Baseline of 30 meters Energy range of 20 to 55 MeV L/E of about 1m/MeV Jonathan Link, Columbia Fermilab Users Meeting

5. LSND’s Unexpected Result Looked for an excess of ne events in a nm beam Saw 87.9 ± 22.4 ± 6.0 events over expectation. With an oscillation probability of (0.264 ± 0.067 ± 0.045)%. 3.3 s evidence for oscillation. Jonathan Link, Columbia Fermilab Users Meeting

6. Why is this Result Interesting? ν3 Dm22 ν2 Dm12 ν1 LEP found that there are only 3 light neutrinos that interact weakly. Three neutrinos allow only 2 independent Dm2 scales. Dm32=Dm12+ Dm22 But we have experimental results in 3 Dm2 regions! Jonathan Link, Columbia Fermilab Users Meeting

7. How Can We Fix the Theory? • Add a fourth sterile neutrino. Giving you three independent Dm2 scales. • Violate CPT. Giving you different mass scales for n and n. n n If MiniBooNE sees an LSND signal with n we can rule this out, but if we don’t then we need to run with n! From Barenboim, et. al., hep-ph 0201080 Jonathan Link, Columbia Fermilab Users Meeting

8. The Other Experiments Several other experiments have looked for oscillations in this region. Allowed Region from Joint Karmen and LSND fit From Church, Eitel, Mills, & Steidl hep-ex/0203023 The most restrictive limits come from the Karmen Experiment. Jonathan Link, Columbia Fermilab Users Meeting

9. A Conclusive Experiment is Needed • With High Significance • At least 5s over the entire LSND region (including systematic and statistical uncertainties) • Demonstrating expected energy dependence for oscillation • Low and Different Systematics (Change the signature) • Change the beam to higher energy • Optimize detector for new signature • High Statistics • About an order of magnitude more events than LSND Jonathan Link, Columbia Fermilab Users Meeting

10. The BooNE Collaboration The BooNE Collaboration Y.Liu, I.Stancu University of Alabama, Tuscaloosa S.Koutsoliotas Bucknell University, Lewisburg E.Church, C.Green, G.J.VanDalen University of California, Riverside E.Hawker, R.A.Johnson, J.L.Raaf, N.Suwonjandee University of Cincinnati, Cincinnati T.Hart, E.D.Zimmerman University of Colorado, Boulder L.Bugel, J.M.Conrad, J.Formaggio, J.M.Link, J.Monroe, M.H.Shaevitz, M.Sorel Columbia University, Nevis Labs, Irvington D.Smith Embry Riddle Aeronautical University C.Bhat, S.Brice, B.Brown, B.T.Fleming, R.Ford, F.G.Garcia, P.Kasper, T.Kobilarcik, I.Kourbanis, A.Malensek, W.Marsh, P.Martin, F.Mills, C.Moore, P.J. Nienaber, E.Prebys, A.D.Russell, P.Spentzouris, R.Stefanski, T.William Fermi National Accelerator Laboratory D.C.Cox, J.A.Green, S.McKenney, H.Meyer, R.Tayloe Indiana University, Bloomington G.T.Garvey, W.C.Louis, G.McGregor, G.B.Mills, E.Quealy, V.Sandberg, B.Sapp, R.Schirato, R.Van de Water, D.H.White Los Alamos National Laboratory R.Imlay, W.Metcalf, M.Sung, M.Wascko Louisiana State University, Baton Rouge J.Cao, Y.Liu, B.P.Roe University of Michigan, Ann Arbor A.O.Bazarko, P.D.Meyers, R.B.Patterson, F.C.Shoemaker Princeton University, Princeton The Booster Neutrino Experiment… BooNE BooNE was formed to search for ne appearance in a nm beam at Fermilab. BooNE consists of about 60 scientists from 14 institutions. Jonathan Link, Columbia Fermilab Users Meeting

11. The MiniBooNE Neutrino Beam nmne? • Start with a very intense 8 GeV proton beam from the Booster. • The beam is delivered to a 71 cm long Be target. • In the target primarily pions are produced, but also some kaons. • Charged pions decay almost exclusively as p±m±nm. • The decays K±p0e±ne and KLp±ene contribute to background. • There are also ne’s from muon decay. Jonathan Link, Columbia Fermilab Users Meeting

12. The MiniBooNE Beam (Continued) • A toroidal field horn focuses the charged particles on the detector. • Initially positive particles will be focused selecting n, • but the horn current can be reversed to select n. • Increases neutrino intensity by an order of magnitude. • The horn is followed by a decay region of 25 m or 50 m. • The decay region is followed by an absorber and 500 m of dirt, beyond which only the neutrino component of the beam survives. • Switching between 25 m and 50 m decay length helps in understanding the ne background from m decay. Jonathan Link, Columbia Fermilab Users Meeting

