PLAN• Introduction to 2β0ν
• NEMO3
 description, performances results 2β2ν results 2β0ν : data phase 1
 fight against radon: result

1.08 year• Prospects: SuperNEMO R&D• Conclusion
S. Jullian
LAL Paris–Sud University
jullian@lal.in2p3.fr

Why looking for 2β0ν
1.

Proton decay experiments
Super Kamiokande experimentpe+πo at a level of 1.6 1033 years (5.4 1033 y updated)pν K+at a level of 6.7 1032 years

robust consequence SU(5) is not the right GUT
2.

Neutrino oscillation experimentsνµ beam from accelerator K2K (≈ 1 GeV)νe, νµ atmospheric K and S.K (≈ GeV)
νe from sun, reactors, Davis, Sage, Gallex, S. Kamioka, Chooz, SNO, Kamland (≈ MeV)mν ≠ 0 but a tiny mass
next soon OPERA νµ → ντ ?
miniboone νs ?
MINOS νµ disappearance3.

If GUT is the line guide then beyond SU5 ν’s are νM with a tiny mass
2β0ν mass mechanism ?

Double beta ββ(0ν) decay:
Physics beyond the standard modelββ(0ν) : 2n → 2p+2e-

ΔL = 2 Process

p
n

W−
νeR

 Majorana Neutrino ν = ν and effective mass <mν>e−

 Right-handed current in weak interactionh Majoron emission

νM
νeL

h

T

e−

W−

n

 SUSY particle exchange

(

p

2

A=<m> xPSx IM

I

2

Nuc.

(Q ββ ~ MeV)

0!
1/2

)

Expected values of <mν> from neutrinos oscillations parameters
NEM O-3QD

3<mν> = Σ mi U2ei eiαj1sin2θ13 = 0.0
IH

Pascoli and Petcov, hep-ph/0310003(best fit νatm + νsol )NEM O-3

QD

Quasi-Degenerate (QD):<mν> > 50 meVInverted Hierarchy (IH):sin2θ13 = 0.02
IH

15 meV < <mν> < 50 meV
Normal Hierarchy (NH):QD
NEM O-3sin2θ13 = 0.04
IH<mν> < 5 meV

2β could give the absolute
neutrino mass

Present limits for different isotopes: direct measurements
IsotopeT1/2(90%CL)(y)<mν>(eV)

Mass (kg.y)

Experiment48Ca> 1.8 1022

< 6.3 - 39.4

0.005

Candle76Ge> 1.9 1025

< 0.35 - 1.05

35.5

76Ge

> 1.57 1025

< 0.3 - 1.1

8.9

IGEX

82Se

> 1.9 1023

< 1.3 - 3.6

0.9

NEMO3

96Zr

> 1.0 1021

< 2.3

0.008

NEMO2

100Mo

> 3.5 1023

< 0.7 - 1.2

7.5

NEMO3

116Cd

> 1.3 1023

< 1.7

0.16

Solotvina

130Te> 1.8 1024

< 0.2 - 1.1

10.8

CUORICINO

136Xe> 4.4 1023

<2-3

2.3

Gotthard

150Nd> 1.2 1021

<3

0.009

TPC M.Moe

HeidelbergMoscou

H.V. Klapdor-Kleingrothaus et al. I Nuclear Instruments and Methods in Physics Research A 522 (2004) 371-406

IGEX experiment116.75 mole.years - 8.87 kg.y

in 76Ge

Running experiments
For mass ≈ 10 kg
Experimentisotope

Mass(kg)

CUORICINO

130Te

11

Bolometer

Gran
Sasso
(Italie)

100Mo

6.9

TrackoCalo

Modane(France)

82Se

0.93

NEMO3

Type
of
detector

Lab.

Expected background (counts/
FWHM.kg.y)

Sensitivity
T1/2 (y)

Limit
<mν>
(eV)

0.5

7 x 1024

0.3

0.3

4 x 1024

0.20-0.35

0.1

8 x 1023

0.65-1.8

NEMO3 Collaboration

CENBG, IN2P3-CNRS Bordeaux University, FranceCharles University, Praha, Czech Republic
CTU, Praha, Czech Republic
INEL, Idaho Falls, USA
INR, Moscow, Russia
IReS, IN2P3-CNRS Strasbourg University, France
ITEP, Moscou, Russia
JINR, Dubna, Russia
Jyvaskyla University, Finland
LAL, IN2P3-CNRS Paris-Sud University, France
LSCE, CNRS Gif sur Yvette, France
LPC, IN2P3-CNRS Caen University, France
Manchester University, Great-Britain
Mount Holyoke College, USA
RRC kurchatov Institute, Moscow, Russia
Saga university, Saga, Japon
UCL, London, Great-Britain

The NEMO3 detector
Fréjus Underground Laboratory : 4800 m.w.e.

