The Future of Neutrino Physics in a Post-MiniBooNE Era
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Transcript of The Future of Neutrino Physics in a Post-MiniBooNE Era
The Future of Neutrino Physics in a Post-
MiniBooNE Era
H. RayLos Alamos National Laboratory
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Outline
Introduction to neutrino oscillationsLSND : The motivation for MiniBooNEMiniBooNE Overview & Current StatusThe Spallation Neutron Source
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Standard Model of Physics
0
1
+2/3
-1/3
0
-1
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Wave-Particle Duality
Flavor states are comprised of mass states
ELECTRON
e
m1
m2
e
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Superposition of Masses
e
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Neutrino Oscillations
e =
Weak state Mass state
1
2
cos cos -sin sin
|(0)> = -sin |1> + cos |2>
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Neutrino Oscillations
e =
Weak state Mass state
1
2
cos cos -sin sin
|(t)> = -sin |1> + cos |2>
e-iE1t e-iE2t
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Neutrino Oscillations
Posc = |<e | (t)>|2
Posc =sin22 sin2 1.27 m2 L
E
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Neutrino Oscillations
Posc =sin22 sin2 1.27 m2 L
E
Distance from point of creation of neutrino beam to detection point
Is the mixing angle
m2 is the difference of the squared masses of the two neutrino states
E is the energy of the neutrino beam
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Neutrino OscillationsP
rob
ab
ilit
y
sin22
Distance from neutrino source (L)
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Current Oscillation Status
m2 = ma2 - mb
2
If there are only 3 :
mac2 = mab
2 + mbc
2
Posc =sin22 sin2 1.27 m2 L E
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Exploring LSND
Want the same L/E Want higher statistics Want different systematics Want different signal signature and
backgrounds
Fit to oscillation hypothesis
Backgrounds
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MiniBooNE
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MiniBooNE Neutrino Beam
Start with an 8 GeV beam of protons from the booster
Fermilab
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MiniBooNE Neutrino Beam
The proton beam enters the magnetic horn where it interacts with a Beryllium target
Focusing horn allows us to run in neutrino, anti-neutrino modeCollected ~6x1020 POT, ~600,000 eventsRunning in anti- mode now, collected ~1x1020 POT
Fermilab
World record for pulses pre-MB = 10M
MB = 100M+
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MiniBooNE Neutrino Beam
p + Be = stream of mesons (, K)Mesons decay into the neutrino beam
seen by the detectorK+ / + + +
+ e+ + + e
Fermilab
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MiniBooNE Neutrino Beam
An absorber is in place to stop muons and un-decayed mesons
Neutrino beam travels through 450 m of dirt absorber before arriving at the MiniBooNE detector
Fermilab
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MiniBooNE Detector
12.2 meter diameter spherePure mineral oil2 regions
Inner light-tight region, 1280 PMTs (10% coverage)
Optically isolated outer veto-region, 240 PMTs
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Detecting Neutrinos
Neutrinos interact with material in the detector. It’s the outcome of these interactions that we look for
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Neutrino Interactions
Elastic ScatteringQuasi-Elastic ScatteringSingle Pion ProductionDeep Inelastic Scattering
MeV
GeV
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Neutrino Interactions Target left intact Neutrino imparts
recoil energy to target
Neutrino in, charged lepton out
Target changes typeNeed minimum neutrino E
Need enough CM energy to make the two outgoing particles
n p
W+
e e-
Elastic Scattering
Quasi-Elastic Scattering
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Observing Interactions
Don’t look directly for neutrinos
Look for products of neutrino interactions
Passage of charged particles through matter leaves a distinct markCerenkov effect / lightScintillation light
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Cerenkov and Scintillation Light
Charged particles deposit energy in the medium
Isotropic, delayed
Charged particles with a velocity greater than the speed of light * in the medium* produce an E-M shock wave v > c/nSimilar to a sonic boom
Prompt light signature
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Event Signature
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MiniBooNE
Lots of e in MiniBooNE
beam vs ~no e in LSND
beamComplicated and
degenerate light sourcesRequire excellent data to
MC agreement in MiniBooNE
MB : e
LSND : e Lots of e in MiniBooNE
beam vs ~no e in LSND
beamComplicated and
degenerate light sourcesRequire excellent data to
MC agreement in MiniBooNE
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The Monte Carlo
Cerenkov lightScintillation lightFluorescence from
Cerenkov light that is absorbed/re-emitted
Reflection Tank walls, PMT faces,
etc.
Scattering off of mineral oil Raman, Rayleigh
PMT Properties
Sources of Light Tank Effects
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Perfecting the Monte Carlo
External Measurements and Laser Calibration
Calibrate with variety of internal Physics samples
Validate final Model through Data to Monte Carlo comparisons
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Quasi-Elastic Events
Constrain the intrinsic e flux estimate - crucial to get right!
