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Beta decay experiments

Beta decay experiments. Fabrice Piquemal CENBG, University Bordeaux 1 CNRS/IN2P3 and LSM (CEA – CNRS). Double beta decay and tritium experiments, current and future. Thanks to: G. Gratta, S. Elliot, A. Giuliani, S. Schoenert, Ch. Weinheimer,T. Kishimito, M. Masaharu.

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Beta decay experiments

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  1. Beta decay experiments Fabrice Piquemal CENBG, University Bordeaux 1 CNRS/IN2P3 and LSM (CEA – CNRS) Double beta decay and tritium experiments, current and future Thanks to: G. Gratta, S. Elliot, A. Giuliani, S. Schoenert, Ch. Weinheimer,T. Kishimito, M. Masaharu

  2. Beta decays: physics case • - Absolute neutrino mass and neutrino mass hierarchy (SDB, DBD) • Nature of neutrino : Dirac (nn) or Majorana (n=n) (DBD) • Right-handed current interaction (DBD) • CP violation in leptonic sector (DBD) • Search of Supersymmetry and new particles (DBD) SDB: Single beta decay DBD: Double beta decay F. Piquemal (CENBG) LP07 Daegu August 2007

  3. Neutrino properties m2atm =m231 = (2.3  0.2 ) 10-3 eV2 m2sol =m212 = (7.9  0.3) 10-5 eV2 Oscillations Atmospheric (SK) Accelerators (K2K,Minos) Reactors (CHOOZ) Accelerators (JPARC) Solar (SNO, SK) Reactors (KamLAND) U ,b : CP Majorana phase tan223=1.0 ± 0.3sin2213 < 0.16tan212=0.39 ± 0.05 CP= CP Dirac phase F. Piquemal (CENBG) LP07 Daegu August 2007

  4. Neutrino mass m2 m12 m22 m32 Mass hierarchy ? ? Inverted hierarchy m2~m1>>m3 Degenerate m1≈m2≈m3» |mi-mj| Normal hierarchy m3>>> m2~m1 Absolute mass ? 1/2 2 2 Beta decaymv= S |Uei| mi<2.3 eV Double betadecay |<mn>| = |SUei mi| < 0.2 - 0.8 eV Cosmologymi=m1+m2+m3 <~1 eV 2 F. Piquemal (CENBG) LP07 Daegu August 2007

  5. averaged neutrino mass Beta decay (A,Z)  (A,Z+1) + e- + ne dN/dE ~[ (E0-Ee)2 – mi2]1/2: 3 Fraction of decay in [Qb – mn, Qb] ~ (DE/Qb)lowest Qb value3H (Qb= 18.6 keV) High counting rate Low background Energy resolution ~ mn F. Piquemal (CENBG) LP07 Daegu August 2007

  6. Beta decay: present status Electron analyzer Electron counter Source 3H integral spectrum: select Ee > Eth MAC-E spectrometers MAINZ:m2 = -0.6 ± 2.2 ± 2.1 eV2 mn< 2.3 eV (95% C.L.) C. Kraus et al., Eur. Phys. J. C 40 (2005) 447 Troisk:m2 = -2.3 ± 2.5 ± 2.0 eV2 mn< 2.05 eV (95% C.L.) But systematics from end-point fluctuations not included F. Piquemal (CENBG) LP07 Daegu August 2007

  7. Beta decay: KATRIN experiment Sensitivity mn < 0.2 eV Improvement of DE:0.93 eV (4.8 eV for Mainz) Larger acceptance Statistics100 days1000 days Commissioning and start : 2010 F. Piquemal (CENBG) LP07 Daegu August 2007

  8. Observables bb(0n) Arbitrary scale Angular distribution Individual electron energy Half-life T1/2 -1 T1/2= F(Qbb,Z)|M0n|2<mn>2 Allow to distinguish the mechanism Qbb Electron energy sum Background : natural radioactivity, radon,neutrons, muons, bb(2n) Neutrinoless double beta decay (A,Z) (A,Z+2) + 2 e- DL = 2 Lepton number violation Light neutrino exchange Majorana neutrino (n=n) Massive neutrino Nuclear matrix element Other possible process : V+A current :<mn>, <l>, <h> Majoron emission :<gM> Supersymmetry : l’111, l’113 Phase space factor 5 <mn>= m1|Ue1|2 + m2|Ue2|2.eia+ m3|Ue3|2.eib |Uei|: mixing matrix elements a et b: Majorana phases Schechter-Valle theorem: bb(0n) Majorana neutrinos F. Piquemal (CENBG) LP07 Daegu August 2007

