NEMO-3 Detector

Preliminary results

• Performance of the detector

• analysis for 100Mo, 82Se and 150Nd

Background study for research (208Tl and Radon)

Future of NEMO

NEMO ExperimentNEMO ExperimentNeutrino Ettore Majorana ObservatoryNeutrino Ettore Majorana Observatory

Journées Neutrinos 27-28 novembre 2003 LPNHE-Paris

Xavier Sarazin for NEMO Collaboration

NEMO ExperimentNEMO ExperimentNeutrino Ettore Majorana ObservatoryNeutrino Ettore Majorana Observatory

Search for neutrinoless double beta decay

Study several isotopes Mo100 , Se82 , Te130 , Cd116 , Zr96 , Ca48 , Nd150

Tag and measure all the components of background e-, e+, ,, neutrons

““zero background” experimentzero background” experiment

DDouble bouble beeta ta (0(0) ) decay : decay : Physics beyond the standard modelPhysics beyond the standard model

(0) : 2n 2p+2e- L = 2 Process Majorana Neutrino and effective mass

<m>

Right-handed current in weak interaction

Majoron emission

SUSY particle exchange

W

Wn

n

p

p

e

e

M

eR

eL

(Q ~ MeV)

( )T0

2/1

h

h

1 sector of NEMO3

Sources: 20 m2, total mass ~ 10 kg, thickness ~ 60 mm Tracking detector (6180 Geiger cells in He+alcohol): Vertex t = 5 mm, z = 1 cm Calorimeter (1940 plastic scintillators + PMTs low radioactivity) E/E = 3% at 3 MeV and neutron shield: Iron shield (18 cm) + water shield + wood shield + parafin magnetic field B=25 G all materials low radioactivity (total activity in 208Tl and 214Bi 300 Bq)

Located in Modane Underground LaboratoryLocated in Modane Underground LaboratoryNEMONEMO--3 3 DetectorDetector

isotope foils

scintillators

PMTs

Calibration tube

Cathodic rings Wire chamber

AUGUST 2001

June 2002 : tests runs

FFebruary 2003 :ebruary 2003 : bbeginning of data takingeginning of data taking

coil

Iron shield

Water tank

wood

Sources preparationSources preparation

Bkg

Sources thicknessmg/cm2)

Q= 3034 keV Q= 2995 keV

82Se (0.93 kg)100Mo (6.9 kg)

Sources in NEMO-3 detectorSources in NEMO-3 detector

Expected backgroundExpected background and sensitivity and sensitivity

External and neutron background negligeable

7 kg of 100Mo

Source contamination :A(214Bi) < 0.3 mBq/kg A(208Tl) < 0.02 mBq/kg

Internal background : 214Bi < 0.04 evts/y/kg 208Tl < 0.04 evts/y/kg 0.11 evts/y/kg

Total Bkg < 1.4 event/yearT1/2(0) > 8.1024 y

m < 0.1 – 0.3 eV

5 years of dataEnergy window: [2.8-3.2] MeVEfficiciency = 14%

1 kg of 82Se

Source contamination :A(214Bi) = 1.20.5 mBq/kg

(measured) A(208Tl) = 0.40.1 mBq/kg

Internal background : 0.01 evts/y/kg

Hot spots:Pollution rejected

Bkg ~ 0 event/yearT1/2(0) > 1.5.1024 ym < 0.6 – 1.2 eV

NEMO-3 Preliminary Results

Performance of the detector

analysis for 100Mo, 82Se, 150Nd

Background analysis for search

Trigger: 1 PM > 150 keV 3 Geiger hits

(2 neighbour layers + 1)Counting rate = 7.5 Hz

Proportion of types of events in raw data:

Type of event Rate (mHz)

1 e, 0 600

1 e, N

150

ee pairs 110

Crossing e 80

event 5.4 mHz

Data TackingData Tacking

October 1st 2003 161 days of data tacking

~ 75 % efficiency

Days of data collecting / month

Efficiency of data collecting / month

Tracking Detector PerformancesTracking Detector Performances

0.5 % Geiger cells OFF 97.5 % Geiger cells with 2 cathodic signals Longitudinal propagation of Geiger plasma:

