NEMO3 Experiment Neutrino Ettore Majorana Observatory FIRST RESULTS

NEMO-3 Experiment Neutrino Ettore Majorana Observatory FIRST RESULTS Xavier Sarazin 1 for the NEMO-3 Collaboration CENBG, IN 2 P 3 -CNRS et Université de Bordeaux, France Charles University, Praha, Czech Republic CTU, Praha, Czech Republic INEEL, Idaho Falls, USA IRe. S, IN 2 P 3 -CNRS et Université de Strasbourg, France ITEP, Moscou, Russia JINR, Dubna, Russia Jyvaskyla University, Finland 1 LAL, IN 2 P 3 -CNRS et Université Paris-Sud, France LSCE, CNRS Gif sur Yvette, France LPC, IN 2 P 3 -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

Plan of the talk: ü NEMO-3 Detector ü Measurement of bb 2 n decay for several nuclei ü Search for bb 0 n decay with 100 Mo and 82 Se

The NEMO 3 detector Fréjus Underground Laboratory : 4800 m. w. e. 20 sectors Source: 10 kg of isotopes cylindrical, S = 20 m 2, e ~ 60 mg/cm 2 Tracking detector: drift wire chamber operating in Geiger mode (6180 cells) Gas: He + 4% ethyl alcohol + 1% Ar + 0. 1% H 2 O Calorimeter: 3 m 1940 plastic scintillators coupled to low radioactivity PMTs B (25 G) 4 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) Able to identify e-, e+, g and a Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14 -19 June 2004

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

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

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

decay isotopes in NEMO-3 detector 2 measurement 116 Cd 405 g Qbb = 2805 ke. V 96 Zr 9. 4 g Qbb = 3350 ke. V 150 Nd 37. 0 g Qbb = 3367 ke. V 48 Ca 7. 0 g Qbb = 4272 ke. V 130 Te 454 g Qbb = 2529 ke. V 100 Mo 6. 914 kg Qbb = 3034 ke. V 82 Se Qbb = 2995 ke. V 0 search Xavier Sarazin for the NEMO-3 Collaboration 0. 932 kg nat. Te 491 g Cu 621 g External bkg measurement (All the enriched isotopes produced in Russia) Neutrino 2004 Paris 14 -19 June 2004

events selection in NEMO-3 Typical 2 event observed from 100 Mo Transverse view 100 Mo Run Number: 2040 Event Number: 9732 Date: 2003 -03 -20 Vertex emission foil Longitudinal view 100 Mo foil Geiger plasma longitudinal propagation Vertex emission Drift distance Deposited energy: E 1+E 2= 2088 ke. V Internal hypothesis: (Dt)mes –(Dt)theo = 0. 22 ns Common vertex: Scintillator (Dvertex) = 2. 1+ mm PMT (Dvertex)// = 5. 7 mm Trigger: > 150 ke. Vevents: Criteria 1 PMT to select • 2 tracks with charge < 03 Geiger hits (2 neighbour layers + 1) • Internal hypothesis (external event rejection) • 2 PMT, each Trigger > 200 ke. V rate = 7 Hz • No other isolated PMT (g rejection) • PMT-Track association bb events: 1 event • every 1. 5 minutes No delayed track (214 Bi rejection) • Common vertex Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14 -19 June 2004

Performance of the detector events from the foil Tracking Detector: Calorimeter: Ø 99. 5 % Geiger cells ON are ON Ø 97% of the PMTs+scintillators - Ø Vertex resolution: 2 e- channels (482 and 976 ke. V) using 207 Bi sources at 3 well known positions in each sector s (DVertex) = 0. 6 cm s// (DVertex) = 1. 3 cm (Z=0) Ø e+/e- Ø Energy Resolution: DVertex calibration runs (every ~ 40 days) with 207 Bi sources FWHM (1 Me. V) separation with a magnetic field of 25 G ~ 3% confusion at 1 Me. V Time Of Flight: Ø Time Resolution (bb channel) 250 ps at 1 Me. V To. F (external crossing e- ) > 3 ns external crossing e- totaly rejected Int. Wall 3" PMTs 14% 17% External Background Ø Daily Laser to control gainthe stability of each PM DVertex = Survey distance between two vertex Ø gamma: efficiency ~ 50 % @ 500 ke. V, Ethr = 30 ke. V (D tm es –D 976 ke. V 207 Biof the detector tc Expected Performance alc ) in s) reachede 2 conversion te has been o. (n rn al 482 ke. V Xavier Sarazin for the NEMO-3 Collaboration Ext. Wall 5" PMTs hy po yp 482 ke. V and 976 rnal h xteke. V )e Dt calc – t mes. ( (D ns FWHM = 135 ke. V ) (13. 8%) Neutrino 2004 Paris 14 -19 June 2004

