1. CENBG, University Bordeaux 1 CNRS/IN2P3
Beta decay experiments
Fabrice Piquemal
CENBG, University Bordeaux 1 CNRS/IN2P3
and LSM (CEA – CNRS)
Double beta decay and tritium experiments, current and future
Thanks to: G. Gratta, S. Elliot, A. Giuliani, S. Schoenert,
Ch. Weinheimer,T. Kishimito, M. Masaharu
F. Piquemal (CENBG) LP07

2. Beta decays: physics case
- Absolute neutrino mass and neutrino mass hierarchy (SDB, DBD)
Nature of neutrino : Dirac (n n) or Majorana (n =n) (DBD)
Right-handed current interaction (DBD)
CP violation in leptonic sector (DBD)
Search of Supersymmetry and new particles (DBD)
SDB: Single beta decay
DBD: Double beta decay
F. Piquemal (CENBG) LP07 Daegu August 2007

3. Accelerators (K2K,Minos)
Neutrino properties
Oscillations
Atmospheric (SK)
Accelerators (K2K,Minos)
Reactors (CHOOZ)
Accelerators (JPARC)
Solar (SNO, SK)
Reactors (KamLAND) U
,b : CP Majorana phase
tan223=1.0 ± sin2213 < tan212=0.39 ± 0.05
CP= CP Dirac phase
m2atm = m231 = (2.3  0.2 ) 10-3 eV2
m2sol = m212 = (7.9  0.3) 10-5 eV2
F. Piquemal (CENBG) LP07 Daegu August 2007

4. Neutrino mass Absolute mass ? Beta decay mv = S |Uei| mi <2.3 eV
1/2 2 2
Beta decay mv = S |Uei| mi <2.3 eV
Double beta decay |<mn>| = |SUei mi| < eV
Cosmology mi = m1+m2+m3 <~1 eV 2 m2
m12
m22
m32
Degenerate
m1≈m2≈m3» |mi-mj|
Normal hierarchy
m3>>> m2~m1
Inverted hierarchy
m2~m1>>m3 ?
Mass hierarchy ?
F. Piquemal (CENBG) LP07 Daegu August 2007

5. Beta decay (A,Z)  (A,Z+1) + e- + ne dN/dE ~ [ (E0-Ee)2 – mi2 ]1/2:
averaged neutrino
mass 3
Fraction of decay in [Qb – mn, Qb] ~ (DE/Qb) lowest Qb value 3H (Qb= 18.6 keV)
High counting rate
Low background
Energy resolution ~ mn
F. Piquemal (CENBG) LP07 Daegu August 2007

6. Beta decay: present status
MAC-E spectrometers
Source
Electron analyzer
Electron counter 3H
integral spectrum: select Ee > Eth
MAINZ: m2 = -0.6 ± 2.2 ± 2.1 eV2
 mn< 2.3 eV (95% C.L.)
C. Kraus et al., Eur. Phys. J. C 40 (2005) 447
Troisk: m2 = -2.3 ± 2.5 ± 2.0 eV2
mn< 2.05 eV (95% C.L.)
But systematics from end-point fluctuations not included
F. Piquemal (CENBG) LP07 Daegu August 2007

7. Improvement of DE: 0.93 eV (4.8 eV for Mainz)
Beta decay: KATRIN experiment
Sensitivity mn < 0.2 eV
Improvement of DE: 0.93 eV (4.8 eV for Mainz)
Larger acceptance
Statistics 100 days  1000 days
Commissioning and start : 2010
F. Piquemal (CENBG) LP07 Daegu August 2007

8. Individual electron energy
Neutrinoless double beta decay
bb(0n)
Electron energy sum
Qbb
Arbitrary scale
Observables
Angular distribution
Individual electron energy
Half-life T1/2
Allow to distinguish the mechanism
Background : natural radioactivity, radon,neutrons, muons, bb(2n)
(A,Z) (A,Z+2) + 2 e-
DL = 2
Lepton number violation
Light neutrino
exchange
Majorana neutrino (n=n)
Massive neutrino
Phase space factor
Nuclear matrix element
Other possible process :
V+A current : <mn>, <l>, <h>
Majoron emission : <gM>
Supersymmetry : l’111, l’113
T1/2= F(Qbb,Z) |M0n|2 <mn>2 -1 5
<mn>= m1|Ue1|2 + m2|Ue2|2.eia + m3|Ue3|2.eib
|Uei|: mixing matrix elements
a et b: Majorana phases
Schechter-Valle theorem:
bb(0n) Majorana neutrinos
F. Piquemal (CENBG) LP07 Daegu August 2007

