Double Beta Decay review
Fabrice Piquemal
Laboratoire Souterrain de Modane (CNRS/IN2P3-CEA/DSM)
and CENBG, University Bordeaux 1 CNRS/IN2P3
NNN 2010, Toyama Dec,14-16 2010
Thanks to: G. Gratta, S., A. Giuliani, S. Schoenert,
T. Kishimito, M. Nomachi, K. Zuber, M. Chen, K. Inoue
Double Beta decay: physics case
(A,Z)  (A,Z+2) + 2e-
- Leptonic number violation
- Nature of neutrino : Dirac (n n) or Majorana (n =n)
- Absolute neutrino mass and neutrino mass hierarchy
- Right-handed current interaction
- CP violation in leptonic sector
- Search of Supersymmetry and new particles
Double Beta decays
Single beta decay forbidden (energy)
or strongly suppressed by large angular
momentum change
bb
Decay to ground state or excited states
e-
bb(0n)
bb(2n)
e-
e-
e-
n
n
2nd order process of weak interaction
Already observed for several nuclei
DL =2
bb(0n)  Majorana neutrino (n=n)
Neutrinoless Double Beta decay
(A,Z)
(A,Z+2) + 2 e-
Discovery implies DL=2 and Majorana neutrino
Phase space factor
-1
Nuclear matrix element
5
T1/2= F(Qbb,Z) |M|2 <mn>2
Effective mass:
<mn>= m1|Ue1|2 + m2|Ue2|2.eia1 + m3|Ue3|2.eia2
|Uei|: mixing matrix element
a1 et a2: Majorana phase
Process
Light neutrino exchange
(V+A) current
Majoron emission
SUSY
parameters
<mn>
<mn>,<l>,<h>
<gM>
l’111,l’113l’131,…..
bb(0n) observables
bb(2n)
bb(0n)
Electron energy sum
Mass
mechanism
RHC
Angular distribution
From G. Gratta
Mass
mechanism
RHC
Ee1 – Ee2 distribution
150Nd distribution s arxiv: 1005.1241v1 [hep-ex]
Why so many experiments or projects ?
Experiments
Isotopes
Techniques
Main caracteristics
NEMO3
100Mo,82Se
Tracking + calorimeter
Bckg rejection, isotope choice
SuperNEMO
82Se, 150Nd
Tracking + calorimeter
Bckg rejection, isotope choice
Cuoricino
130Te
Bolometers
Energy resolution, efficiency
CUORE
130Te
Bolometers
Energy resolution, efficiency
GERDA
76Ge
Ge diodes
Energy resolution, eficiency
Majorana
76Ge
Ge diodes
Energy resolution, efficiency
ZnCdTe semi-conductors
Energy resolution, efficiency
COBRA
130Te, 116Cd
EXO
136Xe
TPC ionisation + scintillation
Mass, efficiency, final state signature
MOON
100Mo
Tracking + calorimeter
Compactness, Bckg rejection
CANDLES
48Ca
CaF2 scintillating crystals
Efficiency, Background
SNO++
150Nd
Nd loaded liquid scintillator
Mass, efficiency
XMASS
136Xe
Liquid Xe
Mass, efficiency
CARVEL
48Ca
CaWO4 scintillating crystals
Mass, efficiency
Yangyang
124Sn
Sn loaded liquid scintillator
Mass, efficiency
DCBA
150Nd
Gazeous TPC
Bckg rejection, efficiency
Double beta decay isotopes
Isotope
Qbb (MeV)
Abondance
isotopique
(%)
48Ca
4.271
0.187
2.44
Laser ?
76Ge
2.040
7.8
0.24
Centrifugation
82Se
2.995
9.2
1.08
Centrifugation
96Zr
3.350
2.8
2.24
Laser ?
100Mo
3.034
9.6
1.75
Centrifugation
116Cd
2.802
7.5
1.89
Centrifugation
130Te
2.528
33.8
1.70
Centrifugation
136Xe
2.479
8.9
1.81
Centrifugation
150Nd
3.367
5.6
8.00
Laser ?
