Transcript Status of the MINOS experiment

Accelerator neutrino
experiments
Jennifer Thomas
University College London
Thanks to s.brice, p.vahle, d.wark
Accelerator neutrino experiments
Direct observation of tau neutrinos
DoNUT
Present neutrino oscillation results
k2k, minos, opera, (lsnd,mini-boone)
Plans for next generation long
baseline experiments
Experiments of general interest
Cross sections : sci-boone, minerva
t2k, nova
conclusion
J.Thomas Lepton-Photon 2007
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Neutrino sector status (2007)
 ν e   c12
  
 ν μ  =  -s12
ν   0
 τ 
s12
c12
0
01

00
1   0
Normal hierarchy
(m3)2
0
c 23
-s 23
0   c13

s 23   0
c 23   -s13e-iδ
(m2)2
Dm2
Dm221
Dm231
(m2)2
21
(m1)2
m2lightest
0
s13eiδ   1

0 0
c13   0
0
eiα/2
0
  ν1 
 
0   ν2 
eiα/2+iβ   ν 3 
0
3 light neutrino flavours: e,m,t
Dm221
: (7.0 - 9.1) × 10-5 eV2
TAN2q12 : 0.34 – 0.62
Dm232
sin2q23
ne
nm
nt
32
1
Inverted hierarchy
(m1)2
Dm2
0
: (2.2 – 2.58) × 10-3 eV2
: 0.31 – 0.71
SIN2q13 ≤ 0.045
d : unknown
Hierarchy : unknown
mlightest < 2.2 eV
Dirac or Majorana: unknown
(m3)2
m2lightest
J.Thomas Lepton-Photon 2007
[updated from Gonzalez-Garcia PASI 2006]
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DONuT: Direct Observation of nt
Analysis complete – 9 nt found in 578 total n
Background ~1.5 events (charm + hadronic int)
Preliminary x-section results (cc)
nt t X relative to nm, ne for energy-indpdt part
 nt 
 1.14  0.45
 n e 
 nt 
 1.23  0.44
 n m 
ntt X
Proof of
principle for
opera
mnm nt
J.Thomas Lepton-Photon 2007
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2-3 long baseline concept
 ν e   c12
  