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MiniBooNE Current Status
MiniBooNE is performing a blind analysis (closed box)Some of the info in all of the dataAll of the info in some of the dataAll of the info in all of the data
Public results : April 11th
MiniBooNE is performing a blind analysis (closed box)Some of the info in all of the dataAll of the info in some of the data
MiniBooNE is performing a blind analysis (closed box)Some of the info in all of the data
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Final Outcomes
Confirm LSND Inconclusive Reject LSND
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Final Outcomes
Confirm LSND Inconclusive Reject LSND
Need to determine what causes oscillations
Sterile neutrinos?
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Final Outcomes
Confirm LSND Inconclusive Reject LSND
Need to collect more data / perform
a new experiment
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Final Outcomes
Confirm LSND Inconclusive Reject LSND
Need to determine what causes oscillations
Need to collect more data / perform
a new experiment
SNS
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Final Outcomes
Confirm LSND Inconclusive Reject LSND
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Final Outcomes
Confirm LSND Inconclusive Reject LSND
SNS
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All Roads Lead to the SNS
Confirm LSND Inconclusive Reject LSND
Need to determine what causes oscillations
Need to collect more data / perform
a new experiment
SNS
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What is the SNS?
Accelerator based neutron source in Oak Ridge, TN
Spallation Neutron Source
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The Spallation Neutron Source
1 GeV protons Liquid Mercury target
First use of pure mercury as a proton beam target
60 bunches/secondPulses 695 ns wide
LAMPF = 600 s wide, FNAL = 1600 ns wide
Neutrons freed by the spallation process are collected and guided through beam lines to various experiments
Hg
Neutrinos come for
free!
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The Spallation Neutron Source
Target Area
- absorbed by target
+ DAR Mono-Energetic!= 29.8 MeV
E range up to 52.8 MeV
(Liquid Mercury (Hg+) target)
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The Spallation Neutron Source
+ + + = 26 ns
+ e+ + + e = 2.2 s
Pulse timing, beam width, lifetime of particles = excellent separation of neutrino types
Simple cut on beam timing = 72% pure
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The Spallation Neutron Source
+ + + = 26 ns
+ e+ + + e = 2.2 s
Mono-energetic E = 29.8 MeV
, e = known distributions end-point E = 52.8 MeV
MiniBooNE
SNS
GeV
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The Spallation Neutron Source
Neutrino spectrum in range relevant to astrophysics / supernova predictions!
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Proposed Experiments
Osc-SNSSterile Neutrinos
-SNSSupernova Cross Sections
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Neutrino Interactions
Elastic ScatteringQuasi-Elastic ScatteringSingle Pion ProductionDeep Inelastic Scattering
MeV
GeV
SNS Allowed Interactions
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Neutrino Interactions @ SNS
All neutrino types may engage in elastic scattering interactions
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Neutrino Interactions @ SNS
All neutrino types may engage in elastic scattering interactions
Muon mass = 105.7 MeV, Electron mass = 0.511 MeVMuon neutrinos do not have a high
enough energy at the SNS to engage in quasi-elastic interactions!
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Neutrino Interactions @ SNS
Appearance : e
e + 12C e- + 12N
12N 12C + e+ (~8 MeV) + e
Intrinsic e vs mono-energetic e
from
E of e- (MeV) E of e- (MeV)
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Why the SNS?
Beam Width
S:B Osc. Candidate
sLSND e
600 s 1:1 35(observed R >
10)
FNAL e
1600 ns
1:3 ~400
SNS e
695 ns 5:1 ~448/yearExpected for LSND best fit point of : sin22 =0.004 dm2 = 1
May be < 500 ns!
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Sterile NeutrinosSterile neutrinos = RH neutrinos, don’t
interact with other matter (LH = Weak)Use super-allowed elastic scattering
interactions to search for oscillations between flavor states and sterile neutrinos
Disappearance : e
+ C + C *C * C + 15.11 MeV photon
One detector : look for deficit in x events
Two detectors : compare overall x event rates
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Sterile Neutrinos
Near Detector only Near + Far Detector
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Sterile Neutrinos
“There are several indirect astrophysical hints in favor of sterile neutrinos at the keV scale. Such neutrinos can explain the observed velocities of pulsars, they can be dark matter, and they can play a role in star formation and reionization of the universe.” Kusenko, hep-ph/0609158
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Sterile Neutrinos
R-process nucleosynthesis Balantekin and Fuller, Astropart. Phys. 18, 433 (2003)
Pulsar kicks Kusenko, Int. J. Mod. Phys. D 13, 2065 (2004)
Dark matter Asaka, Blanchet, Shaposhnikov, Phys. Lett. B 631, 151 (2005)
Formation of supermassive black holes Munyaneza, Biermann, Astron and Astrophys., 436, 805 (2005)
Play impt. role in Big Bang nucleosynthesis Smith, Fuller, Kishimoto, Abazajian, astro-ph/0608377
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… but that’s not all!
