NEMO-3 Experiment Neutrino Ettore Majorana Observatory FIRST RESULTS Dominique Lalanne * for the NEMO-3 Collaboration CENBG, IN2P3-CNRS et Université de

NEMO-3 ExperimentNEMO-3 Experiment

NNeutrino eutrino EEttore ttore MMajorana ajorana OObservatorybservatory

FIRST RESULTSFIRST RESULTS

Dominique Lalanne * 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, Finland * 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

Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

Outline of the talk:

NEMO-3 Detector Measurement of decay for several nuclei

gives information on nuclear processes(2 electron events of energy up to the Q value)

Search for decay with 100Mo and 82Seif signal:

the neutrino is of Majorana type measurement of the effective neutrino mass(2 electron events of energy exactly the Q value)


3 m

4 m

B (25 G)

20 sectorsSource: 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


AUGUST 2001Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

coil

Iron shield

Water tank

wood

NEMO-3 Opening Day, July 2002

Start taking data 14 February 2003


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 (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

Trigger: 1 PMT > 150 keV

3 Geiger hits (2 neighbour layers + 1)

Trigger rate = 7 Hz events: 1 event every 1.5 minute


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

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


(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


22 Monte Carlo


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


• 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 y100Mo 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) (for the electron of low energy in the pair) Esingle (keV)

Esingle (keV)



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)Dominique Lalanne for the NEMO-3 Collaboration ICHEP 2004 Beijing August 16-21, 2004

Search for decay in NEMO-3


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

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


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 keV

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

2.8<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 2.8<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

!


100Mo likelihood analysis

Ec1+Ec2 (keV)

PRELIMINARY

DataMonte-CarloRadonMonte-CarloT1/2 = 3.5 1023 y

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.)


bb0nT1/2 = 1.9 1023

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


May 2004 : Tent surrounding the detector

Today: A(222Rn) in the LSM ~ 15 Bq/m3

September 2004 : Radon Trapping Factory (SuperKamiokande-like)

Expected activity: A(222Rn) ~ 0.2 Bq/m3

150 m3/h500 kg charcoal @ -45oC

Anti-Radon System in constructionToday Radon is the dominant

background for NEMO-3

May 2004

Expected Purification Factor ~ 100

Factor ~ 10 too high


NEMO-3 Expected sensitivity(with 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)


SUMMARYSUMMARY 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)

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 backgound as expected (except Radon presently ~ 10 times too high)Anti-Radon system operating this September 2004Suppression factor ~ 100

Expected sensitivity in 5 years (with 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


Documents

NEMO-3 Experiment Neutrino Ettore Majorana Observatory FIRST RESULTS Dominique Lalanne * for the NEMO-3 Collaboration CENBG, IN2P3-CNRS et Université de