 ν μ  =  -s12
ν   0
 τ 
s12
c12
0
01 0

0   0 c 23
1   0 -s 23

P νμ  νμ
νμ spectrum
Monte
Carlo
Unoscillated
0   c13

s 23   0
c23   -s13e-iδ

0 s13eiδ   1 0
0  ν1 

 
1
0   0 eiα/2
0  ν 2 

0 c13   0 0 eiα/2+iβ 
  ν3 
2

Δ
m
L
2
2
 1 sin θ sin 

E


Spectrum ratio
Monte
Carlo
(m3)2 (m2)2
(m1)2
Dm232
Oscillated
Dm221
(m2)2
Dm231
(m1)2 (m3)2
m2lightest
J.Thomas Lepton-Photon 2007
ne
nm
nt
Dm221
m2lightest
5
K2K: 1st long baseline experiment
Confirmation of sk result
300m near detector
58 single-ring
m-like evts
250km baseline
SuperK far detector
112 observed nm cc
158.1 expected
L/E=0.25Km/MeV
Phys.Rev.D 74, 072003,2006
J.Thomas Lepton-Photon 2007
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MINOS: 2-3 sector precision measurement
Far detector
Far Detector:
Soudan, Minnesota
5.4 kton mass
484 steel/sci planes
8x8x30 m3
2.3% absolute
calibration
B-field~1.3T
Near Detector:
Fermilab, Illinois
1km from target
1 kton mass
282 steel planes
3.1% absolute
calibration
153 scintillator
planes, 3.8x4.8x15 m3
Bfield~1.3T
735 km
baseline
Near detector
J.Thomas Lepton-Photon 2007
l/e=0.4km/mev
7
Neutrinos from the Main Injector (NuMI)
2.5e20 p.o.t.
Used in new analysis
10 μs spill 120 GeV protons every
2.4s
180 kW typical beam power
2.5 1013 protons per pulse
Neutrino spectrum changes
with target and horn position
J.Thomas Lepton-Photon 2007
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MINOS: near detector exploitation
‘Identical’ Detectors ND and FD
n
Calorimeter
Spectrometer
Fiducial Volume
Use ND spectra for:
Beam MC tuning => flux measurement
FD spectrum prediction takes advantage of
all cancellations
Cross section
Detector thresholds
Secondary hadron production (1st order)
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MINOS Beam MC tuning
Use different beam configurations to learn about beam
Discrepancies in different places pointed to beam issues
Parameterize Fluka2005 hadron production
re-weight as f(xF,pT)
Horn focusing, beam misalignments, neutrino energy
scale, n cross section, NC background
Weights applied vs pz & pT
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minos near detector nm cc selection Particle
IDentification Distribution
NC-like
CC-like
Finding muons is main approach
Select cc events with pdf based on
6 parameters reflecting
confidence in event’s track like
characteristics
All Energies
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MINOS FD Spectrum Prediction
x
=
Hadron
production
changes are
2nd order :
affects ND
and FD
together
Measured ND spectrum is transported to FD
Efd is not just End/r2
Pion/Kaon decay kinematics encapsulated in matrix
MC to provide corrections (resolution, acceptance)
P(nm nx)  sin 2 (2q ) sin 2 (1.27Dm2 EL )
6.2 effect <10GeV
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Sector 2-3 allowed parameter space
2
sin
2.380.1
20 .00
08 2
Dm 2  223
1030.eV
32
0.16
sin 2 223  1.000.08
Statistics limited
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MINOS Outlook
M
C
MINOS MC
Muon neutrino
disappearance
6e20 pot by end 2008
Anti-neutrino oscillations
in neutrino beam
anti-n running > 09
Electron neutrino
appearance by end 2007
Search for exotics
Sterile neutrinos
Neutrino decay/de-coh
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Opera : appearance of tau neutrinos
nm
nt
m spectrometer: Dipolar magnet + RPC chambers
Physics goals:
Emulsion
Verify oscillation is to nt
Cloud
Chamber
Search for ne appearance
cngs L/e = 0.04km/MeV (17GeV En)
12 events expected, 1 bkg, after 5 yrs
May 07 cosmic test:
Prediction, extraction, scanning
Turn on sep 07 50-60kbricks
Full compliment mar 08
J.Thomas Lepton-Photon 2007
1 mm
t
Pb
15
Future long baseline : goals nm
 ν e   c12
  
 ν μ  =  -s12
ν   0
 τ 
s12
c12
0
01

00
1   0
0
c 23
-s 23
10-2
0   c13

s 23   0
c 23   -s13e-iδ
0
1
0
ne
s13eiδ   1

0 0
c13   0
0
e iα/2
0
  ν1 
 
0   ν2 
eiα/2+iβ   ν 3 
0
Dm231 [eV2]
high precision 2-3 parameters
observation of ne events
q13 : present sin2q13<0.04
cp violation d
mass hierarchy
(m3)2 (m2)2
10-3
(m1)2
Dm232
sin2q13
Dm221
Schwetz hep/ph 0606060
J.Thomas Lepton-Photon 2007
(m2)2
ne
nm
nt
Dm221
Dm231
(m1)2 (m3)2
m2lightest
m2lightest
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Future long baseline: goals
P(n m  n e )  sin 2 q 23 sin 2 2q13
sin (D31 aL) 2
D31 Patmos
2
(D31 aL)
2
2
sin
(aL) 2
 cos 2 q 23 sin 2 2q12
D 21
2
(aL)
Psolar
a  GF Ne / 2  (4000 km)1
Dij  1.27Dm2ij L / E
L(km), E(GeV), m(eV)
 sin(D31 aL)   sin(aL) 
 cos d sin 2q 23 sin 2q12 sin 2q13 cos D32 
D31  
D 21 

 (D31 aL)
  (aL)
interference
 sin(D31 aL)   sin(aL) 
 sin d sin 2q 23 sin 2q12 sin 2q13 sin D32 
D31  
D 21 

