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Double Beta Decay - status and future. Double beta decay basics Experimental challenges Current experimental status HM(HKK) result Future experimental programmes Dark matter and bb0n.
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Double Beta Decay - status and future Double beta decay basics Experimental challenges Current experimental status HM(HKK) result Future experimental programmes Dark matter and bb0n Based on talks at ApPEC Peer Review of bb0n, Nu2002 (heavily) ….and a night in the Lamb with Kai Züber and Roland
Double Beta Decay Cremonesi Nu2002
bb0n Rates Cremonesi Nu2002
Why do bb0n? Cremonesi Nu2002
Experimental Considerations Measure this Cremonesi Nu2002
Key Issues • Multi-isotopic targets • “Redundancy, redundancy, redundancy” (J. Bahcall) • Background removal by different peak positions (ie noise peak at Q) • Enrichment • Radio-isotopic backgrounds • Energy Resolution • Discrimination • Removal of gamma, beta, neutron backgrounds • bb(2n) background irremovable (separate peaks) • Co-location of daughter ion • Theory • Matrix elements • Analysis techniques • Esp. in light of H-M claim
Current Experimental Limits Cremonesi Nu2002
Current Experimental Limits Cremonesi Nu2002
Heidelberg Moscow Experiment Cremonesi Nu2002
HM(HVKK) Result Cremonesi Nu2002
HM(HVKK) Result Cremonesi Nu2002
Comments on HM(HVKK) Cremonesi Nu2002
Reply to the comments on HM(HVKK) Cremonesi Nu2002
IGEX: Canfranc hep-ex 0202026
Thermal detectors - Milano DB Cremonesi Nu2002
Milano DBD-II Cremonesi Nu2002
MDBD-II: Results Cremonesi Nu2002
MDBD-II: Background Cremonesi Nu2002
Proposed Experiments Cremonesi Nu2002
Proposed Experiments • Half life normalised to 5 years operation 10’s kg scale Tonne scale • Matrix element range. Half life for 50meV mass (in 1026y) Elliott and Vogel Ann. Rev. Nucl. Part. Sci. 52 (2002)
Modularity and prototyping • Modularity • Discrimination through segmentation • Increase in support materials • GENIUS vs. Majorana • Systematics checks • Prototyping • 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-III Cremonesi Nu2002
NEMO-III Cremonesi Nu2002
CUORE Cremonesi Nu2002
CUORicino Cremonesi Nu2002
EXO - Xenon Cremonesi Nu2002
EXO - two approaches Cremonesi Nu2002
Majorana Cremonesi Nu2002
GENIUS Cremonesi Nu2002
GENIUS-TF Cremonesi Nu2002
GEM Cremonesi Nu2002
DCBA/COBRA Cremonesi Nu2002
bb0n and dark matter • Many common elements for rare event searches • Theoretically prejudice for max sensitivity required • DM: 10-10pb covers most of SUSY models • bb: >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 • bb: spatial (co-location of daughter) • Good resolution/threshold (high light yield, etc.) • DM: keV range - bite into DM spectrum • bb: MeV range - separate peaks at Q • Can we do both in one detector? • Xenon is an obvious candidate to consider within U.K. Beware!
Xenon experience in UK/RAL Gotthard Xe TPC DB experiment (Roland) ZEPLIN dark matter programme (RAL, IC, Shef)
ZEPLIN as bb0n experiment • Developing ideas for combining dark matter and bb0n experiments Key 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 b+b+ capability • 124Xe (0.1% in nat. Xe) is one of seven known b+b+ emitters • 2nb+ b+ gives 4x 511keV photon signal • 2nb+ECgives X-ray (30keV) and 2x 511keV photon signal ( • 2nECECgives 2x X-ray (30keV) signal • Current limits for 124Xe are T0.52n > 2x1014 years, T0.50n > 4x1017 years
Conclusions • The 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 300meV • H-M (HVKK) Claim contested • Oscillation results encourage meV searches • Several programmes suggested on Ge, Xe, Te, Mo • Need large scale, good resolution, discrimination, enrichment • Possibility of DM detectors as DB • ZEPLIN programme? • One man’s background….