Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

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Using Reactor Using Reactor Neutrinos to Study Neutrinos to Study Neutrino Oscillations Neutrino Oscillations Jonathan Link Jonathan Link Columbia University Columbia University Heavy Quarks Heavy Quarks and Leptons 2004 and Leptons 2004

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Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University Heavy Quarks and Leptons 2004 June 1, 2004. Doing Physics With Reactors Neutrinos - PowerPoint PPT Presentation

Transcript of Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Page 1: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Using Reactor Neutrinos to Study Using Reactor Neutrinos to Study Neutrino OscillationsNeutrino Oscillations

Jonathan LinkJonathan Link

Columbia UniversityColumbia University

Heavy Quarks and Leptons 2004Heavy Quarks and Leptons 2004 June 1, 2004June 1, 2004

Page 2: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Doing Physics With Doing Physics With Reactors NeutrinosReactors Neutrinos

The original Neutrino discovery The original Neutrino discovery experiment, by Reines and Cowan, experiment, by Reines and Cowan, used reactor neutrinos…used reactor neutrinos…

Reines and Cowan at the Savannah River Reactor

……actually anti-neutrinos. The actually anti-neutrinos. The ννee interacts with interacts with

a free proton via inverse a free proton via inverse ββ-decay:-decay:

νe

e+

pn

W

Later the neutron captures giving a coincidence Later the neutron captures giving a coincidence signal. Reines and Cowan used cadmium to signal. Reines and Cowan used cadmium to capture the neutrons.capture the neutrons.

The first successful neutrino detector

Page 3: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

• Minimum energy for the primary signal is 1.022 MeV from Minimum energy for the primary signal is 1.022 MeV from ee++ee−− annihilation at process threshold.annihilation at process threshold.

• Two part coincidence signal is crucial for background reduction.Two part coincidence signal is crucial for background reduction.

Nuclear Reactors as a Neutrino SourceNuclear Reactors as a Neutrino Source

Arb

itra

ry

Flux Cross

Sectio

n

Observable Spectrum• The observable The observable ee spectrum is the product spectrum is the product

of theof the fluxflux and theand the cross sectioncross section..

• The spectrum peaks around ~3.6 MeV.The spectrum peaks around ~3.6 MeV.

• Visible “positron” energy implies Visible “positron” energy implies νν energy energy

From Bemporad, Gratta and Vogel

• Nuclear reactors are a very intense sources of Nuclear reactors are a very intense sources of ννee deriving from deriving from

the the -decay of the neutron-rich fission fragments.-decay of the neutron-rich fission fragments.

• A typical commercial reactor, with 3 GW thermal power, A typical commercial reactor, with 3 GW thermal power, produces produces 66×10×102020 ee/s/s

EEνν = E = Ee e + 0.8 MeV ( + 0.8 MeV ( ==mmnnmmpp++mmee1.022)1.022)

Page 4: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Uses of Reactor NeutrinosUses of Reactor Neutrinos• Measure cross sections or observe new processes Measure cross sections or observe new processes (e.g. neutral current nuclear coherent scattering)(e.g. neutral current nuclear coherent scattering)

• Search for anomalous neutrino electric dipole Search for anomalous neutrino electric dipole momentmoment

• Measure the weak mixing angle, sinMeasure the weak mixing angle, sin22θθWW

• Monitor reactor core (non-proliferation application)Monitor reactor core (non-proliferation application)

• Measure neutrino oscillation parameters (Measure neutrino oscillation parameters (ΔΔmm22’s and ’s and mixing angles)mixing angles)

Page 5: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Observations of Neutrino OscillationsObservations of Neutrino Oscillations

ΔΔmm22≈3 to 3×10≈3 to 3×10-2 -2 eVeV22

θθ????

