NEMO-3 Experiment N eutrino E ttore M ajorana O bservatory FIRST RESULTS
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NEMO-3 ExperimentNEMO-3 Experiment
NNeutrino eutrino EEttore ttore MMajorana ajorana OObservatorybservatory
FIRST RESULTSFIRST RESULTS
Xavier Sarazin 1
for the
NEMO-3 Collaboration
CENBG, IN2P3-CNRS et Université de Bordeaux, France
Charles University, Praha, Czech Republic
CTU, Praha, Czech Republic
INEEL, Idaho Falls, USA
IReS, IN2P3-CNRS et Université de Strasbourg, France
ITEP, Moscou, Russia
JINR, Dubna, Russia
Jyvaskyla University, Finland1 LAL, IN2P3-CNRS et Université Paris-Sud, France
LSCE, CNRS Gif sur Yvette, France
LPC, IN2P3-CNRS et Université de Caen, France
Mount Holyoke College, USA
RRC Kurchatov Institute, Moscow, Russia
Saga University, Saga, Japon
UCL, London, Great-Britain
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
Plan of the talk:
NEMO-3 Detector
Measurement of decay for several nuclei
Search for decay with 100Mo and 82Se
3 m
4 m
B (25 G)
20 sectors
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
Source: 10 kg of isotopes cylindrical, S = 20 m2, e ~ 60 mg/cm2
Tracking detector: drift wire chamber operating in Geiger mode (6180 cells)Gas: He + 4% ethyl alcohol + 1% Ar + 0.1% H2O
Calorimeter: 1940 plastic scintillators coupled to low radioactivity PMTs
Magnetic field: 25 GaussGamma shield: Pure Iron (e = 18 cm)Neutron shield: 30 cm water (ext. wall)
40 cm wood (top and bottom) (since march 2004: water boron)
Able to identify e, e, and
The NEMO3 detector Fréjus Underground Laboratory : 4800 m.w.e.
isotope foils
scintillators
PMTs
Calibration tube
Cathodic rings Wire chamber
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
AUGUST 2001Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
coil
Iron shield
Water tank
wood
NEMO-3 Opening Day, July 2002
Start taking data 14 February 2003
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
100Mo 6.914 kg Q= 3034 keV
decay isotopes in NEMO-3 detector
82Se 0.932 kg Q= 2995 keV
116Cd 405 g Q= 2805 keV
96Zr 9.4 g Q= 3350 keV
150Nd 37.0 g Q= 3367 keV
Cu 621 g
48Ca 7.0 g Q= 4272 keV
natTe 491 g
130Te 454 g Q= 2529 keV
measurement
External bkg measurement
search
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
(All the enriched isotopes produced in Russia)
Drift distance
100Mo foil100Mo foil
Transverse view Longitudinal view
Run Number: 2040Event Number: 9732Date: 2003-03-20
Geiger plasmalongitudinalpropagation
Scintillator + PMT
Deposited energy: E1+E2= 2088 keVInternal hypothesis: (t)mes –(t)theo = 0.22 nsCommon vertex: (vertex) = 2.1 mm
Vertexemission
(vertex)// = 5.7 mm
Vertexemission
Transverse view Longitudinal view
Run Number: 2040Event Number: 9732Date: 2003-03-20
Criteria to select events:• 2 tracks with charge < 0• 2 PMT, each > 200 keV• PMT-Track association • Common vertex
• Internal hypothesis (external event rejection)• No other isolated PMT ( rejection)• No delayed track (214Bi rejection)
events selection in NEMO-3
Typical 2 event observed from 100Mo
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
Trigger: 1 PMT > 150 keV
3 Geiger hits (2 neighbour layers + 1)
Trigger rate = 7 Hz events: 1 event every 1.5 minutes
Tracking Detector: 99.5 % Geiger cells ON
