Current* Neutrino Oscillation Experiments
PPAP Meeting
Birmingham
15 July 2009
Elisabeth Falk
University of Sussex
Def. current: running or under construction
Outline
• Neutrino-oscillation experiments:
what to measure, and how
• Accelerator-based experiments
• Reactor experiments
• Conclusions and outlook
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What to measure, and how
Neutrino Mixing
3
 e   U e1 U e 2 U e3  1 
  
 
    U 1 U  2 U  3  2 
   U
 
     1 U 2 U 3  3 
Dm2
2
1
e
32


Dm212
U MNSP
Unknown CP-violating phase
U MNSP
 cos 12

   sin  12
 0

sin  12
cos 12
0
Solar  + KamLAND:
12 = (34 ± 3)o
Dm212 = 7.6 x 10-5 eV2
15/7/09
0   cos 13
0 e i CP sin  13   1
0
0 





diag
0  
0
1
0
   0 cos  23 sin  23   U Maj


1    e i CP sin  13 0
cos 13   0  sin  23 cos  23 
Reactor  (CHOOZ):
sin2 213 < 0.11 @ 90% CL
(or 13 <~ 10o)
Dm231 ~ Dm232
E. Falk, U. of Sussex
Atmospheric  +
MINOS, K2K:
23 = (45 ± 7)o
Dm232 = 2.5 x 10-3 eV2
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What to measure, and how
Accelerator-Based vs. Reactor Experiments
LBL accelerator experiments:
Reactor experiments:
sin2
12, Dm232:
•
Near detector to measure unoscillated
spectrum
•
Look for disappearance (  ) as a fnc of
L and E
13, δCP, sign(Dm232):
• Look for appearance (  e) in  beam vs.
L and E
• Near detector to measure background es
(beam + mis-id)
• P (  e) = f (, sign(Dm312))
13 only:
• Look for disappearance (e  e) as a
fnc of L and E
• Near detector to measure unoscillated
flux
• P (e  e) independent of ; matter
effects small
Accelerator-based and reactor experiments complementary
ND
MINOS, T2K, NOA
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FD
Double Chooz, Daya Bay, RENO
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What to measure, and how
Experimental Approach
• () disappearance measurements:
– Measure unoscillated  spectrum at
Near Detector
• Extrapolate using MC
– Compare to measured spectrum at
Far Detector
• e appearance measurements:
– Measure e spectrum at Far Detector
– Near Detector to measure
background es (beam + mis-id)
•
Predict Far Detector background using
MC
 spectrum
Unoscillated
Oscillated
Monte Carlo
spectrum ratio
~ sin2 223
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Monte Carlo
~
Dm2
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E. Falk, U. of Sussex
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Accelerator-based experiments
Neutrino Beam
NuMI
• Protons strike graphite target
• Magnetic horns focus
secondary p/K
NuMI
– Decay of p/K produces
(mostly) muon neutrinos
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Accelerator-based experiments
Players: MINOS, T2K, NOA
MINOS:
• NuMI (Fermilab) to Soudan
mine, MN
–
•
•
•
Two more years of datataking
Large UK involvement
–
–
15/7/09
–
–
735 km baseline
Magnetised sci/steel
calorimeters
Taken beam data since 2005
–
T2K:
• J-PARC (Tokai) to Kamioka
mine
All ana/working groups
have UK co-convener(s)
Made significant h/w &
DAQ contributions
•
•
•
–
–
295 km baseline, off-axis
New beam
FD: Super-K (water
Cerenkov)
Start data-taking in 2010
Large UK involvement
–
NOA:
• NuMI (Fermilab) to Ash
River, MN
•
•
•
810 km baseline, off axis
Upgrade beam power
“Totally active” tracking
liquid sci calorimeters
Start data-taking in 2013
No UK involvement
ND280 off-axis detector
(P0D, ECAL, DAQ, ….)
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Accelerator-based experiments
 disappearance
MINOS
Main physics results to date:
•  disappearance:
|Δm232|=(2.43 ± 0.13) x 10-3 eV2
at 68% C.L.
sin2(2θ23) > 0.90 at 90% C.L.
– Most precise result for |Δm232| to date
• e appearance:
– 1.5s excess (within realms statistical
fluctuation):
– Normal hierarchy (CP = 0):
sin2(2θ13) < 0.29 (90% C.L.)
– Inverted hierarchy (CP = 0):
sin2(2θ13) < 0.42 (90% C.L.)
•  disappearance:
– Study 7%  component
– See 1.9s fewer events than CPTconserving
• Neutral-current interaction rate:
– Limit on sterile neutrinos:
fs < 0.68 (90% C.L.)
15/7/09
e appearance
E. Falk, U. of Sussex
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Accelerator-based experiments
MINOS
Future plans:
• Update all analyses with
more than double the data
set
– Data in the can
(3.2  7E20 POT)
• Muon antineutrino running
– Switch beam magnetic
horns to focus p• Start in September this year
– Make the first direct
measurement
• Reduce uncertainty on Dm232
by an order of magnitude
•  mode for 2E20 POT, or
until July 2010
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Accelerator-based experiments
T2K
• Physics programme:
– Phase I:
• Discovery/measurement of 13
• D(sin2 223) ~ 0.01 (1%)
D|Dm232| < 1 x 10-4 eV (a few %)
(90% CL)
– Potential phase 2:
• Search for CP violation
• Milestones:
– ND suite operational by end of
2009
– Beam power ramped over next few
years
(2009: 30 kW; 2010: 100 kW;
2011: 300 kW; + “a few years”:
750 kW
– Phase 1: total of 5E21 POT
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Accelerator-based experiments
NOA
• Significant injection of funds via
US stimulus package revived NOA
• Physics programme:
– Optimised for e appearance
• An order of magnitude more sensitive than
MINOS
– Improve sin2 223 and |Dm232| by an order of
magnitude (compared to MINOS)
– Mass hierarchy (sign (Dm232))
• Long baseline: only experiment sensitive to
this
• Milestones:
– 1 May 2009: FD groundbreaking
– Autumn 2011: Start of beam upgrades
(400 kW  700 kW)
– 2013: Data-taking with full FD
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Reactor experiments
Measuring 13: e Disappearance
e
Nuclear power station
e
(,
Near Detector
d = 300 - 400 m
)
Far Detector
d = 1 - 1.8 km
Present limit from CHOOZ:
sin2(2 13) < 0.15 (90% C.L.) at
Dm231 = 2.5 x 10-3 eV2
Dominant source of
systematic error in CHOOZ:
Reactor neutrino spectrum
~ Cancels out with two detectors
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Reactor experiments
The Detectors
Example: Double Chooz
Outer Veto:
Plastic scintillator panels
 Target:
10 m3 liquid scintillator
doped with 0.1% Gd
Prompt e+ signal
Eprompt = En – (Mn – Mp) + me
g Catcher:
23 m3 liquid scintillator
Inverse Beta Decay
Buffer:
114 m3 mineral oil with
~400 PMTs
Inner Veto:
90 m3 liquid scintillator
with 80 PMTs
Delayed n capture on Gd
(t ~ 30 ms) with emission
of g cascade ( E ~ 8 MeV)
Shielding:
15 cm steel
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Reactor experiments
Players: Double Chooz, RENO, Daya Bay
RENO, Korea
Expected sin2213~0.03
250 ton-GWth
Double Chooz, France
Expected sin2213~0.03
85 ton-GWth
Small UK interest
(Sussex, no longer funded)
Daya Bay, China
Expected sin2213~0.01
1400 ton-GWth
Main differences:
• Reactor power/no of cores
• Configuration cores vs. detectors; no. of detectors
• Detector target mass
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Reactor experiments
Status and Expected Milestones*
Double Chooz
RENO
N and F tunnels
completed
2009
2009
ND hall + tunnel
construction begins
FD ready for
data-taking
2009
ND and FD
commissioning
ND and FD ready
for data-taking
Near Hall occupancy
First detector complete;
start dry run
2010
Near Hall ready for
data-taking
2011
2011
2012
2012
2012
Far Hall ready for
data-taking;
Ling Ao Hall ready a
bit earlier
2013
2013
2010
2011
2014
sin2 213 ~ 0.06
ND ready for
data-taking
sin2 213 ~ 0.03
2010
Daya Bay
2014
sin2 213 ~ 0.03 ???
2013
2014
– not
15/7/09 * DC schedule includes my estimated delays
E. Falk,
U. ofofficial,
Sussex so don’t quote it!
RENO, DB official schedules, but at least DB will likely be delayed by a few months
sin2 213 ~ 0.01
15
Comparison of 13 Sensitivities
M. Mezzetto, Venice, March 2009
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Comparison of 13 Sensitivities
M. Mezzetto, Venice, March 2009
15/7/09
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Conclusions and Outlook
• Past and present experiments have pinned down 13,
Dm212, 23, Dm232
• MINOS recently announced 1.5s result for 13
• T2K and reactor experiments come on-line within
~a year from now
• Next 5 years will see sensitivity to sin2 213 to ~0.01,
plus order of magnitude improvement on 23 and
Dm232
• Need combination of different baselines + reactor to
resolve 13, δCP, sign (Dm232)
• Would be difficult to search for δCP if sin2 213 < 0.01
