CENBG, University Bordeaux 1 CNRS/IN2P3 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 F. Piquemal (CENBG) LP07

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

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

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

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

Beta decay: present status MAC-E spectrometers Source Electron analyzer Electron counter 3H integral spectrum: select Ee > Eth 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

Improvement of DE: 0.93 eV (4.8 eV for Mainz) Beta decay: KATRIN experiment Sensitivity mn < 0.2 eV Improvement of DE: 0.93 eV (4.8 eV for Mainz) Larger acceptance Statistics 100 days  1000 days Commissioning and start : 2010 F. Piquemal (CENBG) LP07 Daegu August 2007

Individual electron energy Neutrinoless double beta decay bb(0n) Electron energy sum Qbb Arbitrary scale Observables Angular distribution Individual electron energy Half-life T1/2 Allow to distinguish the mechanism Background : natural radioactivity, radon,neutrons, muons, bb(2n) (A,Z) (A,Z+2) + 2 e- DL = 2 Lepton number violation Light neutrino exchange Majorana neutrino (n=n) Massive neutrino Phase space factor Nuclear matrix element Other possible process : V+A current : <mn>, <l>, <h> Majoron emission : <gM> Supersymmetry : l’111, l’113 T1/2= F(Qbb,Z) |M0n|2 <mn>2 -1 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

Effective neutrino mass and neutrino oscillations Inverted hierarchy Normal hierarchy Degenerated 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

Uncertainties for extraction of <mn> Nuclear matrix elements 5 T1/2= F(Qbb,Z) |M0n|2 <mn>2 -1 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

bb(0n) search is a very dynamic field Experiments Isotopes Techniques Main caracteristics NEMO3 100Mo,82Se Tracking + calorimeter Bckg rejection, isotope choice SuperNEMO 82Se, 150Nd Cuoricino 130Te Bolometers Energy resolution, efficiency CUORE GERDA 76Ge Ge diodes Energy resolution, eficiency Majorana COBRA 130Te, 116Cd ZnCdTe semi-conductors EXO 136Xe TPC ionisation + scintillation Mass, efficiency, final state signature MOON 100Mo Compactness, Bckg rejection CANDLES 48Ca CaF2 scintillating crystals Efficiency, Background SNO++ 150Nd Nd loaded liquid scintillator Mass, efficiency XMASS Liquid Xe CARVEL CaWO4 scintillating crystals Yangyang 124Sn Sn loaded liquid scintillator DCBA Gazeous TPC Bckg rejection, efficiency Talk focuses on the running experiments and on some 100 kg scale projects starting within 5 years

bb(0n): Present situation 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 0.06 cts/keV/kg/yr bb(0n) ? Very controversial result 2006 new PSA analysis: 6 s effect T 1/2 >1.9 1025 yr (90% CL) T1/2 = 2.23 1025 yr +0.44 -0.31 <mn> <0.35-1.05 eV (90% CL) <mn> = 0.32 ± 0.03 eV Eur. Phys. J., A 12 (2001) 147 F. Piquemal (CENBG) LP07

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

Cuoricino Bolometers of TeO2 (Qbb= 2.528 MeV) Heat sink Bolomètres: CUORICINO Bolometers of TeO2 (Qbb= 2.528 MeV) Heat sink Signal:∆T = E/C Thermometer Double beta decay 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 214Bi (238U chain) 208Tl (232Th chain) 60Co pile up 5.3 kg.an T1/2 > 1. 1024 ans (90%) <mn> <0.5 – 2.4 eV bb(0n) Energy (keV) Running at Gran Sasso since 2003 F. Piquemal (CENBG) LP07 Daegu August 2007 F. Piquemal (CENBG) LP07

Cuoricino results 0DBD 11.83 kg.yr Gamma region, dominated by gamma and beta events, 0DBD Alpha region, dominated by alpha peaks (internal or surface contaminations) 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

Array of 988 TeO2 5x5x5 cm3 crystals 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 F. Piquemal (CENBG) LP07

NEMO 3 Tracko-calo detector e- e- bb events (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- E1+E2= 2088 keV t= 0.22 ns (vertex) = 2.1 mm E2 bb events F. Piquemal (CENBG) LP07

NEMO3: bb(0n) results 100Mo Phase I, High radon 7.6 kg.yr Phase II, Low radon 5.7 kg.yr Phase I + II 13.3 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 = 8.1 events Nobserved = 7 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 = 11.1 events Nobserved = 11 events Phases I + II T1/2(bb0n) > 5.8 1023 yr (90 % C.L.) <mn> < 0.6 – 1.3 eV T1/2(bb0n) > 2. 1024 yr (90 % CL) <mn> < 0.3 –0.7 eV Expected in 2009

SuperNEMO project Tracko-calo with 100 kg of 82Se or 150Nd (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

EXO Liquid Xe TPC Energy measurement by ionization + scintillation (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

Enriched isotope mass (kg) Summary Summary Experiment Isotope Enriched isotope mass (kg) T1/2 (yr) <mn> (eV) Start Status CUORE 130Te 203 2.1 1026 0.03 - 0.07* 2011 Funded GERDA phase I phase II 76Ge 17.9 40 3. 1025 2. 1026 0.2 – 0.5* 0.07 – 0.2* 2009 Majorana 30 - 60 1.1026 0.1 – 0.3* EXO-200 136Xe 200 6.4 1025 0.2 - 0.7* 2008 SuperNEMO 82Se 150Nd 100 1026 0.05- 0.09* 0.07 R&D CANDLES 48Ca 0.5 ~0.5 MOON II 100Mo 120 0.09 – 0.13 ? DCBA 20 SNO++ 500 COBRA 116Cd, 420 * Calculation with NME from Rodim et al., Suhonen et al., Caurier et al. PMN07

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

Summary Summary Single beta decay KATRIN mn < 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

BACKUP SLIDES

bb(0n) signal ? HM claim 2001 2002 (3.1s) 2004: new calibration (4s) 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

bb(0n) signal ? 6s Today Estimation of the background level +0.44 6s T1/2 = 2.23 1025 yr <mn> = 0.32 ± 0.03 eV -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

Experimental techniques 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) > . . e A M . t NBckg . DE ln2 . N kC.L. (y) Today, no technique able to optimize all the parameters Calorimeter Semi-conductors Source = detector Calorimeter Loaded Scintillator Source = detector Tracko-calo Source  detector Xe TPC Source = detector b b b b b b b b e, DE e, M NBckg, isotope choice e,M, (NBckg) F. Piquemal (CENBG) LP07

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

From Fedor Simkovic PMN07

«bb factory» → tool for precision test NEMO 3:100Mo 2 results Energy sum spectrum Angular distribution 12000 10000 8000 6000 4000 2000 Number of events 12000 10000 8000 6000 4000 2000 219 000 events 6914 g 389 days S/B = 40 219 000 events 6914 g 389 days S/B = 40 NEMO-3 NEMO-3 100Mo 100Mo Number of events/0.05 MeV 7.6 kg.yr 7.6 kg.yr Data 22 Monte Carlo Data 22 Monte Carlo Background subtracted Background subtracted 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 F. Piquemal (CENBG) LP07

Beta decay: MARE experiment 1 mm MicroBolometers of ArReO4 187Re Qb = 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) 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.)

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 projects starting within 5 years F. Piquemal (CENBG) LP07 Daegu August 2007