Vertex resolution:
2 e channels (482 and 976 keV) using 207Bi sources
at 3 well known positions in each sector (Vertex) = 0.6 cm // (Vertex) = 1.3 cm (Z=0)
e/e separation with a magnetic field of 25 G ~ 3% confusion at 1 MeV
-
-
Vertex
Vertex = distance between the two vertex
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
Time Of Flight: Time Resolution ( channel) 250 ps at 1 MeV
ToF (external crossing e ) > 3 ns
external crossing e totaly rejected
External Background
events from the foil
(tmes – tcalc) external hypo. (ns)
(tmes – t
calc ) internal hypo. (ns)
Calorimeter: 97% of the PMTs+scintillators are ON
Energy Resolution: calibration runs (every ~ 40 days) with 207Bi sources
17%14%FWHM (1 MeV)
Int. Wall3" PMTs
Ext. Wall5" PMTs
207Bi2 conversion e 482 keV and 976 keV
482 keV
976 keV
FWHM = 135 keV (13.8%)
Daily Laser Survey to control gain stability of each PM gamma: efficiency ~ 50 % @ 500 keV, Ethr = 30 keV
Expected Performance of the detector has been reached
Performance of the detector
Measurement of decay in NEMO-3
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
(Data 14 Feb. 2003 – 22 Mar. 2004)
T1/2 = 7.72 0.02 (stat) 0.54 (syst) 1018 y
100Mo 22 preliminary results
4.57 kg.y
Cos()
Angular Distribution
Background subtracted
22 Monte Carlo
• Data
145 245 events6914 g
241.5 daysS/B = 45.8
NEMO-3
100Mo
E1 + E2 (keV)
Sum Energy Spectrum
145 245 events6914 g
241.5 daysS/B = 45.8
NEMO-3
100Mo
• Data
Background subtracted
22 Monte Carlo
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
Simkovic, J. Phys. G, 27, 2233, 2001
Single electron spectrum different between SSD and HSD
100Mo 22 Single Energy Distribution
22 HSDMonte Carlo HSD
higher levels Background subtracted
• Data22 SSD Monte Carlo
Background subtracted
• Data
SSDSingle State
HSD: T1/2 = 8.61 0.02 (stat) 0.60 (syst) 1018 y
SSD: T1/2 = 7.72 0.02 (stat) 0.54 (syst) 1018 y
100Mo 22 single energy distribution in favour of Single State Dominant (SSD) decay
4.57 kg.yE1 + E2 > 2 MeV
4.57 kg.yE1 + E2 > 2 MeV
HSD, higher levels contribute to the decay
SSD, 1 level dominates in the decay (Abad et al., 1984, Ann. Fis. A 80, 9)
100Mo
0
100Tc
1
/ndf = 139. / 36 /ndf = 40.7 / 36
NEMO-3 NEMO-3
Esingle (keV) Esingle (keV)
Esingle (keV)
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
Background subtracted
82Se T1/2 = 10.3 0.2 (stat) 1.0 (syst) 1019 y
116Cd if SSD T1/2 = 2.8 0.1 (stat) 0.3 (syst) 1019 y if HSD T1/2 = 3.05 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
82Se
116Cd 150Nd
22 preliminary results for other nuclei
96Zr
• Data
simulation
Data
simulation
Data
simulation
Data
simulation
NEMO-3 932 g241.5 days
2385 eventsS/B = 3.3
NEMO-3 NEMO-3NEMO-3 5.3 g168.4 days72 eventsS/B = 0.9
37 g168.4 days449 events
S/B = 2.8
405 g168.4 days
1371 eventsS/B = 7.5
E1+E2 (keV)
E1+E2 (MeV) E1+E2 (MeV) E1+E2 (MeV)Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
Search for decay in NEMO-3
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
External Background 208Tl (PMTs) Measured with (e, ) external events
~ 103 -like events year1 kg 1 with 2.8<E1 E2<3.2 MeV
Analysis: Background Measurement
< 110 92 18100Mo metal.
400 100316 4682Se
< 100115 13100Mo comp.
A (Bq/kg)HPGe meas.
