Double Beta Decay Present and Future: Double Beta Decay Present and Future Jenny Thomas Rencontres du Vietnam, 2004


Preview: Preview Introduction: why search for 0nbb decay? Status of the search today: 3 experiments Cuoricino NEMO-III Heidleberg-Moscow : signal! Look at parameter space for 0nbb experiments Highlights of a few experiments on the horizon Conclusions


Introduction: oscillations: Introduction: oscillations The neutrino mixing matrix looks like this: From KamLAND, SNO, Super-K (Gonzales-Garcia NOON)


Introduction:oscillations: Introduction:oscillations mmin ~ 0 - 0.01 eV mmin ~ 0.03 - 0.06 eV


Introduction:double beta decay: Introduction:double beta decay Large number of even-even nuclei undergo double-beta decay, but not single-beta decay Standard Model process of 2nbb is also allowed of course Enrichment procedure in place for about 10 isotopes You do not search for peaks in unknown places: you always know where to look Q value of the decay is well known (difference in energy between two isotopes) 2nbb 0nbb


Introduction:double beta decay: Introduction:double beta decay Qbb Endpoint Energy 76Ge example


Introduction:the experiments: Introduction:the experiments Two classes of approach to the experiment: Detector IS the isotope Ionisation detectors Bolometer detectors TPCs Detector Contains the isotope(s) Tracking detectors Measure half life, infer mn Half life sensitivity given by experimental details G-phase space, exactly calculable:G0n ~ Qbb5 M0n-Nuclear Matrix Element, hard to calculate Uncertain to factor 2-10, isotope dependent Motivation to measure several isotopes


Introduction:the isotopes: Introduction:the isotopes What are the usable bb decay isotopes? 76Ge, Q=2.038MeV : MG = 7.3 +0.6 -0.6 x 10 -14 48Ca,Q = 4.272MeV :MG = 5.4+3.0-1.4 x 10 -14 82Se, Q = 2.995MeV : MG = 1.7+0.4-0.3 x 10 -13 100Mo, Q = 3.034MeV :MG = 1.0+0.3-0.3 x 10 -12 116Cd,Q = 2.804MeV :MG = 1.3+0.7-0.3 x 10 -13 130Te,Q = 2.528MeV :MG = 4.2+0.5-0.5 x 10 -13 136Xe,Q = 2.481MeV :MG = 2.8+0.4-0.4 x 10 -14 150Nd,Q = 3.368MeV: MG = 5.7+1.0-0.7 x 10 -12 These can all be enriched by standard processes


A History Plot: A History Plot mscale ~ 0.01 – 0.05 eV from oscillation experiments TeO2


Where are we today?: Where are we today? People have been searching for double beta decay for many years : first suggested in 1937 Presently three experiments taking data CUORICINO : Bolometer NEMO-III: Tracking HEIDLEBERG-MOSCOW : Ionization Ge detector New improved Heidelberg-Moscow result shows 4.2s effect! Cuoricino and NEMO-III will reach this sensitivity


Today:CUORICINO: Located in LNGS, Hall A Cuoricino (Hall A) CUORE R&D (Hall C) CUORE (Hall A) Today:CUORICINO


Slide12: Today: CUORICINO 2 modules, 9 detector each, crystal dimension 3x3x6 cm3 crystal mass 330 g 9 x 2 x 0.33 = 5.94 kg of TeO2 11 modules, 4 detector each, crystal dimension 5x5x5 cm3 crystal mass 790 g 4 x 11 x 0.79 = 34.76 kg of TeO2 40.7kg total 34% natural abundance


Today:CUORICINO: Today:CUORICINO


Today:CUORICINO: Today:CUORICINO 130Te crysals in LNGS Q = 2.528MeV Operation started early 2003 Background 0.19 counts/kev/kg/y Energy resolution ~ 4eV at 2MeV T1/2>7.5x1023 years =0.3-1.6eV : indicates large range of NME calculations available!


Today: NEMO-III: Today: NEMO-III AUGUST 2001 Located in Frejus Underground Lab


Slide16: 100Mo 6.914 kg Qbb = 3034 keV bb decay isotopes in NEMO-3 detector 82Se 0.932 kg Qbb = 2995 keV 116Cd 405 g Qbb = 2805 keV 96Zr 9.4 g Qbb = 3350 keV 150Nd 37.0 g Qbb = 3367 keV Cu 621 g 48Ca 7.0 g Qbb = 4272 keV natTe 491 g 130Te 454 g Qbb = 2529 keV External bkg measurement (All the enriched isotopes produced in Russia) Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004


Slide17: bb events selection in NEMO-3 Deposited energy: E1+E2= 2088 keV Internal hypothesis: (Dt)mes –(Dt)theo = 0.22 ns Common vertex: (Dvertex) = 2.1 mm Vertex emission (Dvertex)// = 5.7 mm Vertex emission Run Number: 2040 Event Number: 9732 Date: 2003-03-20 Typical bb2n event observed from 100Mo


