Double Beta experiment with emulsions? M. Dracos Double Beta experiment with emulsions? M. Dracos, CEA, 10/04/2008

Double Beta Decay ? T 1/2 ~ 1019-1020 years ! The NEMO3 experiment M. Dracos Double Beta Decay allowed double beta double beta without neutrino T 1/2 ~ 1019-1020 years ! ? Observed for: Mo100, Ge76, Se82, Cd116, Te130, Zr96, Ca48, Nd150 Isotope Q(keV) 116Cd116Sn 2804.74.2 82Se82Kr 2995.23.3 100Mo100Ru 3034.86.3 96Zr96Mo 3350.03.5 150Nd150Sm 3367.14.9 48Ca48Ti 4272.04.1 The NEMO3 experiment M. Dracos, CEA, 10/04/2008

plastic scintillator blocks M. Dracos The NEMO3 detector expected sensitivity up to mn~0.3 eV plastic scintillator blocks 3m + photomultipliers (Hamamatsu 3", 5") wire chamber (Geiger) energy and time of flight measurements Sources : 10 kg, 20 m2 2 electron tracks M. Dracos, CEA, 10/04/2008

M. Dracos Event Examples M. Dracos, CEA, 10/04/2008

Results T1/2(bb0n) > 5.8 1023 (90 % C.L.) M. Dracos Results 932 g 389 days 2750 even. S/B = 4 Phase I + II 693 days T1/2(bb0n) > 5.8 1023 (90 % C.L.)  <mn> <0.6-2.5 eV 100Mo ( 7 kg ) 82Se Expected in 2009 T1/2(bb0n) > 2 1024 (90 % C.L.)  <mn> <0.3-1.3 eV 82Se T1/2 = 9.6 ± 0.3 (stat) ± 1.0 (syst)  1019 y 116Cd T1/2 = 2.8 ± 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 48Ca T1/2 = 3.9 ± 0.7 (stat) ± 0.6 (syst)  1019 y 48Ca background subtracted M. Dracos, CEA, 10/04/2008

Super NEMO R&D up to 2009, construction between 2010 and 2013 M. Dracos Super NEMO Improvements: Energy resolution 15%  DE/E = 4% @ 3 MeV Efficiency 15%  20 - 40% @ 3 MeV Source x10 larger 7kg  100 - 200 kg Most promising isotopes 82Se (baseline) or perhaps 150Nd Aim: T1/2 > 2 x 1026 y   Mbb  < 40 - 90 meV R&D up to 2009, construction between 2010 and 2013 source sheet M. Dracos, CEA, 10/04/2008

2 with emulsions e "veto" emulsion, if needed (~50 m like in OPERA?) M. Dracos 2 with emulsions e "veto" emulsion, if needed (~50 m like in OPERA?) beta source (~50 m inNEMO could be less for emulsions) plastic base "2" emulsion thick enough to detect up to 4 MeV electrons (density?) M. Dracos, CEA, 10/04/2008

Tests in Nagoya using OPERA emulsions M. Dracos Tests in Nagoya using OPERA emulsions A. Ariga, diploma thesis 50 m M. Dracos, CEA, 10/04/2008

2 with emulsions simulation simulation 1 MeV e- 2 MeV e- M. Dracos 2 with emulsions 1 MeV e- 2 MeV e- (Akitaka Ariga) simulation simulation M. Dracos, CEA, 10/04/2008

2 with emulsions NEMO3 surface: 20 m2 Super-NEMO surface: 10x20 m2 M. Dracos 2 with emulsions NEMO3 surface: 20 m2 Super-NEMO surface: 10x20 m2 To cover the same isotope source surface with emulsions (both sides to detect the 2 electrons) we need an emulsion surface: 2x200=400 m2. Just for comparison, one OPERA emulsion has about 0.012 m2 and one brick 0.680 m2. So 400 m2 is about the equivalent of 600 OPERA bricks over 150000 (but not with the same thickness of course…). Use the same envelops like the OPERA changeable sheets by introducing at the middle of the two emulsions a double beta source sheet, or use longer emulsion sheets easier to handle by microscopes. Keep all these envelops for some time (e.g. 6-12 months depending on fading) in the experiment and after this period start scanning them one after the other. They could be replaced by new envelops during 5 years in order to accumulate something equivalent to what Super-NEMO could do: 400*5 year*m2 M. Dracos, CEA, 10/04/2008

