Double Beta Decay review

Fabrice PiquemalLaboratoire Souterrain de Modane (CNRS/IN2P3-CEA/DSM)

and CENBG, University Bordeaux 1 CNRS/IN2P3

Thanks to: G. Gratta, S., A. Giuliani, S. Schoenert, T. Kishimito, M. Nomachi, K. Zuber, M. Chen, K. Inoue

NNN 2010, Toyama Dec,14-16 2010

- 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 decay: physics case

- Leptonic number violation

(A,Z) (A,Z+2) + 2e-

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

bb

e-e-

nn

bb(2n) bb(0n) e-

e-

DL =2

bb(0n) Majorana neutrino (n=n)

(V+A) current <mn>,<l>,<h>

(A,Z) (A,Z+2) + 2 e-

Process parameters

T1/2= F(Qbb,Z) |M|2 <mn>2-1

Phase space factor Nuclear matrix element

Effective mass:

<mn>= m1|Ue1|2 + m2|Ue2|2.eia1 + m3|Ue3|2.eia2

|Uei|: mixing matrix element

a1 et a2: Majorana phase

5

Light neutrino exchange <mn>

Majoron emission <gM>SUSY l’111,l’113l’131,…..

Neutrinoless Double Beta decay

Discovery implies DL=2 and Majorana neutrino

bb(0n) observables

Electron energy sum

150Nd distribution s arxiv: 1005.1241v1 [hep-ex]

Angular distribution

Massmechanism

MassmechanismRHC

Ee1 – Ee2 distribution

RHC

bb(2n) bb(0n)

From G. Gratta

Experiments Isotopes Techniques Main caracteristics

NEMO3 100Mo,82Se Tracking + calorimeter Bckg rejection, isotope choiceSuperNEMO 82Se, 150Nd Tracking + calorimeter Bckg rejection, isotope choiceCuoricino 130Te Bolometers Energy resolution, efficiencyCUORE 130Te Bolometers Energy resolution, efficiencyGERDA 76Ge Ge diodes Energy resolution, eficiencyMajorana 76Ge Ge diodes Energy resolution, efficiencyCOBRA 130Te, 116Cd ZnCdTe semi-conductors Energy resolution, efficiencyEXO 136Xe TPC ionisation + scintillation Mass, efficiency, final state signatureMOON 100Mo Tracking + calorimeter Compactness, Bckg rejectionCANDLES 48Ca CaF2 scintillating crystals Efficiency, Background

SNO++ 150Nd Nd loaded liquid scintillator Mass, efficiencyXMASS 136Xe Liquid Xe Mass, efficiencyCARVEL 48Ca CaWO4 scintillating crystals Mass, efficiencyYangyang 124Sn Sn loaded liquid scintillator Mass, efficiencyDCBA 150Nd Gazeous TPC Bckg rejection, efficiency

Why so many experiments or projects ?

Isotope Qbb (MeV)Abondance isotopique

(%)

G0n(an-1) x 1025

Enrichment

method48Ca 4.271 0.187 2.44 Laser ?76Ge 2.040 7.8 0.24 Centrifugation82Se 2.995 9.2 1.08 Centrifugation96Zr 3.350 2.8 2.24 Laser ?100Mo 3.034 9.6 1.75 Centrifugation116Cd 2.802 7.5 1.89 Centrifugation130Te 2.528 33.8 1.70 Centrifugation136Xe 2.479 8.9 1.81 Centrifugation

150Nd 3.367 5.6 8.00 Laser ?Centrifugation ?

Double beta decay isotopes

arXiv:1008.5260v2 : Tomás R. Rodríguez, G. Martinez-Pinedo

Nuclear Matrix Element

Qbb MeV2 3 4

76Ge 130Te76Xe100Mo 82Se

5

150Nd 96Zr

48Ca

Background components

+ bb(2n) for tracko-calo or calorimeter with modest energy resolution

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

+ for pure calorimeter Surface or bulk contamination in a emitters, cosmogenic production

2.614 MeVHighest gamma-ray from natural radioactivity

T n0

2/1 e

A

M . t

NBckg . DE(y)

<mn > M1/4

CalorimeterSemi-conductors

BolometersSource = detector

e, DE

b

b

b

b

Calorimeter(Loaded) Scintillator

Source = detector

e, M

Tracko-caloSource detector

NBckg, isotope choice

Xe TPCSource = detector

b

b

e,M, (NBckg)

b

b

M: masse (g)e : efficiencyKC.L.: Confidence levelN: Avogadro number

t: time (y)NBckg: Background events (keV-1.g-1.y-1)DE: energy resolution (keV)

Experimental sensitivity

Calorimeter vs Tracko-calo

bb(0n) bb(0n)

bb(0n) bb(0n)

Calorimeter Tracko-calo

High energy resolutionModest background rejection

High background rejectionModest energy resolution

keV

keV

MeV

What is the most favorable isotope and the best technique ?

Phase space factor: 48Ca, 150Nd, 96Zr Nuclear matrix element not yet reliable predictions Backgrounds > 2,6 MeV 48Ca, 150Nd, 96Zr, 100Mo, 82Se, 116Cd > 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)

Why so many experiments or projects ?