A (Bq/kg)from (e, N)sources
In agreement with HPGe measurements
208Tl impurities inside the foils Measured with (e,2, (e,3 events coming from the foil
~ 0.1 -like events year1 kg 1 with 2.8<E1 E2<3.2 MeV
100Mo decay T1/2 = 7.7 1018 y (SSD)~ 0.3 -like events year1 kg 1 with 2.8<E1+E2<3.2 MeV
External Neutrons and High Energy gamma Measured with (e,e)int events with E1E2 4 MeV
0.02 -like events year1 kg 1 with 2.8<E1 E2<3.2 MeV ~
Only 2 (e,e)int events with E1E2 4 MeV observed after 260 days of data (without boron) 4253 keV (26 Mar. 2003)
6361 keV (8 Nov. 2003)
In agreement with expected background
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
NEMO-3 can measure each component of its background !
Radon in the NEMO-3 gas of the wire chamber
Analysis: Background Measurement
Due to a tiny diffusion of the radon of the laboratory inside the detector A(Radon) in the lab ~15 Bq/m3
222Rn (3.8 days)
218Po
214Pb
214Bi
214Po
210Pb
s
~ 1 -like events/year/kg with 2.8 < E1+E2 < 3.2 MeV
Radon is the dominant background today for search in NEMO-3 !!!
Two independant measurements of radon in NEMO-3 gas
Good agreement between the two measurements
Radon detector at the input/output of the NEMO-3 gas
~ 20 counts/day for 20 mBq/ m3
(1e + 1 ) channel in the NEMO-3 data:Delayed tracks (<700 s) to tag delayed from 214Po
214Bi 214Po (164 s) 210Pb
~ 200 counts/hour for 20 mBq/m3
A(Radon) in NEMO-3 20-30 mBq/m3
Decay in gas
delayed
214Bi 214Po (164 s) 210Pb
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
Analysis with 100Mo
V-A: T1/2() > 3 1023 y V+A: T1/2 > 1.8 1023 y with E1- E2> 800 keV
Majoron: T1/2 > 1.4 1022 y with Esingle > 700 keVXavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
100Mo
8
7.0 1.7
5.6 1.7
1.4 0.2
55.8 7.0TOTAL Monte-Carlo
2.6<E1+E2<3.2
50DATA
23.5 6.7Radon M-C
32.3 1.9100Mo 22M-C
100Mo
6914 g265 days
DataMonte-CarloRadonMonte-Carlo
E1+E2 (MeV)
arbitrary unit
PRELIMINARY
2.6<E1+E2<3.2
Cu + natTe + 130Te
265 days
RadonMonte-Carlo
Data
E1+E2 (MeV)
Cu + natTe + 130Te
8
11.4 3.4
11.4 3.4
____
2.6 0.7
2
2.6 0.7
____
2.6<E1+E2<3.2 2.6<E1+E2<3.2
100Mo likelihood analysis
3 variables used for the likelihood• Ec1+ Ec2 sum of the kinetic energies of the 2 e
• Ecmin energy of the e of minimal energy
• Cos angle between the two tracks
Ec = Energy at the exit of the 100Mo foil = Energy deposited in scintillator (E) + energy losses in the tracking detector
x is the free parameterN
Ntot
L calculated with events Ec1+Ec2>2 MeV
-
-
CosEc1
Ec2
E1
E2
!
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
100Mo likelihood analysis
Ec1+Ec2 (keV)
Data
Monte-Carlo
RadonMonte-Carlo
100Mo 6914 g
216.4 days4.10 kg.y
PRELIMINARY
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
DataMonte-CarloRadonMonte-CarloT1/2 = 3.5 1023
100Mo 6914 g
216.4 days4.10 kg.y
Ec1+Ec2 (keV)
Previous limit V-A: T1/2() > 5.5 1022 y (Elegant V, Ejiri et al., 2001)
V-A: T1/2() > 3.5 1023 y (90% C.L.) V+A: T1/2 > 2.0 1023 y (90% C.L.)
