Post on 22-Jan-2016
description
Double Beta Decay review
Fabrice PiquemalCENBG, University Bordeaux 1 CNRS/IN2P3
and Laboratoire Souterrain de Modane (CNRS/IN2P3-CEA/DSM)
Thanks to: G. Gratta, S. Elliot, A. Giuliani, S. Schoenert, T. Kishimito, M. Nomachi, K. Zuber, M. Chen
- Nature of neutrino : Dirac ( ) or Majorana ( =)
- Absolute neutrino mass and neutrino mass hierarchy
- Right-handed current interaction
- CP violation in leptonic sector
- Search of Supersymmetry and new particles
Double Beta decay: physics case
- Leptonic number violation
Neutrino properties
Atmospheric (SK)Accelerators (K2K,Minos)
Reactors (CHOOZ)Accelerators (JPARC)
Solar (SNO, SK)Reactors (KamLAND)
tan223
=1.0 ± 0.3 sin2213
< 0.16 tan212
=0.39 ± 0.05
CP
= CP Dirac phase
U
: CP Majorana phase
m2
atm =
m2
31 = (2.3 0.2 ) 10-3 eV2
m2
sol =
m2
12 = (7.9 0.3) 10-5 eV2
Oscillations
Neutrino mass
Beta decay mv = |Uei| mi
<2.3 eV
Double beta decay |<m>| = |Uei mi| < 0.2 - 0.8 eV
Cosmology mi =
m1+m2+m3 <~1 eV
Absolute mass ?
m2
m1
2
m2
2
m3
2
Degeneratem
1≈m2≈m3» |mi-mj|
Normal hierarchym
3>>> m
2~m
1
Inverted hierarchym
2~m
1>>m
3
?
Mass hierarchy ?
2
2
21/2
Double Beta decays
2nd order process of weak interactionAlready observed for several nuclei
Single beta decay forbidden (energy)
or strongly suppressed by large angular
momentum change
Decay to ground state or excited states
e-e-
e-
e-
L =2 Majorana neutrino (=)
Coefficientscontaining phasespacefactor and nuclear m
effectiveneutrino masse
coupling between right lep
atrix elements
ton and left
ν
n
1 42 3
2-1
0 2 2ν νν11/2
e e
ν12 2
e5 5
m :
λ , η :
C :
C C C C
C
T = + + + cosψm m
+ cosψ + cos ψ -ψ
m mλ
C
η λ
η λ ηmm
pha
qua
seb
rks, ri
etween
ght quark
neutrinoand
s
1 2 λ , ηψ ,ψ :
(V+A) current <m>,<>,<>
(A,Z) (A,Z+2) + 2 e-
Process: parameters
T1/2= F(Q,Z) |M|2 <m>2-1
Phase space factor Nuclear matrix element
Effective mass:
<m>= m1|Ue1|2 + m2|Ue2|2.ei1 + m3|Ue3|2.ei2
|Uei|: mixing matrix element
1 et2: Majorana phase
5
Light neutrino exchange <m>
Majoron emission <gM>
SUSY ’111,’113’131,…..
T1/2= F |MJ|2 <gM>2-1
Phase space factor Nuclear matrix element
Coupling between Majoron and neutrinos
R-parity violation T1/2 depends on (’111)2, gluino and squarks mass
Neutrinoless Double Beta decay
Discovery implies L=2 and Majorana neutrino
observables
From G. Gratta
observables
Light neutrino exchange V+A current
Minimum electronenergy
Angular distributionbetwen the 2 electrons
MeV MeV
Cos Cos
Effective neutrino mass and neutrino oscillations
Inverted hierarchy
Normal hierarchy
Degen
erated
Degenerate: can be tested
Inverted hierarchy: tested by the nextgeneration of experiment
Normal hierarchy: inaccessible
<m>
in e
V
Isotope Q (MeV)Isotopic
abundance (%)
G0(yr-1) x 1025
48Ca 4.271 0.187 2.44
76Ge 2.040 7.8 0.24
82Se 2.995 9.2 1.08
96Zr 3.350 2.8 2.24
100Mo 3.034 9.6 1.75
116Cd 2.802 7.5 1.89
130Te 2.528 33.8 1.70
136Xe 2.479 8.9 1.81
150Nd 3.367 5.6 8.00
emitters
T1/2= F(Q,Z) ||2 <m>2-1 5
Nuclear matrix elements
Nuclear matrix elements are calculated using various models:
QRPA (RQRPA, SQRPA, …….)Shell model
Up to recently no convergence for the results
Statement from Bahcall et al. to use the nuclear matrix range as an uncerntainty:« Democratic approach »
Does not take into account the improvements of the Models
Exchanges between groups to understand discrepencies and to evaluate errors
is used by QRPA to fix gpp paramaters for QRPA
A lot of improvements have been done but still discrepanciesUncertainties for extraction of <m>
Nuclear matrix elements
In the following, « latest NME » will refer to these Nuclear Matrix Elements
Shell Model (Poves et al) - QRPA Two different QRPA calculations
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, on some 100 kg scaleprojects starting within 5 years and R&D projects.