Centrifugation ?
G0n(an-1)
x 1025
Enrichment
method
Nuclear Matrix Element
arXiv:1008.5260v2 : Tomás R. Rodríguez, G. Martinez-Pinedo
Background components
2.614 MeV
Highest gamma-ray
from natural radioactivity
76Ge
2
76Xe 130Te
100Mo
150Nd
82Se
96Zr
3
48Ca
4
Natural radioactivity (40K, 60Co,234mPa, external 214Bi and 208Tl…)
214Bi and Radon, 208Tl (2.6 MeV g line) and Thoron, g from (n,g) reaction and muons bremstrahlung
+ bb(2n) for tracko-calo or calorimeter with modest energy resolution
+ for pure calorimeter Surface or bulk contamination in a emitters, cosmogenic production
5
Qbb MeV
Experimental sensitivity
T
0n
1/ 2
e
(y) 
A
M: masse (g)
e : efficiency
KC.L.: Confidence level
N: Avogadro number
Calorimeter
Semi-conductors
Bolometers
Source = detector
M .t
NBckg . DE
t: time (y)
NBckg: Background events (keV-1.g-1.y-1)
DE: energy resolution (keV)
Tracko-calo
Calorimeter
(Loaded) Scintillator Source  detector
Source = detector
b
b
b
b
e, DE
<mn >  M1/4
e, M
Xe TPC
Source = detector
b
b
b
NBckg, isotope choice
b
e,M, (NBckg)
Calorimeter vs Tracko-calo
Tracko-calo
Calorimeter
High energy resolution
Modest background rejection
High background rejection
Modest energy resolution
bb(0n)
bb(0n)
keV
bb(0n)
bb(0n)
keV
MeV
Why so many experiments or projects ?
What is the most favorable isotope and the best technique ?
 Phase space factor: 48Ca, 150Nd, 96Zr
 Nuclear matrix element  not yet reliable predictions
48Ca, 150Nd, 96Zr, 100Mo, 82Se, 116Cd
 Backgrounds > 2,6 MeV
> 3.2 MeV (radon) 48Ca, 150Nd, 96Zr
 Enrichment: 130Te (Natural isotopic abundance 34%)
136Xe (gaz, easy to enrich)
Best techniques :
 Bolometers, Ge diodes: energy resolution 130Te (82Se, 116Cd), 76Ge
 Tracko-calo : background rejection 82Se, (48Ca, 150Nd)
 TPC Xe: background rejection if tagging of Ba 136Xe
 Large liquid scintillator: mass of isotopes 136Xe, 150Nd
A problem to understand: the background at ~100 kg
(related to istopes and techniques)
Effective neutrino mass and q13
Isotope
mass
~ 10 kg
Required background level
2011
~ 1000 kg
|mee|
~ 100 kg 2015
100 – 1000 cts/yr/ton
1 – 10 cts/yr/ton
0.1 – 1 cts/yr/ton
Heidelberg-Moscow (2001)
~11 kg of enriched Ge
bb(0n) ?
