beta decay experiments

Beta decay experiments

Fabrice PiquemalCENBG, 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

- Absolute neutrino mass and neutrino mass hierarchy (SDB, DBD)

- Nature of neutrino : Dirac ( ) or Majorana ( =) (DBD)

- Right-handed current interaction (DBD)

- CP violation in leptonic sector (DBD)

- Search of Supersymmetry and new particles (DBD)

Beta decays: physics case

SDB: Single beta decayDBD: Double beta decay

F. Piquemal (CENBG) LP07 Daegu August 2007

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

m2atm = m2

31 = (2.3 0.2 ) 10-3 eV2

m2sol = m2

12 = (7.9 0.3) 10-5 eV2

Oscillations


dN/dE ~ [ (E0-Ee)2 – mi2 ]1/2:

Beta decay

(A,Z) (A,Z+1) + e- + e

averaged neutrino

mass

Fraction of decay in [Q – m, Q] ~ (E/Qlowest Q value 3H (Q= 18.6 keV)

3

High counting rate Low background

Energy resolution ~ m

me

2 U e i2 m i

2me

2 U e i2 m i

2


MAINZ: m2 = -0.6 ± 2.2 ± 2.1 eV2

m< 2.3 eV (95% C.L.)

C. Kraus et al., Eur. Phys. J. C 40 (2005) 447

Beta decay: present statusMAC-E spectrometers

Source Electron analyzer Electron counter3H

integral spectrum: select Ee > Eth

Troisk: m2 = -2.3 ± 2.5 ± 2.0 eV2

m< 2.05 eV (95% C.L.)

But systematics from end-point fluctuations not includedF. Piquemal (CENBG) LP07 Daegu August 2007

Improvement of E: 0.93 eV (4.8 eV for Mainz)Larger acceptance

Statistics 100 days 1000 days

Beta decay: KATRIN experiment

Commissioning and start : 2010

Sensitivity m < 0.2 eV


5

Other possible process :

V+A current : <m>, <>, <>

Majoron emission : <gM>

Supersymmetry : ’111,

’113

Neutrinoless double beta decay

Light neutrino exchange

T1/2= F(Q,Z) |M0|2 <m>2-1

Phase space factor Nuclear matrix element

<m>= m1|Ue1|2 + m2|Ue2|2.ei + m3|Ue3|2.ei

|Uei|: mixing matrix elements

et: Majorana phases

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

Schechter-Valle theorem: Majorana neutrinos

L = 2Lepton number violation

Majorana neutrino (=)

Massive neutrino


Electron energy sumQ

Arb

itrar

y sc

ale

Observables

Angular distribution

Individual electron energy

Half-life T1/2

Allow to distinguish the mechanism

Background : natural radioactivity, radon,neutrons, muons,

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

A lot of improvements have been done but still a factor 2-3 of discrepancyUncertainties for extraction of <m>

T1/2= F(Q,Z) ||2 <m>2-1 5

Nuclear matrix elements

In the following, « latest NME » will refer to these Nuclear Matrix ElementsF. Piquemal (CENBG) LP07 Daegu August 2007

Shell Model - QRPA Two different QRPA calculations

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

Talk focuses on the running experiments and on some 100 kg scale projects starting within 5 years

Present situationHeidelberg-Moscow (2001) ~11 kg of enriched Ge diodes in 76Ge (86%) Pure calorimeter

T1/2 = 2.23 1025 yr +0.44-0.31

<m> = 0.32 ± 0.03 eV

2006 new PSA analysis: 6 effect

Claim for discovery since 2002(2002 : 3.1 and 2004: 4

<m> <0.35-1.05 eV (90% CL)

2004: 4

High energy resolution and efficiency

But poor background rejection (pulse shape analysis)

T 1/2 >1.9 1025 yr (90% CL)

35.5 k.yr

0.06 cts/keV/kg/yr

Eur. Phys. J., A 12 (2001) 147

Very controversial result

Future Ge experimentsGERDA (Germany, Italy, Belgium, Russia)Majorana (USA, Russia, Japan, Canada)

