Double Beta Decay status and future Double beta

Double Beta Decay - status and future • Double beta decay basics • Experimental challenges • Current experimental status • HM(HKK) result • Future experimental programmes • Dark matter and bb 0 n Based on talks at Ap. PEC Peer Review of bb 0 n, Nu 2002 (heavily) …. and a night in the Lamb with Kai Züber and Roland

Double Beta Decay Cremonesi Nu 2002

bb 0 n Rates Cremonesi Nu 2002

Why do bb 0 n? Cremonesi Nu 2002

Experimental Considerations Measure this Cremonesi Nu 2002

Key Issues • Multi-isotopic targets – “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(2 n) 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 Nu 2002

Heidelberg Moscow Experiment Cremonesi Nu 2002

HM(HVKK) Result Cremonesi Nu 2002

Comments on HM(HVKK) Cremonesi Nu 2002

Reply to the comments on HM(HVKK) Cremonesi Nu 2002

IGEX: Canfranc hep-ex 0202026

Thermal detectors - Milano DB Cremonesi Nu 2002

Milano DBD-II Cremonesi Nu 2002

MDBD-II: Results Cremonesi Nu 2002

MDBD-II: Background Cremonesi Nu 2002

Proposed Experiments Cremonesi Nu 2002

Proposed Experiments • Half life normalised to 5 years operation 10’s kg scale Tonne scale • Matrix element range. Half life for 50 me. V mass (in 1026 y) 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 Nu 2002

CUORE Cremonesi Nu 2002

CUORicino Cremonesi Nu 2002

EXO - Xenon Cremonesi Nu 2002

EXO - two approaches Cremonesi Nu 2002

Majorana Cremonesi Nu 2002

GENIUS Cremonesi Nu 2002

GENIUS-TF Cremonesi Nu 2002

GEM Cremonesi Nu 2002

DCBA/COBRA Cremonesi Nu 2002

Pros and Cons Technique Prototyping Multi. Isotope Enrichment Resolution Mass limit Discrimination Problems CAMEO Cd. WO 4 scintillator Use of B-CF 65 kg array No Needed 10% 1 tonne Active shield Enrichment costs COBRA Cd. Te diodes Underway Yes No (? ) <1% 10 kg Segmemtation Neutron background CUORE Te. O 2 Bolometer Cuoricino approved No Not needed (34% natural) 0. 2% 1 tonne Active shield Segmentation Materials close to target EXO LXe or Xe TPC Approved (Ba tag test, 100 kg Lxe) No Needed <2% 10 tonne Co-location of daughter PSD Cost of enrichment Ba ion extraction GENIUS Naked HPGe Genius-TF approved No G-TF: natural G: 86% enrichment 0. 3% 1 tonne PSD Cost of enrichment Use of LN Cosmogenics Majorana HPGe 1 Ge det under construction No Needed (8% -> 86%) 0. 3% 420 kg Segmentation PSD MOON Mo & Scintillator WLS/Scint /Mo WLS/Scint/Mo testing No Yes 7% 3 tonne (34 tonnes nat. Mo) Localisation High Q (3. 03 Me. V) Resolution NEMO Tracking chamber Scintillator NEMO-I/II Yes 10% 10 kg Tracking Time of flight Magnetic field Radioisotopic impurity Scale-up? TGV HPGe Ca. CO 3 foils TGV 1 (1 g) No Required (73%) 0. 2% ? TGV-2: 10 g Cost of enrichment Enrichment from Ca. F 2 Mass

bb 0 n and dark matter • Many common elements for rare event searches – Theoretically prejudice for max sensitivity required • DM: 10 -10 pb covers most of SUSY models • bb: >10 me. V from oscillations • Both require large mass targets (~1 tonne) Beware! – 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: ke. V range - bite into DM spectrum • bb: Me. V range - separate peaks at Q • Can we do both in one detector? – Xenon is an obvious candidate to consider within U. K.

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

ZEPLIN as bb 0 n experiment • Developing ideas for combining dark matter and bb 0 n 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 Me. V scales • Looks OK in second generation DM targets • There is also b+b+ capability – 124 Xe (0. 1% in nat. Xe) is one of seven known b+b+ emitters – 2 nb+ b+ gives 4 x 511 ke. V photon signal – 2 nb+EC gives X-ray (30 ke. V) and 2 x 511 ke. V photon signal ( – 2 n. ECEC gives 2 x X-ray (30 ke. V) signal • Current limits for 124 Xe are T 0. 52 n > 2 x 1014 years, T 0. 50 n > 4 x 1017 years

Conclusions • The bb 0 n 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 300 me. V – H-M (HVKK) Claim contested • Oscillation results encourage me. V 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….