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….