S T Petcov 2009 J. Phys.: Conf. Ser. 173 012025
This experimental review will be focused on the
last results of 10 kg and 100 kg experiments
bb(0n) : experiments and projects
NEMO3/SuperNEMO (82Se, 150Nd, 48Ca)
NEXT (136Xe)
SNO++ (150Nd)
DCBA (150Nd)
EXO (136Xe)
Majorana (76Ge)
EXO gaz (136Xe)
Cuoricino/CUORE (130Te)
GERDA (76Ge)
COBRA (116Cd)
Calorimeter
Source = detector
CANDLES (48Ca)
KamLAND-ZEN (136Xe
MOON (100Mo)
Tracko-calo
Source  detector
b
b
b
b
bb(0n): Present situation
Ge diode detectors
Heidelberg-Moscow (2001)
~11 kg of enriched 76Ge (86%)
35.5 k.yr
IGEX (2002)
~ 8.4 kg of enriched 76Ge (86%)
8.9 kg.yr without PSA
4.6 kg.y with PSA
0.06 cts/keV/kg/yr
T 1/2 >1.9 1025 yr (90% CL)
T 1/2 >1.57 1025 yr (90% CL)
<mn> <0.35-1.05 eV (90% CL)
<mn> <0.33-1.31 eV (90% CL)
Eur. Phys. J., A 12 (2001) 147
Phys. Rev. D65 (2002) 092007
Cuoricino
Bolomètres: CUORICINO
Bolometers of TeO2
Heat sink
Thermometer
Double beta decay
Crystal absorber
Stopped in 2008
DE/E ~ 8 keV at 2 527 keV
Located in Gran Sasso Laboratory (Italy)
Bolomètres: CUORICINO
Cuoricino
results
CUORE
CUORE
(Italy, USA,Spain)
750 kg of TeO2  203 kg of
130
Te
Array of 988 TeO2 5x5x5 cm3 crystals
Improvement of surface event rejection
Goal :Nbckg=0.01 cts.keV-1.kg-1.yr-1
(Factor 20 compared to Cuoricino)
Nbckg=0.01 cts.keV-1.kg-1.yr-1
LUCIFER:
R&D on scintillating bolometers like 82Se
116CdWO
4
T½ > 2.1 1026 yr
Test of 1 tower of CUORE in Cuoricino in 2011
Expected sensitivity
<mn> < 0.03 – 0.17 eV
Data taking foreseen in 2013
NEMO 3
Tracko-calo detector
Drift chamber (6000 cells)
Plastic scintillator + PMT (2000)
10 kg of isotopes
DE/E (FWHM) : 8 % @ 3 MeV
Located in Modane Underground Lab (France)
Bckg: 0.025 cts/keV/kg/yr
Multi-source detector
E1
bb sources (thickness  0 mg/cm2)
e-
Vertex
bb(2n)
eBckg
E1+E2= 2088 keV
Dt= 0.22 ns
(Dvertex) = 2.1 mm
bb events
E2
82Se
(0,93 kg)
NEMO 3 Results
100Mo,
23.4 kg.yr 620 000 events
Bosonic fraction of
neutrino wave function
Sin c < 0.6
NEMO 3 Results
NEMO 3 Results
From NEMO 3 to SuperNEMO
T1/2 (bb0n) > ln 2 
NA
A

M  e  Tobs
N90
SuperNEMO
NEMO-3
100Mo
isotope
7 kg
isotope mass M
15 %
efficiency e
,
82Se 150Nd
or 48Ca
100 kg
~ 30 %
< 20 mBq/kg
214Bi: < 300 mBq/kg
internal contaminations
208Tl and 214Bi in the bb foil
< 2 mBq/kg
if 82Se: 214Bi < 10 mBq/kg
8% @ 3MeV
energy resolution (FWHM)
4% @ 3 MeV
208Tl:
T1/2(bb0n) > 2 x 1024 y
<mn> < 0.3 – 1.3 eV
208Tl
T1/2(bb0n) > 1026 y
<mn> < 50 – 110 meV
SuperNEMO conceptual design
20 modules for 100 kg
Source (40 mg/cm2) 12m2
Tracking (~2-3000 Geiger cells).
Calorimeter (500 channels)
Total:~ 40 000 – 60 000 geiger cells channels
~ 10 000 PMT
1m
5m
Top view
SuperNEMO
DE/E < 4% (FWHM) @ Qbb demonstrated
Commissioning of wiring robot
(< 8% @ 1 MeV)
FWHM = 7,1 %
(7,6% before energy
loss correction)
SuperNEMO phase I : 2011 – 2014
Contruction demontrator module with 7 kg of 82Se (1 kg of 48Ca ?)
