Optimizing the green-field beta beamOptimizing the green-field beta beam

NuFact 08NuFact 08Valencia, SpainValencia, Spain

June 30-July 5, 2008June 30-July 5, 2008

Walter WinterWalter WinterUniversität WürzburgUniversität Würzburg

June 30, 2008 NuFact 08 - Walter Winter 2

ContentsContents Introduction:Introduction:

Green-field scenarioGreen-field scenario Beta beam for small Beta beam for small 1313

Beta beam for large Beta beam for large 1313

SummarySummary

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Green-field scenarioGreen-field scenario No specific accelerator, L, No specific accelerator, L, Two possible isotope pairs Two possible isotope pairs Different luminosities: TypicallyDifferent luminosities: Typically

– 1.1 101.1 101818 useful ion decays/year for neutrinos useful ion decays/year for neutrinos2.9 102.9 101818 useful ion decays/year for antineutrinos useful ion decays/year for antineutrinos

– 5 years nu + 5 years antinu running5 years nu + 5 years antinu running Corresponds to Corresponds to Luminosity scaling factorLuminosity scaling factor (LSF) = 1 (LSF) = 1

LSF scales useful ion decays (integrated over t) x detector mass x efficiencyLSF scales useful ion decays (integrated over t) x detector mass x efficiency

– Specific detector technology: WC, TASD, MID, etc.Specific detector technology: WC, TASD, MID, etc.Detector mass will be given separately (fct. of technology)!Detector mass will be given separately (fct. of technology)!

Optimize the parameters (isotope pair, LSF, detector Optimize the parameters (isotope pair, LSF, detector technology, L, technology, L, ) for the ) for the best physics outputbest physics output

(http://ie.lbl.gov/toi)

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Isotopes compared: SpectrumIsotopes compared: Spectrum Example: Unoscillated spectrum for CERN-INO Example: Unoscillated spectrum for CERN-INO

Total flux ~ Total flux ~ NN 22 (forward boost!) (forward boost!) (N(N: useful ion decays): useful ion decays)

(from Agarwalla, Choubey, Raychaudhuri, 2006)

Peak E ~ E0 Max. E ~ 2 E0 (E0 >> me assumed;E0: endpoint energy)

(E0 ~ 14 MeV) (E0 ~ 4 MeV)

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Want same neutrino energies (=same X-sections, L, Want same neutrino energies (=same X-sections, L, physicsphysics=MSW, …): Peak energy ~ =MSW, …): Peak energy ~ E E00, flux ~ , flux ~ NN 22

Use high Use high and isotopes with small E and isotopes with small E00 oror low low and isotopes with large E and isotopes with large E0 0

for same total flux for same total flux

Example: NExample: N(B,Li)(B,Li) ~ 12 N ~ 12 N

(He,Ne)(He,Ne) , , (He,Ne)(He,Ne) ~ 3.5 ~ 3.5 (B,Li)(B,Li) NB: NB: : : Accelerator dofAccelerator dof versus N versus N: : ion source dofion source dof

Where is the cost/feasibility break-even point?Where is the cost/feasibility break-even point? NB: Peak energy determines suitable detector technology!NB: Peak energy determines suitable detector technology!

Different isotopes: Some thoughtsDifferent isotopes: Some thoughts

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Small Small 1313::Optimize Optimize 1313, MH, , MH, and CPV discovery and CPV discovery reaches in reaches in 1313 direction direction

Large Large 1313::Optimize Optimize 1313, MH, , MH, and CPV discovery and CPV discovery reaches in (true) reaches in (true) CPCP directiondirection

What defines “large What defines “large 1313”? ”? A Double Chooz, Day Bay, T2K, … discovery?A Double Chooz, Day Bay, T2K, … discovery?

Beta beams for small versus large Beta beams for small versus large 1313

(3m312=0.0022 eV2

Optimization for small 13

Optimization for large 13

T2KK

Beta beam

NuFa

ct

Beta beams with excellent Beta beams with excellent 1313 reach reach

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Minimum wish listMinimum wish list Assume that Double Chooz … do Assume that Double Chooz … do notnot find find 1313 Minimum wish list:Minimum wish list:

confirmation of confirmation of 13 13 > 0> 0– 33 mass hierarchy determination mass hierarchy determination– 33 CP violation determination CP violation determinationFor as small as possible (true) For as small as possible (true) 1313

Two unknowns here:Two unknowns here:– For what fraction of (true) For what fraction of (true) CPCP? ?

