FIRST RESULTS OF THE NEMO 3 EXPERIMENT Laurent SIMARD LAL Orsay (France) HEP-EPS 2003 conference 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 NEMO collaboration
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FIRST RESULTS OF THE NEMO 3 EXPERIMENT Laurent SIMARD LAL Orsay (France) HEP-EPS 2003 conference CENBG, IN2P3-CNRS et Université de Bordeaux, France CFR,
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FIRST RESULTS OF THE NEMO 3 EXPERIMENT
Laurent SIMARDLAL Orsay (France)
HEP-EPS 2003 conference
CENBG, IN2P3-CNRS et Université de Bordeaux, FranceCFR, CNRS Gif sur Yvette, FranceFNSPE, Prague University, Czech RepublicINEEL, Idaho Falls, USAIReS, IN2P3-CNRS et Université de Strasbourg, FranceINR RAS, Moscow, RussiaITEP, Moscow, RussiaJINR, Dubna, Russia Jyvaskyla University, FinlandLAL, IN2P3-CNRS et Université Paris-Sud, FranceLPC, IN2P3-CNRS et Université de Caen, FranceMount Holyoke College, USARRC “Kurchatov Institute”, Moscow, RussiaSaga University, JapanUniversity College London, United Kingdom
NEMO collaboration
L = 2 Process Majorana Neutrino and
effective mass <m>
Right-handed current in weak
interaction
SUSY particle exchange
Majoron emission
(0) : 2n 2p+2e-
W
Wn
n
p
p
e
e
M
eR
eL
( )T0
2/1
h
h
DDouble bêta ouble bêta (0(0) ) decaydecay : Physics : Physics beyond the standard modelbeyond the standard model
DDouble bêta ouble bêta (0(0) ) decaydecay : Physics : Physics beyond the standard modelbeyond the standard model
(Q ~ MeV)
B25G
3 m
located in the Laboratoire Souterrain de Modane (4800 mwe)
10 kg of isotopes(surface: 20 m2, thickness: 60 m for 100Mo)
Reconstruction of vertex (runs with 207Bi sources)
Performances of the NEMO3 Performances of the NEMO3 detectordetector
Performances of the NEMO3 Performances of the NEMO3 detectordetector
Energy calibration(with 207Bi and 90Sr sources)
207Bi
482 keV
976 keV
207Bi : 0.5 MeV and 1 MeV
90Sr : 2.3 MeV
1 MeV) =
ADC channel
Selection of electron-electron events
Selection of electron-electron events
1256 keV
832 keV
• 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 )
6 5 0 h o u r s1 3 7 5 0 e v e n t s
S / B = 4 0
B a c k g r o u n d s u b s t r a c t e d
T1 / 2 = 7 . 8 0 . 0 9 ( s t a t ) 0 . 8 ( s y s t ) 1 0 1 8 y
2 2 M o n t e C a r l oN E M O 3
S/B~100 si E1+E2 > 1000 keV
100Mo 22 preliminary results
100Mo 22 preliminary results
Feb-Mar 2003
Background substractedNEMO 3
22 Monte Carlo
100Mo 22angular distribution
100Mo 22angular distribution
1850 hours400 events
S/B = 4
Background substracted
Contaminated with -emitters
Cuts: E > 300 keV, Cos () < 0.7
y.100.9(syst.)0.4(stat.)9.1T 191/2
NEMO 322 Monte Carlo
82Se 22preliminary result
82Se 22preliminary result
Measurement of the background processes, in other channels :
214Bi Channel e (with T1/2 () ~ 164 s
(214Bi -214Po -210Pb)
208Tl Channels e ’s with E= 2.6 MeV
neutrons, and external gammas
e- crossing > 4 MeV
Background at high energyBackground at high energy
2 isotopes which have the greater Q values :• 214Bi : Q3.27 MeV• 208Tl : QMeV
Study of the background : 208TlStudy of the background : 208Tl
A(208Tl in 100Mo foils) < 100 Bq/kg
look for e, e2, e3 events coming from the foil
Study of the background : 214BiStudy of the background : 214Bi
~1 0-likeevent due to radon expected in a year (same order of magnitude as the sum of other backgrounds)
anti-radon tent in fall 2003air radon free factory in summer 2004
« anti-radon » tent
Specification : A(214Bi in 100Mo) < 300 Bq/kg
main effect : 222Rn (parent of 214Bi) found in the gas volume
for the moment no limit
given on A(214Bi in 100Mo)
2 measurements of 222Rn activity
by NEMO 3 itself (events e(n))
by radon monitor for the chamber out gasA(222Rn inside NEMO3) ~ 30 mBq/m3