View of the field: present and future
T0
2/1 > . . A
M . t
NBckg . Eln2 . N
kC.L.
(y)
Experimental techniques
Today, no technique able to optimize all the parameters
M: masse (g) : efficiencyKC.L.: Confidence levelN: Avogadro numbert: time (y)NBckg: Background events (keV-1.g-1.y-1)E: energy resolution (keV)
CalorimeterSemi-conductorsSource = detector
, E
Calorimeter(Loaded) Scintillator
Source = detector
,
Tracko-caloSource detector
NBckg, isotope choice
Xe TPCSource = detector
,M, (NBckg)
With background:
Calorimeter vs Tracko-calo
Calorimeter Tracko-calo
High energy resolutionModest background rejection
High background rejectionModest energy resolution
keV
keV
MeV
Natural radioactivity (40K, 60Co,234mPa, external 214Bi and 208Tl…) 214Bi and Radon 208Tl (2.6 MeV line) and Thoron from (n,) reaction and muons bremstrahlung
Q MeV2 3 4
76Ge 130Te76Xe
100Mo 82Se
5
150Nd 96Zr 48Ca
Q and background components
+ for tracko-calo or calorimeter with modest energy resolution
+ more specific background for calorimeter
Surface or bulk contamination in emitters
cosmogenic production
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
COBRA 130Te, 116Cd ZnCdTe semi-conductors Energy resolution, efficiency
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
search is a very dynamic field
<m> <0.35-1.05 eV (90% CL)
T 1/2 >1.9 1025 yr (90% CL)
Eur. Phys. J., A 12 (2001) 147
35.5 k.yr
0.06 cts/keV/kg/yr
Heidelberg-Moscow (2001) ~11 kg of enriched 76Ge (86%)
8.9 kg.yr without PSA4.6 kg.y with PSA
Phys. Rev. D65 (2002) 092007
IGEX (2002)~ 8.4 kg of enriched 76Ge (86%)
T 1/2 >1.57 1025 yr (90% CL)
<m> <0.33-1.31 eV (90% CL)
Present situation
High energy resolution and efficiency
But poor background rejection (pulse shape analysis)
Ge diode detectors:
signal ? HM claim
T1/2
= (0.69 – 4.18) 1025
<m> = 0.28-0.58 (90%)
2006: Improvement of PSA (6)
+0.44
-0.31
<m> = 0.32 ± 0.03 eV
2004 (4)
T1/2 = 2.23 1025 yr
Ge detector improvementsStrategies: Ge detectors in liquid nitrogen to remove materials Active shielding and segmentation of detectors to reject gamma-rays
e-
detector segments
e-
Liquid argon
scintillation
crystal anti-coincidence Detector segmentation
pulse shape analysis R&D: liquid argon anti-coincidence
(Germany, Italy, Belgium, Russia)
GERDA
Removal of matter
Use of liquid nitrogen or argon for active shielding
Segmentation
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 2009 at Gran Sasso, results 2010 T1/2 > 3 1025 yr <m> < 250 meV
PHASE II: 40 kg of enriched 76Ge (20 kg segmented)
if B=10-3 cts/keV/kg/an T1/2 > 2 1026 yr in 3 years of data <m> < 110 meV
PHASE III: if PHASE I and II succeed 1 ton if B=10-3 cts/keV/kg/yr
T1/2 > 5 1027 yr in 3 years of data <m> < 20 meV
Majorana
Very pure material(Electroformed cooper)
Segmentation
PSD improvement Deep underground
