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 Enrichment “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 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

Pros and Cons Technique Prototyping MultiIsotope Enrichment Resolution Mass limit Discrimination Problems CAMEO CdWO4 scintillator Use of B-CF 65kg array No Needed 10% 1 tonne Active shield Enrichment costs COBRA CdTe diodes Underway Yes No (?) <1% 10kg Segmemtation Neutron background CUORE TeO2 Bolometer Cuoricino approved Not needed (34% natural) 0.2% Segmentation Materials close to target EXO LXe or Xe TPC Approved (Ba tag test, 100kg Lxe) <2% 10 tonne Co-location of daughter PSD Cost of enrichment Ba ion extraction GENIUS Naked HPGe Genius-TF approved G-TF: natural G: 86% enrichment 0.3% Use of LN Cosmogenics Majorana HPGe 1 Ge det under construction Needed (8% -> 86%) 420kg MOON Mo & Scintillator WLS/Scint/Mo testing 7% 3 tonne (34 tonnes nat. Mo) Localisation High Q (3.03MeV) NEMO Tracking chamber Scintillator NEMO-I/II Tracking Time of flight Magnetic field Radioisotopic impurity Scale-up? TGV CaCO3 foils TGV 1 (1g) Required (73%) ? TGV-2: 10g Enrichment from CaF2 Mass

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+EC gives X-ray (30keV) and 2x 511keV photon signal ( 2nECEC gives 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….