13. The MiniBooNE Horn • The horn operates at 5 Hz • Each 170 kilo-amp (kA) pulse lasts for 150 micro seconds • Design lifetime of 200 million pulses (Tested with 10+ million pulses) • The horn is designed to maximize neutrino flux from 0.5 GeV to 1 GeV • The horn increases neutrino flux at the detector by a factor of 10. MiniBooNE horn during assembly Jonathan Link, Columbia Fermilab Users Meeting

14. Neutrino Flux at the Detector The L/E is designed to be a good match to LSND at ~1 m/MeV. From beam simulations the expected intrinsic ne flux is small compared to the nm flux. Jonathan Link, Columbia Fermilab Users Meeting

15. The MiniBooNE Detector • 12 meter diameter sphere • Filled with 950,000 liters of pure mineral oil — 20+ meter attenuation length • Light tight inner region with 1280 photomultiplier tubes • Outer veto region with 240 PMTs. • Neutrino interactions in oil produce: • Prompt Čerenkov light • Delayed scintillation light • Čerenkov:scintillation ~ 5:1 Jonathan Link, Columbia Fermilab Users Meeting

16. Inside the MiniBooNE Detector PMTs at the bottom of the detector just before sealing up the inner region. View of the Veto Region as the first oil is added to the detector. Jonathan Link, Columbia Fermilab Users Meeting

17. Approximate number of events expected in MiniBooNE with two years of running. Intrinsic ne background: 1,500 events mmis-IDbackground:500 events p0 mis-IDbackground:500 events LSND-based nmne:1,000 events Jonathan Link, Columbia Fermilab Users Meeting

18. Particle Identification: m, e & p0 Particle ID is based on ring id, track length, ratio of prompt/late light Signatures substantially different from LSND Factor 10 higher energy and baseline Neutron capture does not play a role Ideal Ring Fuzzy rings distinguish electrons from muons. p0 from neutral current interactions typically look like 2 electrons, but infrequently the two rings overlap and appear as one. Jonathan Link, Columbia Fermilab Users Meeting

19. Intrinsic Beam Backgrounds ne from m –decay (0.06%) Directly tied to observed nm rate Quadratic decay pipe length dependence ne from K–decay (0.06%) Related to observed high E events Beam surveys: BNL-910, HARP “Little Muon Counters” (LMC) Mis-Identification Neutral current p0 production (0.1%) Scaled from the 99% that are properly reconstructed nm mis-id’ed as ne’s (0.03%) Scaled from the 99.9% that are properly reconstructed Controlling Backgrounds Dump 1 All Backgrounds can be related to data measurements Dump 2 Can change decay pipe length: - ne from m-decay  L2 - nm from p-decay  L - ne from K+-decay  L<1 Jonathan Link, Columbia Fermilab Users Meeting

20. MiniBooNE Sensitivity to LSND With 11021 protons on target MiniBooNE should be able to completely include or exclude the entire LSND signal region. Jonathan Link, Columbia Fermilab Users Meeting

21. First Results: Cross Sections Exotic Searches Oscillations Supernova here? Final Oscillation Result, Including n Letter of Intent The MiniBooNE Timeline Approved 1998 Detector Hall Complete 1999 Detector Complete 2000 Horn Test Complete First Beam Test 2001 Oil Fill Complete Run Begins 2002 51020 protons 11021 protons Jonathan Link, Columbia Fermilab Users Meeting

22. Cosmic Muon Decays Calibration Study • Fit Lifetime: • = 2.12 ± 0.05 ms Expected m lifetime in oil - 2.13 ms with 8% m- capture on Carbon. P.E. 364 Hits Typical m Decay Event 104 Hits Jonathan Link, Columbia Fermilab Users Meeting

23. Animation Each frame is 25 ns with 10 ns steps. Low High Early Late Muon Decay Candidate Charge (Size) Time (Color) Jonathan Link, Columbia Fermilab Users Meeting

24. MiniBooNE as a Supernova n Detector For a Supernova within 10 Kpc we expect to see about 200 n interactions in a 10 second period. From Sharp, Beacom and Formaggio hep-ph/0205035 12B decay Supernova n m decay How the supernova signal might look as a function of time. Jonathan Link, Columbia Fermilab Users Meeting

25. Cross Sections andExotics The n cross sections are not well measured in our energy range. Oscillation probability is small enough that we can ignore it in nm cross section measurements. From Lipari, et al., PRL 74, 4384 Look for things that may not have been conceived of yet Neutrino Magnetic Moment (Very Small in SM) The Karmen Timing Anomaly (see paper by Case, Koutsoliotas and Novak, Phys. Rev. D65:077701, 2002) Jonathan Link, Columbia Fermilab Users Meeting

26. Conclusions • We expect to begin the run late June/early July. • We will take 51020 protons on target in n mode (~1 year). • With this data we should be able to confirm or rule out the full high Dm2oscillation range of LSND (CPT conserving). • If no signal is seen in n mode, n running is needed to investigate CPT violation. • We are studying several other possible physics topics • Cross Sections • Supernova neutrinos • Exotics • Possible upgrade to BooNE, a two detector experiment to carefully measure Dm2 and look for nm disappearance. Jonathan Link, Columbia Fermilab Users Meeting