  9. Effective neutrino mass and neutrino oscillations Degenerated Inverted hierarchy Normal hierarchy Degenerate:can be tested Inverted hierarchy:tested by the next generation of bb experiment <mn> in eV Normal hierarchy:inaccessible F. Piquemal (CENBG) LP07 Daegu August 2007

  10. Nuclear matrix elements 5 -1 T1/2= F(Qbb,Z)|M0n|2<mn>2 Shell Model - QRPA Two different QRPA calculations A lot of improvements have been done but still a factor 2-3 of discrepancy Uncertainties for extraction of <mn> In the following, « latest NME » will refer to these Nuclear Matrix Elements F. Piquemal (CENBG) LP07 Daegu August 2007

  11. bb(0n) search is a very dynamic field Talk focuses on the running experiments and on some 100 kg scale projects starting within 5 years

  12. bb(0n): Present situation +0.44 T1/2=2.231025 yr -0.31 Heidelberg-Moscow (2001) ~11 kg of enriched Ge diodes in 76Ge (86%) Pure calorimeter High energy resolution and efficiency But poor background rejection (pulse shape analysis) Claim for discovery since 2002 (2002 : 3.1 s and 2004: 4 s) 35.5 k.yr 2004: 4 s bb(0n) ? 0.06 cts/keV/kg/yr Very controversial result 2006 new PSA analysis: 6 s effect T 1/2 >1.9 1025 yr (90% CL) <mn> <0.35-1.05 eV (90% CL) <mn> = 0.32 ± 0.03 eV Eur. Phys. J., A 12 (2001) 147

  13. Future Ge experiments GERDA(Germany, Italy, Belgium, Russia) Majorana(USA, Russia, Japan, Canada) Selection of very pure material (Majorana) Removal of matter (GERDA) Segmentation of detectors for background rejection Use of liquid nitrogen or argon for active shielding Improvement of Pulse Shape Analysis GERDA PHASE I:17.9 kg of enriched 76Ge (from HM and IGEX) In 1 year of data (no Background) check of Klapdor’s claim Start 2009 at Gran Sasso, results 2010 PHASE II:40 kg of enriched 76Ge T1/2 > 2 1026 yr in 3 years of data <mn> < 110 meV (no background) Majorana: 30- 60 kg of enriched 76Ge (3 yr) T1/2 > 1. 1026 yr mn < 140 meV Start 2011 Collaboration for 1 ton experiment Reduction of background by a factor 10 – 100 compare to HM

  14. Cuoricino Thermometer Double beta decay 5.3 kg.an 208Tl (232Th chain) T1/2 > 1. 1024 ans (90%) <mn> <0.5 – 2.4 eV 60Co pile up 214Bi (238U chain) bb(0n) Energy (keV) Bolomètres: CUORICINO Bolometers of TeO2 (Qbb= 2.528 MeV) Heat sink Signal:∆T = E/C Crystal absorber High energy resolution 5-7 keV (FWHM) Natural abundance for 130Te: 34% High efficiency: 86% But no electron identification Background from internal and surface contamination in a emitters Running at Gran Sasso since 2003 F. Piquemal (CENBG) LP07 Daegu August 2007

  15. Cuoricino results 0DBD Gamma region, dominated by gamma and beta events, Alpha region, dominated by alpha peaks (internalorsurfacecontaminations) Bckg: 0.18 cts/keV/kg/yr 60Co pile up 130Te 0vBB 11.83 kg.yr Energy (keV) T1/2 > 3. 1024 yr (90% CL) <mn> < 0.2 – 1 eV (90% CL) Expected final sensitivity ~2009:T1/2 > 6. 1024 yr <mn> < 0.1 – 0.7 eV