 (D31 aL)
  (aL)
Measure q13
present limit:
Sin22q13<0.15
Sin2q13<0.04
Sinq13<0.2
q13<11.5o
CP violation and
matter effects are
ambiguous for half
possible values of d
ne
e
e
ne
J.Thomas Lepton-Photon 2007
Second experiment
with different l (or E)
will give
complimentary
information for mass
hierarchy
17
Future long baseline: tools
Off axis beams
Far
Detector
Near
Detector
TargetHorns
Decay Pipe
X-sec measurements:
Minerna and sci-boone
q
Reduces high energy tail
and so NC p0 background
Reduces ne contamination
from K and m decay due to
decay kinematics
High granularity detector in
NuMI beamline : good for nona
wide scope : several z x-sec
measurements at a few GeV
K2K SciBar detector in
the FNAL Booster
Neutrino Beamline
Precision
measurement of x-secs
for T2k : beam well
matched
e/gev
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NOnA
Far detector:
14 kton, fully active segmented
14.5 mrad off NuMI beamline axis
810 km baseline, En~2gev, l/e=0.4km/mev
Near Detector
Functionally same as FD
Will move to sample different
backgrounds
optical
fibre
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Nona: future reach
Matter effect in
Matter effects
increase (decrease)
oscillations for
normal (inverted)
hierarchy for n
Hierarchy can be
resolved if q13 near to
present limit
Nova has
longest baseline:
810km
run with n and n
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T2K: jparc to Super-K
Near Det @ 280m 2.5mrad(off-axis)
Inside ua1/nomad magnet for
momentum measurement
Sandwich calorimeters/tracker
for precision beam measurement
En~0.8GeV, l/e=0.4km/mev
p0 from neutral current
interactions important
background
J.Thomas Lepton-Photon 2007
Ingrid detector @
280m (on-axis)
Iron scintillator
tracker
Determines beam
profile and direction
21
T2K: Sensitivity
Plot from I. Kato/T2K
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T2k and nona: latest
T2K:
Hoping for first data April 2009
Ramp up to 750kW source by 2012
Nova:
Hoping to start detector construction in 2010 and have 700kW
source on same timescale
Many inponderables
50
Reasonable assumptions
Mezzetto
30
20
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conclusions
A decade of discovery has produced 5
effective parameters:
sin2q23,tanq12,|Dm223|,Dm221 and its sign
Lessons learned for the future
Near detector ….is your best friend!
Beam flexibility….is next
Still to be determined: q13, sign (Dm223), dCP
Maybe dCP , Dm223 within reach of next
experiments if sin22q13 >0.01
Point is to find an underlying symmetry:
focus on precision measurements of
parameters
Near detectors
Off axis beams and flexibility
Cross sections
Detector precision
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BACKUP SLIDES
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MINOS Near Detector:
Particle IDentification Input Variables
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What Changed?
Improvements:
•reco & selection
•shower modelling
Data sets:
•Pre-shutdown
•Post-shutdown
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NuMI Alignment
Align the center of n beam to the Far Detector in the
Soudan mine. Goal is within 12 m.
• Fermilab to Soudan surface done using GPS
• determined vector to 0.01 m horiz., 0.06 m vertical
• Soudan surface to 27th level
• 0.7 m per coordinate
• Fermilab surface to underground
• gyrotheodolite with 0.015 mrad precision
• 11 m at Soudan
• Transverse alignment of baffle, target and horn at 0.5 mm
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Event generator
Neutrino-nucleus interactions were generated
using the NEUGEN3 neutrino event generator
(H. Gallagher, Nucl.Phys.Proc.Suppl. 112: 188194, 2002)
Quasi-Elastic: dipole parametrization
of form factors with ma=0.99 GeV/c2
(BBBA05 Bradford et al.
Nucl.Phys.Proc.Suppl.159:127-132,2006)
Resonance Production:
Rein-Seghal model for W<1.7 GeV/c2.
(Annals Phys. 133: 79, 1981)
DIS: Bodek-Yang modified LO model.
For W<1.7 GeV tuned to electron and neutrino
data in the resonance / DIS overlap region.
(Bodek-Yang, Nucl. Phys. Proc. Suppl. 139: 113118, 2005 and H. Gallagher, NuINT05
Proceedings)
Coherent Production:
Rein-Seghal (Nucl. Phys. B 223: 29, 1983)
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Beam Matrix Prediction & Near Detector
Data : RunI/RunIIa
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Effect of MC tuning on the measurement