Effective neutrino mass and q13

100 – 1000 cts/yr/ton

1 – 10 cts/yr/ton

0.1 – 1 cts/yr/ton

Isotopemass

~ 10 kg 2011

~ 1000 kg

Required background level

Heidelberg-Moscow (2001) ~11 kg of enriched Ge

bb(0n) ?

|mee

|

S T Petcov 2009 J. Phys.: Conf. Ser. 173 012025

~ 100 kg 2015

This experimental review will be focused on the last results of 10 kg and 100 kg experiments

SNO++ (150Nd)

EXO (136Xe)Majorana (76Ge)

Cuoricino/CUORE (130Te)GERDA (76Ge)COBRA (116Cd)

CANDLES (48Ca)KamLAND-ZEN (136Xe)MOON (100Mo)

bb(0n) : experiments and projects

CalorimeterSource = detector

b

b

b

b

Tracko-caloSource detector

EXO gaz (136Xe)

DCBA (150Nd)

NEMO3/SuperNEMO (82Se, 150Nd, 48Ca)NEXT (136Xe)

<mn> <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)

<mn> <0.33-1.31 eV (90% CL)

bb(0n): Present situation

Ge diode detectors

Bolomètres: CUORICINOCuoricino

Heat sink

ThermometerDouble beta decay

Crystal absorber

Bolometers of TeO2

DE/E ~ 8 keV at 2 527 keV

Located in Gran Sasso Laboratory (Italy)

Stopped in 2008

Bolomètres: CUORICINOCuoricino results

CUORE

750 kg of TeO2 203 kg of 130Te

Array of 988 TeO2 5x5x5 cm3 crystals

Improvement of surface event rejection

Data taking foreseen in 2013

Nbckg=0.01 cts.keV-1.kg-1.yr-1

T½ > 2.1 1026 yr

<mn> < 0.03 – 0.17 eV

Goal :Nbckg=0.01 cts.keV-1.kg-1.yr-1

Expected sensitivity

(Italy, USA,Spain)

(Factor 20 compared to Cuoricino)

LUCIFER:R&D on scintillating bolometers like 82Se 116CdWO4

CUORE

Test of 1 tower of CUORE in Cuoricino in 2011

Vertex

bb events

E1+E2= 2088 keV Dt= 0.22 ns(Dvertex) = 2.1 mm

E1

E2

e-

e-

NEMO 3Tracko-calo detectorDrift chamber (6000 cells)Plastic scintillator + PMT (2000)10 kg of isotopesDE/E (FWHM) : 8 % @ 3 MeVLocated in Modane Underground Lab (France)

Bckg: 0.025 cts/keV/kg/yr

Bckg

bb sources (thickness 0 mg/cm2)

82Se (0,93 kg)

bb(2n)

Multi-source detector

NEMO 3 Results100Mo, 23.4 kg.yr 620 000 events

Bosonic fraction of neutrino wave functionSin c < 0.6

NEMO 3 Results

NEMO 3 Results

7 kg 100 kg isotope mass M

15 % ~ 30 %

isotope 100Mo

82Se ,150Nd or 48Ca

T1/2 (bb0n) > ln 2 M e Tobs N90

NA

A

NEMO-3 SuperNEMO

internal contaminations 208Tl and 214Bi in the bb foil

208Tl: < 20 mBq/kg214Bi: < 300 mBq/kg

208Tl < 2 mBq/kgif 82Se: 214Bi < 10 mBq/kg

T1/2(bb0n) > 2 x 1024 y<mn> < 0.3 – 1.3 eV

T1/2(bb0n) > 1026 y<mn> < 50 – 110 meV

energy resolution (FWHM) 8% @ 3MeV 4% @ 3 MeV

efficiency e

From NEMO 3 to SuperNEMO

20 modules for 100 kg

Top view

Source (40 mg/cm2) 12m2

Tracking (~2-3000 Geiger cells). Calorimeter (500 channels)

5 m

1 m

Total:~ 40 000 – 60 000 geiger cells channels ~ 10 000 PMT

SuperNEMO conceptual design

SuperNEMO phase I : 2011 – 2014Contruction demontrator module with 7 kg of 82Se (1 kg of 48Ca ?)Commissing @LSM 2013Sensitivity in 1 year: T1/2 < 5 1024 y <mn> < 0.2 – 0.6 eV

SuperNEMO phase II : 2014 – 2019100 kg of 82Se (or 150Nd,or 48Ca)T1/2 > 1026 y <mn> < 0.05 – 0.14 eV

DE/E < 4% (FWHM) @ Qbb demonstrated (< 8% @ 1 MeV)

FWHM = 7,1 %(7,6% before energy loss correction)

SuperNEMO @ LSM extension

Commissioning of wiring robot

SuperNEMO

Ge detector improvementsStrategies: Ge detectors in liquid nitrogen to remove materials Active shielding and segmentation of detectors to reject gamma-rays

e-

g

detector segments

e-

Liquid argon

scintillation

crystal anti-coincidence Detector segmentation

pulse shape analysis R&D: liquid argon anti-coincidence

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 c-lock• May ’10: 1st deployment of FE&detector mock-up • June ‘10: Commissioning with natGe detector string • Soon: start Phase I physics data taking