  16. CUORE (Italy, USA,Spain) 750 kg of TeO2 203 kg of 130Te Array of 988 TeO2 5x5x5 cm3 crystals Improvement of surface event rejection Goal :Nbckg=0.01 cts.keV-1.kg-1.yr-1 (Factor 20 compare to Cuoricino) Data taking foreseen in 2011 Expected sensitivities (5 years of data) Nbckg=0.01 cts.keV-1.kg-1.yr-1 T½ > 2.1 1026 yr <mn> < 0.03 – 0.17 eV Nbckg=0.001 cts.keV-1.kg-1.yr-1 T½ > 6.6 1026 yr <mn> < 0.015 – 0.1 eV

  17. NEMO 3 E1+E2= 2088 keV t= 0.22 ns (vertex) = 2.1 mm (France, UK, Russia, Spain, USA, Japan, Czech Republic,Ukraine, Finland) Tracko-calo detector Central source foil (~50 mm thickness) Tracking detector (6180 drift cells) t = 0,5 cm, z = 1 cm ( vertex ) Calorimeter (1940 plastic scintillators + PMTs) Efficiency 8 % Running at Modane Underground lab since 2003 E1 e- Vertex Multi-isotopes(7 kg of 100Mo, 1 kg of 82Se,…) Identification of electrons Very good bckg rejection(< 10-3 cts/keV/kg/y) Angular distribution and single electron energy (necessary to distinguish the mechanism in case of discovery) But modest energy resolution and efficiency e- E2 bb events

  18. NEMO3: bb(0n)results 100Mo Phase I + II 13.3 kg.yr T1/2(bb0n) > 2. 1024 yr (90 % CL) <mn> < 0.3 –0.7 eV Expected in 2009 Phase I, High radon 7.6 kg.yr Phase II, Low radon 5.7 kg.yr Number of events / 40 keV Number of events / 40 keV Number of events / 40 keV [2.8-3.2] MeV: e(bb0n) = 8 % Expected bkg = 11.1 events Nobserved = 11 events [2.8-3.2] MeV: e(bb0n) = 8 % Expected bkg = 3.0 events Nobserved = 4 events [2.8-3.2] MeV: e(bb0n) = 8 % Expected bkg = 8.1 events Nobserved = 7 events T1/2(bb0n) > 5.8 1023 yr (90 % C.L.) <mn> < 0.6 – 1.3 eV Phases I + II

  19. SuperNEMO project (France, UK, Russia, Spain, USA, Japan, Czech Republic,Ukraine, Finland) Tracko-calo with 100 kg of 82Se or 150Nd (possibility to produce 150Nd with the French AVLIS facility) T½ > 2. 1026 yr <mn> < 0.05 – 0.09 eV Modules based on the NEMO3 principle Measurements of energy sum, angular distribution and individual electron energy 3 years R&D program: improvement of energy resolution Increase of efficiency Background reduction ……. 100 kg 20 modules R&D funded by France, UK and Spain 2009: TDR 2011: commissioning and data taking of first modules in Canfranc (Spain) 2013: Full detector running

  20. EXO (USA, Canada, Switzerland, Russia) Liquid Xe TPC Energy measurement by ionization + scintillation Tagging of Baryum ion (136Xe  136Ba++ + 2 e-) Large mass of Xe Identification of final state  background rejection But no e- identification Poor background rejection without Ba ion tagging R&D for Ba ion tagging in progress Prototype EXO-200 200 kg of 136Xe, no Ba ion tagging Installation in progress in WIPP underground lab 2007 Could measure bb(2n) of 136Xe EXO 200 (2 years) T½ > 6.4 1025 yr (90% CL) <mn> < 0.27- 0.38 eV

  21. Summary Summary * Calculation with NME from Rodim et al., Suhonen et al., Caurier et al. PMN07

  22. <mn> current and future limits . Klapdor claim HM Cuoricino NEMO3 Limits in 2009 HM,NEMO3, Cuoricino Expected limits 2009 – 2015 CUORE,GERDA, Majorana, SuperNEMO, EXO Degenerated Inverted hierarchy Normal hierarchy Use of « latest NME » for all experiments