9. Effective neutrino mass and neutrino oscillations
Inverted hierarchy
Normal hierarchy
Degenerated
Degenerate: can be tested
Inverted hierarchy: tested by the next
generation of bb experiment
<mn> in eV
Normal hierarchy: inaccessible
F. Piquemal (CENBG) LP07 Daegu August 2007

10. Uncertainties for extraction of <mn>
Nuclear matrix elements 5
T1/2= F(Qbb,Z) |M0n|2 <mn>2 -1
Shell Model - QRPA
Two different QRPA calculations
A lot of improvements have been done but still a factor 2-3 of discrepancy
Uncertainties for extraction of <mn>
In the following, « latest NME » will refer to these Nuclear Matrix Elements
F. Piquemal (CENBG) LP07 Daegu August 2007

11. bb(0n) search is a very dynamic field
Experiments
Isotopes
Techniques
Main caracteristics
NEMO3
100Mo,82Se
Tracking + calorimeter
Bckg rejection, isotope choice
SuperNEMO
82Se, 150Nd
Cuoricino
130Te
Bolometers
Energy resolution, efficiency
CUORE
GERDA
76Ge
Ge diodes
Energy resolution, eficiency
Majorana
COBRA
130Te, 116Cd
ZnCdTe semi-conductors
EXO
136Xe
TPC ionisation + scintillation
Mass, efficiency, final state signature
MOON
100Mo
Compactness, Bckg rejection
CANDLES
48Ca
CaF2 scintillating crystals
Efficiency, Background
SNO++
150Nd
Nd loaded liquid scintillator
Mass, efficiency
XMASS
Liquid Xe
CARVEL
CaWO4 scintillating crystals
Yangyang
124Sn
Sn loaded liquid scintillator
DCBA
Gazeous TPC
Bckg rejection, efficiency
Talk focuses on the running experiments and on some 100 kg scale projects starting within 5 years

12. bb(0n): Present situation
Heidelberg-Moscow (2001)
~11 kg of enriched Ge diodes in 76Ge (86%)
Pure calorimeter
High energy resolution and efficiency
But poor background rejection (pulse shape analysis)
Claim for discovery since 2002
(2002 : 3.1 s and 2004: 4 s)
35.5 k.yr
2004: 4 s
0.06 cts/keV/kg/yr
bb(0n) ?
Very controversial result
2006 new PSA analysis: 6 s effect
T 1/2 > yr (90% CL)
T1/2 = yr
+0.44
-0.31
<mn> < eV (90% CL)
<mn> = 0.32 ± eV
Eur. Phys. J., A 12 (2001) 147
F. Piquemal (CENBG) LP07

13. Future Ge experiments GERDA (Germany, Italy, Belgium, Russia)
Majorana (USA, Russia, Japan, Canada)
Selection of very pure material (Majorana)
Removal of matter (GERDA)
Segmentation of detectors for background rejection
Use of liquid nitrogen or argon for active shielding
Improvement of Pulse Shape Analysis
GERDA PHASE I: 17.9 kg of enriched 76Ge (from HM and IGEX)
In 1 year of data (no Background) check of Klapdor’s claim
Start 2009 at Gran Sasso, results 2010
PHASE II: 40 kg of enriched 76Ge
T1/2 > yr in 3 years of data <mn> < 110 meV (no background)
Majorana: kg of enriched 76Ge (3 yr) T1/2 > yr mn < 140 meV
Start 2011
Collaboration for 1 ton experiment
Reduction of background by
a factor 10 – 100 compare
to HM

14. Cuoricino Bolometers of TeO2 (Qbb= 2.528 MeV) Heat sink
Bolomètres: CUORICINO
Bolometers of TeO2 (Qbb= MeV)
Heat sink
Signal:∆T = E/C
Thermometer
Double beta decay
Crystal absorber
High energy resolution 5-7 keV (FWHM)
Natural abundance for 130Te: 34%
High efficiency: 86%
But no electron identification
Background from internal and surface
contamination in a emitters
214Bi
(238U chain)
208Tl
(232Th chain)
60Co
pile up
5.3 kg.an
T1/2 > ans (90%)
<mn> <0.5 – 2.4 eV
bb(0n)
Energy (keV)
Running at Gran Sasso since 2003
F. Piquemal (CENBG) LP07 Daegu August 2007
F. Piquemal (CENBG) LP07

15. Cuoricino results 0DBD 11.83 kg.yr
Gamma region, dominated by gamma and beta events,
0DBD
Alpha region, dominated by alpha peaks
(internal or surface contaminations)
Bckg: 0.18 cts/keV/kg/yr
60Co
pile up
130Te
0vBB
11.83 kg.yr
Energy (keV)
T1/2 > yr (90% CL) <mn> < 0.2 – 1 eV (90% CL)
Expected final sensitivity ~2009: T1/2 > yr <mn> < 0.1 – 0.7 eV

