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bb decay:Present and Future

bb decay:Present and Future. PREVIEW Motivation Present status Status of “evidence” Future projects UK in NEMO/SuperNEMO. Ruben Saakyan UCL 8 November 2004 Manchester University Particle Physics seminar. Motivation. Neutrino Mixing Observed !.

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bb decay:Present and Future

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  1. bb decay:Present and Future • PREVIEW • Motivation • Present status • Status of “evidence” • Future projects • UK in NEMO/SuperNEMO Ruben Saakyan UCL 8 November 2004 Manchester University Particle Physics seminar

  2. Motivation Neutrino Mixing Observed ! From KamLAND, solar n and atmospheric n Dm2LMA≈ 5×10-5 eV2 = (7 meV)2 Dm2atm ≈ 2.5×10-3 eV2 = (50 meV)2 VERY approximately

  3. Neutrino MASSWhat do we want to know? • Relative mass scale (n-osc) • Mass hierarchy (n-osc and bb) • Absolute mass scale (bb +3H b) degenerate: <m> > 0.1 eV <m> ~ 0 - 0.01 eV <m> ~ 0.02 - 0.06 eV Dirac or Majorana preferred by theorists (see-saw) ne n1 n2 n3 Ue12 Ue22 Ue32 Mixing Only from bb From n-osc

  4. bb Decay Basics Qbb Endpoint Energy In many even-even nuclei, b decay is energetically forbidden. This leaves bb as the allowed decay mode.

  5. Double beta decay and neutrino mass DL=0 DL=2 ! Q

  6. Effective Majorana Mass(inverted hierarchy case) Ue22 m2 <mee> Ue32 m3 min Ue12 m1

  7. Isotopes • Best candidates: • 76Ge, Qbb = 2.038 MeV • 48Ca, Qbb= 4.272 MeV • 82Se, Qbb= 2.995 MeV • 100Mo, Qbb= 3.034 MeV • 116Cd, Qbb= 2.804 MeV • 130Te, Qbb= 2. 528 MeV • 136Xe, Qbb= 2.48 MeV • 150Nd, Qbb= 3.368 MeV • High Qbb is important (G0n ~ Qbb5, G2n ~ Qbb11) • In most cases enrichment is a must • Different isotopes must be investigated due to uncertainties in NME calculations !

  8. The Experimental Problem( Maximize Rate/Minimize Background) Natural Activity: t(238U, 232Th) ~ 1010 years Target: t(0nbb) > 1025 years  Detector Shielding Cryostat, or other experimental support Front End Electronics etc. + Cosmic ray induced activity

  9. A History Plot <mn> < 0.35 – 0.9 eV mscale~ 0.05 eV from oscillation experiments

  10. Hieldeberg-Moscow (Gran Sasso)(Spokesperson: E. Klapdor-Kleingrothaus, MPI) First claim (end 2001) <mn> = 0.4 eV ??? • 5 HPGe 11 kg, 86% 76Ge • DE/E 0.2% • >10 yr of data taking <mn> < 0.3 – 0.7 eV If combine HM and IGEX

  11. Heidelberg claim. Recent developments hep-ph/0403018, NIMA, Phys. Rev… Data analysed for 1990 – 2003 • Data reanalyzed with improved • binning/summing • Peak visible • Effect reclaimed with 4.2s • <m> = (0.2 – 0.6) eV, • 0.4 eV best fit • <m> = (0.1 – 0.9) eV (due to NME) 214Bi 214Bi unknown 0nbb Personal view • Looks more like 2.5s of effect • 214Bi line intensities do not match 71.7 kgyr

  12. Current Experiments CUORICINO (bolometer) NEMO-3 (Tracking calorimeter) These two will be determining bb fate until ~2007-2008 Sensitivity ~ 0.2 eV

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

  14. heat bath Thermal sensor absorber crystal Incident particle Today: CUORICINO 40.7kg total 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

  15. Today:CUORICINO • Operation started early 2003 • BG = 0.19 counts/kev/kg/y • DE/E = 4 eV @ 2 MeV Neutrino 2004: mn < 0.3 – 1.6 eV (all NME)

  16. Today: NEMO-III AUGUST 2001

  17. 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 82Se0.932 kg Qbb = 2995 keV External bkg measurement natTe491 g 100Mo6.914 kg Qbb = 3034 keV Cu621 g (All the enriched isotopes produced in Russia)

  18. Transverse view Run Number: 2040 Event Number: 9732 Date: 2003-03-20 Longitudinal view Vertex emission Vertex emission Drift distance 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 • Trigger: 1 PMT > 150 keV • 3 Geiger hits (2 neighbour layers + 1) • Trigger rate = 7 Hz • bb events: 1 event every 1.5 minutes Criteria to select bb events: • 2 tracks with charge < 0 • 2 PMT, each > 200 keV • PMT-Track association • Common vertex • Internal hypothesis (external event rejection) • No other isolated PMT (g rejection) • No delayed track (214Bi rejection) bb events selection in NEMO-3 Typical bb2n event observed from 100Mo Transverse view Run Number: 2040 Event Number: 9732 Date: 2003-03-20 Longitudinal view 100Mo foil 100Mo foil Geiger plasma longitudinal propagation Scintillator + PMT