  23. Summary Summary Single beta decay KATRINmn< 2.3 eV  mn < 0.2 eV results in ~2014 Other possibility : bolometers with 187Re (Qb=2.47 keV) but long R&D (at least 10 years to reach 0.2 eV) Double beta decay Very active field. A claim to be checked Current experiments will reach a sensitivity on<mn> ~(0.2 – 0.7) eV in 2009 Need to measure several nucleus with different techniques (only tracko-calo can distinguish the mechanism in case of discovery) Next generation ~ source mass 100 – 200 kg.<mn> ~ (0.03 – 0.1) eV Will cover partially the inverted hierarchy mass scenario (2011 – 2015) Essential step for 1 ton scale experiment ( background considerations) Need improvements for Nuclear Matrix Element calculations

  24. BACKUP SLIDES

  25. bb(0n) signal ? HM claim 2002 (3.1s) 2001 T1/2 >1.9 1025 <mn> < 0.35-1.05 (90%) T1/2= (0.8-18.3) 1025 yr <mn>= 0.11 – 0.56 eV 2004: new calibration (4s) Best value:0.39 eV

  26. bb(0n) signal ? 6s +0.44 Today <mn> = 0.32 ± 0.03 eV T1/2= 2.23 1025 yr -0.31 (Result with last NME should be <mn> = 0.11 – 0.71 eV) Estimation of the background level Problems for some well-known peaks (214Bi) Some unknow lines in the same region 56Co produced by cosmic rays (2034 keV photon+ 6 keV X-ray) 76Ge(n,)77Ge (2038 keV photon) Some unknown line Inelastic neutron scattering (n,n‘) on lead Other suggestions, can be combination of all

  27. Experimental techniques M . t e A ln2 . N kC.L. (y) > . . NBckg . DE M: masse (g) e : efficiency KC.L.: Confidence level N: Avogadro number t: time (y) NBckg: Background events (keV-1.g-1.y-1) DE: energy resolution (keV) Today, no technique able to optimize all the parameters Calorimeter Semi-conductors Source = detector Tracko-calo Source  detector Xe TPC Source = detector Calorimeter Loaded Scintillator Source = detector b b b b b b b b e, M NBckg, isotope choice e,M, (NBckg) e, DE

  28. GERDA and Majorana crystal anti-coincidence Detector segmentation segments detector e-  pulse shape analysis R&D: liquid argon anti-coincidence Liquid argon e- scintillation Strategy: Ge detectors in liquid nitrogen to remove materials Active shielding and segmentation of detectors to reject gamma-rays

  29. From Fedor Simkovic PMN07

  30. NEMO 3:100Mo2 results 12000 10000 8000 6000 4000 2000 0 Number of events • Data • Data 22 Monte Carlo 22 Monte Carlo Background subtracted Background subtracted Angular distribution Energy sum spectrum 219 000 events 6914 g 389 days S/B = 40 219 000 events 6914 g 389 days S/B = 40 12000 10000 8000 6000 4000 2000 0 NEMO-3 NEMO-3 100Mo 100Mo 7.6 kg.yr Number of events/0.05 MeV 7.6 kg.yr Cos() E1 + E2 (MeV) T1/2(bb2n) = 7.11 ± 0.02 (stat) ± 0.54 (syst)  1018 yr Phys. Rev. Lett. 95 182302 (2005) «bb factory»→ tool for precision test

  31. 1 mm Beta decay: MARE experiment MicroBolometers of ArReO4 187ReQb = 2.47 keV Full energy measurement No systematic from source But time response of sensor  pile-up MARE-I: 300 detectors FWHM ~20 eV t ~100 – 500 ms mn< 2 –4 eV ( 5 years) MARE – II : 5000 detectors (~2018) FWHM ~20 eV t ~1 – 5 ms mn< 0.2 eV (10 years) MIBETA 10 detectors mn2 = -141  211 stat  90 sys eV2 mn< 15 eV (90% c.l.)

  32. View of the field: present and future Today experiments have a mass of enriched source ~10 kg To reject inverted hierarchy mass scenario, enriched source mass  1 ton All projects have this goal but it is unrealistic to plane to go directly from 10 kg to 1 ton scale (understanding and control of the background) Intermediate step at 100 kg scale is needed (as proposed by each project) Talk focuses on the running experiments and on some 100 kg scale projectsstarting within 5 years F. Piquemal (CENBG) LP07 Daegu August 2007

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