current * neutrino oscillation experiments
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Current* Neutrino Oscillation Experiments
PPAP MeetingBirmingham15 July 2009
Elisabeth FalkUniversity of Sussex
Def. current: running or under construction
E. Falk, U. of Sussex 2
Outline
• Neutrino-oscillation experiments:what to measure, and how
• Accelerator-based experiments• Reactor experiments• Conclusions and outlook
15/7/09
E. Falk, U. of Sussex 3
Neutrino Mixing
15/7/09
3
2
1
321
321
321
UUU
UUU
UUU eeee
diagMaj
2323
2323
1313
1313
1212
1212
MNSP
cossin0
sincos0
001
cos0sin
010
sin0cos
100
0cossin
0sincos
CP
CP
U
e
e
Ui
i
MNSPU
Solar n + KamLAND: q12 = (34 ± 3)o
Dm212 = 7.6 x 10-5 eV2
Atmospheric n + MINOS, K2K: q23 = (45 ± 7)o
Dm232 = 2.5 x 10-3 eV2
Unknown CP-violating phase
Reactor n (CHOOZ):sin2 2q13 < 0.11 @ 90% CL(or q13 <~ 10o)Dm2
31 ~ Dm232
Dm212
n2
n1
n3
Dm232
nent n
m
What to measure, and how
E. Falk, U. of Sussex 4
Accelerator-Based vs. Reactor Experiments
Reactor experiments:q13 only:• Look for disappearance (ne nn e) as a fnc of
L and E• Near detector to measure unoscillated flux• P (ne ne) independent of d; matter effects
small
15/7/09
ND FD
LBL accelerator experiments:sin2 q12, Dm2
32:• Look for disappearance (n m nn m) as a fnc of L
and E• Near detector to measure unoscillated spectrumq13, δCP, sign(Dm2
32):• Look for appearance (n m nn e) in nm beam vs. L
and E• Near detector to measure background nes (beam
+ mis-id)• P (nm ne) = f (d, sign(Dm31
2))Accelerator-based and reactor experiments complementary
MINOS, T2K, NOnA Double Chooz, Daya Bay, RENO
What to measure, and how
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Experimental Approach• (nm) disappearance measurements:
– Measure unoscillated nm spectrum at Near Detector• Extrapolate using MC
– Compare to measured spectrum at Far Detector
15/7/09
spectrum ratio
Monte Carlo
Unoscillated
Oscillated
Monte Carlo
nm spectrum
What to measure, and how
• ne appearance measurements:– Measure ne spectrum at Far Detector– Near Detector to measure
background nes (beam + mis-id)• Predict Far Detector background
using MC
~ sin2 2q23
~ Dm232
E. Falk, U. of Sussex 6
Neutrino Beam
• Protons strike graphite target• Magnetic horns focus secondary
p/K– Decay of p/K produces
(mostly) muon neutrinos
15/7/09
Accelerator-based experiments
NuMI
NuMI
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Players: MINOS, T2K, NOnA
MINOS:• NuMI (Fermilab) to Soudan
mine, MN– 735 km baseline
• Magnetised sci/steel calorimeters
• Taken beam data since 2005– Two more years of data-taking
• Large UK involvement– All ana/working groups have
UK co-convener(s)– Made significant h/w & DAQ
contributions15/7/09
Accelerator-based experiments
T2K:• J-PARC (Tokai) to Kamioka
mine– 295 km baseline, off-axis– New beam
• FD: Super-K (water Cerenkov)
• Start data-taking in 2010• Large UK involvement
– ND280 off-axis detector(P0D, ECAL, DAQ, ….)
NOnA:• 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
E. Falk, U. of Sussex 8
MINOSMain physics results to date:• nm 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 |Δm2
32| to date
• ne appearance:– 1.5s excess (within realms statistical
fluctuation):– Normal hierarchy (dCP = 0):
sin2(2θ13) < 0.29 (90% C.L.)
– Inverted hierarchy (dCP = 0):sin2(2θ13) < 0.42 (90% C.L.)