Efficiency > 93% for 90% of Geiger cells

RAW DATA PROCESSED DATA

Transversal Transversal and Longitudinal and Longitudinal Resolution Resolution on the Vertexon the Vertex

1 e channel at 1 Mev: (1 MeV) = 0.2 cm // (1 MeV) = 0.7 cm (Z=0)

2e- channel (1 MeV+ 0.5 MeV) (1 MeV) = 0.6 cm // (1 MeV) = 1.8 cm (Z=0)

207Bi sources at 3 well known positions in each sector(emission of two e- conversion at 1 and 0.5 MeV)

Performances of the calorimeter Performances of the calorimeter

Tube in each sector where calibration sources are introduced (3 positions)3 electron energies : 486 keV and 976 keV with 207Bi, and 2.28 MeV with 90Sr

90Sr

End point 2,28 MeV

At 1 MeV (Q3 MeV for 100Mo and 82Se):

207Bi

482 keV

976 keV

FWHM = 135 keV

FWHM E/E

Ext. Wall (PMTs 5")

14 % 5.8 % / E(MeV)

Int. Wall (PMTs 3")

17 % 7.1 % / E(MeV)

2 event

EVENT OBSERVED BY NEMO-3… EVENT OBSERVED BY NEMO-3…

E1+E2= 2088 keV

(t)mes –(t)theo = 0.22 ns(vertex) = 2.1 mm(vertex)// = 5.7 mm

100Mo 22 preliminary results100Mo 22 preliminary results(14 Feb. 2003 – 30 Sep. 2003)

160 days75535 events

Background substracted

22 Monte CarloNEMO 3

S/B(> 1 MeV) 100

T1/2 = 7.8 0.09 (stat) 0.09 (syst) 1018 y

S/B = 40

100Mo 22 Single Energy Distribution100Mo 22 Single Energy Distribution

Calculations for 100Mo:(Simkovic, J. Phys. G, 27, 2233, 2001)

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

0

1

Effect in one electron spectrum

100Mo 22 angular distribution100Mo 22 angular distribution

Background substractedNEMO 322 Monte Carlo

82Se 22 preliminary results82Se 22 preliminary results(14 Feb. 2003 – 30 Sep. 2003)

Contaminated with low energy -emitters

Cuts: E > 300 keV Cos () < 0.7

3834 hours1100 events

S/B = 4.2

Background substracted

22 Monte Carlo

T1/2 = 9.52 0.25 (stat) 0.9 (syst) 1019 y

150Nd 22 preliminary results150Nd 22 preliminary results(June 2002 – 30 Sep. 2003)

3834 hours400 eventsS/B = 4.2

Background substracted

22 Monte Carlo

T1/2 = 7.5 0.3 (stat) 0.7 (syst) 1018 y

Two natural isotopes which have the greatest Q values > 3 MeV: 214Bi : Q3.27 MeV 208Tl : QMeV

Design NEMO-3 detector for 10 kg:

214Bi in source foils < 0.3 mBq/kg 208Tl in source foils < 0.02 mBq/kg

Total activity of the detector (200 tons) 300 Bq

Origin of Background at high energyOrigin of Background at high energy

In the Modane Underground Laboratory: Fast neutron flux ( 1 MeV): 3.5 ± 1.5 10-6 n.cm-2s-1

Thermal neutron flux (~0.025 eV): 1.6 ± 0.1 10-6 n.cm-2s-1

Electron

Gamma : 50% efficiency at 1 MeV Energy Threshold = 30 keV

Time of Flight : Time Resolution 250 ps at 1 MeV

e/e- separation with a magnetic field of 25 G 3% confusion at 1 MeV

Delayed tracks (<700 s) to tag delayed from Bi207

214Bi 214Po (164 s) 210Pb

How NEMO-3 tags the backgroundHow NEMO-3 tags the background

Measurement of the Measurement of the sources of sources of background background

214Bi channel e (with T1/2 () 164 s

(214Bi -214Po -210Pb)

