M. Dracos 1 Double Beta experiment with emulsions?

M. Dracos 2 Double Beta Decay ? T 1/2 ~ years ! Observed for: Mo 100, Ge 76, Se 82, Cd 116, Te 130, Zr 96, Ca 48, Nd 150 allowed double beta double beta without neutrino Isotope Q   (keV) 116 Cd  116 Sn  Se  82 Kr  Mo  100 Ru  Zr  96 Mo  Nd  150 Sm  Ca  48 Ti  4.1 The NEMO3 experiment

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

M. Dracos 4 Event Examples

M. Dracos 5Results 932 g 389 days 2750 even. S/B = 4 82 Se 82 Se T 1/2 = 9.6  0.3 (stat)  1.0 (syst)  y 116 Cd T 1/2 = 2.8  0.1 (stat)  0.3 (syst)  y 150 Nd T 1/2 = 9.7  0.7 (stat)  1.0 (syst)  y 96 Zr T 1/2 = 2.0  0.3 (stat)  0.2 (syst)  y 48 Ca T 1/2 = 3.9  0.7 (stat)  0.6 (syst)  y 48 Ca background subtracted Phase I + II 693 days T 1/2 (  ) > (90 % C.L.)  < eV Expected in 2009 T 1/2 (  ) > (90 % C.L.)  < eV 100 Mo ( 7 kg )

M. Dracos 6 Super NEMO Improvements: –Energy resolution 15%   E/E = 3 MeV –Efficiency 15%  MeV –Source x10 larger 7kg  kg Most promising isotopes – 82 Se (baseline) or perhaps – 150 Nd Aim: T 1/2 > 2 x y   M   < meV R&D up to 2009, construction between 2010 and 2013 source sheet

M. Dracos 7 e e 2  with emulsions "veto" emulsion, if needed (~50  m like in OPERA?) plastic base "2  " emulsion thick enough to detect up to 4 MeV electrons (density?) beta source (~50  m inNEMO could be less for emulsions) 1 MeV e- 2 MeV e- (Akitaka Ariga)

M. Dracos 8 2  with emulsions NEMO3 surface: 20 m 2 Super-NEMO surface: 10x20 m 2 To cover the same isotope source surface with emulsions (both sides to detect the 2 electrons) we need an emulsion surface: 2x200=400 m 2. Just for comparison, one OPERA emulsion has about m 2 and one brick m 2. So 400 m 2 is about the equivalent of 600 OPERA bricks (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 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*m 2

M. Dracos cm 2 / h TS(1994)NTS(1996)UTS(1998)SUTS(2006)SUTS(2007-) Scanning Power Roadmap 1stage facility CHORUSDONUTOPERA 2  with emulsions How much time is needed to make a full scan of 2000 m 2 (is a full scan in all volume really needed?)? If the Japanese S-UTS scanning system is used with a speed of 50 cm 2 /hour (be careful with thickness…), for one scanning table: 25 m 2 /year (200 working days/year). By using 16 tables and extracting 100 m 2 /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 cm 2 /h. On the other hand, scanning speed increases with time… Nakamura san Nufact07

M. Dracos 10 Pending questions Energy resolution for NEMO: 15% for 3 MeV electrons Required for Super-NEMO: lower than 7% (goal 4%) Emulsion experiment resolution: ??? (monoenergetic 1 MeV 207 Bi electrons could be used to have a good estimate of this resolution) Reconstruction efficiency for NEMO: 15% Required for Super-NEMO: 40% Emulsion experiment efficiency: ?? Afforded background? Could magnetic field help? Possibility to take thinner isotope sheets (60 mm for NEMO3) and have better energy resolution (but also more scanning for the same isotope mass).

M. Dracos 11 Extra Ideas e e decreasing density (25 mm layers) to minimize the emulsion thickness e e emitter in powder better vertex and energy reconstruction ?

M. Dracos 12 END

M. Dracos 13 2  with emulsions for 400 m 2 /year and 400 m 2 isotopes available isotope block number time (years)surface (m 2 )exposure time (years) surface*time (m 2 *years) total