Double Beta Decay - status and futureDouble Beta Decay - status and futureDouble Beta Decay - status and futureDouble Beta Decay - status and future

• Double beta decay basicsDouble beta decay basics

• Experimental challengesExperimental challenges

• Current experimental statusCurrent experimental status

• HM(HKK) resultHM(HKK) result

• Future experimental programmesFuture experimental programmes

• Dark matter and Dark matter and

Based on talks at ApPEC Peer Review of , Nu2002 (heavily) ….and a night in the Lamb with Kai Züber and Roland

Double Beta DecayDouble Beta DecayDouble Beta DecayDouble Beta Decay

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RatesRates RatesRates

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Why do Why do ??Why do Why do ??

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Experimental ConsiderationsExperimental ConsiderationsExperimental ConsiderationsExperimental Considerations

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Measure this

Key IssuesKey IssuesKey IssuesKey Issues

• Multi-isotopic targetsMulti-isotopic targets– “Redundancy, redundancy, redundancy” (J. Bahcall)

– Background removal by different peak positions (ie noise peak at Q)

• EnrichmentEnrichment

• Radio-isotopic backgroundsRadio-isotopic backgrounds

• Energy Resolution Energy Resolution

• DiscriminationDiscrimination– Removal of gamma, beta, neutron backgrounds

– background irremovable (separate peaks)

– Co-location of daughter ion

• TheoryTheory– Matrix elements

• Analysis techniquesAnalysis techniques– Esp. in light of H-M claim

Current Experimental LimitsCurrent Experimental LimitsCurrent Experimental LimitsCurrent Experimental Limits

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Current Experimental LimitsCurrent Experimental LimitsCurrent Experimental LimitsCurrent Experimental Limits

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Heidelberg Moscow ExperimentHeidelberg Moscow ExperimentHeidelberg Moscow ExperimentHeidelberg Moscow Experiment

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HM(HVKK) ResultHM(HVKK) ResultHM(HVKK) ResultHM(HVKK) Result

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HM(HVKK) ResultHM(HVKK) ResultHM(HVKK) ResultHM(HVKK) Result

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Comments on HM(HVKK)Comments on HM(HVKK)Comments on HM(HVKK)Comments on HM(HVKK)

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Reply to the comments on HM(HVKK)Reply to the comments on HM(HVKK)Reply to the comments on HM(HVKK)Reply to the comments on HM(HVKK)

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IGEX: CanfrancIGEX: CanfrancIGEX: CanfrancIGEX: Canfranc

hep-ex 0202026

Thermal detectors - Milano DBThermal detectors - Milano DBThermal detectors - Milano DBThermal detectors - Milano DB

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Milano DBD-IIMilano DBD-IIMilano DBD-IIMilano DBD-II

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MDBD-II: ResultsMDBD-II: ResultsMDBD-II: ResultsMDBD-II: Results

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MDBD-II: BackgroundMDBD-II: BackgroundMDBD-II: BackgroundMDBD-II: Background

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Proposed ExperimentsProposed ExperimentsProposed ExperimentsProposed Experiments

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Proposed ExperimentsProposed ExperimentsProposed ExperimentsProposed Experiments

Elliott and Vogel Ann. Rev. Nucl. Part. Sci. 52 (2002)

10’s kg scale

Tonne scale

• Half life normalised to 5 years operationHalf life normalised to 5 years operation

• Matrix element range. Matrix element range. Half life for 50meV mass Half life for 50meV mass (in 10(in 102626y)y)

Modularity and prototypingModularity and prototypingModularity and prototypingModularity and prototyping

• ModularityModularity– Discrimination through segmentation

– Increase in support materials• GENIUS vs. Majorana

– Systematics checks

• PrototypingPrototyping– Direct scale-up of current technology won’t require prototyping -

too expensive?

– Prototype is first module

– All experiments involved in prototyping• Handling scale up issues (cryostats, mass, etc)

• Handling readout options (laser tag, WLS fibres)

• Cross check against Monte Carlo

NEMO-IIINEMO-IIINEMO-IIINEMO-III

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NEMO-IIINEMO-IIINEMO-IIINEMO-III

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CUORECUORECUORECUORE

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CUORicinoCUORicinoCUORicinoCUORicino

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EXO - XenonEXO - XenonEXO - XenonEXO - Xenon

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EXO - two approachesEXO - two approachesEXO - two approachesEXO - two approaches

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MajoranaMajoranaMajoranaMajorana

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GENIUSGENIUSGENIUSGENIUS

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GENIUS-TFGENIUS-TFGENIUS-TFGENIUS-TF

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GEMGEMGEMGEM

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DCBA/COBRADCBA/COBRADCBA/COBRADCBA/COBRA

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Pros and ConsPros and ConsPros and ConsPros and ConsTechniqueTechnique PrototypingPrototyping MultiIsotopeMultiIsotope EnrichmentEnrichment ResolutionResolution Mass limitMass limit DiscriminationDiscrimination ProblemsProblems

CAMEOCAMEO

CdWOCdWO44

scintillatorscintillator

Use of B-CF 65kg Use of B-CF 65kg arrayarray

NoNo NeededNeeded 10%10% 1 tonne1 tonne Active shieldActive shield Enrichment costsEnrichment costs

