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Double Beta Decay Present and Future

Double Beta Decay Present and Future. Jenny Thomas Rencontres du Vietnam, 2004. Preview. Introduction: why search for 0 nbb decay? Status of the search today: 3 experiments Cuoricino NEMO-III Heidleberg-Moscow : signal! Look at parameter space for 0 nbb experiments

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Double Beta Decay Present and Future

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

  2. 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 J.Thomas, UCL

  3. Introduction: oscillations • The neutrino mixing matrix looks like this: • From KamLAND, SNO, Super-K (Gonzales-Garcia NOON) J.Thomas, UCL

  4. Introduction:oscillations mmin~ 0.03 - 0.06 eV mmin~ 0 - 0.01 eV J.Thomas, UCL

  5. 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 J.Thomas, UCL

  6. Introduction:double beta decay 76Ge example Qbb Endpoint Energy J.Thomas, UCL

  7. 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 J.Thomas, UCL

  8. 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 J.Thomas, UCL

  9. A History Plot TeO2 mscale~ 0.01 – 0.05 eV from oscillation experiments J.Thomas, UCL

  10. 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 J.Thomas, UCL

  11. Today:CUORICINO • Located in LNGS, Hall A CUORE R&D (Hall C) CUORE (Hall A) Cuoricino (Hall A) J.Thomas, UCL

  12. heat bath Thermal sensor absorber crystal Incident particle Today: CUORICINO 40.7kg total 34% natural abundance 2modules, 9detector each, crystal dimension3x3x6 cm3 crystal mass330 g 9 x 2 x 0.33 = 5.94 kg of TeO2 11modules, 4detector each, crystal dimension5x5x5 cm3 crystal mass790 g 4 x 11 x 0.79 = 34.76 kg of TeO2 J.Thomas, UCL

  13. Today:CUORICINO J.Thomas, UCL

  14. 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 <mn>=0.3-1.6eV : indicates large range of NME calculations available! J.Thomas, UCL

  15. Today: NEMO-III AUGUST 2001 Located in Frejus Underground Lab J.Thomas, UCL

  16. bb2n measurement bb0n search bb decay isotopes in NEMO-3 detector 116Cd405 g Qbb = 2805 keV 96Zr 9.4 g Qbb = 3350 keV 150Nd 37.0 g Qbb = 3367 keV 48Ca 7.0 g Qbb = 4272 keV 130Te454 g Qbb = 2529 keV External bkg measurement natTe491 g 100Mo6.914 kg Qbb = 3034 keV 82Se0.932 kg Qbb = 2995 keV Cu621 g (All the enriched isotopes produced in Russia) J.Thomas, UCL Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

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

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

  19. HSD, higher levels contribute to the decay • Data • Data 1+ SSD, 1+ level dominates in the decay (Abad et al., 1984, Ann. Fis. A 80, 9) 100Tc 0+ 100Mo 100Mo 22 Single Energy Distribution Single electron spectrum different between SSD and HSD Simkovic, J. Phys. G, 27,2233, 2001 Esingle (keV) NEMO-3 4.57 kg.y E1 + E2 > 2 MeV 4.57 kg.y E1 + E2 > 2 MeV NEMO-3 22 SSD Monte Carlo 22 HSD Monte Carlo SSD Single State HSD higher levels Background subtracted Background subtracted 2/ndf = 40.7 / 36 2/ndf = 139. / 36 Esingle (keV) Esingle (keV) 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 J.Thomas, UCL Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

  20. Today:NEMO-III • Present 90%CL limits from NEMO-III(216.4 days) • 82Se:T1/2(bb0n) > 1.9 1023 y, mn < 1.3 – 3.6 eV • Simkovic et al., Phys. Rev. C60 (1999) • Stoica, Klapdor, Nucl. Phys. A694 (2001) • Caurier et al., Phys. Rev. Lett. 77 1954 (1996) • 100Mo T1/2(bb0n) > 3.5 1023 y, mn < 0.7 – 1.2 eV • Simkovic et al., Phys. Rev. C60 (1999) • Stoica, Klapdor, Nucl. Phys. A694 (2001) • Expected Reach in 5 years after RadonPurification • 100Mo T1/2(bb0n) > 4.0 1024 y, mn < 0.2 – 0.35 eV • 82Se:T1/2(bb0n) > 8.0 1023 y,,mn < 0.65 – 1.8 eV J.Thomas, UCL

  21. Today: Heidelberg-Moscow • Enriched Germanium ionisation detector J.Thomas, UCL

  22. 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 J.Thomas, UCL

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

  24. 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 J.Thomas, UCL

  25. 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 Tracking, TPC, Drift • DCBA Nd • MOON Mo • Super-NEMO Mo,Se,Nd • EXO Xe Ionisation • Cobra, CdTe • GEM • GENIUS • Majorana • MPI Scintillator • CAMEO Cd • GANDLES Ca • CARVEL Cd • GSO Gd • Xe Xe……. • 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 J.Thomas, UCL

  26. 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 J.Thomas, UCL

  27. 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 J.Thomas, UCL

  28. 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 J.Thomas, UCL

  29. 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 2nbb • (NEMO3) • b) DE/E = 10% at 1 MeV • (8% has already been demonstrated in recent R&D) J.Thomas, UCL

  30. 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 J.Thomas, UCL

  31. Future Plans : Summary weighted world average NMEs a la Frank Avigone, Neutrino 2004 J.Thomas, UCL

  32. 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 J.Thomas, UCL

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