CPT violation (or CP + sterile neutrinos) allows different mixing for , anti-
Possible explanation for positive LSND, null MiniBooNE
Compare , anti- measured oscillation probabilities CP : e e
CPT : X X
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Mass Varying Neutrinos
All positive oscillation signals occur in matter (K2K, KamLAND, LSND); no direct information on oscillation parameters in air/vacuum
Require a path to detector which can be vacated/filled with dirt to test Barger, Marfalia, Whisnant. Phys. Rev. D 73, 013005 (2006) Schwetz, Winter. Phys. Lett. B633, 557-562 (2006)
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Why the SNS?
Confirm LSND Inconclusive Reject LSND
Looking fornew physics
Need much higher statistics
Need to perform analysis with anti-neutrinos to completely rule out LSND
Precise, well-defined neutrino/anti-neutrino beamwith very high statistics and low backgrounds
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Why the SNS?SNS : well known E spectrum to allow
precise measurementsSNS : simultaneous measurements in
neutrino, anti-neutrino modesSNS : different systematics to LSND, MB
Second cross check of LSNDSNS : can perform beyond the standard
model searches not open to MB Sterile neutrino search, CP/CPT, MaVaNus
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The Global Picture
The Neutrino MatrixAPS Multi-Divisional Neutrino Study, Nov 2004 www.aps.org/policy/reports/multidivisional/neutrino/upload/
main.pdf
Pg ii
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The Global Picture
The Neutrino MatrixAPS Multi-Divisional Neutrino Study, Nov 2004 www.aps.org/policy/reports/multidivisional/neutrino/upload/
main.pdf
Pg iii
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The Global Picture
The Neutrino MatrixAPS Multi-Divisional Neutrino Study, Nov 2004 www.aps.org/policy/reports/multidivisional/neutrino/upload/
main.pdf
Pg 27
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The Global Picture
The Neutrino MatrixAPS Multi-Divisional Neutrino Study, Nov 2004 www.aps.org/policy/reports/multidivisional/neutrino/upload/
main.pdf
Pg 27
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Summary
SNS is about to become the best neutrino based facility in the US
DOE proposal for 2 near detectors awaiting funding
Internal LANL proposal produced for far detector
Regardless of the outcome of MiniBooNE, the future of *precision* neutrino measurements in the US lies at the SNS!
Backup Slides
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A Brief History of Neutrinos
1930 : Postulated by Pauli1950-60 : First detection by Reines-
Cowan, inverse beta decay~1935 : First nu mass experiments
1972 Bergkvist, mass upper limit1980 - 85 : Soviet ITEP, mass up&low
limitInfamous 17 keV neutrino
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Ex : Beta Decay
n p
W-
e
e-
dud = -1/3
duu = +2/3
W- = -1
time
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Standard Model of PhysicsAlso have 12 anti-particles (same
mass & lifetime, opposite charge)Gauge particles mediate or transmit
forces between particlesForces that create particles also
dictate which interactions particles can participate in
E-M : particles with electric chargeQuarks, leptons
Strong : binds quarks togetherQuarks
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Standard Model of Physics
Weak : force of transmutation!changes flavor of quarks,
leptons within a familyOnly force that acts on
neutrinosNeutral current = no exchange
of electric charge (Z)Charged current = exchange
electric charge (W+, W-)
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Standard Model of Physics
W- W+
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Quark MixingProblem! If Weak force only acts inside of a
family - how do you explain lambda decay?
-
u u
ud ds
p
W-
u
d
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Quark Mixing
Solution : quark generations are rotated for the purposes of weak interactions
Instead of the Weak force coupling
It couples udu
d’
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Quark Mixing
Where d’ is a linear combination of the d, s, b quarks
s’b’
d’sb
dVud Vus Vub
Vcd
Vtd
=
Weak state Mass state
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Quark Mixing
States which participate in Strong interactions are mass states
States which participate in Weak interactions are mixtures of mass states
W- W+
’ ’ ’
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Standard Model of Physics
NeutrinoOscillationsObserved
Assume NeutrinosHave Mass
Introduce mass into SM via RH field (Sterile Neutrinos)
which mix w/ LH fields(SM )
Use Oscillations to find
Sterile Neutrinos
NeutrinoOscillationsObserved
Assume NeutrinosHave Mass
Introduce mass into SM via RH field (Sterile Neutrinos)
which mix w/ LH fields(SM )
Use Oscillations to find
Sterile Neutrinos
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LSND
800 MeV proton beam + H20 target, Copper beam stop
167 ton tank, liquid scintillator, 25% PMT coverage
E =20-52.8 MeVL =25-35 meters
e + p e+ + n n + p d + (2.2
MeV)
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The LSND Result
Different from other oscillation signals
Higher m2
Smaller mixing angle
Much smaller probability (very small signal) ~0.3%
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The LSND Problem
Posc =sin22 sin2 1.27 m2 L E
m2ab= ma
2 - mb2
Something must be wrong!Flux calculation Measurement in the detectorBothNeither Reminiscent of the great Ray Davis
Homestake missing solar neutrino problem!