  19. 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

  20. 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

  21. 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

  22. Strategy for future.An Ideal Experiment • Large Mass (0.1t) • Good source radiopurity • Demonstrated technology • Natural isotope • Small volume, source = detector • Tracking capabilities • Good energy resolution or/and Particle ID • Ease of operation • Large Q value, fast bb(0n) • Slow bb(2n) rate • Identify daughter • Event reconstruction • Nuclear theory • All requirements can NOT be satisfied • Red – must be satisfied

  23. A Great Number of Proposals(Some may start taking data in 2009-2010)

  24. GERDA. 76Ge • Phase I: collect 76Ge detectors from HM(11kg)+IGEX(8kg) • 15kgy+BG@0.01 c/keV/kg/y  sens-ty: 3·1025 y, 0.24-0.77 eV  Confirm Klapdor with 5s OR rule out at 98% • Phase II:enlarge to ~35-40 kg • BG < 10-3 c/keV/kg/y • within 4 yr ~ 100 kgy  • 2·1026 y, 0.09-0.29 eV • Phase III: 0.5 -1 ton • Possible merge with Majorana • ~ 0.03 eV “Naked” 76Ge detectors in LN2/LAr Original idea from GENIUS (Klapdor)

  25. Berkeley Firenze Gran Sasso Insubria (COMO) Leiden Milano Neuchatel U. of South Carolina Zaragoza Cryogenic Underground Observatory for Rare Events - CUORE Spokesperson Ettore Fiorini Milano

  26. CUORE CUORICINO×20  270 kg 130Te (~ 750 kg natTe) APPROVED ! Compact: 70×70×70 cm3 5 yr in Gran Sasso: <mn> ~ 0.04 eV

  27. Duke U. North Carolina State U. TUNL Argonne Nat. Lab. JINR, Dubna ITEP, Moscow New Mexico State U. Pacific Northwest Nat. Lab. U. of Washington LANL LLNL U. of South Carolina Brown Univ. of Chicago RCNP, Osaka Univ. Univ. of Tenn. The Majorana Project Co-Spokespersons Frank Avignone Harry Miley

  28. Majorana • 0.5 ton of 86% enriched 76Ge • Very well known and successful technology • Segmented detectors using pulse shape discrimination to improve background rejection. • Prototype ready to go this autumn/winter. (14 crystals, 1 enriched) • 100% efficient • Can do excited state decay. 5 yr in a US undegr lab <mn> ~ 0.03 eV

  29. U. of Alabama Caltech IBM Almaden ITEP Moscow U. of Neuchatel INFN Padova SLAC Stanford U. U. of Torino U. of Trieste WIPP Carlsbad Enriched Xenon Observatory - EXO Spokesperson Giorgio Gratta Stanford

  30. EXO • 10 ton, ~70% enriched 136Xe • 70% effic., ~10 atm gas TPC or LXe chamber • Optical identification of Ba ion. • Drift ion in gas to laser path or extract on cold probe to trap. • 200-kg enrXe prototype (no Ba ID) being built • Isotope in hand • 5 yr in a US underground lab <mn> ~ 0.05 eV

  31. Sussex Oxford Dortmund Warwick Cadmium-Telluride O-neutrino double-Beta Research ApparatusCOBRA Project Leader Kai Zuber Sussex • CdTe or CdZnTe semiconductor detectors • Good DE/E • Two isotopes 116Cd and 130Te • Operate at room temperature • New approach • Large R&D programme needed • If successful can get to ~10-20 meV in ~ 20yr

  32. SuperNEMO • NEMO3 x 10 + better DE/E • robust and developed technology • quick start (100 kg of isotope) UCL Manchester IC LAL, Orsay Bordeaux Strasbourg Prague ITEP (Moscow) JINR (Dubna) Saga Univ. (Japan) INEEL (USA) MHC (USA) F ~ (sE/E)6

  33. Isotopes in SuperNEMO Factor of 10 lower BG for82Se Can be produced in centrifuge - $30K-$50K/kg

  34. SuperNEMO • 100 kg 82Se (Qbb = 3 MeV, • large T1/22n) • Sensitivity ~0.04 eV in 5 yr • Feasible if Zero BG experiment: • 1) No BG from radioactivity • the only possible BG from • 2n tail (NEMO-III) • 2) Improve DE/E from • existing (14%-16%)/E to • (8%-10%)/E • Demonstrated (UCL+ Dubna) 4 supermodules Planar geometry Boulby mine is an attractive experimental site

  35. SuperNEMO. Time Scale • 2004 – 2005 scintillator R&D • Attempt to reach 5-6% • 2005-2006: Design study proposal (PPRP, Dec-Feb) • Prototype submodule in Boulby • 2007-20010: Production • 2009-2010: Start taking data • 2014: planned sensitivity ~0.04 eV • Excellent chance to be the first to reach 40-50 meV

  36. Concluding Remarks • Very exciting time for neutrino physics in general and 0nbb in particular • From oscillations: positive signal is a serious possibility • “Good value”: ~$50M for the great potential scientific gain • Several experiments with different isotopes are needed (recall NME uncertainties)

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