geographical issues and physics applications of “very long” neutrino factory baselines
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Geographical issues and physics Geographical issues and physics applications of “very long” neutrinoapplications of “very long” neutrino
factory baselinesfactory baselinesNuFact 05NuFact 05
June 23, 2005June 23, 2005
Walter WinterWalter Winter
Institute for Advanced Study, PrincetonInstitute for Advanced Study, Princeton
June 23, 2005 NuFact 05 - VLBL - Walter Winter
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ContentsContents
IntroductionIntroduction What are “very long” baselines?What are “very long” baselines? Applications of very long baselinesApplications of very long baselines Detector sites for very long baselinesDetector sites for very long baselines SummarySummary
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Picture of three-flavor oscillationsPicture of three-flavor oscillations
Magnitude of Magnitude of 1313 is key to is key to
““subleading” effects: subleading” effects: Mass hierarchy Mass hierarchy
determinationdetermination CP violationCP violation
e e flavor transitions flavor transitions
onon
atmospheric oscillation scaleatmospheric oscillation scale
Coupling strength: 13
Atmosphericoscillation:Amplitude: 23
Frequency: m312
Solaroscillation:Amplitude: 12
Frequency: m212
Sub-leading
effect: CP
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Appearance channels: Appearance channels: ee
All interesting information there: All interesting information there: 1313, , CPCP, mass hier., mass hier.
Complicated: Problems with correlations and degsComplicated: Problems with correlations and degs
(Cervera et al. 2000; Freund, Huber, Lindner, 2000; Freund, 2001)
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Neutrino factoryNeutrino factory Ultimative “high precision” Ultimative “high precision”
instrument!?instrument!? Muon decays in straight Muon decays in straight
sections of storage ringsections of storage ring Decay ring naturally spans Decay ring naturally spans
two baselinestwo baselines
Technical challenges: Target Technical challenges: Target power, muon cooling, maybe power, muon cooling, maybe steep decay tunnelssteep decay tunnels
Timescale: 2025?Timescale: 2025?
(from: CERN Yellow Report )
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““Very long” (VL) baselinesVery long” (VL) baselines Typical baseline: 3,000 km for 50 GeV neutrino factoryTypical baseline: 3,000 km for 50 GeV neutrino factory
(to measure CP violation)(to measure CP violation) Define “very long”: L >> 3,000 kmDefine “very long”: L >> 3,000 km Challenge: Decay tunnel slopes!Challenge: Decay tunnel slopes! Our Our benchmarkbenchmark neutrino factory: NuFact-II neutrino factory: NuFact-II
• EE = 50 GeV, L = 3,000 km (standard configuration) = 50 GeV, L = 3,000 km (standard configuration)• Running time: 4 years in each polarity = 8 yearsRunning time: 4 years in each polarity = 8 years• Detector: 50 kt magnetized iron calorimeterDetector: 50 kt magnetized iron calorimeter• 101021 21 useful muon decays/ year (~ 4 MW target power)useful muon decays/ year (~ 4 MW target power)• 10% prec. on solar params, 5% matter density uncertainty10% prec. on solar params, 5% matter density uncertainty• Atmospheric parameters best measured by disapp. channelAtmospheric parameters best measured by disapp. channel
(for details: Huber, Lindner, Winter, hep-ph/0204352)
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Note:
Pure baseline effect!
A 1: Matter resonance
Phenomenology of VL baselines (1)Phenomenology of VL baselines (1)
(Factor 1)2
(Factor 2)2
(Factor 1)(Factor 2)Prop. To L2; compensated
by flux prop. to 1/L2
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Factor 1:Factor 1: Depends on energy; Depends on energy; can be matter enhanced can be matter enhanced for long L; for long L; however: the longer L, however: the longer L, the stronger change off the stronger change off the resonancethe resonance
Factor 2:Factor 2:Always suppressed for Always suppressed for longer L; longer L; zero at “magic zero at “magic baseline” (indep. of E, baseline” (indep. of E, osc. Params)osc. Params)
Phenomenology of VL baselines (2)Phenomenology of VL baselines (2)
(m312 = 0.0025, =4.3 g/cm3, normal hierarchy)
Factor 2 always suppresses CP and solar terms for very Factor 2 always suppresses CP and solar terms for very long baselines; note that these terms include 1/Llong baselines; note that these terms include 1/L22-dep.!-dep.!
