Optimization of a neutrino factory oscillation experiment

Optimization of a neutrino factory Optimization of a neutrino factory oscillation experimentoscillation experiment

33rdrd ISS Meeting ISS MeetingRutherford Appleton Laboratory, UKRutherford Appleton Laboratory, UK

April 25-27, 2006April 25-27, 2006

Walter WinterWalter WinterInstitute for Advanced Study, PrincetonInstitute for Advanced Study, Princeton

April 25, 2006 ISS RAL NuFact - Walter Winter 2

ContentsContents IntroductionIntroduction Optimization summary: L-EOptimization summary: L-E

Improved detector summaryImproved detector summary Channel requirementsChannel requirements

– Some phenomenology: Why are other channels useful?Some phenomenology: Why are other channels useful?– PlatinumPlatinum– SilverSilver

Where to concentrate the efforts? Synergies?Where to concentrate the efforts? Synergies?How does the optimal neutrino factory look like?How does the optimal neutrino factory look like?

Comparison to beta beamsComparison to beta beams SummarySummary

See my talk(s) at KEK andPatrick’s talk in Boston


Appearance channelsAppearance channels

Complicated, but all interesting information there: Complicated, but all interesting information there: 1313, , CPCP, mass hierarchy (via A), mass hierarchy (via A)

(Cervera et al. 2000; Freund, Huber, Lindner, 2000; Freund, 2001)


Correlations and degeneraciesCorrelations and degeneracies Connected (green) or Connected (green) or

disconnected (yellow) disconnected (yellow) degenerate solutions (at a degenerate solutions (at a chosen CL) in parameter chosen CL) in parameter spacespace

Affect performance of Affect performance of appearance measurements. appearance measurements. For example, For example, 1313 sensitivity sensitivity

(Huber, Lindner, Winter, 2002)(Huber, Lindner, Winter, 2002) Discrete degeneracies: Discrete degeneracies: (also: Barger, Marfatia, Whisnant, 2001)(also: Barger, Marfatia, Whisnant, 2001)

Intrinsic (Intrinsic (,,1313)-degeneracy )-degeneracy (Burguet-Castell et al, 2001)(Burguet-Castell et al, 2001)

sgn-degeneracy sgn-degeneracy (Minakata, Nunokawa, 2001)(Minakata, Nunokawa, 2001)

((2323,,/2-/2-2323)-degeneracy )-degeneracy (Fogli, Lisi, 1996)(Fogli, Lisi, 1996)


Combine with “silver channels” Combine with “silver channels” ee -> -> (Donini, Meloni, Migliozzi, 2002; Autiero et al, 2004)(Donini, Meloni, Migliozzi, 2002; Autiero et al, 2004)

Combine with “platinum channels” Combine with “platinum channels” -> -> ee((sinsin22221313 > 10 > 10-3 -3 ? Depends on BG-level!)? Depends on BG-level!)(Boston workshop: Patrick’s talk)(Boston workshop: Patrick’s talk)

Better detectors: Higher energy Better detectors: Higher energy resolution, higher efficiencies atresolution, higher efficiencies atlow energies (CID!) low energies (CID!) (discussed at KEK, Boston)(discussed at KEK, Boston)

Second NF baseline: “Magic baseline” Second NF baseline: “Magic baseline” ((sinsin22221313 > 10 > 10-4-4))(Lipari, 2000; Burguet-Castell et al, 2001; Barger, Mafatia, Whisnant, 2002; Huber, (Lipari, 2000; Burguet-Castell et al, 2001; Barger, Mafatia, Whisnant, 2002; Huber, Winter, 2003; others)Winter, 2003; others)

Other possibilities?Other possibilities?

NF-Strategies to resolve degeneraciesNF-Strategies to resolve degeneracies

How much does

what help?

Where to concentratethe efforts?

Optimization of a Optimization of a neutrino factoryneutrino factory

4 yr x 1.06 104 yr x 1.06 102121 ++ decays + 4 yr x 1.06 10 decays + 4 yr x 1.06 102121 -- decays decaysDetector: 50 kt magnetized iron calorimeterDetector: 50 kt magnetized iron calorimeterISS-values? ISS-values?