Source: 10 kg of ββ isotopes
cylindrical, S = 20 m2, e ~ 60 mg/cm2

Tracking detector:
drift wire chamber operatingin 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 Gauss
Gamma 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+, γ and α

PMTs

Cathodic rings
Wire chamber

Calibration tube

scintillators

ββ isotope foils

Sources preparation

AUGUST 2001

NEMO-3 Opening Day, July 2002

Start taking data 14 February 2003

Water tank
wood

coil
Iron shieldββ decay isotopes in NEMO-3 detector
ββ2ν measurement
116Cd

405 g

Qββ = 2805 keV
96Zr

9.4 g

Qββ = 3350 keV
150Nd

37.0 gQββ = 3367 keV
48Ca

7.0 g

Qββ = 4272 keV
130Te

454 g

Qββ = 2529 keV

100Mo

6.914 kgQββ = 3034 keV

82Se

0.932 kgQββ = 2995 keV

natTe

491 g

Cu

621 g

External bkg
measurement

ββ0ν search (All the enriched isotopes produced in Russia)

ββ events selection in NEMO-3
Typical ββ2ν event observed from 100Mo
Transverse
Transverseview
view

Run
RunNumber:
Number:2040
2040
Event
EventNumber:
Number:9732
Date:
97322003-03-20
Date: 2003-03-20

Vertexemission

100Mo foil

Drift distance

Deposited energy:
E1+E2= 2088 keVInternal hypothesis:(Δt)mes –(Δt)theo = 0.22 ns
Common vertex:Scintillator+ PMT(Δvertex)⊥ = 2.1
mm

LongitudinalLongitudin
view
al
view
100Mo foil

Geiger plasma
longitudinal
propagation
Vertexemission(Δvertex)// = 5.7mm

Trigger:
1 PMT> 150 keV
Criteria
to select
ββ events:• 2 tracks with charge < 30 Geiger hits (2 neighbour layers + 1)
• Internal hypothesis (external event rejection)• 2 PMT, eachTrigger> 200 keV
rate = 7 Hz
• No other isolated PMT (γ rejection)• PMT-Trackββ
association
events: 1 event every
minutes• No1.5
delayedtrack (214Bi rejection)• Common vertex

Background events observed by NEMO-3…

Electron crossing > 4 MeV Neutron capture

Electron + N γ’s

208Tl(Eγ = 2.6 MeV)Electron + α delay track (164 µs) 214Bi → 214Po → 210Pb→
Electron – positron pair B rejection

NEMO3: detector performances
RUN with radioactive sources energy calibration : absolute
207Bi

2e– lines

90Srβ– end point ≈ 2.2 MeV≈ 0.5 ≈ 1 MeV

 time of flight
60Co

γ1, γ2 2 lines ≈ 1.5 MeV

 tracking detector: σT, σ//neutron source(n,γ)

e– > 4.5 MeV

 aging? absolute calibration 207Bi during 2 years

Transversal and Longitudinal Resolution
on the Vertex
207Bi sources at 3 well known positions in each sector(emission of two e- conversion at ≈ 1 and 0.5 MeV)

1 e− channel at 1 Mev:
σ⊥ (1 MeV) = 0.25 cm
σ// (1 MeV) = 0.95 cm(Z=0)

2e- channel (1 MeV+ 0.5 MeV)σ⊥ (1 MeV) = 0.6 cm
σ// (1 MeV) = 1.3 cm(Z=0)

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

976 keVAt 1 MeV (Qββ≈3 MeV for 100Mo and 82Se):
207Bi

FWHM
Ext.Wall

FWHM = 135 keV
482 keV14 %5.8 % /√E(MeV)

