double beta decay - società italiana di...
TRANSCRIPT
11
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
33
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
5
6
77
Which is the nature of neutrino and its mass
The second mystery of Ettore Majorana
88
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
13
From single beta decay
Present => mn < 2.2 eV
Future (KATRIN) => mn < .2 eV
1414
15
16
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!
17
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
19
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
21
2222
23
• 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
24
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
27
MT M M M M M MT T T TM
27
2828
2929
3030
3131
32
Two neutrino bb decay 2212
1/2|M| G )( nnnt 2
32
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
34
Limits on 0nc
35
3636
<m> ~ 0.34eV
Possibile Evidence of 0nbb in 76Ge
37
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
40
41
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
41
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
49
1995 2000 2005 2010 2015
Progress of thermal detectors
49
5050
CUORICINO
51
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 )
54
55
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
59
60
61
62
63
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
63
64
65
66
67
68
69
70
7171
Ionization
7272
GERDA
73
74
Background predicted in GERDA
7575
76
77
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
82
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
85
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
90
91
9292
9393
94
Going to be installed this year
94
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
103
A new laboratory in South KoreaMainly for Dark Matter CSNaI (crystals, but also for DBD
104
105
Double beta decay
With Calcium depleted of 48Ca
106
107
108
Special crystals produced by the SICCAS factory in Shanghai
109
110110
SICCAS/INFN Clean Room
111111
112
A crystal of 2.15 kg
113
114
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
119
120
121
122
123
124
125
126
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
132132
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
133