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NEMO-3 Experiment N eutrino E ttore M ajorana O bservatory FIRST RESULTS

NEMO-3 Experiment N eutrino E ttore M ajorana O bservatory FIRST RESULTS. Xavier Sarazin 1 for the NEMO-3 Collaboration CENBG , IN2P3-CNRS et Université de Bordeaux, France Charles University , Praha, Czech Republic CTU , Praha, Czech Republic INEEL, Idaho Falls , USA

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NEMO-3 Experiment N eutrino E ttore M ajorana O bservatory FIRST RESULTS

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  1. NEMO-3 Experiment Neutrino Ettore Majorana Observatory FIRST RESULTS Xavier Sarazin 1 for the NEMO-3 Collaboration CENBG, IN2P3-CNRS et Université de Bordeaux, France Charles University, Praha, Czech Republic CTU, Praha, Czech Republic INEEL, Idaho Falls, USA IReS, IN2P3-CNRS et Université de Strasbourg, France ITEP, Moscou, Russia JINR, Dubna, Russia Jyvaskyla University, Finland 1 LAL, IN2P3-CNRS et Université Paris-Sud, France LSCE, CNRS Gif sur Yvette, France LPC, IN2P3-CNRS et Université de Caen, France Mount Holyoke College, USA RRC Kurchatov Institute, Moscow, Russia Saga University, Saga, Japon UCL, London, Great-Britain Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  2. Plan of the talk: • NEMO-3 Detector • Measurement of bb2n decay for several nuclei • Search for bb0n decay with 100Mo and 82Se

