Transcript Document

NEMO 3 and SuperNEMO
experiments
Vladimir Vasiliev,
UCL
2-6 May ’06, Stockholm
on behalf of NEMO and
SuperNEMO collaborations
NEMO collaboration: IReS, Strasbourg, France; LAL, Orsay, France;
INEEL, Idaho Falls, USA; ITEP, Moscow, Russia; CENBG, BordeauxGradignan; JINR, Dubna, Russia; IEAP, Prague, Czech Republic; UCL,
London, UK; LPC, Caen, France; Saga Universityt, Japan; LSCE, Gif-surYvette, France; Jyvaskyla University, Finland; MHC, South Hadley, USA;
Charles University, Prague, Czech Republic; Manchester University, UK.
SuperNEMO collaboration: CENBG Bordeaux-Gradignan; IReS,
Strasbourg, France; LAL, Orsay, France; LPC, Caen, France; LSCE GifSur-Yvette, France; Jyvaskula Uiversity, Finland; Saga University, Japan;
Osaka University, Japan; Fes University, Marocco; INR RAS, Moscow,
Russia; ITEP, Moscow, Russia; JINR, Dubna, Russia; RRC Kurchatov
Institute, Moscow, Russia; Charles University, Prague, Czech Republic;
Technical University, Prague, Czech Republic; Manchester University,
UK; UCL, London, UK; ISMA, Kharkov, Ukraine; INEEL Idaho Falls,
USA; Mount Holyoke College, USA; University of Texas, USA; IFIC,
Valencia, Spain; Canfranc laboratory, Zaragosa, Spain;
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
Neutrinoless bb decay
Experimental signature:
a) 2 electrons
b) Eb1+ Eb2=Qbb
NEMO 3. Tracking experiment a) and b). Better signature, control and
suppression of background. But worse resolution.
Ultimate background – 2b2n decay tail.
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
NEMO-3 detector
20
Frejus underground laboratory 4800 m.w.e.
Source: 10 kg of bb isotopes, foil ~ 50mg/cm2
sectors
Tracking detector: drift wire chamber
operating in Geiger mode (6180 cells)
Gas: He + 4% ethyl alcohol + 1% Ar + 0.1% H2O
sxy=0,6 cm; sz=1,3 cm;
Calorimeter: 1940 plastic scintillators coupled
to low radioactivity PMTs
3m
FWHM=14% (5”); 17% (3”) @ 1MeV
Time resolution = 0.25 ns @ 1MeV
g detection efficiency ≈ 50 %
Magnetic field: 25 Gauss (3% e+/econfusion @ 1 MeV)
Gamma shield: Iron (e = 18 cm)
Neutron shield: 30 cm water + boron
B (25 G)
(ext. wall); 40 cm
wood (top and bottom)
Able to identify e-, e+, g and a
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
Cathodic rings
Wire chamber
PMTs
Calibration tube
scintillators
bb isotope foils
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
bb isotopes in NEMO-3
bb2n measurement
116Cd
405 g
Qbb = 2805 keV
96Zr
9.4 g
Qbb = 3350 keV
150Nd
37.0 g
Qbb = 3367 keV
48Ca
7.0 g
Qbb = 4272 keV
130Te
454 g
Qbb = 2529 keV
100Mo
6.914 kg
Qbb = 3034 keV
82Se
0.932 kg
Qbb = 2995 keV
natTe
491 g
Cu
621 g
Background
measurement
bb0n search
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
Background model