Slide18: (Data 14 Feb. 2003 – 22 Mar. 2004) T1/2 = 7.72 ± 0.02 (stat) ± 0.54 (syst)  1018 y 100Mo 22 preliminary results 4.57 kg.y Cos() Angular Distribution Background subtracted 22 Monte Carlo 145 245 events 6914 g 241.5 days S/B = 45.8 NEMO-3 100Mo E1 + E2 (keV) Sum Energy Spectrum 145 245 events 6914 g 241.5 days S/B = 45.8 NEMO-3 100Mo Background subtracted 22 Monte Carlo Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004


Slide19: Simkovic, J. Phys. G, 27, 2233, 2001 Single electron spectrum different between SSD and HSD 100Mo 22 Single Energy Distribution 22 HSD Monte Carlo HSD higher levels Background subtracted 22 SSD Monte Carlo Background subtracted SSD Single State HSD: T1/2 = 8.61 ± 0.02 (stat) ± 0.60 (syst)  1018 y SSD: T1/2 = 7.72 ± 0.02 (stat) ± 0.54 (syst)  1018 y 100Mo 22 single energy distribution in favour of Single State Dominant (SSD) decay 4.57 kg.y E1 + E2 > 2 MeV 4.57 kg.y E1 + E2 > 2 MeV 2/ndf = 139. / 36 2/ndf = 40.7 / 36 NEMO-3 NEMO-3 Esingle (keV) Esingle (keV) Esingle (keV) Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004


Today:NEMO-III: Today:NEMO-III Present 90%CL limits from NEMO-III(216.4 days) 82Se:T1/2(bb0n) > 1.9 1023 y, mn 3.5 1023 y, mn 4.0 1024 y, mn 8.0 1023 y,,mn < 0.65 – 1.8 eV


Today: Heidelberg-Moscow : Today: Heidelberg-Moscow Enriched Germanium ionisation detector


Today: Heidelberg-Moscow: Today: Heidelberg-Moscow New analysis provides evidence of a peak at the expected value Total 71.7kgy of data Significance is 4.2 s mn =0.24-0.58eV Corresponds to quasi-degenerate neutrino masses


Slide23: Cosmological disfavoured Region (WMAP) Direct hierarchy m212= m2sol Inverse hierarchy m212= m2atm “quasi” degeneracy m1 m2  m3 Present Cuoricino/NEMO-III region Possible evidence (best value 0.39 eV) Feruglio F. , Strumia A. , Vissani F. hep-ph/0201291


Future Plans: Future Plans Only a few approaches Bolometers: Isotope is the detector Tracking : Isotope inside the detector Ionisation : Isotope is the detector Simple formula relates experimental parameters to half life reach: background or no background: a-isotopic abundance,b-background/Kev/kg/y,e-efficiency,dE-energy resolution,t-time,W-molecular weight,m-mass


Future Plans: Future Plans There are presently 16 projects in various stages of planning/approval in Italy,Japan,US,France and perhaps other places, target 0.02-0.05eV in mass Highlight reach of a few CUORE, 720kg TeO2, bolometers EXO, 1Tonne Xenon, TPC amd +Ba identification MAJORANA, 500kg Ge, ionization Super-NEMO several isotopes, tracking Ionisation Cobra, CdTe GEM GENIUS Majorana MPI Scintillator CAMEO Cd GANDLES Ca CARVEL Cd GSO Gd Xe Xe……. Tracking, TPC, Drift DCBA Nd MOON Mo Super-NEMO Mo,Se,Nd EXO Xe


Future Plans : CUORE: Future Plans : CUORE First fully-funded next generation experiment Based on CUORICINO technology, 130TeO2 Located at LNGS Target background 0.001c/kev/kg 720kg of TeO2


Future Plans : EXO: Future Plans : EXO High Pressure Xe TPC with laser tagging of +Ba daughter for background-free measurement 2 Tonne of 136Xe at 10Atm or Liq Xe with cold-finger tagging Energy resolution 2% at 2.5MeV 200kg prototype of Liq Xe funded by DoE (no tagging) will be built at WIPP, New Mexico. 200kg isotope already in hand


Future Plans : Majorana/MPI: Future Plans : Majorana/MPI 500kg enriched segmented conventional Ge detector Feasability has been demonstrated, waiting for approval Will use pulse-shape information to reduce background Based on theory that dominant background is 68Ge from cosmogenics MPI-Ge experiment also proposed Uses Ge mono-crystal in Liquid N or Ar for passive/active shielding Based on theory that dominant background is from Cu etc external to Ge


Future Plans : Super-NEMO: Future Plans : Super-NEMO Based on NEMO-III technology,SM only background study Se,Nd,Mo, low SM background Design study will start 2005 Feasible if: BG only from 2n bb (NEMO3) b) DE/E = 10% at 1 MeV (8% has already been demonstrated in recent R&D)


Future Plans: Future Plans Certain factors dominate reach Some factors are instrinsic to a particular isotope (M), others to the experimental approach T01/2 given by experimental parameters:background,resolution,efficiency The larger M, the lower the reach in mn


Future Plans : Summary: Future Plans : Summary


Conclusions: Conclusions Very exciting time for neutrino physics in general and 0nbb in particular A positive signal is now a serious possibility in light of oscillation results Costs of experiemnts all in the $50M range: this is small potatoes for the potential scientific gain In light of large NME uncertainties, several isotopes should be measured to avoid disappointment