17 %

7.1 % /√E(MeV)(PMTs 5")Int. Wall(PMTs 3")σE/E

Absolute calibration: method

Sr90 -> Y 90 spectrum
IC electrons from Bi207

IC electrons f rom Bi207

Single electron ev ents

Electron & electron-gamma ev ents

Geiger cells "of f "Electron & electron - gamma events
Geiger cells "on" -> track selection

Geiger cells “on” → track selection↑↑

482 keV 976 keVQueue of the Y 90 beta spectrum

2282 keVMean resolution (FWHM/E) in %Aging measurements

IN

L3

L1
L2

L4
EE
EC

Time (days)

60Co run: alignment of the 1940 units calo

60Co source
σ = 5.2 ns

σ = 0.66 ns

ϒ1 ϒ2Difference between measured and calculated times (in ns)

Time resolution (in ns) as a function of the electron energy (in MeV), obtained with two-electron events

Performance of the detector

ββ events from the foil

Tracking Detector:

Calorimeter: 99.5 % Geiger cells ONβ 97% of the PMTs+scintillators
are ON- Vertex resolution:
2 e− channels (482 and 976 keV) using 207Bi sources
at 3 well known positions in each sectorσ⊥ (ΔVertex) = 0.6 cm
σ// (ΔVertex) = 1.3 cm(Z=0)

 Energy ΔResolution:
calibrationVertex
runs (every ~ 40 days) with 207Bi
sourcesβExt. Wall
Int.WallExternal
Background5" PMTs3"
PMTs

FWHM (1 MeV)

 e+/e− separation with a magnetic field of 25 G
~ 3% confusion at 1 MeVTime Of Flight:
 Time Resolution (ββ channel) ≈ 250 ps at 1 MeV
ToF (external crossing e− ) > 3 ns
external crossing e− totaly rejected

14%

17%

ΔVertex = distance between the two vertex

 Daily Laser Survey to control gain stability of each PM

(Δ
tm

es
–

Δt
c

976
keV

207Bi
i
nt
Expected
Performanceof thee− detector
(ns)
.
er
2 conversionopna has been reached rnal hy
482 keV and
lh
te
ex976
)
yp
c
– Δt calo. (Δt mkeVes(ns) FWHM = 135
keV
482(13.8%)keValc)

ββ events selection in NEMO-3
Typical ββ2ν event observed from 100Mo
Transverse
Transverseview
view

Run
RunNumber:
Number:2040
2040
Event
EventNumber:
Number:9732
Date:
97322003-03-20
Date: 2003-03-20

Vertexemission

100Mo foil

Drift distance

Deposited energy:
E1+E2= 2088 keVInternal hypothesis:(Δt)mes –(Δt)theo = 0.22 ns
Common vertex:Scintillator+ PMT(Δvertex)⊥ = 2.1
mm

LongitudinalLongitudin
view
al
view
100Mo foil

Geiger plasma
longitudinal
propagation
Vertexemission(Δvertex)// = 5.7mm

Trigger:
1 PMT> 150 keV
Criteria
to select
ββ events:• 2 tracks with charge < 30 Geiger hits (2 neighbour layers + 1)
• Internal hypothesis (external event rejection)• 2 PMT, eachTrigger> 200 keV
rate = 7 Hz
• No other isolated PMT (γ rejection)• PMT-Trackββ
association
events: 1 event every
minutes• No1.5
delayedtrack (214Bi rejection)• Common vertex

a ββ0ν-like event due to Radon from the gas
Run 2220, event 136.604, May 11th 2003

E1+E2= 2880 keV

α track(delay = 70 µs)
214Po → 210Pb
214Bi → 214Po

β decay
IN THE GASEvent selection criteria• Two tracks of negative charge associated to isolated PM• Energy deposit in each scintillator E > 200 keV.
• Event vertex is inside the foil
• Distance track-to-vertex: ΔXY < 4 cm, ΔZ<8 cm;• TOF cut: internal hypothesis probality > 4%, external hypothesis
probability<1%;• Reject events with the alpha particle found using alpha_search means:• if only 1 extra hit in the tracking detector• if at least 2 hits
search for a short track
Δt > 2 µsec only but all hits on timeΔt > 40 µsec
Δxy < 4 cm
ΔZ < 10 cm• Reject events with two tracks at one side of the foil and a geiger
hit in time at the opposite side fo the foil close to the vertex: Möller
scattering of β decay in gas (Radon).

