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Double beta decay

- First interest in DBD

- Old and new techniques

- Present results

- The future

2

1935 M.Goeppert-Mayer, P.R. 48 (1935) 512 T>1020

1967: 130Te, Geochemical Ogata and Takaoka,

Kirsten

Source=detector => M.Goldhaber E.Fiorini

1987: 82Se, Direct counting Moe et al .

1989 -2008 100Mo, 116Cd, 76Ge, 130Te etc.

DBD and DM (P.Belli)

E. Majorana, Nuovo Cimento 14 (1937) 171

G. Racah, Nuovo Cimento 14 (1937) 322

W.H. Furry Phys.Rev.56 (1939) 11984

A.S.Barabash : Hystorical review of 75 years of research

arXiv: 1104.2714v2 {nuc-ex] 25 April 2011

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4

1. (A,Z) => (A,Z+2) + 2 e- + 2 ne

Two neutrino double beta decay Allowed by the standard model

Found in ten nuclei to ground state and in two to excited state

2. (A,Z) => (A,Z+2) + 2 e- + c ( …2,3 c)

Emission of a massless Goldston boson named Majoron

3. (A,Z) => (A,Z+2) + 2 e-

Neutrinoless double beta decay. The two electrons share the total

transition energy E1 + E2 => DE => a peak appers in the sum

spectrum of the two electrons

Other possible “DL=2” decays

- Double positron decay => b+ b+

- Positron decay + Electron Capture => EC- b+

- Double electron capture => EC-EC

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6

77

Which is the nature of neutrino and its mass

The second mystery of Ettore Majorana

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9

n

Majorana =>1937

Neutrinoless double beta decay and Majorana neutrinos

RIGHT

LEFT

n

What about the neutrino mass => <mn > ?

10

Neutrino oscillations show that D(m12 –m2

2) ≠ 0

11

What could we expect ?

12

From cosmology => S mn ~ 1 eV

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From single beta decay

Present => mn < 2.2 eV

Future (KATRIN) => mn < .2 eV

1414

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Calculation is a severe challenge in nuclear structure physics.

- 2 neutrino bb decay can be described by pure Gamow-Teller transitions through

intermediate 1+-states

-neutrinoless mode can occur through other multipoles

Very first approach Primakoff and Rosen : all matrix elements equal .

A silly note by E.F. => the case of 48Ca

Three methods are employed:

-The Shell Model (SM)

-The Quasiparticle Random Phase Approximation (QRPA) with their modifications

-The Interactiong Boson Model (IBM), more recently

Some help can come from experiments, for instance :=>charge exchange reactions via (d,2He) and (3He,t) linked to the Gamow-Teller strength BGT

for 1+-states

=> ft-value measurements of electron capture and beta decay of the intermediate nucleus

Nuclear Matrix Elements => I am here to learn!

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Shell model

Uses Pauli principle to describe (1949) nuclear structure in terms of

nuclear levels . Nobel prize to E.Wigner, M.Goeppert Mayer and J.Jensen

Disadvantage => small number of single-particle states outside the inert

code which can be included

Advantage => one can include correlations of arbitrary complexity

since they are few

Started in 1984, but recently calculations have been carried out on various

nuclei (48Ca, 76Ge, 72Se, 116Cd, 128Te, 130Te, 136Xe) and attempted on others

Difficult for deformed nuclei like 160Nd,

.

1818

Quasiparticle Random Phase Approximation (QRPA,RQRPA,pnQRPA)

Includes many single -particle states outside a relatively small inert core

At the beginning considerable difficulties and disagreement with

experimental data , in particular for geochemical experiments by one to

two order of magnitude

Explanation on both sides of the Pacific:

Inclusion of of the particle-particle interaction in the nucleus allow to

evaluate correctly the disagreement with experimental data. However:

=> strong dependance of the rate from gpp ( the particle-particle

correlation strenght).

How to evaluate gpp ?

=> from two neutrino double beta decay

=> from single beta and EC processes of the intermediate nuclei

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The microscopic Interacting Boson Model (IBM)

Introduced many years ago by Arima and F.Iachello in nuclear physics.