208Tl channels e  ’s with E= 2.6 MeV

212Bi 212Po e () T1/2()300 ns

neutrons, external gammas

e crossing, ee, ee > 4 MeV

Electron + N ’s 208Tl (E = 2.6 MeV)

Electron crossing > 4 MeV Neutron capture

BACKGROUND EVENTS OBSERVED BY NEMO-3… BACKGROUND EVENTS OBSERVED BY NEMO-3…

Electron + delay track (164 s) 214Bi 214Po 210Pb

Electron – positron pair B rejection

Search for Search for 208208Tl background in the foilsTl background in the foils

3800 h of data analysed14 Feb. 2003 – 30 Sep. 2003

Tl cuts: E1 > 400 keV E2 > 1900 keV E > 200 keV

MC: (Mo) = 0.16% 3.4 Rn events (3800 h.) for 20 sectors

look for e, e2, e3 events coming from the foil

sources N events A (Bq/kg) HPGe measure

100Mo 20 110 25100Mo metal. 17 140 40 < 100100Mo comp. 3 50 < 110

Cu 082Se 10 490 150 400 100

150Nd 10 11800 3700 10000 2000

natTe 5 ~250 < 90

VERY PRELIMINARY

Good agreement with the HPGe measurements

Neutron and High-Energy gamma BackgroundNeutron and High-Energy gamma Background

Only 1 -like event > 4 MeV detected after 160 days of data tacking ! (14 Feb. 2003 – 30 Sep. 2003)

Run 2058 event 34596626 March 2003

130Te source (sector 19)

E1+E2 = 4448 keV

look for ee events > 4 MeV coming from the foil

Two different measurements of radon in the NEMO-3 gas:• Radon detector:

sensitivity: 1 count/day for 1 mBq/m3

Radon measurement 20 mBq/m3

• (1e + 1 ) channel in the NEMO-3 data:

Able to measure Radon every half day

Radon measurement 30 mBq/m3

~ a few 0-likeevents due to radon, expected in 1 year

!!! TOO HIGH !!!

A free Radon Tent surrounding the NEMO-3 detector in construction:• February 2004: 200 kg Charcoal Factor ~ 8 for Radon purification• Spring 2004: Full Radon purification system

Factor ~ 100

222Rn

218Po

214Pb

214Bi

214Po

210Pb

Radon in NEMO-3Radon in NEMO-3

s

E1+E2= 2880 keV

Run 2220, event 136.604, May 11th 2003

a a -like event due to Radon from the gas-like event due to Radon from the gas

track(delay = 70 s)214Po 210Pb

214Bi 214Po decay IN THE GAS

Fall 2003 : Tent surrounding the detectorA(222Rn) ~ Bq/m3

Today : A(222Rn) in the LSM ~10 Bq/m3

Spring 2004 : Radon-free Gas FacoryA(222Rn) ~ 0.2 Bq/m3

150 m3/h

Free-Radon Purification SystemFree-Radon Purification System

Sensitivity of NEMO3 to measure sources of backgroundSensitivity of NEMO3 to measure sources of background

Design NEMO3 for 10 kg: 208 Tl in source foils < 0.02 mBq/kg 214 Bi in source foils < 0.3 mBq/kg neutron flux < 10-8 n cm-2 s-1

Sensitivity NEMO3 after 2 years of data :

208 Tl in source foils < 2 Bq/kg channel e ’s (E= 2.6 MeV) 212 Bi 212 Po e (300 ns)

214 Bi in source foils < 2 Bq/kg measured by channel e (  ( 214 Bi 214 Po 210 Pb; T1/2 = 164 s )

neutrons < 10-9 n cm-2 s-1

measured by e- crossing > 4 MeV

Sensitivity to 100 kg of isotopes

Future for a NEMO Detector

Tracking-Calorimeter Technique

NEMO-3

NEMO-3

NEMO-3

QD

IH

QD

QD

IH

IH

Expected values of Expected values of mm from neutrinos oscillations parameters from neutrinos oscillations parameters

Pascoli and Petcov, hep-ph/0310003(best fit atm + sol )

