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Double Beta experiment with emulsions?

Double Beta experiment with emulsions?. Double Beta Decay. ?. allowed double beta. double beta without neutrino. T 1/2 ~ 10 19 -10 20 years !. Observed for: Mo 100 , Ge 76 , Se 82 , Cd 116 , Te 130 , Zr 96 , Ca 48 , Nd 150. The NEMO3 experiment. The NEMO3 detector.

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Double Beta experiment with emulsions?

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

  2. Double Beta Decay ? allowed double beta double beta without neutrino T1/2 ~ 1019-1020 years ! Observed for: Mo100, Ge76, Se82, Cd116, Te130, Zr96, Ca48, Nd150 The NEMO3 experiment M. Dracos, CEA, 10/04/2008

  3. 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

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

  5. Results 82Se Phase I + II 693 days 48Ca 932 g 389 days 2750 even. S/B = 4 T1/2(bb0n) > 5.8 1023 (90 % C.L.)  <mn> <0.6-2.5 eV 100Mo ( 7 kg ) 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 background subtracted M. Dracos, CEA, 10/04/2008

  6. 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 Super NEMO source sheet M. Dracos, CEA, 10/04/2008

  7. 2 with emulsions e 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

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

  9. 2 with emulsions 1 MeV e- (Akitaka Ariga) 2 MeV e- simulation simulation M. Dracos, CEA, 10/04/2008

  10. 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

  11. 2 with emulsions Scanning Power Roadmap 700 1000 140 60 40 100 1stage 7.0 facility 10 1.2 0.1 / h 1 2 cm 0.1 0.1 0.003 0.01 0.003 0.001 TS(1994) NTS(1996) UTS(1998) SUTS(2006) SUTS(2007-) CHORUS DONUT OPERA • 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… Nakamura san Nufact07 M. Dracos, CEA, 10/04/2008

  12. 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

  13. 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

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

  15. 2 with emulsions for 400  m2/year and 400 m2 isotopes available M. Dracos, CEA, 10/04/2008

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

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

  18. NEMO3 Proportion of types of events in raw data: M. Dracos, CEA, 10/04/2008

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