vertex

100Mo 2β2ν preliminary results(Data Feb. 2003 – Dec. 2004)

Sum Energy Spectrum
NEMO-3

100Mo

219 000 events
6914 g389 days
S/B = 40

• Data2β2νMonte Carlo
Backgroundsubtracted

Angular Distribution
NEMO-3100Mo• Data219 000 events
6914 g389 days
S/B = 402β2νMonte Carlo
Backgroundsubtracted

E1 + E2 (keV)
7.37 kg.y

T1/2 = 7.11 ± 0.02 (stat) ± 0.54 (syst) × 1018 y

Cos(θ)

100Mo 2β2ν Single Energy Distribution
Single electron spectrum different
between SSD and HSD

HSD, higher levels
contribute to the decay

1+
100Tc

SSD, 1+ level

Simkovic,
J. Phys. G, 27, 2233, 2001

dominates in the decay(Abad et al., 1984,
Ann. Fis. A 80, 9)

0+
100Mo

Esingle (keV)

NEMO-3

4.57 kg.y

4.57 kg.y

NEMO-3E1 + E2 > 2 M eV

E1 + E2 > 2 M eV

• Data• DataHSDhigher levels

χ2/ndf = 139. / 36

2β2ν HSD
Monte Carlo
Backgroundsubtracted

Esingle (keV)SSD
S ingle S tate2β2ν SSD
Monte Carlo
Backgroundsubtracted

χ2/ndf = 40.7 / 36
Esingle (keV)

HSD: T1/2 = 8.61 ± 0.02 (stat) ± 0.60 (syst) × 1018 y

100Mo 2β2ν single energy distribution

SSD: T1/2 = 7.72 ± 0.02 (stat) ± 0.54 (syst) × 1018 y

in favour of Single State Dominant (SSD) decay2β2ν preliminary results for other nuclei
NEMO-382Se

932 g
389 days
2750 events
S/B = 4

• Data2β2νMonte Carlo
Backgroundsubtracted

82Se

T1/2 = 9.6 ± 0.3 (stat) ± 1.0 (syst) × 1019 y

116Cd

T1/2 = 2.8 ± 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

Background subtracted
E1+E2 (keV)

NEMO-3

116Cd

405 g
168.4 days
1371 events
S/B = 7.5

NEMO-3150Nd

37 g
168.4 days
449 events
S/B = 2.8

NEMO-396Zr

5.3 g
168.4 days
72 events
S/B = 0.9

Data

Data

Data

ββ2ν
simulation

ββ2ν
simulation

ββ2ν
simulation

E1+E2 (MeV)

E1+E2 (MeV)

E1+E2 (MeV)Ca48 analysis 1st preliminary result
Hideaki Ohsumi analysis

 why 2β2ν 48Ca: test of the shell model calculation

 7g of 48Ca enough radiopure after chemistry 214Bi, 208Tl but 30m Bq of 90Sr!
pure beta emitter criteria to remove Möller scattering E1 and E1 > 0.7 MeV
cosθ < 0 back to backT1/2 = 3.4 ± 1.2 1019 years

Esmall > 0.2 MeV+ Data– 2νββ MC– 90Y MC
– 0.1× (Cu – Bkg)

result 35 events background 2

Esmall > 0.7 MeV cos(θ)<0.0

Search for 2β0ν decay in NEMO-3

Origin of Background at high energy
Two natural isotopes which have the greatest Qβ values > 3 MeV:
214Bi : Q ≈ 3.27 MeVβ
208Tl : Q ≈ 4.99 MeVβDesign 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 (30 tons) ≈ 1120 Bq

40K

= 800

214Bi = 300
208Tl =

20

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

How NEMO-3 tags the background Electron and positron 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 µs) to tag delayed α from Bi207
214Bi → 214Po (164 µs) → 210Pb

ββ0ν Analysis: Background Measurement
NEMO-3 can measure each component of its background !
 External Background 208Tl (PMTs)
Measured with (e−, γ) external events~ 10−3 ββ0ν-like events year−1 kg −1 with 2.8<E1+ E2<3.2 MeV
 External Neutrons and High Energy gamma
Measured with (e−,e−)int events with E1+E2 > 4 MeV−1−1~< 0.02 ββ0ν-like events year kg with 2.8<E1+ E2<3.2 MeV