One has to make a choice (e.g. max. CP violation, for all One has to make a choice (e.g. max. CP violation, for all CPCP, , for a CP fraction 50%, …)for a CP fraction 50%, …)

– How small How small 1313 is actually good enough? is actually good enough? Minimal effort is a matter of cost!Minimal effort is a matter of cost!

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Optimal Optimal A matter of cost! A matter of cost! Fix L/Fix L/=1.3, LSF = 1.6=1.3, LSF = 1.6

The higher The higher , the better (modulo detector!), the better (modulo detector!)

(Huber, Lindner, Rolinec, Winter, 2005)(Huber, Lindner, Rolinec, Winter, 2005)

500 kt 50 kt

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Optimal baseline?Optimal baseline?A matter of the performance indicator, detector, A matter of the performance indicator, detector, , …, …

(Huber, Lindner, Rolinec, Winter, 2005)(Huber, Lindner, Rolinec, Winter, 2005)

L/=

2.6

L/=

0.8 L/

=1.

3

L/=

2.1

Points towards two baselines!

CP = 0

CP = /2

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Isotope pair comparison: Isotope pair comparison: 1313 sensitivity sensitivity MID (50kt), MID (50kt),

LSF=1LSF=1 Two set of Two set of

baselines can baselines can be identified:be identified:– Short Short

(L/(L/=0.8 or =0.8 or 2.6) 2.6)

– Long (magic)Long (magic) Long baseline Long baseline

better for B/Li better for B/Li if if > 350 > 350

(Agarwalla, Choubey, (Agarwalla, Choubey, Raychaudhuri, Winter, Raychaudhuri, Winter, 2008)2008)

Mag

ic b

asel

ine

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A matter of luminosity? A matter of luminosity? Isotope pairs compared: Short vs. long baselineIsotope pairs compared: Short vs. long baseline

Gamma increase: ~ 3.5

Same physics for ~ 10 x luminosity

(Agarwalla, Choubey, Raydchaudhuri, Winter, 2008)(Agarwalla, Choubey, Raydchaudhuri, Winter, 2008)MID, 50kt

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MH and CPV for MH and CPV for ~ 500 ~ 500 MH:MH:

Use (B,Li) Use (B,Li) at magic at magic baseline;baseline;energy!energy!

CPV:CPV:Use Use (Ne,He) at (Ne,He) at short short baselinebaseline(different (different detector?)detector?)

MID, 50kt

(Agarwalla, Choubey, Raydchaudhuri, Winter, 2008)(Agarwalla, Choubey, Raydchaudhuri, Winter, 2008)

CP dependence

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Optimal green-field scenario for Optimal green-field scenario for small small 1313

Use two baselines, two isotope pairs:Use two baselines, two isotope pairs:– (B,Li) at magic baseline for MH sensitivity(B,Li) at magic baseline for MH sensitivity

Detector: MID, TASD, …Detector: MID, TASD, …– (Ne,He) at short baseline for CPV sensitivity(Ne,He) at short baseline for CPV sensitivity

Detector: TASD, WC, MID?, …Detector: TASD, WC, MID?, … Either one for Either one for 1313 sensitivity sensitivity

(For two-baseline implementations, see: (For two-baseline implementations, see: Coloma, Donini, Fernandez-Martinez, Lopez-Pavon, 2007; Agarwalla, Choubey, Raydchaudhuri, 2008)Coloma, Donini, Fernandez-Martinez, Lopez-Pavon, 2007; Agarwalla, Choubey, Raydchaudhuri, 2008)

Beta beams for large Beta beams for large 1313

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Minimum wish listMinimum wish list Assume that Assume that

Double Chooz finds Double Chooz finds 1313

Minimum wish listMinimum wish listeasy to define:easy to define:– 55 independent confirmation of independent confirmation of 13 13 > 0> 0– 33 mass hierarchy determination for any (true) mass hierarchy determination for any (true) CPCP

– 33 CP violation determination for 80% (true) CP violation determination for 80% (true) CPCP

For any (true) For any (true) 1313 in 90% CL D-Chooz allowed range! in 90% CL D-Chooz allowed range! What is the minimal (effort) beta beam for that?What is the minimal (effort) beta beam for that?

