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

2. 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 ~ 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

3. 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

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

5. 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) > (90 % C.L.)
 <mn> < eV
100Mo
( 7 kg )
82Se
Expected in 2009
T1/2(bb0n) > (90 % C.L.)
 <mn> < 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

6. 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%  % @ 3 MeV
Source x10 larger 7kg  kg
Most promising isotopes
82Se (baseline) or perhaps
150Nd
Aim: T1/2 > 2 x 1026 y
  Mbb  < meV
R&D up to 2009, construction
between 2010 and 2013
source sheet
M. Dracos, CEA, 10/04/2008

7. 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

8. 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

9. 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

10. 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 m2 and one brick m2. So 400 m2 is about the equivalent of 600 OPERA bricks over (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*m2
M. Dracos, CEA, 10/04/2008

11. 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

12. 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

13. 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

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

15. 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

16. 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

17. 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 , May 11th 2003
a track
(delay = 70 ms)
214Po  210Pb
214Bi  214Po
decay
IN THE GAS
M. Dracos, CEA, 10/04/2008

18. 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