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Double Beta Decay - status and future

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

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  1. 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

  2. Double Beta Decay Cremonesi Nu2002

  3. bb0n Rates Cremonesi Nu2002

  4. Why do bb0n? Cremonesi Nu2002

  5. Experimental Considerations Measure this Cremonesi Nu2002

  6. 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

  7. Current Experimental Limits Cremonesi Nu2002

  8. Current Experimental Limits Cremonesi Nu2002

  9. Heidelberg Moscow Experiment Cremonesi Nu2002

  10. HM(HVKK) Result Cremonesi Nu2002

  11. HM(HVKK) Result Cremonesi Nu2002

  12. Comments on HM(HVKK) Cremonesi Nu2002

  13. Reply to the comments on HM(HVKK) Cremonesi Nu2002

  14. IGEX: Canfranc hep-ex 0202026

  15. Thermal detectors - Milano DB Cremonesi Nu2002

  16. Milano DBD-II Cremonesi Nu2002

  17. MDBD-II: Results Cremonesi Nu2002

  18. MDBD-II: Background Cremonesi Nu2002

  19. Proposed Experiments Cremonesi Nu2002

  20. 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)

  21. 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

  22. NEMO-III Cremonesi Nu2002

  23. NEMO-III Cremonesi Nu2002

  24. CUORE Cremonesi Nu2002

  25. CUORicino Cremonesi Nu2002

  26. EXO - Xenon Cremonesi Nu2002

  27. EXO - two approaches Cremonesi Nu2002

  28. Majorana Cremonesi Nu2002

  29. GENIUS Cremonesi Nu2002

  30. GENIUS-TF Cremonesi Nu2002

  31. GEM Cremonesi Nu2002

  32. DCBA/COBRA Cremonesi Nu2002

  33. Pros and Cons

  34. 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!

  35. Xenon experience in UK/RAL Gotthard Xe TPC DB experiment (Roland) ZEPLIN dark matter programme (RAL, IC, Shef)

  36. 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

  37. 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….

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