ΔΔmm22≈2.5×10≈2.5×10-3 -3 eVeV22

θθ2323 & & θθ1313

ΔΔmm22≈7.5×10≈7.5×10-5 -5 eVeV22

θθ1212

Short BaselineShort Baseline: 10 to 100 meters : 10 to 100 meters Bugey, Gosgen & KrasnoyarskBugey, Gosgen & Krasnoyarsk

Medium BaselineMedium Baseline: 1 to 2 km : 1 to 2 km Chooz, Palo Verde & futureChooz, Palo Verde & future

Long BaselineLong Baseline: 100+ km : 100+ km KamLANDKamLAND

Reactor neutrinos can probe oscillations in all three observed Reactor neutrinos can probe oscillations in all three observed ΔΔmm22 regions. regions.

Oscillations are observed as a Oscillations are observed as a deficit of deficit of ννee with respect to with respect to

expectation.expectation.

Page 6: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Short Baseline Oscillation SearchesShort Baseline Oscillation Searches

ReactorExcluded

Experiments like Bugey rule out the low Experiments like Bugey rule out the low ΔΔmm22, large mixing angle , large mixing angle region of the LSND signal.region of the LSND signal.

Bugey looked for evidence of oscillations between 15 & 45 Bugey looked for evidence of oscillations between 15 & 45 meters. Gosgen was closer and Krasnoyarsk farther away.meters. Gosgen was closer and Krasnoyarsk farther away.

Neutrons Neutrons capture on capture on LithiumLithium

The Bugey Detector

Page 7: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Observations of Neutrino OscillationsObservations of Neutrino Oscillations

ΔΔmm22≈3 to 3×10≈3 to 3×10-2 -2 eVeV22

θθ????

ΔΔmm22≈2.5×10≈2.5×10-3 -3 eVeV22

θθ2323 & & θθ1313

ΔΔmm22≈7.5×10≈7.5×10-5 -5 eVeV22

θθ1212

Short BaselineShort Baseline: 10 to 100 meters : 10 to 100 meters Bugey, Gosgen & KrasnoyarskBugey, Gosgen & Krasnoyarsk

Medium BaselineMedium Baseline: 1 to 2 km : 1 to 2 km Chooz, Palo Verde & futureChooz, Palo Verde & future

Long BaselineLong Baseline: 100+ km : 100+ km KamLANDKamLAND

Reactor neutrinos can probe oscillations in all three observed Reactor neutrinos can probe oscillations in all three observed ΔΔmm22 regions. regions.

Oscillations are observed as a Oscillations are observed as a deficit of deficit of ννee with respect to with respect to

expectation.expectation.

Page 8: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Medium Baseline Oscillation SearchesMedium Baseline Oscillation Searches

Chooz Nuclear Reactors, FranceChooz Nuclear Reactors, France

Experiments like Chooz looked for oscillations in the atmospheric Experiments like Chooz looked for oscillations in the atmospheric ΔΔmm22. At the time they ran the atmospheric parameters were . At the time they ran the atmospheric parameters were determined by Kamiokande, not Super-K (larger determined by Kamiokande, not Super-K (larger ΔΔmm22). ).

Gadolinium Gadolinium loaded liquid loaded liquid scintillating scintillating target.target.

1050 m baseline1050 m baseline

Page 9: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

• sinsin22221313< 0.18 at 90% CL (at < 0.18 at 90% CL (at

mm22=2.0=2.0×10×10-3-3))

• Future experiments should try to Future experiments should try to improve on these limits by improve on these limits by at leastat least an order of magnitude.an order of magnitude.

Down to sinDown to sin222213 13 0.010.01

In other words, a In other words, a measurement to better than measurement to better than

1% is needed!1% is needed!

<~

• No evidence found for No evidence found for ee oscillation. oscillation.

• This null result eliminated This null result eliminated →→ee as the primary mechanism for as the primary mechanism for

the Super-K atmospheric deficit.the Super-K atmospheric deficit.

Medium Baseline Oscillation SearchesMedium Baseline Oscillation Searches

Page 10: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Observations of Neutrino OscillationsObservations of Neutrino Oscillations

ΔΔmm22≈3 to 3×10≈3 to 3×10-2 -2 eVeV22

θθ????