16. Array of 988 TeO2 5x5x5 cm3 crystals
CUORE
(Italy, USA,Spain)
750 kg of TeO2  kg of 130Te
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 compare to Cuoricino)
Data taking foreseen in 2011
Expected sensitivities (5 years of data)
Nbckg=0.01 cts.keV-1.kg-1.yr-1
T½ > yr
<mn> < 0.03 – 0.17 eV
Nbckg=0.001 cts.keV-1.kg-1.yr-1
T½ > yr
<mn> < – 0.1 eV
F. Piquemal (CENBG) LP07

17. NEMO 3 Tracko-calo detector e- e- bb events
(France, UK, Russia, Spain, USA, Japan, Czech Republic,Ukraine, Finland)
Tracko-calo detector
Central source foil (~50 mm thickness)
Tracking detector (6180 drift cells)
t = 0,5 cm, z = 1 cm ( vertex )
Calorimeter (1940 plastic scintillators + PMTs)
Efficiency 8 %
Running at Modane Underground lab since 2003 E1 e-
Vertex
Multi-isotopes (7 kg of 100Mo, 1 kg of 82Se,…)
Identification of electrons
Very good bckg rejection (< 10-3 cts/keV/kg/y)
Angular distribution and single electron energy
(necessary to distinguish the mechanism in case
of discovery)
But modest energy resolution and efficiency e-
E1+E2= 2088 keV
t= 0.22 ns
(vertex) = 2.1 mm E2
bb events
F. Piquemal (CENBG) LP07

18. NEMO3: bb(0n) results 100Mo
Phase I, High radon
7.6 kg.yr
Phase II, Low radon
5.7 kg.yr
Phase I + II
13.3 kg.yr
Number of events / 40 keV
Number of events / 40 keV
Number of events / 40 keV
[ ] MeV: e(bb0n) = 8 %
Expected bkg = 8.1 events
Nobserved = 7 events
[ ] MeV: e(bb0n) = 8 %
Expected bkg = 3.0 events
Nobserved = 4 events
[ ] MeV: e(bb0n) = 8 %
Expected bkg = 11.1 events
Nobserved = 11 events
Phases I + II
T1/2(bb0n) > yr (90 % C.L.) <mn> < 0.6 – 1.3 eV
T1/2(bb0n) > yr (90 % CL) <mn> < 0.3 –0.7 eV
Expected in 2009

19. SuperNEMO project Tracko-calo with 100 kg of 82Se or 150Nd
(France, UK, Russia, Spain, USA, Japan, Czech Republic,Ukraine, Finland)
Tracko-calo with 100 kg of 82Se or 150Nd
(possibility to produce 150Nd with the French AVLIS facility)
T½ > yr <mn> < 0.05 – 0.09 eV
Modules based on the NEMO3 principle
Measurements of energy sum, angular distribution
and individual electron energy
3 years R&D program: improvement of energy resolution
Increase of efficiency
Background reduction
…….
100 kg 20 modules
R&D funded by France, UK and Spain
2009: TDR
2011: commissioning and data taking of first modules in Canfranc (Spain)
2013: Full detector running

20. EXO Liquid Xe TPC Energy measurement by ionization + scintillation
(USA, Canada, Switzerland, Russia)
Liquid Xe TPC
Energy measurement by ionization + scintillation
Tagging of Baryum ion (136Xe  136Ba e-)
Large mass of Xe
Identification of final state  background rejection
But no e- identification
Poor background rejection without Ba ion tagging
R&D for Ba ion tagging in progress
Prototype EXO-200
200 kg of 136Xe, no Ba ion tagging
Installation in progress in WIPP underground lab 2007
Could measure bb(2n) of 136Xe
EXO 200 (2 years) T½ > yr (90% CL) <mn> < eV

21. Enriched isotope mass (kg)
Summary
Summary
Experiment
Isotope
Enriched isotope mass (kg)
T1/2 (yr)
<mn> (eV)
Start
Status
CUORE
130Te
203 *
2011
Funded
GERDA phase I
phase II
76Ge
17.9 40
0.2 – 0.5*
0.07 – 0.2*
2009
Majorana
1.1026
0.1 – 0.3*
EXO-200
136Xe
200 *
2008
SuperNEMO
82Se
150Nd
100
1026 *
0.07
R&D
CANDLES
48Ca
0.5
~0.5
MOON II
100Mo
120
0.09 – 0.13 ?
DCBA 20
SNO++
500
COBRA
116Cd,
420
* Calculation with NME from Rodim et al., Suhonen et al., Caurier et al. PMN07

22. <mn> current and future limits. HM
Cuoricino
NEMO3
Klapdor
claim
Limits in 2009
HM,NEMO3,
Inverted hierarchy
Normal hierarchy
Degenerated
Expected limits
2009 – 2015
CUORE,GERDA,
Majorana,
SuperNEMO,
EXO
Use of « latest NME » for all experiments

