Status of the MINOS Experiment

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Status of the MINOS Experiment

• Elizabeth Buckley-Geer
• Fermi National Accelerator Lab
• (for the MINOS Collaboration)

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Outline

• The MINOS experiment
• The neutrino beam
• Civil construction status
• The detectors
• Physics measurements
• Summary

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The MINOS Experiment
Two Detector Neutrino Oscillation
Experiment (Start 2004)
Near detector 980 tons
Far detector 5400 tons
Det. 2
Det. 1
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The MINOS Collaboration
Over 250 Physicists and Engineers
IHEP-Beijing ?Athens ? Dubna ? ITEP-Moscow ?
Lebedev ? Protvino ? Oxford ? Rutherford ? Sussex
? University College London ? Argonne ?
Brookhaven ? Caltech ? Chicago ? Elmhurst ?
Fermilab ? James Madison ? Harvard ? Indiana ?
Livermore ? Minnesota ? Northwestern ?
Pittsburgh ? South Carolina ? Stanford ?
Texas-Austin ? Texas AM ? Tufts ? Western
Washington ? Wisconsin
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Two detector experiment
Far detector
Near detector
F(L)F0/L2
N(NC)nFnsNC N(CC)nFnsCC
N(NC)fFfsNC N(CC)fFfsCC

• Make two detectors as identical as possible -
  same scintillator, same steel etc.
• Measure n spectrum in the near detector in the
  absence of oscillations
• Predict the n spectrum in the far detector in the
  absence of oscillations
• Near-far comparisons reduce the systematic errors

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Neutrino Beam Line
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Magnetic Horns
Magnetic field measurements agree with very well
with calculations Prototype is high quality
Now doing destructive testing Continuous
unattended pulsing So far about 2 million pulses
at full current - corresponds to about 1 month
of operation
The inner conductor for the prototype of Horn 1
Requires 200 kAmp current
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Hadronic Hose
p lifetime
Will be included if funding permits
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Beam Options
Target and horn 2 are moveable - can change the
beam energy
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What neutrino beam energy should we start with?
SuperK best fit for Dm2 is ? 3 ? 10-3 eV2
Oscillation Probability
Need the low energy beam with ltEngt 7.6 GeV to
see 1st oscillation maximum which occurs at ? 2
GeV
En
1st oscillation maximum
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Civil Construction at Fermilab
Detector shaft about 3/4 complete
Location of TBM
Excavation complete
4000 ft (1200 m)
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Civil Construction at Fermilab
The target hall
Tunneling started May 5 150 feet so far
The tunnel boring machine
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Civil Construction at Soudan
Excavation is complete
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Civil Construction at Soudan
The MINOS cavern at Soudan Outfitting is on
schedule Beneficial occupancy end July 2001-
begin detector assembly in August 2001
n
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MINOS Far Detector
8m Octagonal Tracking Calorimeter 486 layers of
2.54cm Fe 2 supermodules, each 15m long 4cm wide
solid scintillator strips with WLS fiber
readout 25,800 m2 active detector planes Magnet
coil provides ltBgt ? 1.3T 5.4kt total mass
One supermodule of the far detector
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Steel Scintillator Plane Layout
4-Plane prototype built at Fermilab in Summer 1999
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MINOS Near Detector
16.6 m long, 980 tons 282 squashed octagon
planes Forward section 120 planes 4/5
partially instrumented 1/5 planes full
area coverage Spectrometer section162 planes
4/5 planes not instrumented 1/5
planes full area coverage
Coil hole Beam
fiducial region Instrumented area
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Scintillator Readout Schematic

• Strips assembled into 20 or
• 28 strip modules - 8m long
• 2-ended WLS fiber readout
• WLS fiber connected to clear fiber
• 8 fibers/PMT pixel in far
• detector
• 1 fiber/PMT pixel in near
• detector
• Multi pixel PMTS from
• Hammamatsu M16 (far)
• and M64 (near)

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Module Production
Fiber spool
Module production is underway at Caltech,
Argonne, Minnesota 10 of the modules have
been produced and most of them have been
delivered to Soudan
Glue dispenser
Gluing apparatus
28 strip-wide module
Fibers at connector
Assembled Scintillator Plane
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Light Output Measurements
The light output vs position for cosmic ray muons
passing vertically through a scintillator
module. Uses full MINOS readout The output is
averaged over all strips in a module This is one
of the best modules A typical module has about
9-12 p.e.
Number of observed photoelectrons
Distance along the module (m)
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Physics Measurements

• Obtain firm evidence for oscillations
• Charge current (CC) interaction rate and energy
  distribution
• NC/(CCNC) ratio (T-test)
• Measurement of oscillation parameters, Dm2,
  sin22q
• CC energy distribution
• Determination of the oscillation mode(s)
• nt or ns from NC and CC energy distributions
• nm ? ne limits or observation by identification
  of electrons

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Limit from the T-test
NCC-like ? events with identified muon NNC-like
? events with no muon 10 kton-yr exposure 2
overall flux uncertainty 2 CC effciency
uncertainty 2 NC trigger efficiency uncertainty
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Limit from the CC Energy Spectrum
10 kton-yr exposure 2 overall flux
uncertainty 2 bin-to-bin flux uncertainty 2 CC
efficiency uncertainty
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CC Energy Spectrum for various Dm2
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Dm2, sin22q Sensitivity
10 kton-yr exposure 2 overall flux
uncertainty 2 bin-to-bin flux uncertainty 2 CC
efficiency uncertainty For Dm2 0.0035 eV2
should be able to achieve better than 10 error
at 68 C.L on both Dm2 and sin22q
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Limit on nm ? ne
MINOS 10 kt-yr 90 C.L. limit
Chooz 1999
m3 gt m2 Matter effects included Dm2solar 3 ?
10-5 eV2 q12 q23 45 degrees d 0 10
systematic error on background
Ue32 lt 0.013 _at_ Dm2gt3 ? 10-3 eV2 sin22q13 lt 0.05 _at_
Dm2gt3 ? 10-3 eV2
Already close to systematics limited with 10
error on background
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nm ? ns or nm ? nt
nm ? ns implies depletion of neutral current
interactions relative to nm ? nt Use rate and
shape of visible energy spectrum for NC-like
events to discriminate between nm ? ns and nm ? nt
nm ? nt
No oscillations
50 nm ? ns 50 nm ? nt
nm ? nt
SuperK allowed regions based on analysis of
hep-ph/0009299 Fogli, Lisi Marrone
nm ? ns
Dm2
50 nm ? ns 50 nm ? nt
nm ? ns
fsterile
Have also done 4-flavor analysis
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Summary

• Civil construction and Soudan is almost complete
  - beneficial occupancy in July 2001- detector
  assembly starts August 2001
• Civil construction at Fermilab is proceeding -
  the target hall is dug and the TBM has started
  excavating the decay tunnel. The detector shaft
  is mostly dug
• Detector construction is on schedule
• Physics measurements using the low energy beam
• No-oscillation hypothesis - MINOS will cover the
  whole of the SuperK allowed region at 90 C.L
• Oscilations hypothesis - MINOS will be able to
  confirm SuperK results and also observe the first
  oscillation maximum
• For Dm2 0.0035 eV2 and sin22q ? 0.9 should be
  able to determine the mixing parameters to better
  than 10 at 68 C.L.
• Improve the limit on nm ? ne by about factor of 2
  with 10 kton-yr of data
• Reduce the fraction of nm ? ns allowed at 90 CL
  to ? 30 - down from current 67 at SuperK
• Looking forward to beam in Spring 2004