M. Dracos 2 with emulsions How much time is needed to make a full scan of 2000 m2 (is a full scan in all volume really needed?)? If the Japanese S-UTS scanning system is used with a speed of 50 cm2/hour (be careful with thickness…), for one scanning table: 25 m2/year (200 working days/year). By using 16 tables and extracting 100 m2/3 months (1 year exposure at the beginning and putting back new emulsions with the same isotopes), this finally will take less than 5 years (as Super-NEMO). Probably the emulsion thickness needed to detect these electrons will need more scanning time and the speed would be significantly less than 50 cm2/h. On the other hand, scanning speed increases with time… 0.003 0.1 1.2 7.0 40 60 140 700 0.001 0.01 1 10 100 1000 cm 2 / h TS(1994) NTS(1996) UTS(1998) SUTS(2006) SUTS(2007-) Scanning Power Roadmap 1stage facility CHORUS DONUT OPERA Nakamura san Nufact07 M. Dracos, CEA, 10/04/2008

Pending questions Energy resolution for NEMO: 15% for 3 MeV electrons M. Dracos Pending questions Energy resolution for NEMO: 15% for 3 MeV electrons Required for Super-NEMO: lower than 7% (goal 4%) Emulsion experiment energy resolution: ??? (monoenergetic 1 MeV 207Bi electrons could be used to have a good estimate of this resolution) Reconstruction efficiency for NEMO: 15% Required for Super-NEMO: 40% Emulsion experiment reconstruction efficiency: ?? (here also a well calibrated 207Bi source or other sources could be used) Minimum electron energy (~1 MeV, 0.5 MeV for NEMO3?) Afforded background? Could magnetic field help (better momentum resolution or  rejection)? Possibility to take thinner isotope sheets (60 m for NEMO3) and have better energy resolution (but also more scanning for the same isotope mass). M. Dracos, CEA, 10/04/2008

M. Dracos Extra Ideas after discussion with Fuji engineers, all these ideas are possible! e e e e decreasing density (25 mm layers) emitter in powder (diluted in an emulsion layer) to minimize the emulsion thickness and better energy resolution at the end of the track better vertex and energy reconstruction ? M. Dracos, CEA, 10/04/2008

M. Dracos END M. Dracos, CEA, 10/04/2008

2 with emulsions for 400 m2/year and 400 m2 isotopes available M. Dracos 2 with emulsions for 400  m2/year and 400 m2 isotopes available isotope block number time (years) surface (m2) exposure time (years) surface*time (m2*years) 1 1.00 100 2 1.25 125 3 1.50 150 4 1.75 175 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 total 1200 13.50 1350 M. Dracos, CEA, 10/04/2008

BACKGROUND EVENTS OBSERVED BY NEMO-3 M. Dracos BACKGROUND EVENTS OBSERVED BY NEMO-3 Electron crossing > 4 MeV Neutron capture Electron + a delay track (164 ms) 214Bi  214Po  210Pb  Electron + N g’s 208Tl (Eg = 2.6 MeV) Electron – positron pair B rejection M. Dracos, CEA, 10/04/2008

bb0n-like event due to Radon from the gas (NEMO3) M. Dracos bb0n-like event due to Radon from the gas (NEMO3) E1+E2= 2880 keV Run 2220, event 136.604, May 11th 2003 a track (delay = 70 ms) 214Po  210Pb 214Bi  214Po decay IN THE GAS M. Dracos, CEA, 10/04/2008

NEMO3 Type of event Rate (mHz) 1 e-, 0g 600 1 e-, Ng (N1) 150 M. Dracos NEMO3 Proportion of types of events in raw data: Type of event Rate (mHz) 1 e-, 0g 600 1 e-, Ng (N1) 150 e+e- pairs 110 Crossing e- 80 bb event 5.4 mHz M. Dracos, CEA, 10/04/2008