 208Tl impurities inside the foils
Measured with (e−,2γ), (e−,3γ) events coming from the foil
~ 0.1 ββ0ν-like events year−1 kg −1 with 2.8<E1+ E2<3.2 MeV

Only 2 (e−,e−)int events with E1+E2 > 4 MeV
observed after 260 days of data (without boron)
4253 keV (26 Mar. 2003)
6361 keV (8 Nov. 2003)
In agreement with expected backgroundsources
100Mo

A (µBq/k)
A (µBq/k)−from(e ,Nγ) HPGe meas.
92 ± 18

metal.
100Mocomp. 115 ± 13
82Se
316 ± 46

< 110
< 100
400 ±100

In agreement with HPGe measurements

 100Mo ββ2ν decay T1/2 = 7.7 1018 y (SSD)~ 0.3 ββ0ν-like events year−1 kg −1 with 2.8<E1+E2<3.2 MeV

ββ0ν Analysis: Background Measurement
Radon in the NEMO-3 gas of the wire chamber
Due to a tiny diffusion of the radon of the laboratory inside the detector
A(Radon) in the lab ~15 Bq/m3

Two independant measurements of radon in NEMO-3 gas
 Radon detector at the input/output of the NEMO-3 gas

β−

214

α

Bi → 214Po (164 µs) → 210Pb

222Rn (3.8 days)~ 20 counts/day for 20 mBq/ m3

 (1e− + 1 α) channel in the NEMO-3 data:
Delayed tracks (<700 µs) to tag delayed α from 214Po
214Bi → 214Po (164 µs) → 210Pb~ 200 counts/hour for 20 mBq/m3

Good agreement between the two measurements

218Po

β

Decay
in gas 214Bi

214Pb

A(Radon) in NEMO-3 ≈ 20-30 mBq/m3~ 1 ββ0ν-like events/year/kg with 2.8 < E1+E2 < 3.2 MeV

Radon is the dominant background today
for ββ0ν search in NEMO-3 !!!

214Po

β−
α

delayedα

164 µs210Pb

Limit on the effective mass of the Majorana neutrino
Phase 1 (Feb. 2003 – Sept. 2004: 1.08 y of data) with radon bkg(limits @ 90% CL)
100Mo (6.914 kg)

T1/2

82Se (0.932 kg)(ββ0ν) > 4.6 1023 y

T1/2(ββ0ν) > 1.0 1023 y〈mν〉 < 0.66 – 2.81 eV〈mν〉 < 1.75 – 4.86 eV

100Mo

Cu+natTe+130Te
In agreement with only
Radon bkg expected

82Se[2.8-3.2] MeV: ε(ββ0ν) = 8 %Expected bkg = 8.1 ± 1.3
Nobserved = 7 events

Previous limits: T1/2(ββ0ν) > 5.5 1022 y
Ejiri et al. (2001)[2.7-3.2] MeV: ε(ββ0ν) = 13 %Expected bkg = 3.1 ± 0.6
Nobserved = 5 events

Previous limits: T1/2(ββ0ν) > 9.5 1021 y
Arnold et al. (1992)

Nuclear Matrice Elements Ref: Simkovic (1999), Stoica (2001), Suhonen (1998,2003), Rodin (2005), Caurier (1996)

Limit on Majoron and V+A
Phase 1 (Feb. 2003 – Sept. 2004: 1.08 y of data) with radon bkg(limits @ 90% CL)

Limit on Majoron
100Mo:

T1/2 (ββ0νΜ) > 1.8 1022 y

82Se:

gM < (5.3 – 8.5) 10−5 (best limit)

T1/2 (ββ0νΜ) > 1.5 1022 y
gM < (0.7 – 1.6) 10−4

Simkovic (1999), Stoica (1999)

Simkovic (1999), Stoica (2001)

Limit on V+A
100Mo:

T1/2 (ββ0ν V+Α) > 2.3 1023 y
λ < (1.5 – 2.0) 10−6
Tomoda (1991), Suhonen (1994)

82Se:

T1/2 (ββ0ν V+Α) > 1.0 1023 y
λ < 3.2 10−6
Tomoda (1991)

Radon was the dominant backgroundfor ββ0ν search in NEMO-3
Radon in the NEMO-3 gas of the wire chamber
Due to a tiny diffusion of the radon of the laboratory inside the detector
A(Radon) in the lab ~15 Bq/m3