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Reactor Experiment Howto:
Improve on Chooz
CHOOZ : Rosc = 1.01 ± 2.8% (stat) ± 2.7% (syst)
• Statistics
– More powerful reactor (multi-core)
– Larger detection volume
– Longer exposure
• Experimental error:
 flux and cross-section uncertainty
– Multi-detector
– Identical detectors
• Reduce inter-detector systematics (normalisation, calibration...)
• Background
– Improve detector design
Larger S/B
– Increase overburden
– Improve knowledge of background by direct measurement
Reach ~1% precision
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Double Chooz Systematic Uncertainties
n energy, Dt, (distance e+ - n)
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Reactor experiments
Baselines and Reactor Power
Double Chooz
Daya Bay
RENO
P = 8.2 GWth/2 cores
L = 1.05 km
P = 11.6 GWth/4 cores
~2011:
17.4 GWth/6 cores
L ~ 1.8 km
P = 16.1 GWth/6 cores
L ~ 1.4 km
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Daya Bay and Ling Ao Nuclear Power Plant
LingAo II NPP 2.9GW2
Under construction (2010)
Daya Bay NPP 2.9GW2
LingAo NPP 2.9GW2
Reactor experiments
Daya Bay Run Plan
Far (80 t)
• Istall first two detectors
in DB Near Hall within
a year from now
• Take data (engineering run)
while Ling Ao and Far Halls
completed
• Additional detectors
DYB (40 t)
deployed in pairs, one in
Ling Ao and one in Far Hall,
as they become ready – except last pair
• One detector to be moved from Near to Far Hall
• Last pair deployed in Near + Far Halls
• Run for three years
• Publish
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LA (40 t)
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Daya Bay: Redundancy
• Measuring sin2213 to 0.01 need to control systematic errors very well.
• We believe that the relative (near/far) detector systematic error could be
lowered to 0.38%, with near/far cancellation and improved detector design.
• Side-by-side calibration: Event rates and spectra in two detectors at the
same near site can be compared  How IDENTICAL our detectors are?
• Detector swapping: Daya Bay antineutrino detectors are designed to be
MOVABLE. All detectors are assembled and filled with liquids at the same
place. Detectors at the near sites and the far site can be swapped, although
not necessary to reach our designed sensitivity, to cross check the
sensitivity and further reduce the systematic errors.
Far (80 t)
LA (40 t)
DYB (40 t)
Reactor experiments
Comparison of 13 Sensitivities
Daya Bay
sin2213 limit
Double Chooz
ssys= 0.6%
Far+Near Detectors
ssys= 2.6%
Far Detector
only
2010
15/7/09
2011
2012
2013
2014
2015
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Comparison of 13 Sensitivities
M. Mezzetto, Venice March 2009
Assumptions:
•
DC to start end of 2009;
ND 1.5 yrs later
•
•
DB to start mid 2011
•
•
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From C. White:
Schedule slipping by a
few months
T2K: 0.1 MW in 2010;
0.45 MW in 2011;
0.75 MW thereafter
•
•
More likely 2nd quarter
of 2010 (my estimate)
From D. Wark:
0.1 MW in 2010;
0.3 MW in 2011; ramp
to 0.75 MW over a few
years
MINOS, OPERA: sensitivity
as per proposal, scaled by
POT
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MINOS
Overview
• Long baseline
Fermilab  735 km  Soudan
• Near detector at Fermilab
– Measure beam composition, energy
spectrum
• Far detector in Minnesota
– Search for and study oscillations
• Test the   x oscillation
hypothesis
– Measure precisely |Dm232| and
sin2 (223)
• Search for sub-dominant   e
oscillations
– Sensitive to 13
• Other MINOS physics:
– Search for sterile neutrinos,
CPT/Lorentz violation
– Compare ,  oscillations
– Studies of cosmic rays and
atmospheric neutrinos
– Neutrino interaction studies in the
Near Detector
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MINOS
Muon-Neutrino Disappearance
Analysis
• Strong energy-dependent
spectrum distortion
• Spectrum fit with two-flavour
oscillation hypothesis
• Fit constrained to physical region
+ includes three largest
systematics
• Results:
PRL 101 131802 (2008)
|Δm232|=(2.43 ± 0.13) x 10-3 eV2
at 68% C.L.