23. Summary Summary Single beta decay
KATRIN mn < 2.3 eV  mn < 0.2 eV results in ~2014
Other possibility : bolometers with 187Re (Qb=2.47 keV) but long R&D
(at least 10 years to reach 0.2 eV)
Double beta decay
Very active field. A claim to be checked
Current experiments will reach a sensitivity on <mn> ~(0.2 – 0.7) eV in 2009
Need to measure several nucleus with different techniques (only tracko-calo
can distinguish the mechanism in case of discovery)
Next generation ~ source mass 100 – 200 kg <mn> ~ (0.03 – 0.1) eV
Will cover partially the inverted hierarchy mass scenario (2011 – 2015)
Essential step for 1 ton scale experiment ( background considerations)
Need improvements for Nuclear Matrix Element calculations

24. BACKUP SLIDES

25. bb(0n) signal ? HM claim 2001 2002 (3.1s) 2004: new calibration (4s)
T1/2 > <mn> < (90%)
T1/2= ( ) 1025 yr <mn>= 0.11 – 0.56 eV
2004: new calibration (4s)
Best value:0.39 eV

26. bb(0n) signal ? 6s Today Estimation of the background level
+0.44 6s
T1/2 = yr
<mn> = 0.32 ± eV
-0.31
(Result with last NME should be <mn> = 0.11 – 0.71 eV)
Estimation of the background level
Problems for some well-known peaks (214Bi)
Some unknow lines in the same region
56Co produced by cosmic rays (2034 keV photon+ 6 keV X-ray)
76Ge(n,)77Ge (2038 keV photon)
Some unknown line
Inelastic neutron scattering (n,n‘) on lead
Other suggestions, can be combination of all

27. Experimental techniques
M: masse (g)
e : efficiency
KC.L.: Confidence level
N: Avogadro number
t: time (y)
NBckg: Background events (keV-1.g-1.y-1)
DE: energy resolution (keV)
> e A
M . t
NBckg . DE
ln2 . N
kC.L.
(y)
Today, no technique able to optimize all the parameters
Calorimeter
Semi-conductors
Source = detector
Calorimeter
Loaded Scintillator
Source = detector
Tracko-calo
Source  detector
Xe TPC
Source = detector b b b b b b b b
e, DE
e, M
NBckg, isotope choice
e,M, (NBckg)
F. Piquemal (CENBG) LP07

28. GERDA and Majorana
Strategy: Ge detectors in liquid nitrogen to remove materials
Active shielding and segmentation of detectors to
reject gamma-rays e- 
detector
segments
Liquid argon
scintillation
crystal anti-coincidence
Detector segmentation
pulse shape analysis
R&D: liquid argon anti-coincidence

29. From Fedor Simkovic PMN07

30. «bb factory» → tool for precision test
NEMO 3:100Mo 2 results
Energy sum spectrum
Angular distribution
12000
10000
8000
6000
4000
2000
Number of events
12000
10000
8000
6000
4000
2000
events
6914 g
389 days
S/B = 40
events
6914 g
389 days
S/B = 40
NEMO-3
NEMO-3
100Mo
100Mo
Number of events/0.05 MeV
7.6 kg.yr
7.6 kg.yr
Data
22
Monte Carlo
Data
22
Monte Carlo
Background
subtracted
Background
subtracted
Cos()
E1 + E2 (MeV)
T1/2(bb2n) = 7.11 ± 0.02 (stat) ± 0.54 (syst)  1018 yr
Phys. Rev. Lett (2005)
«bb factory» → tool for precision test
F. Piquemal (CENBG) LP07

31. Beta decay: MARE experiment
1 mm
MicroBolometers of ArReO4
187Re Qb = 2.47 keV
Full energy measurement
No systematic from source
But time response of sensor  pile-up
MARE-I: 300 detectors
FWHM ~20 eV
t ~100 – 500 ms
mn < 2 –4 eV ( 5 years)
MARE – II : 5000 detectors (~2018)
t ~1 – 5 ms
mn < 0.2 eV (10 years)
MIBETA
10 detectors
mn 2 = -141  211 stat  90 sys eV2
mn < 15 eV (90% c.l.)

32. View of the field: present and future
Today experiments have a mass of enriched source ~10 kg
To reject inverted hierarchy mass scenario, enriched source mass  1 ton
All projects have this goal but it is unrealistic to plane to go directly
from 10 kg to 1 ton scale (understanding and control of the background)
Intermediate step at 100 kg scale is needed (as proposed by each project)
Talk focuses on the running experiments and on some 100 kg scale
projects starting within 5 years
F. Piquemal (CENBG) LP07 Daegu August 2007