ΔΔmm22≈2.5×10≈2.5×10-3 -3 eVeV22

θθ2323 & & θθ1313

ΔΔmm22≈7.5×10≈7.5×10-5 -5 eVeV22

θθ1212

Short BaselineShort Baseline: 10 to 100 meters : 10 to 100 meters Bugey, Gosgen & KrasnoyarskBugey, Gosgen & Krasnoyarsk

Medium BaselineMedium Baseline: 1 to 2 km : 1 to 2 km Chooz, Palo Verde & futureChooz, Palo Verde & future

Long BaselineLong Baseline: 100+ km : 100+ km KamLANDKamLAND

Reactor neutrinos can probe oscillations in all three observed Reactor neutrinos can probe oscillations in all three observed ΔΔmm22 regions. regions.

Oscillations are observed as a Oscillations are observed as a deficit of deficit of ννee with respect to with respect to

expectation.expectation.

Page 11: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Long Baseline OscillationsLong Baseline OscillationsThe KamLAND experiment uses neutrinos from 69 reactors to The KamLAND experiment uses neutrinos from 69 reactors to measure the solar mixing angle (measure the solar mixing angle (θθ1212) at an average baseline of ) at an average baseline of

180 km.180 km.

Neutron Capture on Neutron Capture on Hydrogen results in Hydrogen results in a 2.2 MeV gammaa 2.2 MeV gamma

Scatter plot of energies for Scatter plot of energies for the prompt and delayed the prompt and delayed signalssignals

In 145 days of running they saw 54 In 145 days of running they saw 54 events where 86.8events where 86.8±5.6 events where ±5.6 events where expected.expected.

The fit energy confirms the oscillation The fit energy confirms the oscillation

hypothesis.hypothesis.

Page 12: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Long Baseline OscillationsLong Baseline Oscillations

Eliminates all but the large Eliminates all but the large mixing angle (LMA) solution. mixing angle (LMA) solution.

The best fit sinThe best fit sin2222θθ1212= 0.91= 0.91

The best fit The best fit ΔΔmm22 = 6.9×10 = 6.9×10-5-5 eV eV22

KamLAND ResultsKamLAND Results

The The ΔΔmm22 sensitivity comes sensitivity comes primarily from the solar primarily from the solar measurements measurements

Page 13: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Future Experiments to Search for Future Experiments to Search for a Non-zero Value of sina Non-zero Value of sin2222θθ1313

Subject of a lot of interest because of it Subject of a lot of interest because of it relevance to lepton CP violation and relevance to lepton CP violation and neutrino mass hierarchy.neutrino mass hierarchy.

See Whitepaper: hep-ex/0402041 See Whitepaper: hep-ex/0402041

Page 14: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

νe

νe

νe

νe

νe

νe

Distance

Pro

babi

lity

ν e

1.0

EEνν ≤ 8 MeV≤ 8 MeV

1200 to 1800 meters

SinSin2222θθ1313 Reactor Experiment Reactor Experiment BasicsBasics

Unoscillated flux Unoscillated flux observed hereobserved here

Well understood, isotropic source Well understood, isotropic source of electron anti-neutrinosof electron anti-neutrinos Oscillations observed Oscillations observed

as a deficit of as a deficit of ννee

sinsin2222θθ1313

)/27.1(sin θ2sin1)νν( ν213

213

2 ELmP ee Survival ProbabilitySurvival Probability

Page 15: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Proposed Sites Around the WorldProposed Sites Around the World

SiteSitePowerPower

(GW(GWthermalthermal))BaselineBaseline

Near/Far (m)Near/Far (m)

ShieldingShieldingNear/Far (mwe)Near/Far (mwe)

SensitivitySensitivity90% CL90% CL

Krasnoyarsk, RussiaKrasnoyarsk, Russia 1.61.6 115/1000115/1000 600/600600/600 0.030.03

Kashiwazaki, JapanKashiwazaki, Japan 2424 300/1300300/1300 150/250150/250 0.020.02

Double Chooz, FranceDouble Chooz, France 8.98.9 150/1050150/1050 30/30030/300 0.030.03