Quasi-Degenerate (QD):

m > 0.6 eV

Inverted Hierarchie (IH):

0.015 eV < m < 0.6 eV

Normal Hierarchie (NH):

m < 5. 10-3 eV~

~

~~

Next Generation of NEMO detector« detect » 1 gold event/year

with m ~ 20 meV

Number of event detected / year:

ln2 . N . . MA . T1/2 (y)0

N / year N : AvogadroA : atomic massM : mass (g) of enrich. Isotope: detection efficiency

Future of NEMOFuture of NEMO

Real measurement with 1 GOLD EVENT / YEAR

• M = k 100 kg of 100Mo or 82Se• = 0.5• Background = 0.1 event / year• 1 Gold event detected / year

0T1/2 2 k 1026 yearsm = 20 – 60 meV

Goal of a next NEMO detector:

3-4-5 December 2003: 1st meeting for Future of NEMOStart working groups to prepare a design proposal for a future NEMO detector

Advantage of a Calo-Tracking approach:• Can measure several isotopes• Tag and measure all backgounds : zero background experiment• May detect « Gold events »

Start with realistic 100 kg isotope module…could be extended to 1 ton with several modules)

Working groups:• R&D Calorimeter • R&D Tracking• Sources Enrichment (100Mo, 82Se, 150Nd…) • Purification sources• Simulation

Main challenges:• Energy resolution• Efficiency• Sources (enrichment, purification)

Future of NEMOFuture of NEMO

ENERGY RESOLUTION IS ONE OF THE MAIN CHALLENGEENERGY RESOLUTION IS ONE OF THE MAIN CHALLENGEGoal: < 0.1 event/year in the energy window

FWHM ( ray at 3 MeV) 350 keV

one event/year expected in the energy windowNEMO-3 (7 kg):

2 ( ray) = 2 (Calorimeter) + 2 (dE/dX in foil) + 2 (dE/dX in tracking)

CALORIMETER: separate e/ measurement to improve e energy resolution(NEMO-3 ~ 15% at 1 MeV) electron: Silicon (Li) detector (~ 5 mm, noise ~ 20-30 keV at normal To)

Very good thin scintillator (~ 2 cm) gamma: thicker scintillators (100% efficiency instead of 50%)

SOURCES: Decrease the energy losses in the foil (NEMO-3 ~ 50-80 g/cm2, 60 m: <E> ~150 keV)

Active sources (ex: 2 foils 20 m + counters) internal Background rejection

TRACKING: Similar Geiger drift wire chamber TPC in He (Japan group)

e

208Tl internal bkg

ILIAS European funding ILIAS European funding for for research research

JRA1: low bkg. techn. for Deep Underground Laboratories• Links LSM and Boulby• Develop. Ultra Low Bkg. Facility: Big effort on Germanium• Radon factory

NEMO people involved in ILIAS (5 years)

JRA2: R&D for next detectors• R&D for calorimeter (silicon, scintillators…)• 82Se 2 kg production, purification and source making (2004-2005)• 150Nd enrichment study

N4: next generation of detectors• NEMO-Next working groups and Proposal

300 kEuros

300 kEuros

60 kEuros

IN2P3(5 years)

NOUVEAUX COLLABORATEURS

SONT LES BIENVENUS

New members already interested: USA (Texas University), UK (UCL), Japan (KEK)

CONCLUSIONSCONCLUSIONS

NEMO-3 Detector running since 14 Feb. 2003 Data tacking efficiency ~75%

Performance of the detector has been reached !

preliminary results for 100Mo, 82Se and 150Nd already more than 75.000 events collected

Background study for search:• 208Tl (e N channel) : good agreement with HPGe measurements• Neutrons and High-energy : only 1 -like event > 4 MeV !• Radon: 20-30 mBq/m3 inside the detector a few -like events/year expected Too high !

Free radon purification system under constructionRadon/8 in Feb. 2004Radon/50 in Spring 2004

Future of NEMO: First meeting 3-5 december 2003 start working groups to prepare a design proposal for a next detector

Goal (dream ?) for Next NEMO:be able to « detect » 1 gold event/year with m ~ 20 meV