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Application 1: “Magic baseline”Application 1: “Magic baseline” Idea:Idea:
Factor 2=0Factor 2=0 independent independent of E, osc. Paramsof E, osc. Params
Purpose: Purpose: “Clean” measurement of “Clean” measurement of 1313 and mass hierarchy and mass hierarchy
Drawback: No Drawback: No CPCP measurement at magic baseline measurement at magic baseline combine with shorter baseline, such as L=3 000 kmcombine with shorter baseline, such as L=3 000 km
1313-range: 10-range: 10-4-4 < sin < sin22221313 < 10 < 10-2-2,,where most problems with degeneracies are presentwhere most problems with degeneracies are present
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Unstable: Disappears for different parameter
values
Magic baseline: Magic baseline: 1313 sensitivity sensitivityUse two-baseline space (LUse two-baseline space (L11,L,L22) with (25kt, 25kt) and compute ) with (25kt, 25kt) and compute 1313
sensitivity including correlations and degeneracies:sensitivity including correlations and degeneracies:
No CP violation measurement there!
Optimal performance for
all quantities:
Animation in Animation in
1313--CPCP-space:-space:
(Huber, Winter,PRD 68, 2003, 037301, hep-ph/0301257)
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CP coverage and “real synergies”CP coverage and “real synergies”
3 000 km + 7 500 km3 000 km + 7 500 kmversus all detector mass at versus all detector mass at 3 000 km (2L)3 000 km (2L)
Magic baseline allows a Magic baseline allows a risk-minimized risk-minimized measurement (unknown measurement (unknown ))
““Staged neutrino factory”: Staged neutrino factory”: Option to add magic Option to add magic baseline later if in “bad” baseline later if in “bad” quadrants?quadrants?
Range of all fit values which fit a chosen simulated value of CP
Any “extra” gain beyond a simple addition of statistics
One baseline enoughOne baseline enough Two baselines necessaryTwo baselines necessary(Huber, Lindner, Winter, JHEP, hep-ph/0412199)
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Magic baseline: Detector sites?Magic baseline: Detector sites?“Hot spots”:
Interesting for many labsPyhaesalmi mine,
Finland: MB from JHF
Gran Sasso, Italy: MB from Fermilab China, India:
MB from CERN?
(http://www.sns.ias.edu/~winter/BasePlots.htm)
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Appl. 2: Matter effect sensitivity for Appl. 2: Matter effect sensitivity for 1313=0=0 Idea: For Idea: For 1313=0 only =0 only
“solar term” survives. “solar term” survives. Factor 2 Factor 2 is suppressed in is suppressed in matter vs. vacuum :matter vs. vacuum :
Purpose: Verify MSW effect Purpose: Verify MSW effect at high CL even for at high CL even for 1313=0=0
Drawback: No mass hierarchy measurement (this term)Drawback: No mass hierarchy measurement (this term) 1313-range: Interesting for sin-range: Interesting for sin22221313 < 10 < 10-3-3
Note: No 1/LNote: No 1/L22 suppression of solar term in vacuum! suppression of solar term in vacuum!
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MSW sensitivity: MSW sensitivity: 1313-L-dependence-L-dependence
For sinFor sin22221313 >> >> 22 ~ 10 ~ 10-3-3::
Depending on sinDepending on sin22221313, L=3 , L=3
000 km might be sufficient000 km might be sufficient For sinFor sin22221313 << << 22 ~ 10 ~ 10-3-3::
Independent of sinIndependent of sin22221313, ,
even works foreven works for sinsin22221313=0:=0:
L > 6 000 km required!L > 6 000 km required!