Commissing @LSM 2013
Sensitivity in 1 year: T1/2 < 5 1024 y <mn> < 0.2 – 0.6 eV
SuperNEMO phase II : 2014 – 2019
100 kg of 82Se (or 150Nd,or 48Ca)
T1/2 > 1026 y <mn> < 0.05 – 0.14 eV
SuperNEMO @ LSM extension
Ge detector improvements
Strategies: Ge detectors in liquid nitrogen to remove materials
Active shielding and segmentation of detectors to
reject gamma-rays
crystal anti-coincidence
detector
Detector segmentation
segments
e-
g
pulse shape analysis
R&D: liquid argon anti-coincidence
Liquid argon
e-
scintillation
GERDA
Removal of matter
Use of liquid nitrogen or argon for
active shielding
Segmented detectors in futur
Improvement of Pulse Shape Analysis
PHASE I: 17.9 kg of enriched 76Ge (from HM and IGEX)
In 1 year of data if B=10-2 cts/keV/kg/yr (check of Klapdor’s claim)
Start 2011 at Gran Sasso
T1/2 > 3 1025 yr
<mn> < 0.25 eV
PHASE II: 40 kg of enriched 76Ge (20 kg segmented) 2012
if B=10-3 cts/keV/kg/an T1/2 > 2 1026 yr in 3 years of data <mn> < 0.1 eV
GERDA
• Nov/Dec.’09: Liquid argon
fill
• Jan ’10: Commissioning of
cryogenic system
• Apr/Mai ’10: emergency
drainage tests of water tank
• Apr/Mai ’10: Installation clock
• May ’10: 1st deployment of
FE&detector mock-up
• June ‘10: Commissioning
with natGe detector string
• Soon: start Phase I physics
data taking
Majorana
(USA, Russia, Japan)
Ge diodes
Very pure material
(Electroformed copper)
Segmentation
PSD improvement
R&D phase 30-60 kg of 86% enriched 76Ge crystals
Some of the crystals segmented
Bckg goal ~ 1 count/ROI/t-yr (after analysis cuts)
30 kg of enriched Ge, running 3 yr. Data taking scheduled for 2011
T1/2 > 1. 1026 yr
<mn> < 0.14 eV (could confirm or refute Klapdor’s claim)
Collaboration with Gerda for 1 ton detector
EXO - 200
(USA, Canada, Switzerland, Russia)
Liquid Xe TPC
Ionization + scintillation
DE/E (FWHM)= 3.3 % @Qbb
Possibility of Baryum ion tagging by
Laser florescence (136Xe  136Ba++ + 2 e
R&D in progress
Gazeous TPC R&D
200 kg of 136Xe, no Ba ion tagging
Installation in WIPP underground lab
Possibility to measure bb(2n)
EXO-200 full of natural Xe
- Tuning on all systems
- Engineering runs
- Physics mode as soon as possible
SNO++
Scintillator loaded with Nd.
500 kg of 150Nd
1 year
<mn> = 150 meV
Test of light attenuation
Study of Nd purification (factor 1000
per pass in Th and Ra)
56 kg of 150Nd (0,1 % of natural Nd)
500 kg of 150Nd 4yr <mn> ~ 0.03 eV
only internal Th
and 8B solar
neutrino
backgrounds
are important
4 yr of data <mn> ~0.08 eV
KamLAND-Zen
CANDLES
(Japan)
Pure CaF2 crystals
Liquid Scintillator
(Veto Counter)
Wave length shifter in LS
PSD to reject g and a
CaF2(Pure)
Buffer Oil
Large PMT
CANDLES III
103 cm3 × 96 crystals  305 kg
Data taking in 2011 @ Kamioka
Expected BG: 0.14 event/yr (30 µBq/kg)
<mn> ~0.5 eV
CANDLES IV : 3 tons of CaF2 (3 mBq/kg) 6 yr <mn> ~0.1 eV
DCBA
Drift Chamber beta-ray Analyser
Prototype with 207Bi :
10% (FWHM) energy resolution
X position s= 0.5 mm
Y position s= 0.02 mm
X position s= 6 mm
COBRA
(UK, Germany, Italy, poland, Slovaquia, Finland, USA)
Array of 1cm3 CdZnTe detectors
Cd-113 beta decay
with half-life of
about 1016 yrs
4x4x4 detector array = 0.42 kg CdZnTe
Installed at LNGS
Test of coincidence rejection
Measure of 113Cd
Sensitivities 2013 - 2018
Technique
EXO
GERDA
Location
Liquid Xe
136Xe
WIPP
(USA)
Diode Ge
76Ge
Gan sasso
(Italy)
CUORE-0
CUORE
SN module0
Mass
kg
start
Cts/keV/kg/yr
T1/2(0n)
<mee>
meV
200
2011
0.002
6.4 1025
< 109 – 135
18
2011
0.01
3. 1025
< 250– 380
40
2012
0.001
3. 1026
< 80 - 120
0.12
8. 1025
<100 - 200
2.1 1026
6.5 1026
< 41 -82
< 23- 47
< 200 –600
13
Bolometers
130Te
Gan sasso
(Italy)
Tracko-calo Modane
82Se, 150Nd
(France)
SuperNEMO
2011
Bckg
200
2013
0.01
0.001
7
2013
0.0001
6. 1024
100
2015
0.0001
1026
SNO+
Liq. Scint.