Recently applied by Iachello and collaborators to Double Beta Decay.

=> protons and neutrons pair essentially acting as a single particle with

boson properties with integral spin of 0, 2 or 4.

Seen from the nucleus the process consists in the annihilation of a couple of

protons with an angular momentum J in a couple of neutrons with the

same angular momentum.

IBM-I treats both type of nucleons the same and considers only pairs of

nucleon coupled to an angular momentum of 0 and 2 called s and p.

IMB-II treats protons and neutrons separately.

GT, Fermi and tensor terms are considered

2020

Reasonable agreement IMB-II with QRPA but disagrement by a factor

around 2 with Shell Model.

A considerable effect is due to the parameter gA (from 1 to 1.2 whose

value is squared in the bb operator

Recent calculations by F.Iachello

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2222

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• A terrible phrase from a recent paper A.Faessler et al: Multi-isotope degeneracy of neutrinoless double beta decay mechanisms in the quasi-particle-random-phase –approximation, arXiv:1103.2504v1 [hep-ph] 13 Mar 2011 –

• ”we find that, unfortunately, current NME uncertainties appear to prevent a robust determination of the relative contribution of each mechanism to the deacy amplitude, even assuming accurate measurement of the decay lifetimes”

A word from a poor experimentalist

<mn > proportional to NME

limit on <mn > proportional to t -1/2

t proportional to i.a and to M1/2 T ½ B -1/2

limit on <mn > proportional to M-1/4 T -1/4 B 1/4

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Source detectorSource = detector

(calorimetric)

e-

e-

e-

e-

source

detector

detector

Geochemical experiments82Se = > 82Kr, 96Zr = > 96Mo (?) , 128Te = > 128Xe (confirmed), 130Te = > 130Xe

Radiochemical experiments238U = > 238Pu

Direct experiments

Indirect experiments

2525

Source=detector => first 76Ge experiment

2626

Very rare radioactive processes => “cosmic silence” is needed.

Underground laboratories

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MT M M M M M MT T T TM

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2828

2929

3030

3131

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Two neutrino bb decay 2212

1/2|M| G )( nnnt 2

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130Te t 2n => (7.0 ±.9stat± 1.1sist ) x 1020 a

3333

Nucl. Experiment % Qbb Enr Technique T0n (y) <mn) Iachello

48Ca Elegant IV 0.1

9

4271 scintillator >1.4x1022 20-28

76Ge Heidelberg-

Moscow

7.8 2039 87 ionization >1.9x1025 .23 – .64 <.29

76Ge IGEX 7.8 2039 87 Ionization >1.6x1025 .25 – .70 <.27

76Ge Klapdor et

al

7.8 2039 87 ionization 1.2x1025 .29-81 ~.34

82Se NEMO 3 9.2 2995 97 tracking >3.6x1023 .9-.24 1.1

100Mo NEMO 3 9.6 3034 95-

99

tracking >1.1x1024 .41-.91 .49

116Cd Solotvina 7.5 2809 83 scintillator >1.7x1023 1.5 – 2.8 1.5

128Te Bernatovitz 34 866 geochem >7.7 1024 .8-1.9

130Te Cuoricino 33.

8

2528 bolometric >2.8 x1024 .3-.7 .36

136Xe DAMA 8.9 2476 69 scintillator >1.2x1024 1.1 -2.9 .61

150Nd Irvine 5.6 3367 91 tracking >1.2x1021 3 - ?

Neutrinoless bb decay

t

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Limits on 0nc

35

3636

<m> ~ 0.34eV

Possibile Evidence of 0nbb in 76Ge

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NEMO 3:

bb(2n)

100Mo

100Mo

V.Tretyak

3838

3939

Incident

particle

absorber

crystal

Thermal sensor

Energy resolution <1 eV ~ 2eV @ 6 keV

~10 eV ~keV @ 2 MeV

VC

Q T D

J/K )( v

v 1944 C 3

m

V

T

A new technique => Thermal detectors

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First ideas

1880 => Langley => resistive bolometers for infrrared rays from SUN

1903 => Curie et Laborde => calorimetric measurement of radioactivity

1927 => Ellis and Wuster => heat less then expected => the neutrino

1949 => D. Andrews, R. Fowler, M. Williams => a particle detection

1983 => T.Niinikoski =>observe pulses in resistors due to cosmic rays

1984 => S.H.Moseley et LT detectors for astrophysics and n mass

=> Fiorini and Niinikoski Low temperature detectors for rare events

=> A. Drukier, L. Stodolsky, => neutrino physics and astronomy

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4242

4343

4444

4545

Energy resolution of a TeO2 crystal 5x5x5 cm3 (~ 760 g )

