Neutrino Ettore Majorana Observatory NEMO-3 Experiment Neutrino Ettore Majorana Observatory FIRST RESULTS Dominique Lalanne * 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 * 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 Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

Measurement of bb2n decay for several nuclei Outline of the talk: NEMO-3 Detector Measurement of bb2n decay for several nuclei gives information on nuclear processes (2 electron events of energy up to the Q value) Search for bb0n decay with 100Mo and 82Se if signal: the neutrino is of Majorana type measurement of the effective neutrino mass (2 electron events of energy exactly the Q value) Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

Fréjus Underground Laboratory : 4800 m.w.e. The NEMO3 detector 3 m 4 m B (25 G) 20 sectors Fréjus Underground Laboratory : 4800 m.w.e. 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) 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 Able to identify e-, e+, g and a Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

PMTs scintillators Cathodic rings Wire chamber Calibration tube bb isotope foils Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

AUGUST 2001 Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

Start taking data 14 February 2003 NEMO-3 Opening Day, July 2002 Start taking data 14 February 2003 Water tank wood coil Iron shield Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

bb decay isotopes in NEMO-3 detector bb2n measurement 116Cd 405 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 130Te 454 g Qbb = 2529 keV External bkg measurement 100Mo 6.914 kg Qbb = 3034 keV 82Se 0.932 kg Qbb = 2995 keV natTe 491 g Cu 621 g bb0n search (All the enriched isotopes produced in Russia) Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

bb events selection in NEMO-3 Deposited energy: E1+E2= 2088 keV Internal hypothesis: (Dt)mes –(Dt)theo = 0.22 ns Common vertex: (Dvertex) = 2.1 mm Vertex emission (Dvertex)// = 5.7 mm Transverse view Longitudinal view Run Number: 2040 Event Number: 9732 Date: 2003-03-20 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 Drift distance Scintillator + PMT Trigger: 1 PMT > 150 keV 3 Geiger hits (2 neighbour layers + 1) Trigger rate = 7 Hz bb events: 1 event every 1.5 minute Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

Expected Performance of the detector Time Of Flight: Time Resolution (bb channel)  250 ps at 1 MeV ToF (external crossing e- ) > 3 ns external crossing e- totaly rejected External Background bb events from the foil (Dtmes – Dtcalc) external hypo. (ns) (Dtmes – Dtcalc) internal hypo. (ns) Calorimeter: 97% of the PMTs+scintillators are ON Energy Resolution: calibration runs (every ~ 40 days) with 207Bi sources 17% 14% FWHM (1 MeV) Int. Wall 3" PMTs Ext. Wall 5" PMTs 207Bi 2 conversion e- 482 keV and 976 keV 482 keV 976 keV FWHM = 135 keV (13.8%) Daily Laser Survey to control gain stability of each PM gamma: efficiency ~ 50 % @ 500 keV, Ethr = 30 keV 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 b- DVertex DVertex = distance between the two vertex Expected Performance of the detector has been reached Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

Measurement of 2b2n decay in NEMO-3 Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

100Mo 22 preliminary results (Data 14 Feb. 2003 – 22 Mar. 2004) Sum Energy Spectrum Angular Distribution NEMO-3 145 245 events 6914 g 241.5 days S/B = 45.8 NEMO-3 145 245 events 6914 g 241.5 days S/B = 45.8 100Mo 100Mo Data 22 Monte Carlo Data Background subtracted 22 Monte Carlo Background subtracted E1 + E2 (keV) Cos() 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

100Mo 22 Single Energy Distribution HSD SSD HSD, higher levels contribute to the decay SSD, 1+ level dominates in the decay (Abad et al., 1984, Ann. Fis. A 80, 9) 100Mo 0+ 100Tc 1+ 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 NEMO-3 4.57 kg.y E1 + E2 > 2 MeV Data Data 22 SSD Monte Carlo 22 HSD Monte Carlo HSD higher levels SSD Single State Background subtracted Background subtracted 2/ndf = 139. / 36 2/ndf = 40.7 / 36 Esingle (keV) (for the electron of low energy in the pair) 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 Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

