MiniBooNE Status Report Ray Stefanski for the MiniBooNE Collaboration.

1. Seventh International Workshop onTOPICS IN ASTROPARTICLE AND UNDERGROUND PHYSICSSeptember 8-12, 2001Laboratori Nazionali del Gran Sasso, Assergi (ITALY) MiniBooNE Status Report Ray Stefanski for the MiniBooNE Collaboration. in four movements.

2. The road to oscillations with MiniBooNE • Medium baseline oscillation detectors? pascaglia • What we expect to observe and when? minueta • How are we doing? sonata alegro • Summary & conclusions coda

3. pascaglia LSND and KARMEN(M. Steidl) are precursor experiments to M’BooNE, the “Mini” Booster Neutrino Experiment. LSND: MeV decay at rest MeV decay in flight Final results, 1993-98 data; event excess; evidence for oscillations. KARMEN: MeV decay at rest. Experiment ended March 2001; no excess; does not confirm LSND, but does not rule it out either. MiniBooNE: MeV 8 GeV protons, 3 GeV Under construction; first data summer 2002; will confirm/reject LSND at the five sigma level.

4. pascaglia LSND and KARMEN experimental scheme muon decay at rest detect prompt e track, 20<Ee<60 MeV neutron capture: 2.2 MeV, 8 MeV g correlated in position and in time with e no B-field, e and g sequence distinguishes e+ from e-

5. pascaglia likelihood that g is correlated likelihood that g is uncorrelated LSND Beam on-off excess Total excess: Excess for 100% transmutation: Oscillation probability

6. pascaglia Search for neutrino oscillations at higher Dm2. • MiniBooNE addresses the LSND signal. • Oscillations imply • neutrinos have a mass spectrum; • neutrinos flavor mix. • The LSND result is in the “cosmologically interesting” region; • MiniBooNE is unique in fully addressing this signal. Hot dark matter. Formation of galaxies.

7. pascaglia We expect that a great deal will be understood in the next five years regarding n oscillations and n mass. Clarification of the LSND region is crucial for an understanding of these issues.

8. pascaglia • In the next five years, we would like to observe oscillatory • behavior, and clarify the sterile neutrino issue. • There are many models for sterile neutrinos, and the existence of • sterile neutrinos immediately implies new physics. By 2004 data from MiniBooNE, SNO and Kamland should shed considerable light on this picture.

9. minueta An Overview of MiniBooNE Uses an intense neutrino beam with mean energy at ~1 GeV to detect the appearance of electron neutrinos in a relatively pure muon neutrino beam. The detector is a 12 meter diameter Cerenkov detector filled with mineral oil. Muon monitors Alabama – Bucknell – Cincinnati – Columbia – Embry-Riddle Holy Cross – Indiana – Louisiana Michigan – Princeton – Riverside FNAL - LANL

10. minueta The Booster 8 GeV proton accelerator built to supply beam to the Main Ring, it now supplies the Main Injector Booster must now run at record intensity MiniBooNE will run simultaneously with the other programs: e.g. Run II + BooNE; 5 x 1012 protons per pulse at a rate of 7.5 Hz; (5 Hz for BooNE) BooNE: 5 x 1020 p.o.t in one year Challenges are radiation issues, losses

11. minueta Beam-line civil construction: • In only a few months, the excavation • has been filled with a beam tunnel. • The project is ready for some early • tunnel installation. • Progress is adequate for • first beam in the spring. • Some of the initial runs • will be devoted to • systems checkout.

12. minueta Horn & Target System • 20M pulse tests of proto-horn are • about to begin. Initial 170 kamp, • 5 Hz runs have been made. • An aluminum proto-target is • available for these tests. • Beryllium target will be available • in December. • The horn power supply is • complete. • The water cooling system is • complete.

13. minueta Target Hall & Decay Pipe Construction was delayed because of heavy snow during the winter and difficulty with our contractor. This enclosure will contain the target, horn, and associated shielding. Above the enclosure will sit a service building that will contain a 30 T crane.

14. minueta Muon monitors The muon detector, to act as a beam monitor. The little muon counter to measure muons from K – decay.

15. Sonata alegro MiniBooNE detector mineral oil total volume: 800 tons (6 m radius) fiducial volume: 445 tons (5m radius) 1280 PMTs in detector at 5.5 m radius 10% photocathode coverage 240 PMTs in veto Phototube support structure provides opaque barrier between veto and main volumes

16. Sonata alegro PID based on ring id, track extent, ratio of prompt/late light signatures substantially different from LSND x10 higher energy neutron capture does not play a role If LSND correct: ~500 events (2 years) Backgrounds are mis-id of m’s and p’s, and intrinsic ne in the beam

17. Sonata alegro Oil Tester We’ve received samples of oil from potential vendors. These samples will be tested to find the best oil. A beam of light of given wavelength is passed through air, and a tube of oil. Transmission as a function of wavelength is measured for each oil. Procurement decision will be made in about a month.

18. Sonata alegro PMTs Most of the 1500 PMTs have been installed in the detector. This photo shows The PMTs ready for installation. Note the wire mounting bracket, and potted bases. All of the LSND tubes tested well. A few of the new batch of 300 had faults.

19. Sonata alegro MiniBooNE status Virtually all PMTs are installed. Tests will be done with the tank empty, and using flashers. Most of the cables are installed, electronics are progressing, and work continues on DAQ.

20. Sonata alegro

21. Coda Signal vs. Background

22. Coda C* ???

23. Coda Summary LSND observes appearance of oscillations at relatively high and low mixing angle This observation needs confirmation. MiniBooNE will start collecting data in spring 2002, and will make a definitive statement about LSND after two years.