100 kt, 5+5 years running time = factor 2.36 100 kt, 5+5 years running time = factor 2.36 luminosity increase for 10luminosity increase for 102121 useful decays/year useful decays/year

Most of the following work is done in collaboration with

P. HuberM. LindnerM. Rolinec


Optimization summary: L-EOptimization summary: L-E

Example: Example: 1313 sensitivity sensitivity

relativerelative to minimum to minimum in in each plot (5each plot (5 – new!) – new!)

““Magic baseline” good Magic baseline” good degeneracy resolverdegeneracy resolver

L ~ 2000 – 4000 kmL ~ 2000 – 4000 kmgood for statisticsgood for statistics

EE > 40 GeV > 40 GeV

At 5At 5 very robust to very robust to

– Threshold effectsThreshold effects

– mm313122 larger larger

– LuminosityLuminosity (Huber, Lindner, Rolinec, Winter, to appear)


CP violation and mass hierarchyCP violation and mass hierarchy

L ~ 3000 – 5000 km good for CP violation (large L ~ 3000 – 5000 km good for CP violation (large 1313 : 1500 – 6000) : 1500 – 6000)

L > 6000 km necessary for mass hierarchy (if small L > 6000 km necessary for mass hierarchy (if small 1313))

Use 4000 and 7500 km (“magic baseline”) as standard baselinesUse 4000 and 7500 km (“magic baseline”) as standard baselines

CP violation Mass hier.


Improved (golden) detector summaryImproved (golden) detector summary Better energy resolution?Better energy resolution?

Was: 0.15 x E (approximation) Was: 0.15 x E (approximation) Improve to: ? Improve to: ?

Lower appearance threshold?Lower appearance threshold?Was: 4 GeV, linearly Was: 4 GeV, linearly climbing to maximum at 20 GeVclimbing to maximum at 20 GeVImprove to: Max. already at 1 GeV?Improve to: Max. already at 1 GeV?

CC/NC Backgrounds: Assume CC/NC Backgrounds: Assume BG fraction BG fraction x Ex E-2-2 such that such that ~ 5 x 10~ 5 x 10-6-6 integrated over spectrum ( integrated over spectrum ( ~ 10 ~ 10-3-3)) Background increases at low energiesBackground increases at low energies Even if CID improved, NC background limits performance!Even if CID improved, NC background limits performance!

(Fig. from Huber, Lindner, Winter, 2002;

Gray curve from Cervera et al, 2000)

(Cervera et al, 2000)


Improved detector: MH and CP violationImproved detector: MH and CP violation

Improved detector would be excellent degeneracy resolver!Improved detector would be excellent degeneracy resolver! Also: EAlso: E = 20 GeV possible (while 50 GeV do not harm) = 20 GeV possible (while 50 GeV do not harm)

Blue shading:Optimization

potential: Golden*


Improved detector: SystematicsImproved detector: Systematics CP violationCP violation

measurement verymeasurement veryrobust with respectrobust with respectto systematics to systematics (signal normalization (signal normalization error) anderror) andBG level as long as BG level as long as 1010-2-2

Note that 20% BG Note that 20% BG uncertainty assumeduncertainty assumed

Standard“improved”

detector


Systematics: Leading atm. parametersSystematics: Leading atm. parameters

For Dm312 systematics somewhat For Dm312 systematics somewhat importantimportant

Dashed:10% error onsolar params

Energy resolution important for leading atm. parametersEnergy resolution important for leading atm. parameters Systematics somewhat important for Systematics somewhat important for mm3131

22, ,

but impact of solar input much largerbut impact of solar input much larger


Channel requirements: PhenomenologyChannel requirements: Phenomenology

(Akhmedov, Johansson, Lindner, Ohlsson, Schwetz, 2004)

Antineutrinos:Antineutrinos: Magic baseline:Magic baseline: Silver:Silver: Platinum:Platinum:

Assume specific hierarchy


Platinum channelPlatinum channel

Changes sign of CP-odd termChanges sign of CP-odd term Compare to antineutrinos:Compare to antineutrinos: Antineutrino channel without matter effect Antineutrino channel without matter effect

suppression/enhancement (dep. on hierarchy)suppression/enhancement (dep. on hierarchy) Support information on Support information on CPCP for large for large 1313??


