Mini Overview Peter Kasper NBI 2002

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Mini OverviewPeter KasperNBI 2002
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The MiniBooNE Collaboration

• University of Alabama, Tuscaloosa
• Bucknell University, Lewisburg
• University of California, Riverside
• University of Cincinnati, Cincinnati
• University of Colorado, Boulder
• Columbia University, Nevis Labs, Irvington
• Embry Riddle Aeronautical University
• Fermi National Accelerator Laboratory
• Indiana University, Bloomington
• Los Alamos National Laboratory
• Louisiana State University, Baton Rouge
• University of Michigan, Ann Arbor
• Princeton University, Princeton

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MiniBooNE Goals

• MiniBooNEs primary goal is to unequivocally
  confirm or refute the LSND oscillation signal for
  ?? ? ?e
• Similar L/E 1 to LSND but 10x higher energy
• En 0.5 - 1 GeV
• L 500 m
• Experimental signatures and backgrounds are
  completely different from LSND
• provides a truly independent test of their
  result.
• If the signal is confirmed, a second detector
  will be built ...
• i.e. full BooNE

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LSND and KARMEN Results

• KARMEN limits
• Solid curve calculated with the Feldman
  Cousins approach
• Dashed curve is experiments sensitivity
• LSND signal region
• ? 90
• Lmax - L lt 2.3
• ? 99
• Lmax - L lt 4.6

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The LSND Signal

• Signal discrimination is encapsulated into a
  variable Rg
• Ratio of likelihood that e and g are correlated
  to likelihood that g is accidental.
• 87.9 22.4 6.0 event excess consistent with
  ?ne p ? e n followed by n p ? d g.
• 4 times the expected rate from beam?ne s

signal
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LSND Implications

• What we know from other experiments
• Atmospheric nms oscillate at Dm2 10-3 with
  maximal mixing ( e.g. SuperK )
• nm ? nt favored
• Solar nes oscillate at Dm2 lt 10-4 ( e.g. SNO )
• nm ? nt/e favored
• LSND results has Dm2 10-1 for?nm ??ne
• hence require ? 4 neutrino mass states
• Only 3 active flavors ( LEP )
• hence sterile ns are required
• OR
• neutrino masses ? antineutrino masses

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An Experimentally Allowed Model

• Bimaximal mixing in 3 1 models
• W. Krolikowski HEP-PH/0106350
• R.N.Mohapatra Phys.Rev. D64 (2001) 091301,

n4
Dm2 LSND
ne
n3
nm
Dm2 Atm.
nt
n2
Dm2 Solar
ns
n1
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An Alternative Model

• Maximal CPT violation in Dirac mass terms
• Barenboim, Borissov, Lykken Smirnov
  HEP-PH/0108199
• Generates independent masses for ns and?ns
• Motivated by branes with extra dimensions

?n3
ne
nm
nt
Dm2 LSND
n3
?n2
Dm2 Atm.
n2
?n1
Dm2 Solar
n1
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Proton Beam

• MiniBooNEs neutrino beam will be produced with
  a high intensity ( 5E12 _at_ 5 Hz ) 8 GeV proton
  beam from the Fermilab Booster.
• The Booster cycles at 15 Hz and produces 1.6 msec
  beam pulses.

• New construction
• Proton beam line
• Target Hall
• Decay pipe
• Detector building

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Beam Layout

• Civil construction for the 8 GeV Beamline, Target
  Hall, and Decay Pipe began in June 2000.

• 50m long
• decay pipe

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Beam Line Construction

• Civil Construction is complete and component
  installation is well advanced. Ready for beam
  tests this April.

24-Jan-02
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Target Hall Construction

• Civil and target pile construction is complete.
  Horn installation is scheduled to start in early
  May.

24-Jan-02
24-Jan-02
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Decay Pipe Construction

• Two absorbers at 25m (removable) and 50m (fixed)
  provide a cross check of the intrinsic ne
  component in the beam.

50m absorber with muon counters
24-Jan-02
Air heat exchanger for cooling berm
25m absorber
13-Nov-00
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The Target

• A 65cm, air cooled Be target will be inserted
  inside a single focussing horn

7-Feb-02
Hadroproduction studies will be done for our
energy and target. (BNL910 and HARP)
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The Horn

• A single horn system will be used ( proposal had
  two )
• Less flux but also less background from high
  energy (gt1 GeV) neutrinos than the original 2
  horn design
• Horn has been built and tested for gt 107 pulses

20-Jun-01
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The Neutrino Beam

• Intrinsic ne contamination can be ..
• Inferred from nm events
• Simulated using hadroproduction measurements
• Measured using muon counters in and around the
  decay pipe
• Checked by comparing 50m and 25m absorber results

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The Detector

• The detector is a 40ft (12.2m) diameter sphere
  filled with 800 tons of pure mineral oil and
  instrumented with 1500 8 PMTs.
• It is housed underground in order to provide some
  cosmic ray shielding.

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The Detector (cont.)

• It will consist two optically separated regions
  ...
• An inner sphere with 1280 PMTs viewing a 445 ton
  fiducial volume ( 10 photocathode coverage)
• An outer veto shell 35cm thick monitored by 240
  PMTs.

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Detector Status

• The detector enclosure was completed in December
  2000.
• The PMT installation was completed in October
  2001.
• Oil fill started early January and the detector
  is now 60 full.

Detector Enclosure Jan 2001
PMT installation Sept. 2001
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A Possible Stopping Cosmic Ray Muon
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Event Reconstruction

• MiniBooNE will reconstruct quasi-elastic ne
  interactions by identifying the characteristic
  Cerenkov rings produced by the electrons ...

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Approximate of Events after 1-2 Years
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MiniBooNE Sensitivity 2 yrs of nm

• The major backgrounds
• misid ms from CC nm
• misid p0s from NC nm
• Uncertainties in these rates to be lt 5 in each
  case.
• nes Intrinsic to the beam have a different
  energy distribution than oscillation nes
• Event energy can be measured using scintillation
  light

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Summary

• All civil construction projects for MiniBooNE are
  essentially complete.
• The detector instrumentation is complete and the
  oil fill is well under way.
• MiniBooNE is on schedule for taking first data
  later this summer.
• The biggest issue facing the experiment at this
  point is the Boosters ability to deliver the
  required number of protons.
• The limits will be due to radiation levels both
  in the tunnel and above ground.