(Winter, PLB 613, 2005, 73, hep-ph/0411309)
No sensitivity here
(CP=0)
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MSW effect vs. mass hierarchyMSW effect vs. mass hierarchy Both qualitatively similar Both qualitatively similar
for large for large 1313,, but:but:
matter effect sens. hardermatter effect sens. harder(Difference vacuum-matter < (Difference vacuum-matter < difference normal-inverted)difference normal-inverted)
Small Small 13: 13: No mass No mass
hierarchy sensitivity hierarchy sensitivity whatsoever whatsoever
Some dependence onSome dependence onCPCP, ,
but L > 6 000 km safebut L > 6 000 km safe
(5dashed curve: no correlations)
(Winter, PLB 613, 2005, 73, hep-ph/0411309)
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Application 3: Application 3: Measurement of the Earth’s core densityMeasurement of the Earth’s core density
Idea:Idea:Factor 1Factor 1 does not drop prop. does not drop prop. 1/L1/L22 close to resonance close to resonance
But: The longer L, the sharper But: The longer L, the sharper the change off the resonancethe change off the resonance Very sensitive to matter Very sensitive to matter density especially for large Ldensity especially for large L
Purpose: Purpose: Measure the absolute density of the Earth’s coreMeasure the absolute density of the Earth’s core
Drawbacks: Not possible to measure Drawbacks: Not possible to measure CPCP; ; “vertical” decay tunnel sophisticated“vertical” decay tunnel sophisticated
1313-range: sin-range: sin22221313 >> 10 >> 10-3-3
13 large,A~1 (resonance)
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Core density measurement: Core density measurement: PrinciplesPrinciples Most Most directdirect information on the matter density from Earth’s mass and information on the matter density from Earth’s mass and
rotational inertia, but:rotational inertia, but:
Least sensitive to the innermost partsLeast sensitive to the innermost parts Seismic waves: s-waves mainly Seismic waves: s-waves mainly
reflected on core boundariesreflected on core boundaries Least information on inner coreLeast information on inner core No “direct” matter density measurement; No “direct” matter density measurement;
depends on EOSdepends on EOS No “absolute” densities: mainly sensitive No “absolute” densities: mainly sensitive
to density jumpsto density jumps Neutrinos: Measure Baseline-Neutrinos: Measure Baseline-
averaged density:averaged density:
Equal contribution of innermost parts. Measure least known innermost density!Equal contribution of innermost parts. Measure least known innermost density!
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Core density measurement: ResultsCore density measurement: Results First: consider “ideal” First: consider “ideal”
geographical setup:geographical setup:Measure Measure ICIC (inner core) with (inner core) with L=2 RL=2 REE
Combine with L=3000 km to Combine with L=3000 km to measure oscillation parametersmeasure oscillation parameters
Key question: Key question: Does this Does this measurement survive the measurement survive the correlations with the unknown correlations with the unknown oscillation parameters?oscillation parameters?
For sinFor sin22221313 > 0.01 a precision at > 0.01 a precision at the per cent level is realistic the per cent level is realistic
For 0.001 < sinFor 0.001 < sin22221313 < 0.01: < 0.01:Correlations much worse Correlations much worse without 3000 km baselinewithout 3000 km baseline
(Winter, hep-ph/0502097)
(1, 2, 3, CP=0, Dashed: no correlations)
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Density measurement: GeographyDensity measurement: GeographySomething else than water in “core shadow”?
Inner core shadow
Outer core
shadow
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““Realistic geography”Realistic geography”… … and sinand sin22221313=0.01. Examples for =0.01. Examples for ICIC::
There are potential detector locations!There are potential detector locations! Per cent level precision not unrealisticPer cent level precision not unrealistic
(Winter, hep-ph/0502097)
BNL
CERN
JHF
Inner core
shadow
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Summary: VL baseline applicationsSummary: VL baseline applications
Excluded
10-1 10-2 10-3 10-4 10-5 10-6
sinsin22221313
Pur-Pur-posepose
Measure Measure density of the density of the Earth’s coreEarth’s core
Magic baseline: Magic baseline: Resolve Resolve correlations/correlations/degeneraciesdegeneracies
Verify Earth Verify Earth matter effects at matter effects at high CLhigh CL
LL L>10 665 kmL>10 665 km
(outer core)(outer core)
L ~ 7 500 kmL ~ 7 500 km L > 6 000 kmL > 6 000 km
Major challenge: Decay ring/decay tunnel slopeMajor challenge: Decay ring/decay tunnel slope Open question: Simultaneous or subsequent operation of VL Open question: Simultaneous or subsequent operation of VL
baseline? baseline? Feasiblity study for storage ring configurations needed!Feasiblity study for storage ring configurations needed!
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