Platinum channel: AssumptionsPlatinum channel: Assumptions Electron detection properties are MINOS-like Electron detection properties are MINOS-like

(NuMI note NuMI-L-714)(NuMI note NuMI-L-714)

2.5 GeV threshold2.5 GeV threshold 40% efficiency40% efficiency Energy resolution 0.15 x EEnergy resolution 0.15 x E 1% BG from all neutral current events1% BG from all neutral current events 1% BG from charge identification1% BG from charge identification

Fiducial detector mass: same as “golden” massFiducial detector mass: same as “golden” mass Matter density uncertainty: Matter density uncertainty:

Correlated with golden channelCorrelated with golden channel If platinum is possible, use it in all “golden” detectors, If platinum is possible, use it in all “golden” detectors,

such as for NuFact+NuFact@MB at both places!such as for NuFact+NuFact@MB at both places!

Limits the 13

for which thischannel is useful!


Platinum channel: ResultsPlatinum channel: Results

BG-dominated

Golden

Golden+Platinum Golden+Platinum

Golden

Good degeneracy resolver; especially for large Good degeneracy resolver; especially for large 1313!!


Silver channelSilver channel

Changes sign of CP-even Changes sign of CP-even andand CP-odd terms CP-odd terms Here: Here: we only test maximal mixingwe only test maximal mixing Interesting for Interesting for matter density correlationmatter density correlation::

22ndnd and 3 and 3rdrd terms fully correlated/anticorrelated with matter terms fully correlated/anticorrelated with matter density uncertainty from 1density uncertainty from 1stst term term(if same matter profile as golden channel) (if same matter profile as golden channel)


Silver channel: AssumptionsSilver channel: Assumptions Emulsion cloud chamber a la OPERAEmulsion cloud chamber a la OPERA

(Autiero et al, 2004)(Autiero et al, 2004)

Threshold starting at 2.5 GeV Threshold starting at 2.5 GeV (Fig. 7, Autiero et al, 2004)(Fig. 7, Autiero et al, 2004)

Energy resolution 0.20 x E (optimistic?)Energy resolution 0.20 x E (optimistic?) 10 kt fiducial mass10 kt fiducial mass Only neutrinos detectedOnly neutrinos detected Matter density uncertainty: Matter density uncertainty:

Correlated with golden channel Correlated with golden channel if at same baselineif at same baseline Also: Test improved Silver* with 5 x Signal, 3 x BGAlso: Test improved Silver* with 5 x Signal, 3 x BG

(if all leptonic and hadronic (if all leptonic and hadronic decay channels could be decay channels could be measured?) measured?) (Migliozzi, private communication)(Migliozzi, private communication)


Silver channel: OptionsSilver channel: Options Which baseline?Which baseline?

– Same as golden channel + correlated matter effectSame as golden channel + correlated matter effect– Different from golden channel + uncorrelated matter Different from golden channel + uncorrelated matter

effect (e.g., L=732 km)effect (e.g., L=732 km) Main results (qualitatively):Main results (qualitatively):

– Muon energies should probably not be too low Muon energies should probably not be too low (higher tau production threshold!)(higher tau production threshold!)

– Silver channel hardly affects golden channel opt.Silver channel hardly affects golden channel opt.– Correlated matter effect helps and makes Correlated matter effect helps and makes

4000 + 4000 km attractive4000 + 4000 km attractive


Silver channel: Results and comparisonSilver channel: Results and comparison

Matter density correlation helpsMatter density correlation helps Silver without upgrades not competitive to platinumSilver without upgrades not competitive to platinum Silver* at “golden” baseline complementary to platinumSilver* at “golden” baseline complementary to platinum

Effect ofcorrelated

matter effect


Better detector vs. new channelsBetter detector vs. new channels

Better detector = increase reach by improved statistics/energy infoBetter detector = increase reach by improved statistics/energy info Different channel = resolve degs by complementary informationDifferent channel = resolve degs by complementary information


Overall picture: Comparison matrixOverall picture: Comparison matrix

BaselinesBaselines

Detector effortDetector effort

One baselineOne baseline Two baselinesTwo baselines

11 GoldenGolden

(Golden)(Golden)MBMB

Beta beam Beta beam ((=350, L=730 km)=350, L=730 km)