  3. 20 sectors B(25 G) 3 m Magnetic field: 25 Gauss Gamma shield: Pure Iron (e = 18 cm) Neutron shield: 30 cm water (ext. wall) 40 cm wood (top and bottom) (since march 2004: water + boron) 4 m Able to identify e-, e+, g and a The NEMO3 detector Fréjus Underground Laboratory : 4800 m.w.e. Source: 10 kg of  isotopes cylindrical, S = 20 m2, e ~ 60 mg/cm2 Tracking detector: drift wire chamber operating in Geiger mode (6180 cells) Gas: He + 4% ethyl alcohol + 1% Ar + 0.1% H2O Calorimeter: 1940 plastic scintillators coupled to low radioactivity PMTs Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  4. Cathodic rings Wire chamber PMTs Calibration tube scintillators bb isotope foils Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  5. AUGUST 2001 Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  6. NEMO-3 Opening Day, July 2002 Start taking data 14 February 2003 Water tank wood coil Iron shield Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  7. 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) Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  8. 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 Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  9. Calorimeter: • 97% of the PMTs+scintillators are ON • Energy Resolution: calibration runs (every ~ 40 days) with 207Bi sources bb events from the foil Ext. Wall 5" PMTs Int. Wall 3" PMTs Tracking Detector: • 99.5 % Geiger cells ON • Vertex resolution: 2 e- channels (482 and 976 keV) using 207Bi sources at 3 well known positions in each sector • s (DVertex) = 0.6 cm • s// (DVertex) = 1.3 cm(Z=0) • e+/e- separation with a magnetic field of 25 G ~ 3% confusion at 1 MeV FWHM (1 MeV) 14% 17% b- External Background • Daily Laser Survey to control gain stability of each PM • gamma: efficiency ~ 50 % @ 500 keV, Ethr = 30 keV DVertex 976 keV • Time Of Flight: • Time Resolution (bb channel)  250 ps at 1 MeV ToF (external crossing e- ) > 3 ns external crossing e- totaly rejected b- 207Bi 2 conversion e- 482 keV and 976 keV Expected Performance of the detector has been reached DVertex = distance between the two vertex FWHM = 135 keV (13.8%) (Dtmes – Dtcalc) internal hypo. (ns) (Dtmes – Dtcalc) external hypo. (ns) 482 keV Performance of the detector Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  10. Measurement of 2b2n decay in NEMO-3 Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  11. 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 Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  12. 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 Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  13. Data Data Data 22 preliminary results for other nuclei NEMO-3 932 g 241.5 days 2385 events S/B = 3.3 Background subtracted 82Se 82Se T1/2 = 10.3 ± 0.2 (stat) ± 1.0 (syst)  1019 y 116Cd if SSD T1/2 = 2.8 ± 0.1 (stat) ± 0.3 (syst)  1019 y if HSD T1/2 = 3.05 ± 0.1 (stat) ± 0.3 (syst)  1019 y 150Nd T1/2 = 9.7 ± 0.7 (stat) ± 1.0 (syst)  1018 y 96Zr T1/2 = 2.0 ± 0.3 (stat) ± 0.2 (syst)  1019 y • Data bb2n simulation E1+E2 (keV) NEMO-3 NEMO-3 NEMO-3 37 g 168.4 days 449 events S/B = 2.8 405 g 168.4 days 1371 events S/B = 7.5 5.3 g 168.4 days 72 events S/B = 0.9 96Zr 150Nd 116Cd bb2n simulation bb2n simulation bb2n simulation E1+E2 (MeV) E1+E2 (MeV) E1+E2 (MeV) Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  14. Search for 2b0n decay in NEMO-3 Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  15. 100Mo bb2n decay T1/2 = 7.7 1018 y (SSD) ~ 0.3 bb0n-like events year-1 kg -1 with 2.8<E1+E2<3.2 MeV Only 2 (e-,e-)int events with E1+E2> 4 MeV observed after 260 days of data (without boron) • ExternalNeutrons and High Energy gamma • Measured with (e-,e-)int events with E1+E2> 4 MeV 4253 keV (26 Mar. 2003) 6361 keV (8 Nov. 2003) In agreement with expected background  0.02 bb0n-like events year-1 kg -1 with 2.8<E1+ E2<3.2 MeV ~ • External Background 208Tl (PMTs) • Measured with (e-, g) external events sources A (mBq/kg) from (e-, Ng) A (mBq/kg) HPGe meas. • 208Tl impurities inside the foils • Measured with (e-,2g), (e-,3g) events coming from the foil 100Mo metal. 92  18 < 110 100Mo comp. 115  13 < 100 ~ 10-3bb0n-like events year-1 kg -1 with 2.8<E1+ E2<3.2 MeV ~ 0.1 bb0n-like events year-1 kg -1 with 2.8<E1+ E2<3.2 MeV 82Se 316  46 400  100 In agreement with HPGe measurements bb0n Analysis: Background Measurement NEMO-3 can measure each component of its background ! Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  16. 