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-3 405 g 168.4 days 1371 events S/B = 7.5 NEMO-3 37 g 168.4 days 449 events S/B = 2.8 NEMO-3 5.3 g 168.4 days 72 events S/B = 0.9 116Cd 150Nd 96Zr Data Data Data bb2n simulation bb2n simulation bb2n simulation E1+E2 (MeV) E1+E2 (MeV) E1+E2 (MeV) Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

Search for 2b0n decay in NEMO-3 Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

bb0n Analysis: Background Measurement NEMO-3 can measure each component of its background ! External Background 208Tl (PMTs) Measured with (e-, g) external events ~ 10-3 bb0n-like events year-1 kg -1 with 2.8<E1+ E2<3.2 MeV External Neutrons and High Energy gamma Measured with (e-,e-)int events with E1+E2 > 4 MeV  0.02 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) 4253 keV (26 Mar. 2003) 6361 keV (8 Nov. 2003) In agreement with expected background < 110 92  18 100Mo metal. 400  100 316  46 82Se < 100 115  13 100Mo comp. A (mBq/kg) HPGe meas. from (e-, Ng) sources In agreement with HPGe measurements 208Tl impurities inside the foils Measured with (e-,2g), (e-,3g) events coming from the foil ~ 0.1 bb0n-like events year-1 kg -1 with 2.8<E1+ E2<3.2 MeV 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 Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

Radon is the dominant background today 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 Two independant measurements of radon in NEMO-3 gas Good agreement between the two measurements 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(Radon) in NEMO-3  20-30 mBq/m3 Decay in gas b- delayed a 222Rn (3.8 days) 218Po 214Pb 214Bi 214Po 210Pb b a 164 ms ~ 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 !!! Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

bb0n Analysis with 100Mo 100Mo Cu + natTe + 130Te 100Mo PRELIMINARY 6914 g 265 days Data bb2n Monte-Carlo Radon E1+E2 (MeV) bb0n arbitrary unit Cu + natTe + 130Te 265 days Radon Monte-Carlo Data E1+E2 (MeV) 8 11.4  3.4 ____ 2.6  0.7 2 2.6<E1+E2<3.2 2.8<E1+E2<3.2 100Mo 2.6<E1+E2<3.2 2.8<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 TOTAL Monte-Carlo 55.8  7.0 7.0  1.7 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 y with Esingle > 700 keV Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

100Mo bb0n likelihood analysis 3 variables used for the likelihood Ec1+ Ec2 sum of the kinetic energies of the 2 e- Ecmin energy 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 ! b- Cos Ec1 Ec2 E1 E2 Nbb0n xbb0n = is the free parameter Ntot L calculated with bb events Ec1+Ec2>2 MeV Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

100Mo bb0n likelihood analysis PRELIMINARY 100Mo bb0n likelihood analysis Data bb2n Monte-Carlo Radon bb0n T1/2 = 3.5 1023 y 100Mo 6914 g 216.4 days 4.10 kg.y Ec1+Ec2 (keV) Previous limit V-A: T1/2(bb0n) > 5.5 1022 y (Elegant V, Ejiri et al., 2001) V-A: T1/2(bb0n) > 3.5 1023 y (90% C.L.) V+A: T1/2 > 2.0 1023 y (90% C.L.) -Log(Likelihood) xbb0n = Nbb0n Ntot Ec1+Ec2 (keV) Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

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 Data bb2n Monte-Carlo Radon Data bb2n Monte-Carlo Radon bb0n T1/2 = 1.9 1023 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) Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

Limit on the effective mass of the Majorana neutrino, on Majoron and on V+A Limits on T1/2 are @ 90% C.L. Simkovic et al., Phys. Rev. C60 (1999) Stoica, Klapdor, Nucl. Phys. A694 (2001) Caurier et al., Phys. Rev. Lett. 77 1954 (1996) 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 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) Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

Anti-Radon 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 May 2004 : Tent surrounding the detector September 2004 : Radon Trapping Factory (SuperKamiokande-like) Expected activity: A(222Rn) ~ 0.2 Bq/m3 150 m3/h 500 kg charcoal @ -45oC Expected Purification Factor ~ 100 Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

NEMO-3 Expected sensitivity (with 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) Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

SUMMARY 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) 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 backgound as expected (except Radon presently ~ 10 times too high) Anti-Radon system operating this September 2004 Suppression factor ~ 100 Expected sensitivity in 5 years (with 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 Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004