Goal 500 kg of 76Ge (modules of 60 kg)
R&D phase 30-60 kg of 86% enriched 76Ge crystals
Some of the crystals segmented
T1/2 > 1. 1026 yr <m < 140 meV (could confirme or refute Klapdor’s claim)
Bckg goal ~ 1 count/ROI/t-yr (after analysis cuts)
30 kg of enriched Ge, running 3 yr. Data taking scheduled for 2011
Collaboration with Gerda for 1 ton detector
(USA, Russia, Japan)
Bolomètres: CUORICINOCuoricino
Heat sink
ThermometerDouble beta decay
Crystal absorber
Signal:∆T = E/C
High energy resolution 5-7 keV (FWHM)Natural abundance for 130Te: 34%High efficiency: 86%
But no electron identificationBackground from internal and surfacecontamination in emitters
Bolometers of TeO2 (Q= 2.528 MeV)
Running at Gran Sasso since 200310.4 kg of 130Te
60Copile up
130Te0vBB
T1/2 > 3. 1024 yr (90% CL) <m> < 0.2 – 1 eV (90% CL)
Expected final sensitivity ~2009: T1/2 > 6. 1024 yr <m> < 0.1 – 0.7 eV
Energy (keV)
11.83 kg.yr
Cuoricino results
Bckg: 0.18 cts/keV/kg/yr
Gamma regionGamma region, dominated by gamma and beta events,
0DBD
Alpha regionAlpha region, dominated by alpha peaks
(internal or surface contaminations)
750 kg of TeO2 203 kg of 130Te
Array of 988 TeO2 5x5x5 cm3 crystals
Improvement of surface event rejection
CUORE
Data taking foreseen in 2011
Nbckg=0.01 cts.keV-1.kg-1.yr-1
T½ > 2.1 1026 yr
<m> < 0.03 – 0.17 eV
Nbckg=0.001 cts.keV-1.kg-1.yr-1
T½ > 6.6 1026 yr
<m> < 0.015 – 0.1 eV
Goal :Nbckg=0.01 cts.keV-1.kg-1.yr-1
Expected sensitivities (5 years of data)
(Italy, USA,Spain)
(Factor 20 compared to Cuoricino)
(R&D on other bolometers like 116CdWO4)
Central source foil (~50 m 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
Vertex
events
E1+E2= 2088 keV t= 0.22 ns(vertex) = 2.1 mm
E1
E2
e-
e-
NEMO 3
Multi-isotopes (7 kg of 100Mo, 1 kg of 82Se,…)Identification of electronsVery good bckg rejection (< 10-3 cts/keV/kg/yr)Angular distribution and single electron energy(necessary to distinguish the mechanism in caseof discovery)But modest energy resolution and efficiency
(France, UK, Russia, Spain, USA, Japan, Czech Republic,Ukraine, Finland)
Tracko-calo detector
T1/2() > 5.8 1023 yr (90 % C.L.) <m> < 0.6 – 1.3 eVPhases I + II
Phase I, High radon7.6 kg.yr
Phase I + II13.3 kg.yr
[2.8-3.2] MeV: () = 8 % Expected bkg = 8.1 events
Nobserved = 7 events
Nu
mb
er o
f ev
ents
/ 40
keV
Phase II, Low radon5.7 kg.yr
[2.8-3.2] MeV: () = 8 % Expected bkg = 3.0 events
Nobserved = 4 events
Nu
mb
er o
f ev
ents
/ 40
keV
Nu
mb
er o
f ev
ents
/ 40
keV
results 100Mo
T1/2() > 2. 1024 yr (90 % CL) <m> < 0.3 –0.7 eVExpected in 2009
[2.8-3.2] MeV: () = 8 % Expected bkg = 11.1 events
Nobserved = 11 events
SuperNEMO project
Tracko-calo with 100 kg of 82Se or 150Nd(possibility to produce 150Nd with the French AVLIS facility)
3 years R&D program: improvement of energy resolution Increase of efficiency Background reduction …….