Measurement of 2 b 2 n decay in NEMO-3 Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14 -19 June 2004

100 Mo 2 2 preliminary results (Data 14 Feb. 2003 – 22 Mar. 2004) Sum Energy Spectrum NEMO-3 100 Mo 145 245 events 6914 g 241. 5 days S/B = 45. 8 Angular Distribution 145 245 events 6914 g 241. 5 days S/B = 45. 8 NEMO-3 100 Mo • • Data 2 2 Monte Carlo Background subtracted Cos( ) E 1 + E 2 (ke. V) 4. 57 kg. y Xavier Sarazin for the NEMO-3 Collaboration T 1/2 = 7. 72 0. 02 (stat) 0. 54 (syst) 1018 y Neutrino 2004 Paris 14 -19 June 2004

100 Mo 2 2 Single Energy Distribution HSD, higher levels contribute to the decay 1+ 100 Tc Single electron spectrum different between SSD and HSD SSD, 1+ level Simkovic, J. Phys. G, 27, 2233, 2001 dominates in the decay (Abad et al. , 1984, Ann. Fis. A 80, 9) 0+ 100 Mo Esingle (ke. V) NEMO-3 4. 57 kg. y NEMO-3 E 1 + E 2 > 2 Me. V • HSD higher levels 2/ndf = 139. / 36 E 1 + E 2 > 2 Me. V • Data 2 2 HSD Monte Carlo Background subtracted SSD Single State Xavier Sarazin for the NEMO-3 Collaboration 2 2 SSD Monte Carlo Background subtracted 2/ndf = 40. 7 / 36 Esingle (ke. V) HSD: T 1/2 = 8. 61 0. 02 (stat) 0. 60 (syst) 1018 y SSD: T 1/2 = 7. 72 0. 02 (stat) 0. 54 (syst) 1018 y Data Esingle (ke. V) 100 Mo 2 2 single energy distribution in favour of Single State Dominant (SSD) decay Neutrino 2004 Paris 14 -19 June 2004

2 2 preliminary results for other nuclei NEMO-3 82 Se 932 g 241. 5 days 2385 events S/B = 3. 3 • Data 2 simulation Background subtracted 82 Se 116 Cd T 1/2 = 10. 3 0. 2 (stat) 1. 0 (syst) 1019 y if SSD T 1/2 = 2. 8 0. 1 (stat) 0. 3 (syst) 1019 y if HSD T 1/2 = 3. 05 0. 1 (stat) 0. 3 (syst) 1019 y 150 Nd T 1/2 = 9. 7 0. 7 (stat) 1. 0 (syst) 1018 y 96 Zr T 1/2 = 2. 0 0. 3 (stat) 0. 2 (syst) 1019 y E 1+E 2 (ke. V) NEMO-3 116 Cd 405 g 168. 4 days 1371 events S/B = 7. 5 NEMO-3 150 Nd 37 g 168. 4 days 449 events S/B = 2. 8 NEMO-3 96 Zr 5. 3 g 168. 4 days 72 events S/B = 0. 9 Data bb 2 n simulation E 1+E 2 (Me. V) Xavier Sarazin for the NEMO-3 Collaboration E 1+E 2 (Me. V) Neutrino 2004 Paris 14 -19 June 2004

Search for 2 b 0 n decay in NEMO-3 Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14 -19 June 2004

0 Analysis: Background Measurement NEMO-3 can measure each component of its background ! Ø External Background 208 Tl (PMTs) Measured with (e-, g) external events ~ 10 -3 bb 0 n-like events year-1 kg -1 with 2. 8<E 1+ E 2<3. 2 Me. V Ø External Neutrons and High Energy gamma Measured with (e-, e-)int events with E 1+E 2 > 4 Me. V Only 2 (e-, e-)int events with E 1+E 2 > 4 Me. V observed after 260 days of data (without boron) -1 -1 ~ 0. 02 bb 0 n-like events year kg with 2. 8<E 1+ E 2<3. 2 Me. V Ø 208 Tl impurities inside the foils Measured with (e-, 2 g), (e-, 3 g) events coming from the foil ~ 0. 1 bb 0 n-like events year-1 kg -1 with 2. 8<E 1+ E 2<3. 2 Me. V 4253 ke. V (26 Mar. 2003) 6361 ke. V (8 Nov. 2003) In agreement with expected background sources A (m. Bq/kg) from (e-, Ng) A (m. Bq/kg) HPGe meas. 100 Mo metal. 92 18 < 110 100 Mo comp. 115 13 < 100 316 46 400 100 82 Se In agreement with HPGe measurements Ø 100 Mo 2 decay T 1/2 = 7. 7 1018 y (SSD) ~ 0. 3 bb 0 n-like events year-1 kg -1 with 2. 8<E 1+E 2<3. 2 Me. V Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14 -19 June 2004