Selection of very pure material (Majorana)Removal of matter (GERDA) Segmentation of detectors for background rejectionUse of liquid nitrogen or argon for active shieldingImprovement 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 > 2 1026 yr in 3 years of data <m> < 110 meV (no background)

Majorana: 30- 60 kg of enriched 76Ge (3 yr) T1/2 > 1. 1026 yr m < 140 meV Start 2011 Collaboration for 1 ton experiment

Reduction of background bya factor 10 – 100 compareto HM

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 2003F. Piquemal (CENBG) LP07 Daegu August 2007

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 crystalsImprovement 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 compare to Cuoricino)

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/y)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

Num

ber

of e

vent

s / 4

0 ke

V

Phase II, Low radon5.7 kg.yr



Num

ber

of e

vent

s / 4

0 ke

V

Num

ber

of e

vent

s / 4

0 ke

V

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

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 II

76Ge17.940

3. 1025

2. 1026

0.2 – 0.5*0.07 – 0.2*

20092011

FundedFunded

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

150Nd100 100

2. 1026

1026

0.05- 0.09*0.07

2011 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 R&D

COBRA116Cd,

130Te420

R&D

SummarySummary* C

alculation with N

ME

from R

odim et al., Suhonen et al., C

aurier et al. PMN

07

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

Single beta decay

KATRIN m < 2.3 eV m < 0.2 eV results in ~2014

Other possibility : bolometers with 187Re (Q=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 <m> ~(0.2 – 0.7) eV in 2009

Need to measure several nucleus with different techniques (only tracko-calocan 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

BACKUP SLIDES

2001

T1/2= (0.8-18.3) 1025 yr <m>= 0.11 – 0.56 eV

2002 (3.1)

2004: new calibration (4)

T 12

0.69 4.18 1025ans 90 CLm 0.28 0.58eV Best value:0.39 eV

T1/2 >1.9 1025 <m> < 0.35-1.05 (90%)

signal ? HM claim

signal ?

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 lineInelastic neutron scattering (n,n‘) on lead

Other suggestions, can be combination of all

(Result with last NME should be <m> = 0.11 – 0.71 eV)

T1/2 = 2.23 1025 yr +0.44-0.31

<m> = 0.32 ± 0.03 eVToday 6

T 0

2/1 > . . A

M . tNBckg . E

ln2 . NkC.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-conductors

Source = detector

, E

CalorimeterLoaded ScintillatorSource = detector

,

Tracko-caloSource detector

NBckg, isotope choice

Xe TPCSource = detector

,M, (NBckg)

GERDA and MajoranaStrategy: 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

From Fedor Simkovic PMN07

Cos()

Angular distribution219 000 events

6914 g389 daysS/B = 40

NEMO-3

100Mo

E1 + E2 (MeV)

Energy sum spectrum219 000 events

6914 g389 daysS/B = 40

NEMO-3

100Mo

Background subtracted

• Data22 Monte Carlo

• Data22 Monte CarloBackground subtracted

« factory» → tool for precision test

T1/2() = 7.11 0.02 (stat) 0.54 (syst) 1018 yr

12000

10000

8000

6000

4000

2000

0

N

umbe

r of

eve

nts

12000

10000

8000

6000

4000

2000

0

Num

ber

of e

vent

s/0.

05 M

eV

NEMO 3:100Mo 2 results

Phys. Rev. Lett. 95 182302 (2005)

7.6 kg.yr 7.6 kg.yr

187Re Q = 2.47 keV

MIBETAMIBETA

m 2 = -141 211 stat 90 sys eV2

m15 eV (90% c.l.)

1 mm

Beta decay: MARE experiment

MicroBolometers of ArReO4

Full energy measurementNo systematic from sourceBut time response of sensor pile-up

MARE-I: 300 detectors FWHM ~20 eV ~100 – 500 s m2 –4 eV ( 5 years)

MARE – II : 5000 detectors (~2018) FWHM ~20 eV ~1 – 5 s m0.2 eV (10 years)

10 detectors

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 scaleprojects starting within 5 years

View of the field: present and future


beta decay experiments

Documents

piquemal cenbg lp07

dbd nature of neutrino

effective neutrino mass

beta decaya

neutrino massbeta decay

neutrino mass hierarchy

dirac n n

double beta decayf