:

0.8 keV FWHM @ 46 keV

1.4 keV FWHM @ 0.351 MeV

2.1 keV FWHM @ 0.911 MeV

2.6 keV FWHM @ 2.615 MeV

3.2 keV FWHM @ 5.407 MeV

(the best a spectrometer so far

210Po a line

4646

209Bi considered the only stable isotope of Bi and the stable nucleus with higher Z

A very interesting application of thermal detectors => decay of 209Bi

Scintillation and heat experiment in Paris by P.de Marcillac et al with a BGO of 47 g

DE = 3137 1stat 2syst => 1,9 0.2 x 1019 a

4747

4848

130 Te = 130 Xe + 2 e- (+2n ) a.i,. ~ 34% DE = 2528 keV

Mibeta (only Milano) 20 TeO2 bolometers of 340 g => 6.8 kg

CUORICINO (CUORICINO Coll.)44 crystals of 790 g and 18 of 330 g (enrich.) =>40.7 kg

CUORE (CUORE coll) 988 crystals 750 g => 741 kg

Exxperiments with thermal detectors

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1995 2000 2005 2010 2015

Progress of thermal detectors

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5050

CUORICINO

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52

5353

Funny consequence in change of DQ => New

Statistics Q- value Background Limit (90% cl) <mn > < 0.3 - .7

yr x kg130Te (keV) c/kev/kg/y years

19.75 ~2527.5 0.162± 0.006 2.8 1024 (was 3 x 1024 )

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5656

5757

NEW => AMoRE => CaMoO4 (S.K.Kim)

5858

COBRAK. Zuber CdTe

Semiconductors with good E-

resolution to study 116Cd 0nbb

and others at Gran sasso

Goal 64K 1% 10-1/t y

K.Zuber

Ionization

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MAJORANA - GERDA

• ‘Bare’ enrGe array in liquid argon • Shield: high-purity liquid Argon / H2O• Phase I (2011): ~18 kg (HdM/IGEX diodes)• Phase II (2012): add ~20 kg new detectors - Total

~40 kg

GERDA

Joint Cooperative Agreement:• Open exchange of knowledge & technologies (e.g. MaGe, R&D)

• Intention is to merge for 1 ton exp. Select best techniques developed and tested in GERDA and MAJORANA

• Modules of enrGe housed in high-purity electroformed copper cryostat

• Shield: electroformed copper / lead • Initial phase: R&D demonstrator module:

Total ~40 kg (up to 30 kg enr.)

MAJORANA

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7171

Ionization

7272

GERDA

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Background predicted in GERDA

7575

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TRACKING

150Nd

7878

79797979

Super NEMO

8080

81

=> (TPC) filled with high-pressure gaseous xenon, calorimetry and tracking

=> 136Xe, to be installed in the Canfranc Underground Laboratory.

Tracking +ligth

I

NEXT

electrons => ionization +excitation , emission of UVL-primary scintillation => start up

negative charges => drift towards TPC anode (EL region with intense field)

=> scatter, excite or even ionize gas => further VUV emitted isotropically

=> detected by photo detectors behind cathode => energy measurement

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8383Bari, 2 agosto 2009 Ettore Fiorini, Congresso SIF 2009 83

ELEGANT V 1990

MOON 1 prototype detector PL 6 layers, 53x53x1 cc BC408. equ.100Mo, 142g 40mg, 3 layers

Fig.4.3.6. This show the energy resolution of plastic scintillator (PL), which is seen by 31

PMTs. The energy resolution of PL are obtained by reconstructing the rays from

radioactive isotopes (40K 1.46MeV, 208Tl 2.61MeV) and checking source (22Na 1.27MeV).