0 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/m 3 Two independant measurements of radon in NEMO-3 gas Ø Radon detector at the input/output of the NEMO-3 gas 214 Bi 214 Po 222 Rn a (164 ms) 210 Pb (3. 8 days) ~ 20 counts/day for 20 m. Bq/ m 3 Ø (1 e- + 1 a) channel in the NEMO-3 data: Delayed tracks (<700 ms) to tag delayed a from 214 Po 214 Bi 214 Po (164 ms) 210 Pb ~ 200 counts/hour for 20 m. Bq/m 3 Good agreement between the two measurements 218 Po b Decay in gas 214 Bi 214 Po b- a delayed 164 ms a 210 Pb 214 Pb A(Radon) in NEMO-3 20 -30 m. Bq/m 3 ~ 1 0 -like events/year/kg with 2. 8 < E 1+E 2 < 3. 2 Me. V Radon is the dominant background today for 0 search in NEMO-3 !!! Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14 -19 June 2004

RY A N MI 0 Analysis with 100 Mo I L RE P 6914 g 265 days 100 Mo Data 265 days Cu + nat. Te + 130 Te Data bb 2 n Monte-Carlo Radon Monte-Carlo 0 arbitrary unit E 1+E 2 (Me. V) Cu + nat. Te + 130 Te 100 Mo 2. 6<E 1+E 2<3. 2 100 Mo 2 2 M-C Radon M-C TOTAL Monte-Carlo DATA 32. 3 1. 9 1. 4 0. 2 ____ 23. 5 6. 7 5. 6 1. 7 11. 4 3. 4 2. 6 0. 7 55. 8 7. 0 50 7. 0 1. 7 8 11. 4 3. 4 8 2. 6 0. 7 2 V-A: V+A: Majoron: Xavier Sarazin for the NEMO-3 Collaboration 2. 6<E 1+E 2<3. 2 T 1/2(bb 0 n) > 3 1023 y T 1/2 > 1. 8 1023 y T 1/2 > 1. 4 1022 y with E 1 - E 2 > 800 ke. V with Esingle > 700 ke. V Neutrino 2004 Paris 14 -19 June 2004

100 Mo 0 likelihood analysis 3 variables used for the likelihood • Ec 1+ Ec 2 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 100 Mo foil = Energy deposited in scintillator (E) + energy losses in the tracking detector Ec 1 Ec 2 - E 1 Cos - E 2 N 0 x 0 = is the free parameter Ntot L calculated with bb events Ec 1+Ec 2>2 Me. V Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14 -19 June 2004

LI E PR 0 likelihood analysis 100 Mo 6914 g 216. 4 days 4. 10 kg. y Data bb 2 n Monte-Carlo Radon Monte-Carlo 0 T 1/2 = 3. 5 1023 -Log(Likelihood) RY A N MI Ec 1+Ec 2 (ke. V) x 0 = N 0 Ntot Ec 1+Ec 2 (ke. V) V-A: V+A: T 1/2( 0 ) > 3. 5 1023 y (90% C. L. ) T 1/2 > 2. 0 1023 y (90% C. L. ) Previous limit V-A: T 1/2( 0 ) > 5. 5 1022 y (Elegant V, Ejiri et al. , 2001) Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14 -19 June 2004

I EL RY A N MI 82 Se 0 likelihood analysis PR 82 Se 932 g 216. 4 days 0. 55 kg. y Data bb 2 n Monte-Carlo Radon Monte-Carlo Ec 1+Ec 2 (ke. V) V-A: T 1/2( 0 ) > 1. 9 1023 y (90% C. L. ) V+A: T 1/2 > 1. 0 1023 y (90% C. L. ) Majoron: T 1/2 > 1. 2 1022 y (90% C. L. ) Xavier Sarazin for the NEMO-3 Collaboration Ec 1+Ec 2 (ke. V) Previous limit V-A: T 1/2( 0 ) > 9. 5 1021 y (NEMO-2) Arnold et al. Nucl. Phys. A 636 (1998) Neutrino 2004 Paris 14 -19 June 2004