Diablo Canyon, CADiablo Canyon, CA 6.76.7 400/1700400/1700 50/70050/700 0.010.01

Angra, BrazilAngra, Brazil 5.95.9 500/1350500/1350 50/50050/500 0.020.02

Braidwood, ILBraidwood, IL 7.27.2 200/1700200/1700 450/450450/450 0.010.01

Daya Bay, ChinaDaya Bay, China 11.511.5 250/2100250/2100 250/1100250/1100 0.010.01

Krasnoyarsk, RussiaKrasnoyarsk, Russia 1.61.6 115/1000115/1000 600/600600/600 0.030.03

Kashiwazaki, JapanKashiwazaki, Japan 2424 300/1300300/1300 150/250150/250 0.020.02

Double Chooz, FranceDouble Chooz, France 8.98.9 150/1050150/1050 30/30030/300 0.030.03

Diablo Canyon, CADiablo Canyon, CA 6.76.7 400/1700400/1700 50/70050/700 0.010.01

Angra, BrazilAngra, Brazil 5.95.9 500/1350500/1350 50/50050/500 0.020.02

Braidwood, ILBraidwood, IL 7.27.2 200/1700200/1700 450/450450/450 0.010.01

Daya Bay, ChinaDaya Bay, China 11.511.5 250/2100250/2100 250/1100250/1100 0.010.01

StatusStatus

Page 16: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

The combination of these two plus a complex The combination of these two plus a complex analysis gives you the anti-neutrino fluxanalysis gives you the anti-neutrino flux

What is the Right Way to Design the Experiment?What is the Right Way to Design the Experiment?

Start with the dominate systematic errors from previous Start with the dominate systematic errors from previous experiments and work backwards…experiments and work backwards…

CHOOZ Systematic Errors, Normalization

Near DetectorNear Detector

CHOOZ Background Error

BG rate 0.9%

Statistics may also be a limiting factor in the sensitivity.Statistics may also be a limiting factor in the sensitivity.

Identical Near and Far DetectorsIdentical Near and Far Detectors

Movable Detectors, Source Movable Detectors, Source Calibrations, etc.Calibrations, etc.

Muon Veto and Neutron Shield (MVNS)

Page 17: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

BackgroundsBackgroundsThere are two types of background…There are two types of background…

1.1. Uncorrelated Uncorrelated − Two random events that occur close together − Two random events that occur close together in space and time and mimic the parts of the coincidence.in space and time and mimic the parts of the coincidence.

This BG rate can be estimated by measuring the singles rates, This BG rate can be estimated by measuring the singles rates, or by switching the order of the coincidence events.or by switching the order of the coincidence events.

2.2. Correlated − One event that mimics both parts of the Correlated − One event that mimics both parts of the coincidence signal.coincidence signal.

These may be caused fast neutrons (from cosmic These may be caused fast neutrons (from cosmic ’s) that ’s) that strike a proton in the scintillator. The recoiling proton mimics strike a proton in the scintillator. The recoiling proton mimics the the ee++ and the neutron captures. and the neutron captures.

Or they may be cause by muon produced isotopes like Or they may be cause by muon produced isotopes like 99Li and Li and 88He which sometimes decay to He which sometimes decay to ββ++n.n.

Estimating the correlated rate is much more difficult!Estimating the correlated rate is much more difficult!

Page 18: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Veto Detectors

p

n

n

1. Go as deep at you can (300 mwe → 0.2 BG/ton/day at CHOOZ)

Reducing BackgroundReducing Background

2. Veto ’s and shield neutrons (Big effective depth)

3. Measure the recoil proton energy and extrapolate into the signal region. (Understand the BG that gets through and subtract it)

6 meters

Shielding

Page 19: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Isotope Production by MuonsIsotope Production by Muons

SourceSource300 mwe 300 mwe (/ton/day)(/ton/day)

450 mwe 450 mwe (/ton/day)(/ton/day)

Comments:Comments:

99Li+Li+88HeHe 0.17 ± 0.030.17 ± 0.03 0.075 ± 0.0140.075 ± 0.014E E ≤ 13.6 MeV, ≤ 13.6 MeV, ττ½½ = 0.12 to 0.18 s = 0.12 to 0.18 s

