Download - Double Beta Decay review

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

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



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



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

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