(Burguet-Castell et al, 2005)(Burguet-Castell et al, 2005)

n/an/a

22 (Golden)(Golden)2L2L

Golden*Golden*

Golden+SilverGolden+Silver

Golden+PlatinumGolden+Platinum

Golden+(Golden)Golden+(Golden)MBMB

Golden+(Silver)Golden+(Silver)732732

33 Golden+Silver+PlatinumGolden+Silver+Platinum Golden*+(Golden*)Golden*+(Golden*)MBMB

Golden+(Golden)Golden+(Golden)MBMB+Platinum+Platinum

44 Golden*+(Golden*)Golden*+(Golden*)MBMB+Platinum+Platinum


Accelerator degree of freedom

Comparison matrix: Explanations Comparison matrix: Explanations D

etector degree of freedom

Synergies:Comparablestatistics

Directcomparison ofoptions at same

baseline Overall effort

Optimized detector, additional channel, or increased luminosity increase “detector effort” by oneBaseline: 4000 km, unless different one in index (MB=“Magic baseline”). Muon energy: 50 GeVStars: Improved golden detector; in any star option the muon energy is 20 GeV


““Simple” optionsSimple” options

No surprises: L=4000 km good for CP violation,No surprises: L=4000 km good for CP violation,L=7500 km good for mass hierarchyL=7500 km good for mass hierarchy

Beta beam very good for CP violation, but cannot measure mass Beta beam very good for CP violation, but cannot measure mass hierarchy for small hierarchy for small 1313


Synergies for detector effort “two”Synergies for detector effort “two”

Synergies and optimal performance in “competing regions” for Golden*, Synergies and optimal performance in “competing regions” for Golden*, Golden+Platinum, Golden+(Golden)Golden+Platinum, Golden+(Golden)MBMB

NEW: Magic baseline helps for large NEW: Magic baseline helps for large 1313!!

Compare to (Golden)2L:

If better in some region, real

synergy effect!

Compare with each other: If

similar impact,concentrate on

better one?

(Thick curves: two baselines)


Physics case: Large sinPhysics case: Large sin22221313

For large For large 1313, only , only CP violation an CP violation an issueissue

Beta beam best Beta beam best option even after option even after optimizationoptimization

CP violation (3)

Mass hierarchy (3)

sin2213 (5)

Discovery reaches for:


Physics case: Interm. sinPhysics case: Interm. sin22221313

““Typical” physics Typical” physics case for a neutrino case for a neutrino factory!?factory!?

Improved detector Improved detector and magic baseline and magic baseline sufficient to make sufficient to make physics case physics case against beta beam against beta beam forfor any any performance performance indicator used hereindicator used here


Physics case: Small sinPhysics case: Small sin22221313

Clear physics case Clear physics case for neutrino for neutrino factory even with factory even with “moderate” “moderate” improvementsimprovements

Optimal reach for Optimal reach for improved detector improved detector and magic baselineand magic baseline

Beta beam cannot Beta beam cannot determine massdetermine masshierarchy hierarchy


Where to concentrate the efforts?Where to concentrate the efforts?

Optimized NuFact: Measure mass hierarchy and CP violation Optimized NuFact: Measure mass hierarchy and CP violation almost down to sinalmost down to sin22221313 = 10 = 10-5-5! !

(including all degeneracies, for maximal mixing, 3(including all degeneracies, for maximal mixing, 3))


Comparison to beta beamsComparison to beta beamsAssumptionsAssumptions:: 2.9 102.9 101818 66He decays/yearHe decays/year

1.1 101.1 101818 1818Ne decays/year at Ne decays/year at simultaneous operation for eight yearssimultaneous operation for eight years(or double ion decays/year)(or double ion decays/year)

=350, L=730 km, 500 kt WC=350, L=730 km, 500 kt WCMaximum at CERN?Maximum at CERN? (Burguet-Castell et al, 2005)(Burguet-Castell et al, 2005)

=1000, L=1300 km, 50 kt TASD=1000, L=1300 km, 50 kt TASDHigh end. Optimal for CP violationHigh end. Optimal for CP violation(Huber, Lindner, Rolinec, Winter, 2005)(Huber, Lindner, Rolinec, Winter, 2005)

=1000, L=2600 km, 50 kt TASD=1000, L=2600 km, 50 kt TASDHigh end. Optimal for mass hierarchyHigh end. Optimal for mass hierarchy(Huber, Lindner, Rolinec, Winter, 2005)(Huber, Lindner, Rolinec, Winter, 2005)

=1000, L=1300 km + 2600 km=1000, L=1300 km + 2600 kmWhy not two baselines similar to Why not two baselines similar to NuFact?NuFact?


