Seventh International Workshop on

TOPICS IN ASTROPARTICLE AND UNDERGROUND

PHYSICSSeptember 8-12, 2001

Laboratori Nazionali del Gran Sasso, Assergi (ITALY)

MiniBooNE Status ReportRay Stefanski

for the MiniBooNE Collaboration.

in four movements.

The road to e 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

LSND: e 20020 E

MeV

decay at rest

e MeV

6020 E

decay in flight

Final results, 1993-98 data; event excess; evidence for oscillations.

KARMEN: e

6020 E

MeV decay at rest.

Experiment ended March 2001; no excess; does not confirm LSND, but does not rule it out either.

MiniBooNE: e 1500500 E MeV

Under construction; first data summer 2002; will confirm/rejectLSND at the five sigma level.

8 GeV protons, 3 GeV

LSND and KARMEN(M. Steidl) are precursor experiments to M’BooNE, the “Mini” Booster Neutrino Experiment.

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LSND and KARMEN experimental scheme

ee

emuon decay at rest

nepe detect prompt e track, 20<Ee<60 MeV

neutron capture: dnp 2.2 MeV, ),( nGd 8 MeV

correlated in position and in time with eno B-field, e and sequence distinguishes e+ from e

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LSND

Beam onoff excessevents 4.229.117

events 9.35.19 DAR :bkgd events 6.45.10 DIF

Total excess:

events 0.64.229.87

Excess for 100% transmutation: events 333033300 Oscillation probability 0.045)%0.067(0.264

MeV 6020 eE Rlikelihood that is correlatedlikelihood that is uncorrelated

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• MiniBooNE addresses the LSND signal.•Oscillations imply

o neutrinos have a mass spectrum;o neutrinos flavor mix.

• The LSND result is in the “cosmologically interesting” region;• MiniBooNE is unique in fully addressing this signal.

e

Search for neutrino oscillationsat higher m2.

2m

Hot dark matter.Formation of galaxies.

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We expect that a greatdeal will be understoodin the next five yearsregarding oscillationsand mass.

Clarification of the LSNDregion is crucial for anunderstanding of theseissues.

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By 2004 data from MiniBooNE, SNO and Kamland should shedconsiderable light on this picture.

o There are many models for sterile neutrinos, and the existence ofsterile neutrinos immediately implies new physics.

o In the next five years, we would like to observe oscillatorybehavior, and clarify the sterile neutrino issue.

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An Overview of MiniBooNE

Alabama – Bucknell – Cincinnati – Columbia – Embry-Riddle Holy Cross – Indiana – LouisianaMichigan – Princeton – Riverside

FNAL - LANL

Uses an intense neutrino beam with mean energy at ~1 GeVto detect the appearance of electron neutrinos in a relativelypure muon neutrino beam. The detector is a 12 meterdiameter Cerenkov detector filled with mineral oil.

Muon monitors

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

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.

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.

minueta

Target Hall & Decay Pipe

Construction was delayed because of heavy snow during the winter and difficulty with our contractor.

This enclosure willcontain the target, horn, andassociated shielding. Above theenclosure will sit a service building that will contain a 30 Tcrane.

minueta

Muon monitors

The little muon counterto measure muons fromK – decay.

The muon detector, to act as abeam monitor.

minueta

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

Sonata alegro

tiondiscrimina ,, :Analysis 0e

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 ’s and ’s, and intrinsic e in the beam

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. Procurementdecision will be made in about a month.

Sonata alegro

PMTs

Most of the 1500PMTs have been installed in the detector.

This photo showsThe PMTs ready forinstallation. Note thewire mounting bracket,and potted bases.

All of the LSND tubes tested well. A few of the new batch of 300 had faults.

Sonata alegro

MiniBooNE statusSonata alegro

Virtually all PMTs are installed.Tests will be done with the tank empty, and using flashers.

Most of the cablesare installed, electronics are progressing, and work continues on DAQ.

Sonata alegro

Signal vs. Background

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Coda

C* ???

Summary

LSND observes appearance of oscillations at relatively high and low mixing angle

e 2m

This observation needs confirmation.

MiniBooNE will start collecting data in spring 2002, and will make a definitive statement about LSND after two years.

Coda