• nm disappearance:– Study 7% nm component – See 1.9s fewer events than CPT-conserving
• Neutral-current interaction rate:– Limit on sterile neutrinos:
fs < 0.68 (90% C.L.)15/7/09
Accelerator-based experiments nm disappearance
ne appearance
E. Falk, U. of Sussexß 9
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 Dm2
32 by an order of magnitude
• nm mode for 2E20 POT, or until July 2010
15/7/09
Accelerator-based experiments
E. Falk, U. of Sussex 10
T2K
• Physics programme:– Phase I:
• Discovery/measurement of q13
• D(sin2 2q23) ~ 0.01 (1%)D|Dm2
32| < 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
15/7/09
Accelerator-based experiments
E. Falk, U. of Sussex 11
NOnA
• Significant injection of funds via US stimulus package revived NOnA
• Physics programme:– Optimised for ne appearance
• An order of magnitude more sensitive than MINOS
– Improve sin2 2q23 and |Dm232| by an order of
magnitude (compared to MINOS)– Mass hierarchy (sign (Dm2
32))• 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
15/7/09
Accelerator-based experiments
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Dominant source of systematic error in CHOOZ:Reactor neutrino spectrum~ Cancels out with two detectors
Measuring q13: ne Disappearance
15/7/09
Reactor experiments
Nuclear power station Far Detectord = 1 - 1.8 km
ne ne
Present limit from CHOOZ:sin2(213) < 0.15 (90% C.L.) atDm2
31 = 2.5 x 10-3 eV2
Near Detectord = 300 - 400 m
(nm,t
)
E. Falk, U. of Sussex 13
The Detectors
15/7/09
Prompt e+ signalEprompt = En – (Mn – Mp) + me
Delayed n capture on Gd(t ~ 30 ms) with emissionof g cascade ( E ~ 8 MeV)
Outer Veto:Plastic scintillator panels
n Target:10 m3 liquid scintillatordoped with 0.1% Gd
g Catcher:23 m3 liquid scintillator
Buffer:114 m3 mineral oil with~400 PMTs
Inner Veto:90 m3 liquid scintillatorwith 80 PMTs
Shielding:15 cm steel
Reactor experiments
Example: Double Chooz
Inverse Beta Decay
E. Falk, U. of Sussex 14
Players: Double Chooz, RENO, Daya Bay
15/7/09
Reactor experiments
Double Chooz, FranceExpected sin22n13~0.03
85 ton-GWth
Small UK interest
(Sussex, no longer funded)
Daya Bay, ChinaExpected sin22n13~0.01
1400 ton-GWth
RENO, KoreaExpected sin22n13~0.03
250 ton-GWth
Main differences:• Reactor power/no of cores• Configuration cores vs. detectors; no. of detectors• Detector target mass
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Status and Expected Milestones*
15/7/09
Reactor experiments
2009
2010
2011
2012
2013
2014
2009
2010
2011
2012
2013
2014
2009
2010
2011
2012
2013
2014
Double Chooz RENO Daya Bay
* DC schedule includes my estimated delays – not official, so don’t quote it! RENO, DB official schedules, but at least DB will likely be delayed by a few months
ND and FD readyfor data-taking
N and F tunnelscompleted
ND and FD commissioning
sin2 2q13 ~ 0.03 ???
First detector complete; start dry run
Near Hall ready for data-taking
Far Hall ready for data-taking;Ling Ao Hall ready abit earlier
Near Hall occupancy
sin2 2q13 ~ 0.01
FD ready for data-taking
sin2 2q13 ~ 0.06ND ready fordata-taking
sin2 2q13 ~ 0.03
ND hall + tunnelconstruction begins
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Comparison of q13 Sensitivities
15/7/09
M. Mezzetto, Venice, March 2009
E. Falk, U. of Sussex 1715/7/09
Comparison of q13 SensitivitiesM. Mezzetto, Venice, March 2009
E. Falk, U. of Sussex 18
Conclusions and Outlook
• Past and present experiments have pinned down q13, Dm2
12, q23, Dm232
• MINOS recently announced 1.5s result for q13
• T2K and reactor experiments come on-line within ~a year from now
• Next 5 years will see sensitivity to sin2 2q13 to ~0.01, plus order of magnitude improvement on q23 and Dm2
32
• Need combination of different baselines + reactor to resolve q13, δCP, sign (Dm2
32)
• Would be difficult to search for δCP if sin2 2q13 < 0.01
15/7/09
E. Falk, U. Sussex 19
Reactor Experiment Howto: Improve on Chooz
• Statistics– More powerful reactor (multi-core)– Larger detection volume– Longer exposure
• Experimental error: n flux and cross-section uncertainty– Multi-detector– Identical detectors
• Reduce inter-detector systematics (normalisation, calibration...)