16% to 50%16% to 50% correlated correlated ββ+n+n

88LiLi 0.28 ± 0.110.28 ± 0.11 0.13 ±0.050.13 ±0.05 E E ≤ 16 MeV, ≤ 16 MeV, ττ½½ = 0.84 s = 0.84 s

66HeHe 1.1 ± 0.21.1 ± 0.2 0.50 ± 0.070.50 ± 0.07 E E ≤ 3.5 MeV, ≤ 3.5 MeV, ττ½½ = 0.81 s = 0.81 s

1111CC 63 ± 963 ± 9 28 ± 428 ± 4 E E ≤ 0.96 MeV, ≤ 0.96 MeV, ττ½½ = 20 m = 20 m

1010CC 8.0 ± 1.58.0 ± 1.5 3.6 ± 0.63.6 ± 0.6 E E ≤ 1.98 MeV, ≤ 1.98 MeV, ττ½½ = 19 s = 19 s

99CC 0.34 ± 0.110.34 ± 0.11 0.15 ± 0.050.15 ± 0.05 E E ≤ 16 MeV, ≤ 16 MeV, ττ½½ = 0.13 s = 0.13 s

88BB 0.50 ± 0.120.50 ± 0.12 0.22 ± 0.050.22 ± 0.05 E E ≤ 13.7 MeV, ≤ 13.7 MeV, ττ½½ = 0.77 s = 0.77 s

77BeBe 16.0 ± 2.616.0 ± 2.6 7.2 ± 1.17.2 ± 1.1 E E ≤ 478 keV, ≤ 478 keV, ττ½½ = 0.53 d = 0.53 d

1212BB 1111 33 E E ≤ 13.4 MeV, ≤ 13.4 MeV, ττ½½ = 0.02 s = 0.02 s

A ½ second veto after every muon that deposits more that A ½ second veto after every muon that deposits more that 2 GeV in the detector should eliminate 70 to 80% of all 2 GeV in the detector should eliminate 70 to 80% of all correlated decays.correlated decays.

The vetoed sample can be used to make a background The vetoed sample can be used to make a background subtraction of in a fit to the energy spectrum.subtraction of in a fit to the energy spectrum.

Page 20: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Movable Detector ScenarioMovable Detector ScenarioThe far detector spends about 10% of the run at the near site where the relative The far detector spends about 10% of the run at the near site where the relative normalization of the two detectors is measured head-to-head. normalization of the two detectors is measured head-to-head.

Build in all the calibration tools needed for a fixed detector system and verify Build in all the calibration tools needed for a fixed detector system and verify them against the head-to-head calibration.them against the head-to-head calibration.

1500 to 1800 meters

Page 21: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Reactor SensitivityReactor Sensitivity

• Sensitivity to sinSensitivity to sin2222θθ1313 ≤ ≤ 0.01 at 0.01 at

90% CL is achievable.90% CL is achievable.

• Combining with off-axis some of Combining with off-axis some of the CP phase, the CP phase, δδ,, range can be ruled range can be ruled out.out.

• Unexpected results are possible & Unexpected results are possible & might break the standard model.might break the standard model.

Page 22: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Is the mixing angle Is the mixing angle θθ2323

is not exactly 45º then is not exactly 45º then sinsin22θθ2323 has a two-fold has a two-fold

degeneracy.degeneracy.

Combining reactor Combining reactor results with off-axis results with off-axis breaks this degeneracy.breaks this degeneracy.

With the 0.03 precision With the 0.03 precision of the Double Chooz of the Double Chooz experiment the experiment the degeneracy is not degeneracy is not broken.broken.

Reactor SensitivityReactor Sensitivity

Page 23: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

2003 2004 2005 2006 2007 2008 2009 2010

Run

2011

Aggressive Experiment TimelineAggressive Experiment Timeline

Construction

Years

1 year1 year 22 years years 2 years2 years 3 years (initially)3 years (initially)

Site Selection: Currently underway.Site Selection: Currently underway.