2009: TDR2011: commissioning and data taking of first modules in Canfranc (Spain)2013: Full detector running
Modules based on the NEMO3 principleMeasurements of energy sum, angular distributionand individual electron energy
R&D funded by France, UK and Spain
T½ > 2. 1026 yr <m> < 0.05 – 0.09 eV
(France, UK, Russia, Spain, USA, Japan, Czech Republic,Ukraine, Finland)
100 kg 20 modules
EXO
Prototype EXO-200200 kg of 136Xe, no Ba ion taggingInstallation in progress in WIPP underground lab 2007Could measure of 136Xe
Liquid Xe TPC Energy measurement by ionization + scintillationTagging of Baryum ion (136Xe 136Ba++ + 2 e-)
(USA, Canada, Switzerland, Russia)
Large mass of Xe Identification of final state background rejection
But no e- identificationPoor background rejection without Ba ion tagging
R&D for Ba ion tagging in progress
EXO 200 (2 years) T½ > 6.4 1025 yr (90% CL) <m> < 0.27- 0.38 eV
CANDLES
CaF2(Pure)
Liquid Scintillator(Veto Counter)
Buffer Oil
Large PMT
Pure CaF2 crystals
Wave length shifter in LS
PSD to reject and
Efficiency, 48Ca (background)
But mass of isotope, no e- identification
CANDLES III : Prototype 103 cm3 × 60 crystals 191 kg (~ 350g of 48Ca) In test in Osaka University
Full detector 103 cm3 × 96 crystals 305 kg Installation in spring 2008 at Kamioka
Expected BG: 0.14 event/yr (30 Bq/kg) <m> ~0.5 eV
CANDLES IV : 3 tons of CaF2 (3 Bq/kg) 6 yr <m> ~0.1 eV
(Japan)
MOON
CompactnessMulti-isotopesElectron identification
But energy resolution andbckg rejection (ToF)
Compact tracko-calo
Moon 1: Data acquisition with 142 g of 100Mo (40 mg/cm2) In progress: Improvement energy resolution
Waveform readout Design of a module
Module: 2011 20 kg of source <m> ~100 meV
(Japan, USA)
DCBA(Japan)
Drift Chamber beta-ray Analyser
Electron identificationMulti-isotopes
But Efficiency, Energy resolution
Prototype with 207Bi : 10% (FWHM) energy resolutionX position = 0.5 mmY position = 0.02 mmX position = 6 mm
4x4x4 detector array = 0.42 kg CdZnTe Installed at LNGS
Test of coincidence rejection
Measure of 113Cd
COBRA
Array of 1cm3 CdZnTe detectors
Good energy resolutionSeveral isotopes at the same timeEfficiency
But background rejection
(UK, Germany, Italy, poland, Slovaquia, Finland, USA)
Cd-113 beta decaywith half-life of about 1016 yrs
SNO++
Scintillator loaded with Nd.
only internal Th and 8B solar neutrino backgrounds are important
500 kg of 150Nd1 year<m> = 150 meV
MassEfficiency
But energy resolutionNo e- identification
Test of light attenuation
Study of Nd purification (factor 1000per pass in Th and Ra)
56 kg of 150Nd (0,1 % of natural Nd)4 yr of data <m> ~80 meV
500 kg of 150Nd 4yr <mn> ~30 meV
Similar prospect in KamLAND
Experiment IsotopeEnriched
isotope mass (kg)
T1/2 (yr) <m> (eV) Start Status
CUORE 130Te 203 2.1 1026 0.03 - 0.07* 2011 Funded
GERDA phase I
phase II76Ge
17.9
40
3. 1025
2. 1026
0.2 – 0.5*
0.07 – 0.2*
2009
2011
Funded
Funded
Majorana 76Ge 30 - 60 1.1026 0.1 – 0.3* 2011 Funded
EXO-200 136Xe 200 6.4 1025 0.2 - 0.7* 2008 Funded
SuperNEMO82Se
150Nd
100
100
2. 1026
1026
0.05- 0.09*
0.072011 R&D
CANDLES 48Ca 0.5 ~0.5 2008 Funded
MOON II 100Mo 120 0.09 – 0.13 ? R&D
DCBA 150Nd 20 ? R&D
SNO++ 150Nd 500 0.03 ? R&D
COBRA116Cd,
130Te420
? ? ? R&D
SummarySummary* C
alculation
with
NM
E from
Rod
im et al., S
uh
onen
et al., Cau
rier et al. PM
N07
Inverted hierarchy
Normal hierarchy
Degen
erated
m current and future limits
Expected limits2009 – 2015
CUORE,GERDA,Majorana,
SuperNEMO,EXO,….
Use of « latest NME » for all experiments
.HM Cuoricino NEMO3 Klapdor
claimLimits in 2009
HM,NEMO3, Cuoricino
Very active field. A claim to be checked
Current experiments will reach a sensitivity on <m> ~(0.2 – 0.7) eV in 2009
Need to measure several nucleus with different techniques (only tracko-calocould distinguish the mechanism in case of discovery)
Next generation ~ source mass 100 – 200 kg. <m> ~ (0.03 – 0.1) eVWill 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
SummarySummary
Present situation
SSE(Single Site Event)
(Multiple Site Event)
Pulse shape analysis with Ge detectors
SSE
MSE