NB: Such a minimum wish list is non-trivial for small NB: Such a minimum wish list is non-trivial for small 1313 NB: CP fraction 80% comes from comparison with IDS-NF baseline etc.NB: CP fraction 80% comes from comparison with IDS-NF baseline etc.

(Sim. from hep-ph/0601266; (Sim. from hep-ph/0601266; 1.5 yr far det. + 1.5 yr both det.)1.5 yr far det. + 1.5 yr both det.)

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Minimal effort beta beamMinimal effort beta beam Minimal effort =Minimal effort =

– One baseline onlyOne baseline only– Minimal Minimal – Minimal LSFMinimal LSF– Any L (green-field!)Any L (green-field!)

Example: Fix LSF and Example: Fix LSF and optimize L-optimize L- Sharp cutoff by MH Sharp cutoff by MH

from left, from CPV from left, from CPV from bottomfrom bottom

Use fixed L >= 730 km Use fixed L >= 730 km to avoid fine-tuningto avoid fine-tuning

(Winter, arXiv:0804.4000)(Winter, arXiv:0804.4000)

Sensitivity for entire Double Chooz allowed range!

LSF=1

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Luminosity scaling for fixed LLuminosity scaling for fixed L What is theWhat is the

minimal LSF x minimal LSF x ?? (Ne,He):(Ne,He):

LSF = 1 possibleLSF = 1 possible(B,Li):(B,Li):LSF = 1 not sufficientLSF = 1 not sufficient

But: If LSF >= 5:But: If LSF >= 5: can be lower for can be lower for (B,Li) than for (B,Li) than for (Ne,He), because MH (Ne,He), because MH measurement measurement dominates there dominates there (requires energy!)(requires energy!)

(Winter, arX

iv:0804.4000)(W

inter, arXiv:0804.4000)

(100kt)(500kt)

only < 150!

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Minimal Minimal beta beam beta beam(W

inter, arXiv:0804.4000)

(Winter, arX

iv:0804.4000)

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Minimal beta beam at the CERN-SPS?Minimal beta beam at the CERN-SPS?(( fixed to maximum at SPS) fixed to maximum at SPS)

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SummarySummary Optimal beta beam for small Optimal beta beam for small 1313::

Uses two baselines, two isotope pairs:Uses two baselines, two isotope pairs:– (B,Li) at magic baseline for MH sensitivity(B,Li) at magic baseline for MH sensitivity

Detector: MID, TASD, …Detector: MID, TASD, …– (Ne,He) at shorter (L/(Ne,He) at shorter (L/ ~ 1) baseline for CPV sensitivity ~ 1) baseline for CPV sensitivity

Detector: TASD, WC, MID?, …Detector: TASD, WC, MID?, … Minimal beta beam for large Minimal beta beam for large 1313::

One baseline only: L >> 500 kmOne baseline only: L >> 500 km– Use (B,Li) if high enough useful ion decays LSF ~ 5: Use (B,Li) if high enough useful ion decays LSF ~ 5: > 80 > 80 – Use (Ne,He) if LSF ~ 1: Use (Ne,He) if LSF ~ 1: > 190 > 190

Minimal Minimal will be determined by baseline and Double will be determined by baseline and Double Chooz resultChooz result

BackupBackup

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Comparison Comparison of setupsof setups

(Huber, Lindner, Rolinec, (Huber, Lindner, Rolinec,

Winter, 2005) Winter, 2005)

33

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Mass hierarchy determinationMass hierarchy determination

(Agarwalla, Choubey, (Agarwalla, Choubey, Raychaudhuri, Winter, Raychaudhuri, Winter, 2008)2008)

June 30, 2008 NuFact 08 - Walter Winter 25

CP violation determinationCP violation determination

(Agarwalla, Choubey, (Agarwalla, Choubey, Raychaudhuri, Winter, Raychaudhuri, Winter, 2008)2008)