Two independent measurements of radon in NEMO-3 gas
 Radon detector at the input/output of the NEMO-3 gas−
α214Bi β→ 214Po (164 µs) → 210Pb

222Rn (3.8 days)~ 20 counts/day for 20 mBq/ m3

 (1e− + 1 α) channel in the NEMO-3 data:
Delayed tracks (<700 µs) to tag delayed α from 214Po
214Bi → 214Po (164 µs) → 210Pb~ 200 counts/hour for 20 mBq/m3

Good agreement between the two measurements

218Po

β

Decay
in gas 214Bi

214Pb

A(Radon) in NEMO-3 ≈ 20-30 mBq/m3~ 1 ββ0ν-like events/year/kg with 2.8 < E1+E2 < 3.2 MeV

214Po

β−
α

delayedα

164 µs210Pb

Free-Radon Purification System
May 2004 : Tent surrounding the detector

1/2Free-Radon Air factory
Starts running Oct. 4th 2004
in Modane Underground Lab.
1 ton charcoal @ -50oC, 7 bars
Activity: A(222Rn) < 15 mBq/m3 !!!
Flux: 125 m3/h a factor 1000

Radon purification of the air surronding the detector- Results  A(Radon) in the lab………………………………….. ~15 Bq/m3
 A(Radon) in the tent after flushing free-radon air……

~ 5 Bq/m3⇓• source of radon inside the tent
• ground and electronics degasing• 20-21 oct. 2004: the detector has been roughly isolated
from the ground and electronics⇓
 A(Radon) in the upper part, surrounding the detector... ~ 0.15 Bq/m3
air flux: 125 m3/h

Activity of Radon surrounding the detector
has been reduced by a factor ~ 100Radon level inside the detector- Results Level of radon measured inside the wire chamber,by analysing (1e− + 1 α) channel in the NEMO-3 data
Without tent: A ~ 1.5 Bq

Residual level toAfter flushing radon-free air
inside the tent: A ~ 0.15 Bq

be understoodsources ?

0

17

Radon level reduced by a factor of 10
Thanks a lot to S.K especially

40
Time (days)

M.Nakahata,S.Tasaka

NEMO-3 Expected sensitivity
Background
External Background: negligible
Internal Background:

208Tl :

60 µBq/kg for 100Mo
300 µBq/kg for 82Se
214Bi : < 300 µBq/kg~ 0.1 count kg−1 y −1 with 2.8<E1+E2<3.2 MeV

ββ2ν 100Μο: T1/2 = 7.14 1018 y~ 0.3 count kg−1 y −1 with 2.8<E1+E2<3.2 MeV

in 2009 after 5 years of data
6914 g of 100Mo

T1/2(ββ0ν) > 4 1024 y (90% C.L.)<mν> < 0.2 – 1.3 eV

932 g of 82Se

T1/2(ββ0ν) > 8 .1023 y<mν> < 0.6 – 1.7 eV(90% C.L.)

Nuclear Matrice Elements Ref: Simkovic (1999), Stoica (2001), Suhonen (1998,2003), Rodin (2005), Caurier (1996)

Prospects•

We live a « prenatal period » for the double beta decay experiments ≈ 10 kg ofisotopes NEMO3 ≈ 0.2 eV 100Mo with a small background
CUORECINO ≈ 0.2 eV 130Te, the background would be improved soon
76Ge ≈ 0.3 eV with backgrounds•

NEMO3 phase 2 : a zero background exp. with 10 kg 82Se or a dream 10 kg of
150Nd

•

76Ge experiment : a 10 kg exp. backgrounds would be improved: GERDA• then experiments with at least 100 kg of isotope to reach<mν> ≈ a few 10 meV

Projects near future: 10 years
Lab.

Background(counts FWHM
Kg.y)

Sensitivity
T1/2(y)Limit

Comment

Bolometer

Gran
Sasso

0.001

3 x 1026

0.015-0.090

R&D start

15

Ge
Detector

Gran
Sasso

0.01

3 x 1025

0.3-0.9

2006

100

Ge
Detector

Gran
Sasso

0.001

2 x 1026

0.090.29

2009

100

Tracko-Calo

?

0.002

2 × 10 26

0.03-0.06

R&D
2005→ 2007

500

Ge
Detector?