External background
 Detector radioactivity (PMT, iron, g flux
from lab). Measured by g Compton
scattering in the foil.
Radon in tracking chamber
 214Bi pollution of wires and foil surfaces.
Measured by delayed 214Po a-decay.
Source foil
 Internal radioactivity. e and eg events
from foil.
 bb2n decay
NEMO 3 and SuperNEMO experiments
Cu foil
SNOW 2006, Stockholm
Radon free air facility
adsorption unit @ -50°C
buffer
15 Bq/m3
15 mBq/m3
compressor
9-10 bar
In the tent around NEMO 3 Rn = 150 mBq/m3
In the tracker Rn = 4.5 mBq/m3  does not
depend any more from Rn level in the tent.
2 sets of data
Phase-I, before 4/10/04, Rn ≈ 22.2 mBq/m3,
Phase-II, Rn=4.5 mBq/m3
dryer
NEMO 3 and SuperNEMO experiments
cooler & heater
SNOW 2006, Stockholm
bb results for 100Mo
SSD simulation
T1/2 = 7.11 ± 0.02 (stat) ± 0.54 (syst)  1018 y
Phys Rev Lett 95, 182302 (2005)
SSD model confirmed
HSDof, higher
100Ru levels
Decay to the excited 0+ state
contribute to the decay
T1/2 = 5.7 ± 1.3 (stat) ± 0.8 (syst)  1020 y
To be published soon
1+
+
0+
bb0n
SSD, 1
level
Phase I + II ( 587d)dominates in the decay
100Tc
(Abad et al., 1984,
Use MC Limit approach: shape
information,
Ann. Fis. A 80, 9)
differentSingle
background
for PI
and PII
100Mo
electronlevel
spectrum
different
E1+E2>2between
MeV SSD and HSD
12952 evs MC = 12928 ± 70 e0n=18.1 %
T1/2 > 5.6∙1023 y, 90% CL
Simkovic,
J. Phys. G, 27, 2233, 2001
Window method [2.78-3.20] MeV, (690d)
14 evs MC = 13.4 e0n=8.2 %
NEMO 3 and SuperNEMO experiments
T1/2 > 5.8∙1023 y, 90%
CL
Esingle (keV)
SNOW 2006, Stockholm
bb results for 82Se
T1/2 = 9.6 ± 0.3 (stat) ± 1.0 (syst)  1019 y
Phys Rev Lett 95, 182302 (2005)
bb0n Phase I + II ( 587d)
Use MC Limit approach
E1+E2>2 MeV
238 evs MC = 240.5 ± 7 e0n=17.6 %
T1/2 > 2.7∙1023 y, 90% CL
Window method [2.62-3.20] MeV, (690d)
7 evs MC = 6.4 e0n=14.4 %
T > 2.1∙1023 y, 90% CL
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
bb2n decay for other isotopes
116Cd,
T1/2=(2.8±0.1(stat)±0.3(syst))∙1019 y
150Nd
,
T1/2=(9.7±0.7(stat) ±1.0(syst))∙1018y
96Zr,
T1/2 =(2.0±0.3(stat)±0.2(syst))∙1019y
48Ca,
T1/2=(5.3±0.9(stat)±0.5(syst))∙1019 y
Very preliminary results, to be crosschecked and published soon
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
Exotic processes search


V+A current in electroweak lagrangian
Neutrino coupled axions c (majorons)
V+A *
n=1 **
n=2 **
n=3 **
n=7 **
Mo
>3.2∙1023
l<1.8∙10-6 [1]
>2.7∙1022
g<(0.4-1.8)∙10-4 [3]
>1.7∙1022
>1.0∙1022
>7∙1019
Se
>1.2∙1023
l<2.8∙10-6 [2]
>1.5∙1022
g<(0.7-1.9)∙10-4 [3]
>6.0∙1021
>3.1∙1021
>5.0∙1020
*
new PI+PII data
** R.Arnold et al. Nucl. Phys. A765 (2006) 483
NME Calculations:
[1] J. Suhonen, Nucl. Phys. A 700 (2002) 649
[2] M. Aunola and J. Suhonen, Nucl. Phys. A 463 (1998) 207
[3] F. Simkovic et al., Phys. Rev. C 60 (1999) 055502; S.Stoica and H.
Klapdor-Kleingrothaus, Nucl. Phys. A 694 (2001) 269; O. Civatarese and J.
Suhonen, Nucl. Phys. A 729 (2003) 867
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
SuperNEMO project




extension of NEMO 3 technique
100 kg of isotopes, thin source between tracking
volumes, surrounded by calorimeter.
sensitivity 1-2∙1026 y, 40-70 meV
main improvements needed:




energy resolution (8% FWHM @ 1MeV ≡ 4% @
3MeV)
detection efficiency (factor 2)
source radio purity (factor 10)
background rejection methods
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
SuperNEMO milestones
2006-8: Design study
Calorimeter
Tracker
Source
Site selection (Frejus, Gran Sasso, Canfranc, Bulby)
Approved and funded R&D program in UK and France.
Spain, Russian and Japan groups applied for funding.
end 2008: Full Proposal
2009 – 2011: Production
2010-2011: Start taking data
2015: planned sensitivity ~0.04 eV
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
Modular design
source
tracker
calorimeter
1m
4m
5m
Top view
NEMO 3 and SuperNEMO experiments
Side
view
SNOW 2006,
Stockholm
Alternative design (bar scintillator)
Double sided readout
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
Calorimeter R&D so far
7-8% FWHM @ 1MeV for
small scintillator 5x5x2 cm
9% FWHM @ 1 MeV for
15x15x2 cm … but because of
light guide!
11-13% FWHM @ 1 MeV for
200 cm bar scintillator.
Attenuation length 150 cm!
looking for better plastic.
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
Wiring robot
The challenge:
from 6,000 to
~60,000+ cells
Wires must be
 strung
 terminated
 crimped
This can not be done
manually (~10 min/wire)
Complications
Copper pick-ups
Must be cost
effective
NEMO
3 and SuperNEMO experiments
Solder can not be used (radiopurity)
SNOW 2006, Stockholm
BiPo device, ultra low purity msr.
WHY? g spectroscopy doesnt sensitive to purity level required ~10 mBq/kg
Bi-Po Process
238U
b
214Po
(164 ms)
a
214Bi
(19.9 mn)
0.021%
210Pb
Q
MeMeV
Qbb(214
(212Bi)=3.2
Bi) = 2.2
e- prompt
Scintillator + PMT
e-
e-
a delay
22.3 y
Tracking
(wire chamber)
210Tl
(1.3 mn)
a
232Th
b
212Bi
36%
(60.5 mn)
208Tl
(3.1 mn)
Source foil
(40 mg/cm2)
212Po
(300 ns)
a
208Pb
(stable)
Delay a
Shield
radon, neutron,g
T1/2 ~ 300 ns Edeposited ~ 1 MeV
2 modules 23 m2 → 12 m2
Background < 1 event / month
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
Isotope choice
Detector allows to hold any isotope. Choice depends on:
- enrichment possibilities. Obligatory!
- Qbb value (phase space factor, background)
- bb(2n) life-time
82Se
good candidate
 100 kg per 2-3 y enrichment rate possible in Russia
 Qbb = 2995 keV. Concern about 214Bi and 208Tl only.
 test 2kg sample produced. Under purification now
150Nd
even better!
 SILVA group (SACLAY, France) was contacted. 150Nd
enrichment is possible!
 Qbb = 3367 keV. Concern about 208Tl only
 Large phasespace. 2n tale only 1.6 bigger then for 82Se
 NME & G0n much better then for 82Se
NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
Conclusion
NEMO 3 is continuing to take data
 no bb0n signal so far.

 100Mo:
*F.
T1/2>5.8∙1023 y; mn<0.6-1.0 eV*
 82Se: T1/2>2.1∙1023 y; mn<1.2-2.5 eV*
Simkovic et al., Phys. Rev. C 60 (1999) 055502; S.Stoica and H. KlapdorKleingrothaus, Nucl. Phys. A 694 (2001) 269; O. Civatarese and J.
Suhonen, Nucl. Phys. A 729 (2003) 867
a number of bb2n results to be published soon
 SuperNEMO R&D is in progress. 3 year program
funded in UK and France.

NEMO 3 and SuperNEMO experiments
SNOW 2006, Stockholm
WE ARE IN THE MIDDLE OF THE ROAD
EXIT
THAT COULD LEAD BEYOND SM
thank you for your attention!