150Nd
SNOLAB
(Canada)
44
2012
KamLAND
Liq. Scinti
136Xe
Kamioka
(Japan)
400
2011
(2yr)
(1yr)
< 53 – 140
< 100
< ~ 60
(2 yr)
Summary
Present 10 kg experiment reach a sensitivity <mn> < 0.3 – 1 eV
Background ~100 – 1000 cts/ton/yr
1OO kg experiments will reach a sensitivity on <mn> < ~50 meV in the next 5 yr
Background ~ 1 – 10 cts/ton/yr
(Remark: to win a factor 10 on bckg it takes 5 – 10 yrs)
Step by step approach: GERDA, MAJORANA, CUORE, SuperNEMO
Agressive approach (no 10 kg prototype): EXO, SNO++, KamLAN-Zen, NEXT
Possibility to enrich 150Nd, 96Zr or 48Ca in the futur ?
100 kg experiments essential to validate technique and background
for 1 ton experiments
100 kg experiments
Step by step approach
GERDA Ge diode in LAr
CUORE 130Te bolometers
Gran Sasso laboratory
Gran Sasso laboratory
2010: 18 kg of 76Ge
(HM and IGEX crystals)
CUORE-0 39 kg of natTe
13 kg of 130Te
Data taking 2011
1st results 2011
+ Energy resolution
2012: 40 kg of 76Ge
MAJORANA Ge segmented Diode
DUSEL laboratory
2011: 20 kg of natGe
2013 ? : 30 kg of 76Ge
+ Energy resolution
+ Energy resolution
+ Natural Te
CUORE 200 kg
Data taking 2013
(scintillating bolometres ?)
SuperNEMO tracko-calo
Modane laboratory
Module-0
7 kg of 82Se (150Nd)
Data taking 2013
+ Background rejection 20 Module 100 kg
Data taking 2015
+ Multi-isotopes
100 kg experiments
Agressive approach (no 10 kg prototype)
EXO liquid Xenon
WIPPL laboratory
2010: 200 kg of 136Xe
Results 2013
Ba tagging R&D
+ Large mass
+ Possibility to tag daughter nucleus
KamLAND-Zen Xe + liq. scintillator
SNO++ Nd salt + liquid scintillator
SNOLAB laboratory
2010: 740 kg of natNd
(44 kg of 150Nd)
Dissolved in scintillator
+ Large mass
+ low background detector
NEXT Xe high pressure TPC
Canfranc laboratory
Kamioka laboratory
2011: 1 kg of 136Xe
2011: 400 kg of 136Xe
Dissolved in
liq. scintillator
+ Large mass
2013 : 100 kg
+ Background rejection
bb(0n) signal ? HM claim
2006: Improvement of PSA (6s)
2004 (4s)
T1/2 = (0.69 – 4.18) 1025
<mn> = 0.28-0.58 (90%)
T1/2 = 2.23
+0.44
1025 yr
-0.31
<mn> = 0.32 ± 0.03 eV
Nuclear Matrix Element
arXiv:1008.5260v2 : Tomás R. Rodríguez, G. Martinez-Pinedo
From F. Simkovic (neutrino 2010)