0.01

4 10270.0340.039

for 10 years of
running

0.015
0-0.0018

21026
8.3 x 1026

0.39-1.2
0.0510.14

Start 2005?

0.2-0.3
0.03

R&D inprogress

0.5

start

isotope

Mass
kg

Type ofdetector

CUORE

130Te

200

GERDA phase I

76Ge

GERDA phase II

76Ge

Experiment

Super NEMO
Majorana

82Se ou
150Nd
76Ge

EXO

136Xe

200
1000

TPC

WIPP
(US)

MOON

100Mo

10
1000

Tracko-calo?

CANDLES

48Ca

0.180

CaF2
(200kg)10

CdZnTeOtho(Japon)Boulby
U.K

COBRA

130Te
116Cd

DCBA

150Nd

20

TPC

?

XMASS

Xe

800

Calo.

Kamioka

10

27

0.3
0.2, 0.03

1 x 1024

0.7
0.05

R&D inprogress
R&D inprogress
R&D inProgress
100 kgWhat we learnt with NEMO3• to identify and measure all the sources of background• to build a very low-background detector• to prove the reliability of the chosen techniques• to purify ββ isotopes by removing parents of 214Bi, 208Tl• to remove background due to Radon (recently)• to develop ultra low background H P Ge detectors
technique can be extrapolated
R&D program approved recently in France
3 years: 2005, 2006, 2007

From NEMO to SuperNEMO
Factor 100 on the ββ(0ν) period T1/2, reach few 1026 years
Light Majorana neutrino exchange: <mν> ~50 meV
Detection efficiency

Mass of isotope ββ (g)

m
m .t
ε
ε
ln2
.
N
(y)
T 1/2 >
.
.
N
R
NBDF
kC.L.
A
BDF . R
0!

Background (y-1. g-1. keV-1)

N : Avogadro Number
kC.L. =1,6 à 90% C.L.
A : Mass numbert : measurement time (y)FWHM (keV)

Mass~100 kg
Resolution(FWHM): ~ 7 % at 3 MeV (will be dominated by source foil)
instead of ~ 11 % at 3 MeV for NEMO 3 (dominated by calorimeter)

Efficiency
improvement by a factor 2
Backgroundinternal contaminations in 208Tl and 214Bi to be improved by a factor of 10

SuperNEMO preliminary design
Plane geometry
Source (40 mg/cm2) 12m2 , tracking volume (~3000 channels) and calorimeter (~1000 PMT)
Modular (~ 5 kg of enriched isotope/module)
100 kg: 20 modules~ 60 000 channels for drift chamber~ 20 000 PMT
4m
1m

5m

Top view

Side view

Water shield

1,5m

1,5m

Need of cavity of ~ 60m x 15m x15m
Possible in Gran Sasso or in Modane if a new cavity

-1T½ = F.|M|2x0.12

Choice of the nucleus

Suhonen Neutrino 2004

No strong theoritical criteria. Nucleus choice depends on:- enrichment possibilities- experimental technics-Q
ββ value (phase space factor, background)Qββ
Isotopic(MeV) AbundanceR&D for the source of 82Se
Goal: To be able to produce 100 kg of 82Se with internal contaminations less than
2 µBq/kg in 208Tl and 10 µBq/kg in 214Bi (60 decays/year)
Production: 5kg of 82Se funded by ILIAS
100 kg possible
Development of ICR for enrichment ?

Purification: 2x100 g natSe already processed at INEEL
5kg of 82Se funded by ILIAS
1kg of 82Se
2005
82
2kg of Se
2006
82
5kg of Se
2007

then radiopurety measurements to qualify theprocess
1) H P Ge
2) device "à la NEMO"

Thickness: ~250 m2 with 40 mg/cm2 thickness
Participants: CENBG, LAL, LSCE (France)
ITEP, Kurchatov, JINR (Russia)
INEEL, MHC (USA)(6% (FWHM) at 3 MeV)

Conclusion
 NEMO3 is running for ≈ 5 years
 R&D program for SuperNEMO 2005, 2006, 2007 a real challenge !
 Coordination started at the European level (ILIAS)
 Neutrinoless double beta decay can be one of the experimental
key for understanding neutrino physics: a long way but promising ?

Thank you

Serge Jullian, LAL, Paris–Sud University
jullian@lal.in2p3.fr