COBRACOBRA

CdTe CdTe

diodesdiodes

UnderwayUnderway YesYes No (?)No (?) <1%<1% 10kg10kg SegmemtationSegmemtation Neutron backgroundNeutron background

CUORECUORE

TeOTeO22 Bolometer BolometerCuoricino Cuoricino approvedapproved

NoNoNot neededNot needed

(34% natural)(34% natural)0.2%0.2% 1 tonne1 tonne

Active shieldActive shield

SegmentationSegmentationMaterials close to targetMaterials close to target

EXOEXO

LXe or Xe TPCLXe or Xe TPC

ApprovedApproved

(Ba tag test, 100kg (Ba tag test, 100kg Lxe)Lxe)

NoNo NeededNeeded <2%<2% 10 tonne10 tonneCo-location of daughterCo-location of daughter

PSDPSD

Cost of enrichmentCost of enrichment

Ba ion extractionBa ion extraction

GENIUSGENIUS

Naked HPGeNaked HPGeGenius-TF Genius-TF approvedapproved

NoNoG-TF: naturalG-TF: natural

G: 86% G: 86% enrichmentenrichment

0.3%0.3% 1 tonne1 tonne PSDPSD

Cost of enrichmentCost of enrichment

Use of LNUse of LN

CosmogenicsCosmogenics

MajoranaMajorana

HPGeHPGe1 Ge det under 1 Ge det under constructionconstruction

NoNoNeeded (8% -> Needed (8% -> 86%)86%)

0.3%0.3% 420kg420kgSegmentationSegmentation

PSDPSD

Cost of enrichmentCost of enrichment

MOONMOON

Mo & Mo & ScintillatorScintillator

WLS/Scint/Mo WLS/Scint/Mo testingtesting

NoNo YesYes 7%7%3 tonne 3 tonne

(34 tonnes nat. (34 tonnes nat. Mo)Mo)

LocalisationLocalisation

High Q (3.03MeV)High Q (3.03MeV)ResolutionResolution

NEMONEMO

Tracking Tracking chamber chamber ScintillatorScintillator

NEMO-I/IINEMO-I/II YesYes YesYes 10%10% 10kg10kg

TrackingTracking

Time of flightTime of flight

Magnetic fieldMagnetic field

Radioisotopic impurityRadioisotopic impurity

Scale-up?Scale-up?

TGV TGV

HPGeHPGe

CaCOCaCO33 foils foilsTGV 1 (1g)TGV 1 (1g) NoNo Required (73%)Required (73%) 0.2%0.2% ? TGV-2: 10g? TGV-2: 10g

Enrichment from CaFEnrichment from CaF22

MassMass

• Many common elements for rare event searchesMany common elements for rare event searches– Theoretically prejudice for max sensitivity required

• DM: 10-10pb covers most of SUSY models• : >10 meV from oscillations• Both require large mass targets (~1 tonne)

– Low backgrounds required• High radio-purity materials• Good shielding

– Discrimination required• DM: nuclear vs. electron recoil, spatial• : spatial (co-location of daughter)

– Good resolution/threshold (high light yield, etc.)• DM: keV range - bite into DM spectrum• : MeV range - separate peaks at Q

• Can we do both in one detector?Can we do both in one detector?– Xenon is an obvious candidate to consider within U.K.

and dark matterand dark matter and dark matterand dark matter

Beware!

Xenon experience in UK/RALXenon experience in UK/RALXenon experience in UK/RALXenon experience in UK/RALGotthard Xe TPC DB experiment (Roland)

ZEPLIN dark matter programme(RAL, IC, Shef)

ZEPLIN as ZEPLIN as experiment experimentZEPLIN as ZEPLIN as experiment experiment

• Developing ideas for combining dark matter and Developing ideas for combining dark matter and experimentsexperimentsKey issues are

– Energy scales of interest• Primarily a DAQ issue, saturation of readouts, etc.

– Discrimination of backgrounds• Can position sensitivity in ZEPLIN be improved to check co-locality in DB?

– Resolution at MeV scales• Looks OK in second generation DM targets

• There is also There is also capability capability– 124Xe (0.1% in nat. Xe) is one of seven known emitters

– gives 4x 511keV photon signal

– ECgives X-ray (30keV) and 2x 511keV photon signal (

– ECECgives 2x X-ray (30keV) signal• Current limits for 124Xe are T0.5

2 > 2x1014 years, T0.50 > 4x1017 years

ConclusionsConclusionsConclusionsConclusions

• The bb0n decay search has the promise of illuminatingThe bb0n decay search has the promise of illuminating– Absolute mass scale of neutrinos

(note this is effective mass, unlike beta end point: KATRIN)

– Lepton number violation

– Majorana vs. Dirac description

• Current limits/claims 300meVCurrent limits/claims 300meV– H-M (HVKK) Claim contested

• Oscillation results encourage meV searchesOscillation results encourage meV searches

• Several programmes suggested on Ge, Xe, Te, MoSeveral programmes suggested on Ge, Xe, Te, Mo– Need large scale, good resolution, discrimination, enrichment

• Possibility of DM detectors as DBPossibility of DM detectors as DB– ZEPLIN programme?

– One man’s background….