The early work on a proposal is currently underway.The early work on a proposal is currently underway.

With movable detectors, the detectors are constructed in parallel With movable detectors, the detectors are constructed in parallel with the civil constructionwith the civil construction

Run Phase: Initially planned as a three year run. Results or Run Phase: Initially planned as a three year run. Results or events may motivate a longer run.events may motivate a longer run.

Site Selection Proposal

Page 24: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Conclusions and ProspectsConclusions and Prospects• Reactor neutrinos are relevant to oscillations in all observed Reactor neutrinos are relevant to oscillations in all observed ΔΔmm22 regions. regions.

• The KamLAND experiment has been crucial to resolving the The KamLAND experiment has been crucial to resolving the oscillation parameters in the solar oscillation parameters in the solar ΔΔmm22 region. region.

• There are many ideas for reactor There are many ideas for reactor θθ1313 experiments around the experiments around the

world and it is likely that more than one will go forward.world and it is likely that more than one will go forward.

• Controlling the systematic errors is the key to making this Controlling the systematic errors is the key to making this measurement.measurement.

• With a 3+ year run, the sensitivity in sinWith a 3+ year run, the sensitivity in sin22221313 should reach 0.01 should reach 0.01

(90% CL) at (90% CL) at mm22 = 2.0 = 2.0×10×10-3-3. .

• Reactor sensitivities are similar off-axis and the two methods Reactor sensitivities are similar off-axis and the two methods are complementary.are complementary.

• The physics of reactor neutrinos is interesting and important.The physics of reactor neutrinos is interesting and important.

Page 25: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Question SlidesQuestion Slides

Page 26: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

With GdWithout Gd

With GdWithout Gd

Why Use Gadolinium?Why Use Gadolinium?Gd has a huge neutron capture cross section. So you get faster capture times and smaller spatial separation. (Helps to reduce random coincidence backgrounds)

Also the 8 MeV capture energy (compared to 2.2 MeV on H) is distinct from primary interaction energy.

~30 μs

~200 μs

Page 27: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

From CHOOZ

interactions

?

Characterizing BG with Vetoed EventsCharacterizing BG with Vetoed EventsMatching distributions from vetoed events outside the signal region to the non-veto events will provide an estimate of correlated backgrounds that evade the veto.

Proton recoils

Other Useful Distributions:

• Spatial separation prompt and delayed events

Faster neutrons go farther

• Radial distribution of eventsBGs accumulate on the outside of the detector.

Page 28: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Medium Baseline Oscillation SearchesMedium Baseline Oscillation Searches

• Homogeneous detectorHomogeneous detector

• 5 ton, Gd loaded, scintillating 5 ton, Gd loaded, scintillating target target

• 300 meters water equiv. shielding300 meters water equiv. shielding

• 2 reactors: 8.9 GW2 reactors: 8.9 GWthermalthermal

• Baselines 1115 m and 998 mBaselines 1115 m and 998 m

• Used new reactors Used new reactors →→ reactor off reactor off data for background measurementdata for background measurement

Chooz Nuclear Reactors, FranceChooz Nuclear Reactors, France

Page 29: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Palo VerdePalo Verde

• 32 mwe shielding (Shallow!)

• Segmented detector: Better at handling the cosmic rate of a shallow site

• 12 ton, Gd loaded, scintillating target

• 3 reactors: 11.6 GWthermal

• Baselines 890 m and 750 m

• No full reactor off running

Palo Verde Generating Station, AZPalo Verde Generating Station, AZ

Page 30: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

Exelon has agreed to work with us to determine the feasibility of using their reactors to perform the experiment.

“We are excited about the possibility of participating in a scientific endeavor of this nature”

“At this time we see no insurmountable problems that would preclude going forward with this project.”

They have given us reams of geological data which we are currently digesting.

