Physics applications of “very long” neutrino factory baselines

Physics applications of “very long” Physics applications of “very long” neutrino factory baselinesneutrino factory baselines

PHENO 2005PHENO 2005May 3, 2005May 3, 2005

Walter WinterWalter Winter

Institute for Advanced Study, PrincetonInstitute for Advanced Study, Princeton

May 3, 2005 PHENO 2005 - Walter Winter 2

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


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 transitionsflavor transitions

in atmospheric oscillationsin atmospheric oscillations

Coupling strength: 13

Atmosphericoscillation:Amplitude: 23

Frequency: m312

Solaroscillation:Amplitude: 12

Frequency: m212

Sub-leading

effect: CP


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)


Long-baseline experimentsLong-baseline experiments

Artificial source:

Accelerator, Reactor

Often: Near detector to measure X-sections, control

systematics, …

Far detector

Baseline: L ~ E/m2

(osc. length)

?


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 )


““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• 5.3 105.3 102020 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)


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


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.!


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


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)


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, hep-ph/0412199)


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)


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!


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, hep-ph/0411309, to appear in PLB)

No sensitivity here

(CP=0)


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 (includes disappearance (includes disappearance channel!)channel!)

Some dependence onSome dependence onCPCP, , but L > 6 000 km safebut L > 6 000 km safe

(5dashed curve: no correlations)

(Winter, hep-ph/0411309, to appear in PLB)


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)


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!


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)


Density measurement: GeographyDensity measurement: GeographySomething else than water in “core shadow”?

Inner core shadow

Outer core

shadow


““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


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? Feasiblity study for storage ring configurations needed!baseline? Feasiblity study for storage ring configurations needed!

Physics applications of “very long” neutrino factory baselines

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