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Confirming LSND
Posc =sin22 sin2 1.27 m2 L E
m2ab= ma
2 - mb2
Want the same L/EWant higher statisticsWant different sources of systematic errorsWant different signal signature and
backgrounds
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Step 1 : External Measurements
Start with external desktop measurements
IU Cyclotron 200 MeV proton beamExtinction rate = 1 / Extinction Length
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Step 2 : Internal Samples
Identify internal samples which isolate various components of the OM
UVF, Scint are both isotropic, same wave-shifting/time constants
Low-E Neutral Current Elastic events below Cerenkov threshold
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Step 3 : Verify MC Evolution
Calibration Sample
Provide e Constraint
Background to CCQE Sample
Mean = 1.80, RMS = 1.47Mean = 1.19, RMS = 0.76
Mean = 20.83, RMS = 25.59Mean = 3.48, RMS = 3.17
Mean = 16.02, RMS = 25.90Mean = 3.24, RMS = 2.94
Examine cumulative 2/NDF distributions across many physics samples, many variables
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Signal Region e Events
PRELIMINARY
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SNS Stats~17% of incident protons produce pions2.3 x 10-5 - decay before capture+ stopped <0.3 ns1.3 GeV protons produce :
0.098 +, 0.061 -
For 9.6 x 1015 protons/sec on target get 0.94 x 1015 of each flavor : , Anti-, e
Anti-e / Anti- < 3 x 10-4
Flux @ 50 m from target = 3 x 106 s-1 cm-
2
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-SNS Near Detectors
Homogeneous, Segmented Primary function = cross sections for astrophysics Most relevant for supernova neutrino detection =
2H, C, O, Fe, Pb
Full proposal submitted to DOE in August, 2005
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Osc-SNS Far Detector
MiniBooNE/LSND-type detector
Higher PMT coverage (25% vs 10%)
Mineral oil + scintillator (vs pure oil)
Faster electronics (200 MHz vs 10 MHz)
~60m upstream of the beam dump/targetRemoves DIF bgd
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Appearance Osc. Searches2 oscillation searches at SNS can be
performed with CC interactions to look for flavor change
Appearance : e (ala LSND)e + p e+ + nn + p d + 2.2 MeV photon
Appearance : e
e + 12C e- + 12Ngs
12Ngs 12C + e+ (~8 MeV) + e
MiniBooNE uses e + n e- + p
lower E e
vs higher E e
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Sterile Neutrinos
Near detector : ~2056 events/year (25 ton)Far detector : ~3702 events/year (500 ton)
+ C + C *
C * C + 15.11 MeV photon
Event rates only for
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Event Rates per Year
250 ton detector @ 60 m, 100% eff
e 12C e- 12Ngs 9378
e 12C e- 12N* 4294
Total e 12C e- X 13,672
12C
12C*15.11 3702
12C
12C*15.11 7504
e 12C e
12C*15.11 6186
Total 12C
12C*15.11
17,392
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Lorentz ViolationLSND, Atm, Solar oscillations explained by
small Lorentz violationSize of violation consistent with size of
effects emerging from underlying unified theory at Planck scale Kostelecky, Mewes. hep-ph/0406255 (2004)
Oscillations depend on direction of propagation
Don’t need to introduce neutrino mass!Look for sidereal variations in oscillation
probability
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Neutron Background
109 neutrons/day pass through near detectors
CC measurements = bgd freeneutron bgds greatly suppressed for t > ~1
s after start of beam spill production is governed by lifetime (~2.2
s )
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Near Detector Rates
Segmented (10 ton fiducial mass)Iron = 3200 CC/yearLead = 14,000Al = 3,100
HomogeneousCarbon = 1,000Oxygen = 450
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Minos
98.0ionNormalizat
syst) (stat 00.12sin
eV10syst) (stat 74.2m
13.0232
2344.026.0
232
=+=
×+=
−
−+−
120 GeV proton beamGraphite target2 movable horns1.27x1020 POTNext up : e osc search
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MINERAPlaced in NuMi beamline,
directly upstream of MinosSegmented solid
scintillator detector, use Minos as det
C, Fe, Pb targetsQuasi-Elastic Q2, CC
Coherent prod. at very high E (6, 20 GeV)
Construction complete by 2009
4 yr run plan
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NOA
Off-Axis detector Near & Far Detectors