Majorana

Very pure material(Electroformed copper)

SegmentationPSD improvement

R&D phase 30-60 kg of 86% enriched 76Ge crystals

Some of the crystals segmented

T1/2 > 1. 1026 yr <mn> < 0.14 eV (could confirm 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)

Ge diodes

EXO - 200

200 kg of 136Xe, no Ba ion tagging

Installation in WIPP underground labPossibility to measure bb(2n)

EXO-200 full of natural Xe - Tuning on all systems - Engineering runs - Physics mode as soon as possible

Liquid Xe TPC Ionization + scintillation DE/E (FWHM)= 3.3 % @Qbb

Possibility of Baryum ion tagging byLaser florescence (136Xe 136Ba++ + 2 eR&D in progress

Gazeous TPC R&D

(USA, Canada, Switzerland, Russia)

SNO++

Scintillator loaded with Nd.

only internal Th and 8B solar neutrino backgrounds are important

500 kg of 150Nd1 year<mn> = 150 meV

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 <mn> ~0.08 eV

500 kg of 150Nd 4yr <mn> ~ 0.03 eV

KamLAND-Zen

CANDLES

CaF2(Pure)

Liquid Scintillator(Veto Counter)

Buffer Oil

Large PMT

Pure CaF2 crystalsWave length shifter in LS

PSD to reject g and a

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

(Japan)

DCBA

Drift Chamber beta-ray Analyser

Prototype with 207Bi : 10% (FWHM) energy resolutionX position s= 0.5 mmY position s= 0.02 mmX position s= 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

(UK, Germany, Italy, poland, Slovaquia, Finland, USA)

Cd-113 beta decaywith half-life of about 1016 yrs

Technique Location Masskg start Bckg

Cts/keV/kg/yrT1/2(0n) <mee>

meVEXO Liquid Xe

136XeWIPP (USA) 200 2011 0.002 6.4 1025 < 109 – 135

(2yr)

GERDA Diode Ge76Ge

Gan sasso (Italy)

18

40

2011

2012

0.01

0.001

3. 1025

3. 1026

< 250– 380

< 80 - 120CUORE-0

CUORE Bolometers 130Te

Gan sasso (Italy)

13

200

2011

2013

0.12

0.010.001

8. 1025

2.1 1026

6.5 1026

<100 - 200

< 41 -82< 23- 47

SN module0

SuperNEMO

Tracko-calo82Se, 150Nd

Modane (France) 7

100

2013

2015

0.0001

0.0001

6. 1024

1026

< 200 –600 (1yr)

< 53 – 140SNO+ Liq. Scint.

150NdSNOLAB(Canada) 44 2012 < 100

KamLAND Liq. Scinti136Xe

Kamioka(Japan) 400 2011 < ~ 60 (2 yr)

Sensitivities 2013 - 2018

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

CUORE 130Te bolometers

CUORE-0 39 kg of natTe13 kg of 130TeData taking 2011

CUORE 200 kgData taking 2013(scintillating bolometres ?)

GERDA Ge diode in LAr

2010: 18 kg of 76Ge(HM and IGEX crystals)

1st results 2011

2012: 40 kg of 76Ge

MAJORANA Ge segmented Diode

2011: 20 kg of natGe

2013 ? : 30 kg of 76Ge

SuperNEMO tracko-calo

Module-0 7 kg of 82Se (150Nd)Data taking 2013

20 Module 100 kgData taking 2015

Step by step approach

Gran Sasso laboratoryGran Sasso laboratory

DUSEL laboratoryModane laboratory

+ Energy resolution+ Energy resolution+ Natural Te

+ Energy resolution+ Background rejection+ Multi-isotopes

100 kg experiments

Agressive approach (no 10 kg prototype)

SNO++ Nd salt + liquid scintillator

2010: 740 kg of natNd(44 kg of 150Nd)Dissolved in scintillator

EXO liquid Xenon

2010: 200 kg of 136XeResults 2013

Ba tagging R&D

2011: 400 kg of 136XeDissolved in liq. scintillator

NEXT Xe high pressure TPC

2011: 1 kg of 136Xe

2013 : 100 kg

KamLAND-Zen Xe + liq. scintillatorKamioka laboratory Canfranc laboratory

SNOLAB laboratoryWIPPL laboratory

+ Large mass+ Possibility to tag daughter nucleus

+ Large mass+ low background detector

+ Large mass + Background rejection

bb(0n) signal ? HM claim

T1/2 = (0.69 – 4.18) 1025

<mn> = 0.28-0.58 (90%)

2006: Improvement of PSA (6s)

+0.44-0.31

<mn> = 0.32 ± 0.03 eV

2004 (4s)

T1/2 = 2.23 1025 yr

arXiv:1008.5260v2 : Tomás R. Rodríguez, G. Martinez-Pinedo From F. Simkovic (neutrino 2010)

Nuclear Matrix Element