sin2(2θ23) > 0.90
at 90% C.L.
Most precise measurement of |Dm232| to date
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MINOS
Antimuon-Neutrino
Disappearance Analysis
• Measure |Δm232|, sin2(2θ23)
• Test CPT
• FNAL Wine & Cheese three
weeks ago
•  CC events are 7% of beam
– Mis-ID muon and NC backgrounds
relatively larger
– As CC analysis, but with extra cuts
• Track-length likelihood, charge-sign
significance
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The Future
All these analyses have used 3x1020 of the 7x1020 protons-on-target that have been recorded
–
As of this June’s summer shutdown
Over the next year, the analyses will be updated with the increased dataset
–
Using the blind analysis policy on the new data
Graphs below show the θ13 sensitivity for 7x1020 PoT
If the excess persists
16th-22nd July 2009
If the excess goes away
30
Justin Evans
MINOS
Electron-Neutrino Appearance Analysis
CC Event
• Sub-dominant neutrino oscillations
P(νμ→νe) ≈ sin2θ23 sin22θ13 sin2(1.27Δm231L/E)
• Also CPv and matter effects: not shown here but
included in fit
NC Event
• ANN algorithm to select e events
• Background measured in ND
– NC events, high-y  CC, beam e, oscillated
 at FD
– Data-driven technique: compare horn
on/off data
eCC Event
• Predict FD background from measured ND
background + MC
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MINOS
Electron-Neutrino
Appearance Analysis
• Far Detector spectrum obtained after
blind analysis
• Expected background:
27 ± 5(stat) ± 2(syst)
• Contours from Feldman-Cousins
method
– Fit to number of events
• Observed events:
37
• Results:
– Normal hierarchy (CP = 0):
sin2(2θ13) < 0.29 (90% C.L.)
– Inverted hierarchy (CP = 0):
sin2(2θ13) < 0.42 (90% C.L.)
• 1.5s excess
– Well within realms of statistical
fluctuation
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MINOS
Neutral Current Analysis
• General NC analysis overview:
– All active neutrino flavours
participate in NC interaction
– Mixing to a sterile ν will cause
a deficit of NC events in Far
Detector
– Assume one sterile neutrino
and that mixing between νμ, νs
and ντ occurs at a single Δm2
• Survival and sterile oscillation
probabilities become:
Simultaneous fit to CC and NC energy
spectra yields the fraction of νμ that
oscillate to νs:
(αμ,s = mixing fractions)
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MINOS
Future Plans
• Update all analyses with
more than double the
data set
• Muon antineutrino
possibilities
– Switch beam magnetic
horns to focus p– MINOS can make the first
direct measurement
• Reduce uncertainty on
Dm232 by an order of
magnitude
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T2K
Main Measurements: sin213
Simulated SK spectrum
• Use CCQE: e + n  e- + p
• Main backgrounds:
– Beam e contamination
– NC p0 events
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T2K
Main Measurements: sin223, Dm232
• Use CC quasi-elastic events:
 + n  - + p
– Background from nonCCQE interactions
 disappearance
sin2223
•
Dm322
15/7/09
•
E. Falk, U. of Sussex
Precision prospect:
D (sin2223) ~ 0.01 (1%)
D (Dm232) < 1 x 10-4 eV2 (a few %)
at 90% C.L.
@ Dm2 ~ 2.5 x 10-3 eV2
36
T2K
J-PARC Accelerator Complex
Commissioned,
in use for material & life science
Commissioned,
15/7/09in use for material & life science
Protons to 30 GeV on 23/12/08
Commissioning is on time
 beam-line components
Commissioning in progress
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Neutrino Beam Line
T2K
Near Detectors at 280 m
• On- and off-axis detectors
280 m downstream of
target
– Understand the neutrino
beam before oscillations
occur
• T2K timeline
– Apr 09: Beam-line
commissioning 10 days
– Summer-autumn 09:
Install INGRID & ND280
– Oct 09: Restart beam
commissioning
– Dec 09-June 10: Physics
run
• Aim to improve CHOOZ
limit
15/7/09
ND 280: Off-axis detectors
inside UA1 magnet
On-axis: INGRID
Scintillator/iron
modules
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T2K
Beam Power Projections
April 1, 2009
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T2K
Discovery Potential
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