• Background– Improve detector design– Increase overburden– Improve knowledge of background by direct measurement
Larger S/B
CHOOZ : Rosc = 1.01 ± 2.8% (stat) ± 2.7% (syst)
Reach ~1% precision
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Double Chooz Systematic Uncertainties
n energy, Dt, (distance e+ - n)
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Baselines and Reactor Power
15/7/09
Reactor experiments
Double Chooz RENODaya Bay
P = 16.1 GWth/6 coresL ~ 1.4 km
P = 8.2 GWth/2 coresL = 1.05 km
P = 11.6 GWth/4 cores ~2011: 17.4 GWth/6 coresL ~ 1.8 km
Daya Bay and Ling Ao Nuclear Power Plant
Daya Bay NPP 2.9GWn2 LingAo NPP 2.9GWn2
LingAo II NPP 2.9GWn2Under construction (2010)
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Daya Bay Run Plan
• 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 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
15/7/09
Reactor experiments
DYB (40 t)
LA (40 t)
Far (80 t)
Daya Bay: Redundancy
• Measuring sin22n13 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.
DYB (40 t)
LA (40 t)
Far (80 t)
E. Falk, U. of Sussex 2515/7/09
Reactor experiments
2010 2011 201420132012 2015
sin2 2
q13
lim
it
Far Detectoronly
Far+Near Detectorsssys= 2.6%
ssys= 0.6%
Comparison of q13 SensitivitiesDaya Bay
Double Chooz
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Comparison of q13 Sensitivities
15/7/09
M. Mezzetto, Venice March 2009
Assumptions:
• DC to start end of 2009; ND 1.5 yrs later• More likely 2nd quarter of
2010 (my estimate)
• DB to start mid 2011• From C. White: Schedule
slipping by a few months
• T2K: 0.1 MW in 2010; 0.45 MW in 2011; 0.75 MW thereafter• 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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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 nm nx oscillation hypothesis– Measure precisely |Dm2
32| and sin2 (2q23)
• Search for sub-dominant nm ne oscillations– Sensitive to q13
• Other MINOS physics:– Search for sterile neutrinos, CPT/Lorentz
violation– Compare nm, nm oscillations– Studies of cosmic rays and atmospheric
neutrinos– Neutrino interaction studies in the
Near Detector15/7/09
MINOS
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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:
|Δm232|=(2.43 ± 0.13) x 10-3 eV2
at 68% C.L.
sin2(2θ23) > 0.90
at 90% C.L.
15/7/09
PRL 101 131802 (2008)
Most precise measurement of |nm232| to date
MINOS
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Antimuon-Neutrino Disappearance Analysis
• Measure |Δm232|, sin2(2θ23)
• Test CPT• FNAL Wine & Cheese three
weeks ago• nm 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
15/7/09
MINOS
16th-22nd July 2009 30Justin Evans
The FutureAll 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 If the excess goes away
E. Falk, U. of Sussex 31
Electron-Neutrino Appearance Analysis
• 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
• ANN algorithm to select ne events
• Background measured in ND– NC events, high-y nm CC, beam ne, oscillated nt
at FD– Data-driven technique: compare horn
on/off data
• Predict FD background from measured ND background + MC
15/7/09
nnCC Event
NC Event
neCC Event
MINOS
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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 (dCP = 0):
sin2(2θ13) < 0.29 (90% C.L.)
– Inverted hierarchy (dCP = 0):sin2(2θ13) < 0.42 (90% C.L.)
• 1.5s excess– Well within realms of statistical
fluctuation15/7/09
MINOS
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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:
(αμ,s = mixing fractions)
15/7/09
Simultaneous fit to CC and NC energy spectra yields the fraction of νμ that oscillate to νs:
MINOS
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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
15/7/09
MINOS
E. Falk, U. of Sussex 35
Main Measurements: sin2q13
• Use CCQE: ne + n e- + p• Main backgrounds:
– Beam ne contamination– NC p0 events
15/7/09
T2K
Simulated SK spectrum
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Main Measurements: sin2q23, Dm232
• Use CC quasi-elastic events:nm + n m- + p– Background from non-CCQE
interactions
15/7/09
T2K
Dm322
sin22q23
nm disappearance
• Precision prospect: D (sin22q23) ~ 0.01 (1%) D (Dm2
32) < 1 x 10-4 eV2 (a few %) at 90% C.L.
• @ Dm2 ~ 2.5 x 10-3 eV2
E. Falk, U. of Sussex 37
J-PARC Accelerator Complex
15/7/09
T2K
Commissioned,in use for material & life science
Protons to 30 GeV on 23/12/08Commissioning is on time
Commissioned,in use for material & life science
n beam-line componentsCommissioning in progress
Neutrino Beam Line
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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
On-axis: INGRIDScintillator/ironmodules
ND 280: Off-axis detectorsinside UA1 magnet
T2K
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Beam Power Projections
15/7/09
April 1, 2009
T2K
E. Falk, U. of Sussex 40
Discovery Potential
15/7/09
T2K
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