-Log
(Lik
elih
ood)
x N
Ntot
Previous limit V-A: T1/2() > 9.5 1021 y (NEMO-2) Arnold et al. Nucl. Phys. A636 (1998)
82Se likelihood analysisPRELIM
INARY
Data
Monte-Carlo
RadonMonte-Carlo
82Se 932 g
216.4 days0.55 kg.y
Data
Monte-Carlo
RadonMonte-Carlo
82Se 932 g
216.4 days0.55 kg.y
Ec1+Ec2 (keV) Ec1+Ec2 (keV)
V-A: T1/2() > 1.9 1023 y (90% C.L.) V+A: T1/2 > 1.0 1023 y (90% C.L.) Majoron: T1/2 > 1.2 1022 y (90% C.L.)
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
Limit on the effective mass of the Majorana neutrino,on Majoron and on V+A
Limits on T1/2 are @ 90% C.L.
Limit on Majoron 100Mo: T1/2 > 1.4 1022 y < (5.3 – 8.5) 105 Simkovic (1999), Stoica (1999) 82Se: T1/2 > 1.2 1022 y < (0.7 – 1.6) 104 Simkovic (1999), Stoica (2001)
Limit on V+A 100Mo: T1/2 > 2.0 1023 y < (1.5 – 2.0) 106 Tomoda (1991), Suhonen (1994) 82Se: T1/2 > 1.0 1023 y < 3.2 106 Tomoda (1991)
Simkovic et al., Phys. Rev. C60 (1999)Stoica, Klapdor, Nucl. Phys. A694 (2001)
Simkovic et al., Phys. Rev. C60 (1999)Stoica, Klapdor, Nucl. Phys. A694 (2001)Caurier et al., Phys. Rev. Lett. 77 1954 (1996)
Limit on the Majorana neutrino effective mass 100Mo: T1/2() > 3.5 1023 y
m < 0.7 – 1.2 eV
82Se: T1/2() > 1.9 1023 y
m < 1.3 – 3.6 eV
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
May 2004 : Tent surrounding the detector
Today: A(222Rn) in the LSM ~ 15 Bq/m3
August 2004 : Radon-free SuperKamiokande-like
Air FactoryExpected activity:
A(222Rn) ~ 0.2 Bq/m3
150 m3/h500 kg charcoal @ -40oC
Free-Radon Purification Systemin construction
Today Radon is the dominant background for NEMO-3
May 2004
Expected Purification Factor ~ 75
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
Factor ~ 10 too high
NEMO-3 Expected sensitivity(after Radon purification)
Background : External Background is negligible Internal Background:
208Tl : 100 Bq/kg for 100Mo 300 Bq/kg for 82Se214Bi : < 300 Bq/kg
~ 0.1 count kg1 y 1 with 2.8<E1+E2<3.2 MeV : T1/2 = 7.7 1018 y (SSD)
~ 0.3 count kg1 y 1 with 2.8<E1+E2<3.2 MeV
5 years of data
6914 g of 100Mo T1/2() 4 .1024 y (90% C.L.)m < 0.2 – 0.35 eV
932 g of 82Se T1/2() 8 .1023 y (90% C.L.)m < 0.65 – 1.8 eV
(conservative limit)
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
CONCLUSIONSCONCLUSIONS NEMO-3 Detector running since 14 Feb. 2003
Expected performance of the detector has been reached !
preliminary results for 100Mo, 82Se, 96Zr, 116Cd and 150Nd already more than 140 000 events collected 100Mo: in favour of Single State Dominance (SSD) 100Mo decay to excited state has been measured with ~ 4
Preliminary T1/2() limit (216.4 days of data):
• 100Mo (4.10 kg.y) T1/2() > 3.5 1023 y m < 0.7 – 1.2 eV
• 82Se (0.55 kg.y) T1/2() > 1.9 1023 y m < 1.3 – 3.6 eV
Level of backgounds as excepted except Radon ~ 10 times too highFree radon purification system in operation in August 2004Supression factor ~ 75
Expected sensitivity in 5 years after radon purification
• 100Mo: T1/2() > 4 .1024 y m < 0.2 – 0.35 eV
• 82Se: T1/2() > 8 1023 y m < 0.65 – 1.8 eV
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004