Here, the energy EPL is determined by using the energy resolution of a NaI detector (ID)

at the energy regions (511keV, 1.27MeV) .

Plastic scintillator EPL(keV)

RP

L%

(FW

HM

)

137Cs 624keV

Conversion electron

207Bi 976keV

Conversion electron

22Na 1.274 MeV

Reconstructed gamma ray

40K 1.460 MeV

Reconstructed gamma ray

208Tl 2.614 MeV

Reconstructed gamma ray

H. Ejiri, Czeck. J. Physics, 56 (2006) H. Nakamura, et al., JPSJ 76 (2007) .

Resolution s = 2.8 % → 2.2 % position dep. corrected at Qbb=3 MeV

Tracking

8484

B MOON -PL OSAKA CTU JINR LANL UNC TU UW VNIIEF

Multilayer PL plates and PL fiber planes

with thin bb source film.

<m> ~ 44– 31 meV for 100

Mo –82

Se 90 % CL

H. Ejiri, et al., PRL, 85, 2000.

H. Ejiri et al., Czech. J. Phsy. 56, „06.

H. Ejiri European Phys. J. 162 „08

Detector ≠bb source

Select bb sources

Solar n as well

MOON 1 shows the efficiency e= 0.25

E-resolution s=2.2~1.7%

100Mo Foil

Plastic Scintillator

PMT

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Level and decay scheme of 100Mo

• 100Tc

100Mo

100Mo

1+ -0.168 pp, Be n

0+ 1.293

0+ 1.904

2+ 2.594

0+ 3.034

bb

n b

b

Possible search of solar neutrinos

8686

P.Gorla et al

MOON 100

M0 with Qbb =3.034MeV BG free except 2nbb Qb=0.167MeV solar/low E n

A.PS-CUORE / MOON Phonon Scintillator (Fiorini)

Phase 100Mo kg Detector year BG / ton y DE keV m eV

I 12 ZnMoO4 3 50 5 115

II 220 ZnMoO4 5 50 5 30

III 480 PL 5 16 115 45

8787

48Ca 0.187 %

Extension of

ELEGANT VI

Scintillation

8888

89

SNO

SNOLAB

90

Detector filled with scintillator => April 2012

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91

9292

9393

94

Going to be installed this year

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95

9696

T2=3.2x1021T2=3.2x1021

BOREXINO

0.7-2 % 136Xe

0.32-0.9 t in FV

100 meV 5y

9797

98

9999

100100

Presently taking data !_

101101

102102

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A new laboratory in South KoreaMainly for Dark Matter CSNaI (crystals, but also for DBD

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Double beta decay

With Calcium depleted of 48Ca

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Special crystals produced by the SICCAS factory in Shanghai

109

110110

SICCAS/INFN Clean Room

111111

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A crystal of 2.15 kg

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115

CUORE0

Substantially a column of CUORE to test the automatic construction of

CUORe, but also a good starting double beta decay experiment

116

The calibration system

117

The problem of the Roman lead

118

Lack of 210Pb (t1/2~ 22.3 y)

Lack of U and Th (< one ng/g measured with neutron activation

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127127

Compound Isotopic abundance Transiton energy

48CaF2 .0187 % 4272keV

76Ge 7.44 " 2038.7 "

100MoPbO4 9.63 " 3034 "

116CdWO4 7.49 " 2804 "

130TeO2 34 " 2528 "

150NdF3150NdGaO3 5.64 " 3368“

Other possible candidates for thermal detectors

The future

128128

Scintillation + Heat (in coin cidence)

129129

The first scintillating bolometer (1992)

CaF2

130130130

CdWO4: 508g

ZnSe:337 g

LUCIFER R&D approved by ERC

(European Research Council)

CaMoO4: 157g

131131

Lucifer: a R&D project of the Europen Community

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Searching for neutrinoless bb decay is a betSee Blaise Pascal

Neutrinos are Dirac particles => no hope

Neutrinos are Majorana, but direct hierarchy

=> for our children or grand children

Neutrinos are Majorana and indirect hierarchy

=> we could find it !

Conclusions

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