Limit on the effective mass of the Majorana neutrino, on Majoron and on V+A Limits on T 1/2 are @ 90% C. L. Limit on the Majorana neutrino effective mass 100 Mo: T ( 0 ) > 3. 5 1023 y Simkovic et al. , Phys. Rev. C 60 (1999) 1/2 Stoica, Klapdor, Nucl. Phys. A 694 (2001) m < 0. 7 – 1. 2 e. V 82 Se: T 1/2( 0 ) > 1. 9 1023 y m < 1. 3 – 3. 6 e. V Simkovic et al. , Phys. Rev. C 60 (1999) Stoica, Klapdor, Nucl. Phys. A 694 (2001) Caurier et al. , Phys. Rev. Lett. 77 1954 (1996) Limit on Majoron 100 Mo: T 22 1/2 > 1. 4 10 y < (5. 3 – 8. 5) 10 -5 82 Se: T 1/2 > 1. 2 1022 y < (0. 7 – 1. 6) 10 -4 Simkovic (1999), Stoica (1999) Limit on V+A 100 Mo: T 23 1/2 > 2. 0 10 y l < (1. 5 – 2. 0) 10 -6 82 Se: T 1/2 > 1. 0 1023 y l < 3. 2 10 -6 Tomoda (1991), Suhonen (1994) Xavier Sarazin for the NEMO-3 Collaboration Simkovic (1999), Stoica (2001) Tomoda (1991) Neutrino 2004 Paris 14 -19 June 2004

Free-Radon Purification System in construction Today Radon is the dominant background for NEMO-3 Today: A(222 Rn) in the LSM ~ 15 Bq/m 3 Factor ~ 10 too high May 2004 : Tent surrounding the detector May 2004 August 2004 : Radon-free Super. Kamiokande-like Air Factory Expected activity: A(222 Rn) ~ 0. 2 Bq/m 3 150 m 3/h 500 kg charcoal @ -40 o. C Expected Purification Factor ~ 75 Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14 -19 June 2004

NEMO-3 Expected sensitivity (after Radon purification) Background : Ø External Background is negligible Ø Internal Background: 208 Tl : 100 m. Bq/kg for 100 Mo 300 m. Bq/kg for 82 Se 214 Bi : < 300 m. Bq/kg ~ 0. 1 count kg-1 y -1 with 2. 8<E 1+E 2<3. 2 Me. V Ø 2 : T 1/2 = 7. 7 1018 y (SSD) ~ 0. 3 count kg-1 y -1 with 2. 8<E 1+E 2<3. 2 Me. V 5 years of data 6914 g of 100 Mo T 1/2( 0 ) > 4. 1024 y (90% C. L. ) <m > < 0. 2 – 0. 35 e. V 932 g of 82 Se T 1/2( 0 ) > 8. 1023 y (90% C. L. ) <m > < 0. 65 – 1. 8 e. V (conservative limit) Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14 -19 June 2004

CONCLUSIONS Ø NEMO-3 Detector running since 14 Feb. 2003 Expected performance of the detector has been reached ! Ø 2 b 2 n preliminary results for 100 Mo, 82 Se, 96 Zr, 116 Cd and 150 Nd already more than 140 000 2 b 2 n events collected 100 Mo: in favour of Single State Dominance (SSD) 100 Mo bb 2 n decay to excited state has been measured with ~ 4 s Ø Preliminary T 1/2( 0 ) limit (216. 4 days of data): • 100 Mo (4. 10 kg. y) T (bb 0 n) > 3. 5 1023 y m < 0. 7 – 1. 2 e. V 1/2 82 23 • Se (0. 55 kg. y) T 1/2(bb 0 n) > 1. 9 10 y m < 1. 3 – 3. 6 e. V Ø Level of backgounds as excepted except Radon ~ 10 times too high Free radon purification system in operation in August 2004 Supression factor ~ 75 Ø Expected sensitivity in 5 years after radon purification • 100 Mo: T (bb 0 n) > 4. 1024 y <m > < 0. 2 – 0. 35 e. V 1/2 • 82 Se: T 1/2(bb 0 n) > 8 1023 y mn> < 0. 65 – 1. 8 e. V Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14 -19 June 2004