Page 31: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

6 GW, 50 tons and 1200 meters Baseline

0

0.005

0.01

0.015

0.02

0.025

0.03

0 5 10 15 20

Years

Sen

siti

vity

Fixed

Movable

6 GW, 50 tons and 1200 meters Baseline

0

0.005

0.01

0.015

0.02

0.025

0.03

0 5 10 15 20

Years

Sen

siti

vity

Fixed 0.8%

Fixed 0.4%

Movable

Quantitative Analysis of Movable vs. Quantitative Analysis of Movable vs. Fixed DetectorsFixed Detectors

Both the Kashiwazaki and Krasnoyarsk proposals assume that they can get the relative normalization systematic down to 0.8% with fixed detectors.

Even if you halve the relative normalization, fixed detector are not as sensitive for a two year (or longer) run.

All fixed detector scenario quickly become systematics limited.

Double Chooz believes that 0.6% is achievable.

Page 32: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

At the preferred m2 the optimal region is quite wide. In a configuration with a tunnel connecting the two detector sites, one should choose a far baseline that gives the shortest tunnel (1200 to 1400 meters).

One must consider both the location of the oscillation maximum (~2200 m at Δm2=2×10-3) and statistics loss due to 1/r2 flux.

Optimal Far BaselineOptimal Far Baseline7 GW, 50 tons, 200 meters Near BL and 3 Years

0

0.01

0.02

0.03

0.04

0.05

600 800 1000 1200 1400 1600 1800 2000Far Baseline (meters)

90%

CL

Sen

siti

vity

Δm2=2.0E-3

Δm2=5.0E-3

Δm2=1.0E-3

7 GW, 50 tons, 5 years

0

0.003

0.006

0.009

0.012

0.015

0.018

30 40 50 60 70 80 90 100 110 120Kinimatic Phase (Degrees)

90%

CL

Sen

sitiv

ity

Δm2=1.5E-3

Δm2=2.5E-3

Kinimatic Phase ≡ 1.27Δm2L/E for E=3.6 MeV

Page 33: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

60

65

70

75

80

85

90

0 100 200 300 400 500 600 700

% Systematic Error at Kinimatic Phase of 60 Degrees

Op

tim

al B

asel

ine

in K

inim

atic

Ph

ase

(deg

rees

) Δm2=2.5E-3

Δm2=1.5E-3

Sensitivity Scaling with Systematic ErrorSensitivity Scaling with Systematic ErrorFor a rate only analysisFor a rate only analysis

The optimal baseline is very sensitive to the level of systematic error.

The standard assumption of 0.8% relative efficiency error for fixed detectors is ~250% of the statistical error after 3 years at Braidwood.

Page 34: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

0

0.02

0.04

0.06

0.08

0.1

20 70 120

Kinimatic Phase (degrees)

Sen

siti

vity

at

90%

C.L

. Counting

Shape

0

0.005

0.01

0.015

0.02

0.025

0.03

20 70 120

Kinimatic Phase (degrees)

Sen

siti

vity

at

90%

C.L

.

Counting

Shape

Comparison of Shape & RateComparison of Shape & RateSystematics Limited

Systematic Error = 0%

0

0.01

0.02

0.03

0.04

0.05

0.06

20 70 120

Kinimatic Phase (degrees)

Sen

siti

vity

at

90%

C.L

.

Counting

Shape

Systematic Error = 200%

Systematic Error = 600%

The optimal Baseline for the systematics limited shape analysis is ~40º.

The optimal baseline for the systematics limited counting experiment is at the least optimal spot for a shape analysis!

You better know what regime your working in.

Statistics Limited

Page 35: Using Reactor Neutrinos to Study Neutrino Oscillations Jonathan Link Columbia University

7 GW, 50 tons, 1200 meters Far Baseline and 3 years

0.007

0.008

0.009

0.01

0.011

0.012

0.013

0.014

0.015

0.016

0 100 200 300 400 500 600 700

Near Baseline

Sen

siti

vity

Sensitivity wrt Near BaselineSensitivity wrt Near BaselineUltimately the location of the near detector will be determined by the reactor owners. The main question here is what can we live with?

There is a 1/r2 dependence in statistics (a small effect) and increasing oscillation probability with distance.

Sensitivity degrades with increasing near baseline.

When Lnear=Lfar the sensitivity is about the same as CHOOZ.