222Rn (3.8 days) a b- 214Bi  214Po (164 ms)  210Pb Two independant measurements of radon in NEMO-3 gas 214Po 218Po b • Radon detector at the input/output of the NEMO-3 gas ~ 20 counts/day for 20 mBq/ m3 • (1e- + 1 a) channel in the NEMO-3 data: • Delayed tracks (<700 ms) to tag delayed a from 214Po 214Bi  214Po (164 ms)  210Pb • ~ 200 counts/hour for 20 mBq/m3 a 164 ms 214Bi b- Decay in gas 210Pb 214Pb delayed a Good agreement between the two measurements A(Radon) in NEMO-3  20-30 mBq/m3 ~ 1 bb0n-like events/year/kg with 2.8 < E1+E2 < 3.2 MeV Radon is the dominant background today for bb0n search in NEMO-3 !!! bb0n Analysis: Background Measurement Radon in the NEMO-3 gas of the wire chamber Due to a tiny diffusion of the radon of the laboratory inside the detector A(Radon) in the lab ~15 Bq/m3 Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  17. PRELIMINARY 6914 g 265 days 100Mo 265 days Cu + natTe + 130Te Data E1+E2 (MeV) Data bb2n Monte-Carlo Cu + natTe + 130Te Radon Monte-Carlo Radon Monte-Carlo 2.6<E1+E2<3.2 2.6<E1+E2<3.2 ____ ____ bb0n arbitrary unit 11.4  3.4 2.6  0.7 11.4  3.4 2.6  0.7 8 2 E1+E2 (MeV) bb0n Analysis with 100Mo 100Mo 2.6<E1+E2<3.2 2.6<E1+E2<3.2 100Mo 2b2n M-C 32.3  1.9 1.4  0.2 Radon M-C 23.5  6.7 5.6  1.7 55.8  7.0 7.0  1.7 TOTAL Monte-Carlo DATA 50 8 V-A: T1/2(bb0n) > 3 1023 y V+A: T1/2 > 1.8 1023 y with E1- E2> 800 keV Majoron: T1/2 > 1.4 1022 ywith Esingle > 700 keV Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  18. b- E1 Cos Ec1 b- Ec2 E2 100Mo bb0n likelihood analysis • 3 variablesused for the likelihood • Ec1+ Ec2sum of the kinetic energies of the 2 e- • Ecminenergy of the e- of minimal energy • Cosangle between the two tracks Ec = Energy at the exit of the 100Mo foil = Energy deposited in scintillator (E) + energy losses in the tracking detector ! Nbb0n xbb0n= is the free parameter Ntot L calculated with bb events Ec1+Ec2>2 MeV Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  19. PRELIMINARY 100Mo 6914 g 216.4 days 4.10 kg.y Data -Log(Likelihood) bb2n Monte-Carlo Radon Monte-Carlo Data Nbb0n bb2n Monte-Carlo xbb0n= Ntot Radon Monte-Carlo Ec1+Ec2 (keV) bb0n T1/2 = 3.5 1023 V-A: T1/2(bb0n) > 3.5 1023 y (90% C.L.) V+A: T1/2 > 2.0 1023 y (90% C.L.) Previous limit V-A: T1/2(bb0n) > 5.5 1022 y (Elegant V, Ejiri et al., 2001) 100Mo bb0n likelihood analysis 100Mo 6914 g 216.4 days 4.10 kg.y Ec1+Ec2 (keV) Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  20. Data Data bb2n Monte-Carlo bb2n Monte-Carlo Radon Monte-Carlo Radon Monte-Carlo 82Se bb0n likelihood analysis PRELIMINARY 82Se 932 g 216.4 days 0.55 kg.y 82Se 932 g 216.4 days 0.55 kg.y Ec1+Ec2 (keV) Ec1+Ec2 (keV) V-A: T1/2(bb0n) > 1.9 1023 y (90% C.L.) V+A: T1/2 > 1.0 1023 y (90% C.L.) Majoron: T1/2 > 1.2 1022 y (90% C.L.) Previous limit V-A: T1/2(bb0n) > 9.5 1021 y (NEMO-2) Arnold et al. Nucl. Phys. A636 (1998) Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  21. Limit on the Majorana neutrino effective mass 100Mo: T1/2(bb0n) > 3.5 1023 y mn < 0.7 – 1.2 eV 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) Simkovic et al., Phys. Rev. C60 (1999) Stoica, Klapdor, Nucl. Phys. A694 (2001) Caurier et al., Phys. Rev. Lett. 77 1954 (1996) Limit on Majoron 100Mo: T1/2 > 1.4 1022 y  < (5.3 – 8.5) 10-5 Simkovic (1999), Stoica (1999) 82Se: T1/2 > 1.2 1022 y  < (0.7 – 1.6) 10-4 Simkovic (1999), Stoica (2001) Limit on V+A 100Mo: T1/2 > 2.0 1023 y l < (1.5 – 2.0) 10-6 Tomoda (1991), Suhonen (1994) 82Se: T1/2 > 1.0 1023 y l < 3.2 10-6 Tomoda (1991) Limit on the effective mass of the Majorana neutrino, on Majoron and on V+A Limits on T1/2 are @ 90% C.L. Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  22. Free-Radon Purification System in construction Today Radon is the dominant background for NEMO-3 Today: A(222Rn) in the LSM ~ 15 Bq/m3 Factor ~ 10 too high May 2004 :Tent surrounding the detector May 2004 August 2004 : Radon-free SuperKamiokande-like Air Factory Expected activity: A(222Rn) ~ 0.2 Bq/m3 150 m3/h 500 kg charcoal @ -40oC Expected Purification Factor ~ 75 Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  23. NEMO-3 Expected sensitivity (after Radon purification) Background : • External Background is negligible • Internal Background: • 208Tl : 100 mBq/kg for 100Mo • 300 mBq/kg for 82Se • 214Bi : < 300 mBq/kg • ~ 0.1 count kg-1 y -1 with 2.8<E1+E2<3.2 MeV • bb2n:T1/2 = 7.7 1018 y (SSD) • ~ 0.3 count kg-1 y -1 with 2.8<E1+E2<3.2 MeV 5 years of data 6914 g of 100Mo T1/2(bb0n) > 4 .1024 y (90% C.L.) <mn> < 0.2 – 0.35 eV 932 g of 82Se T1/2(bb0n) > 8 .1023 y (90% C.L.) <mn> < 0.65 – 1.8 eV (conservative limit) Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

  24. CONCLUSIONS • NEMO-3 Detector running since 14 Feb. 2003 Expected performance of the detector has been reached ! • 2b2n preliminary results for 100Mo, 82Se, 96Zr, 116Cd and 150Nd already more than 140 000 2b2n events collected 100Mo: in favour of Single State Dominance (SSD) 100Mo bb2n decay to excited state has been measured with ~ 4 s • Preliminary T1/2(bb0n) limit (216.4 days of data): • 100Mo (4.10 kg.y) T1/2(bb0n) > 3.5 1023 y mn < 0.7 – 1.2 eV • 82Se (0.55 kg.y) T1/2(bb0n) > 1.9 1023 y mn < 1.3 – 3.6 eV • Level of backgounds as excepted exceptRadon ~ 10 times too high Free radon purification system in operation in August 2004 Supression factor ~ 75 • Expected sensitivity in 5 years after radon purification • 100Mo: T1/2(bb0n) > 4 .1024 y <mn> < 0.2 – 0.35 eV • 82Se: T1/2(bb0n) > 8 1023 y <mn> < 0.65 – 1.8 eV Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004

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