Prsentation PowerPoint

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FIRST RESULTS OF THE NEMO 3 EXPERIMENT
NEMO collaboration
CENBG, IN2P3-CNRS et Université de Bordeaux,
France CFR, CNRS Gif sur Yvette, France FNSPE,
Prague University, Czech Republic INEEL, Idaho
Falls, USA IReS, IN2P3-CNRS et Université de
Strasbourg, France INR RAS, Moscow, Russia ITEP,
Moscow, Russia JINR, Dubna, Russia Jyvaskyla
University, Finland LAL, IN2P3-CNRS et Université
Paris-Sud, France LPC, IN2P3-CNRS et Université
de Caen, France Mount Holyoke College, USA RRC
Kurchatov Institute, Moscow, Russia Saga
University, Japan University College London,
United Kingdom
Laurent SIMARD LAL Orsay (France)
HEP-EPS 2003 conference
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Double bêta bb(0n) decay Physics beyond the
standard model

• DL 2 Process
• Majorana Neutrino n n and effective mass ltmngt
• Right-handed current in weak interaction
• SUSY particle exchange
• Majoron emission

bb(0n) 2n ? 2p2e-
p
n
W-
e-
neR
h
nM
neL
h
e-
W-
n
p
(Qbb MeV)
3
The NEMO3 detector
located in the Laboratoire Souterrain de Modane
(4800 mwe)
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The NEMO3 detector
AUGUST 2001
June 2002 tests runs
February 2003 beginning of data taking
5
The sources in NEMO3
6
Potentialities of the NEMO3 detector
7
Performances of the NEMO3 detector
8
Selection of electron-electron events

• 2 e- tracks associated with PMs hits, originated
  from the same vertex on the foil
• Time of flight decay in the source
• No delayed hit near the vertex (rejection of a)

9
100Mo 2b2n preliminary results
Feb-Mar 2003
S/B100 si E1E2 gt 1000 keV
10
100Mo 2b2n angular distribution
Background substracted
NEMO 3
2?2? Monte Carlo
11
82Se 2b2n preliminary result
Background substracted
NEMO 3
2?2? Monte Carlo
1850 hours 400 events S/B 4
Contaminated with ?-emitters
Cuts E gt 300 keV, Cos (?) lt 0.7
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Background at high energy

• 2 isotopes which have the greater Qb values
• 214Bi Qb ? 3.27 MeV
• 208Tl Qb ? 4.99 MeV

13
Study of the background 208Tl
A(208Tl in 100Mo foils) lt 100 mBq/kg
14
Study of the background 214Bi
15
Sensitivity of the NEMO3 detector (limits at the
90 CL level)
Efficiency (bb0n) in2.8-3.2 MeV 14


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Conclusion
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Anti-radon tent for NEMO3 detector

S
E
W
N
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Mo 2b2n HSD ans SSD mechanism
HSD, higher levels contribute to the decay
SSD, 1 level dominates in the decay Abad et al.,
1984, Ann. Fis. A 80, 9
Calculations for Mo F. Simkovic et al., J. Phys.
G, 27 (2001) 2233-2240
Effect in one electron spectrum

• NEMO
• High 2?2? statistics
• Measures each electron
• could see it!