Far Predicted Spectra using the
Beam Matrix and with/without
hadron production tuning
Ratio of Far Prediction using the
Beam Matrix and with/without
hadron production tuning
Using tuned MC for
energy smearing and
acceptance corrections
Using tuned MC for
energy smearing and
acceptance corrections
Using nominal MC for
energy smearing and
acceptance corrections
Using nominal MC for
energy smearing and
acceptance corrections
Using Beam Matrix Method, hadron production tuning does not
affect the Unoscillated prediction (obtained from the ND data)
by more than 1-2%.
However, its use improves the MC (make it more similar to the
data) and therefore uncertainties due to energy smearingJ.Thomas Lepton-Photon 2007
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unsmearing and acceptance
become smaller.
MINOS: new analysis 2007
New PID has higher overall efficiency and higher
background rejection (less contamination from NC
interactions)
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MINOS: Near Detector Data/MC
normalized to area
Event Vertices (X Y Z)
Track Angles (X Y Z)
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MINOS: systematic uncertainties
The main remaining systematic uncertainties are
Near/Far normalization, absolute hadronic
energy scale and NC contamination
Overall systematics reduced by use of near
detector
Shift in Dm2
Shift in
(10-3 eV2)
sin2(2q
Near/Far normalization 4%
0.065
<0.005
Absolute hadronic energy scale 10%
0.075
<0.005
NC contamination 50%
0.010
0.008
All other systematic uncertainties
0.041
<0.005
Total systematic (in quadrature)
0.11
0.008
Statistical error (data)
0.17
0.080
Uncertainty
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Data Sample
FD
Expected
Data/Prediction
Data ( Unoscillated)
nmCClike All
563
738 30
0.76 (4.4 )
nm CClike (<10 GeV)
310
496 20
0.62 (6.2 )
nmCClike (<5 GeV)
198
350 14
0.57 (6.5 
For energies between 0-10 GeV a deficit of
38% is observed, with respect to the no
disappearance hypothesis.
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MINOS Detector Technology
2.54 cm
Fe
Scintillator strip
Extruded
PS scint.
4.1 x 1 cm
M16 PMT
Near and Far Detectors
are functionally
identical:
U V planes
+/- 450
WLS
fiber
2.54cm thick 1.3 T
magnetised steel plates
co-extruded
scintillator strips
orthogonal orientation
on alternate planes –
U,V
Clear
Fiber cables
Multi-anode PMT
optical fibre readout
to multi-anode PMTs
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LSND result
Excess of ne events in a nm
beam
87.9 ± 22.4 ± 6.0 over
background
~4 evidence for oscillation
Dm2 different from the solar
and atmospheric Dm2s.
With 3 standard model
neutrinos 2 independent Dm2s
could lsnd result be evidence
for a sterile neutrino?
Mini-boone sees no excess in
nm ne
l/e=0.001kev/km
L/E=0.001km/MeV
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0-3 GeV
3-6 GeV
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After q13
P ~ (Patmos)1/2 + (Psolar)1/2 + interference terms
probability
L=735km
E (GeV)
Much information within :± Dm2,d,matter effect
Effects are non-trivial to disentangle
Complimentarity with different L,E and production
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MINOS NC analysis : near detector Spectra
Search for sterile n
MC error band beam,
cross-section and
energy scale
uncertainties
Fogli et al. 3+1 model
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MINOS: nm
ne appearance status
Using full power of the
near detector
Comparison of mc/data
shows discrepency
Same effect in muon
removed cc sample points
to shower modelling
Bkgd spectrum will be
derived from nd data
m nm
nm
Hadronic
n
shower
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Future long baseline: tools
x-sec measurements : basic foundation of n probes
CCQE x-sec is best
known
search for tiny
signals: background
estimate is
paramount
eg: high y cc events
which oscillate
cannot be estimated
in near detector
2 experiments
being mounted to
address these issues
Compilation of nm CC Quasi-Elastic x-Section Measurements
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MINOS: measurement vs prediction
P(nm nx)  sin 2 (2q ) sin 2 (1.27Dm2 EL )
P(c2,n.d.f) = 0.18
c2 /n.d.f = 139.2/36 =3.9
No Disappearance Hypothesis
c2 /n.d.f = 41.2/34 = 1.2
Oscillation Hypothesis best fit
P(c2,n.d.f) = 0.18
6.2 effect below 10GeV
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