Comparison to beta beams (2)Comparison to beta beams (2)

NF good for NF good for 1313 discovery, MH discovery and discovery, MH discovery and CPCP for small for small 1313

Beta beam competitive for CP violation (large Beta beam competitive for CP violation (large 1313); But: Extreme ); But: Extreme effort to measure MH if effort to measure MH if 13 13 small could make physics case difficult!small could make physics case difficult!


SummarySummary Physics case for neutrino factory for small/intermediate Physics case for neutrino factory for small/intermediate

sinsin22221313 established; no clear physics case for large established; no clear physics case for large 13 13 yetyet

(baseline reopt. and reduced matter density uncertainties help somewhat …)(baseline reopt. and reduced matter density uncertainties help somewhat …)

The optimal neutrino factory has (at least)The optimal neutrino factory has (at least)– Two baselines with golden channel detectorsTwo baselines with golden channel detectors

– A golden detector as optimized as possible A golden detector as optimized as possible

– Electron neutrino detection in all golden detectorsElectron neutrino detection in all golden detectors The silver channel could be interesting ifThe silver channel could be interesting if

– Improved efficiencies (more tau decay channels)Improved efficiencies (more tau decay channels)

– Correlated matter effects (put detector to golden baseline)Correlated matter effects (put detector to golden baseline)

– Specific physics case (non-maximal mixing, unitarity test etc.)Specific physics case (non-maximal mixing, unitarity test etc.)


(Our) plans(Our) plans

Refine systematics/BG impact studyRefine systematics/BG impact study Check what one has to do for improved leading Check what one has to do for improved leading

atm. parameter measurementsatm. parameter measurements Re-check silver channel baseline optimization:Re-check silver channel baseline optimization:

732 km? Both at same baseline? Change of732 km? Both at same baseline? Change ofoptimization? Muon energies?optimization? Muon energies?

Test impact of matter density uncertaintiesTest impact of matter density uncertaintiesafter (correlated) platinum/silver channelsafter (correlated) platinum/silver channels

Possibly some work on large Possibly some work on large 1313 case case Finish this analysis (writeup as paper)Finish this analysis (writeup as paper)

Additional slidesAdditional slides


MINOS: Larger value of MINOS: Larger value of mm313122??

No qualitative changes in L-E-optimization,No qualitative changes in L-E-optimization,but improved absolute reaches!but improved absolute reaches!

Physics case for magic baseline even strongerPhysics case for magic baseline even stronger

Example: 0.003 eVExample: 0.003 eV22


Better detector: Better detector: 1313 sensitivity sensitivity

High CL chosen (4High CL chosen (4):):avoid threshold effectsavoid threshold effects

((1313,,CPCP)-degeneracy )-degeneracy

affects sensitivity limitaffects sensitivity limitat L ~ 1500-5000 kmat L ~ 1500-5000 km

Better detector threshold:Better detector threshold:L=2000-3000 km most L=2000-3000 km most attractive attractive 1313-baseline-baseline

“Magicbaseline”


Better detector: Large Better detector: Large 1313

Both better Eres and threshold usefulBoth better Eres and threshold useful Both better detector and smaller matter density uncertainty usefulBoth better detector and smaller matter density uncertainty useful Either or combination sufficient to compete with the superbeam upgrades (prel.)Either or combination sufficient to compete with the superbeam upgrades (prel.) Large Large +better detector prefers shorter baselines (1000-2000km); E+better detector prefers shorter baselines (1000-2000km); E small OK small OK

No

CP a

t Lm

agic!


Better detector in L-E-space: Better detector in L-E-space: 13 13 sens.sens. 33 sensitivity to sin sensitivity to sin22221313

Better Eres Better threshold Better Eres+thresh.

(Huber, Lindner, Rolinec, Winter, to appear)


Better detector in L-E-space: Large Better detector in L-E-space: Large 1313

CP fraction for CP CP fraction for CP violation (3violation (3

“Standard”“Standard”

“Optimal “Optimal appearance”appearance”L=1000 km/EL=1000 km/E=20 GeV=20 GeV

possible alternative?possible alternative?(Huber, Lindner, Rolinec, Winter, to appear)


Silver channel: Optimal baseline?Silver channel: Optimal baseline?

Correlated matter effect with LCorrelated matter effect with LECCECC=4000 km better than any other =4000 km better than any other baseline (except baseline (except 1313 sensitivity for L ~ 1500 km) sensitivity for L ~ 1500 km)

Optimization of a neutrino factory oscillation experiment

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