1. Comments on Neutrinoless Double Beta Decay Experiments
Huan Zhong Huang (黄焕中)
Department of Physics and Astronomy
University of California, Los Angeles 90095
OCPA Underground Sciences Workshop
Hong Kong, July
Thanks to F. Avignone, S.J. Freedman,
E. Fiorini, R. Maruyama

2. Neutrino Physics Program
Critical Questions for Future Neutrino Physics Program
1) Are neutrinos their own anti-particles?
Dirac or Majorana neutrinos
2) What are the scale of neutrino masses and the
hierarchy of the neutrino mass ordering?
3) What is the remaining neutrino mixing angle q13?
4) Do neutrinos violate the CP symmetry and
contribute to the matter-antimatter
asymmetry?

3. Massive Neutrinos: Majorana or Dirac?
Lorentz Invariance:
massive particle velocity < speed of light c
spin
Left-handed nLH
Momentum
(Lab)
Right-handed nRH
(Speed-of-light Frame)
Majorana Neutrino
Neutrino=anti-neutrino
Dirac Neutrino
Neutrino and anti-neut distinct
Boost
Boost
nLH
nRH
nLH
nRH
CPT
CPT
CPT

4. Double Beta Decay (A,Z+1) 2 (A,Z) bb (A,Z+2) e– 1935
Even-even nucleus
2
2nbb: T1/2 ≥ 1018y e–
(A,Z)
(A,Z+2) W
1935
M. Goeppert-Mayer
(A,Z)  (A,Z+2) + 2e– + 2ne

5. Dirac or Majorana Neutrinos?
0
1937 n e e–
(A,Z)
(A,Z+2) W
(A,Z)  (A,Z+2) + 2e–
0nbb: T1/2 ≥ 1025y
Majorana  neutrino = anti-neutrino
Lepton Number violation !

6. Measuring Neutrino Masses
Direct Measurement
tritium decays
E0 = 18.6 keV
<mb> =
2) Effective Majorana Mass
<mbb> =
ei – CP phase for neutrinos
3) Precise Cosmological Measurement
<mS> =

7. The actual range of mbb depends on the NME !
There is no clear issue identified regarding the
experimental data.

8. The Cuoricino experiment
62 TeO2 bolometers
Total detector mass:
M ~ 11 kg 130Te ~ 5x Te nuclides
Deep underground in the Gran Sasso Laboratory (Italy) (3500 m.w.e.)
Started in 2003, currently the largest operated bolometric experiment

9. Cuoricino Results Neither Support Nor Rule Out Heidelberg-Moscow Claim
Background in bb region
0.18  0.01 c/keV/kg/y
Average 2615keV
~ 8keV
PRELIMINARY
Updated Aug 2007
Tot exposure = kg y 130Te
bb0n
60Co
Results for 0nbb half life
and Majorana mass (90% c.l.):
T1/20n (130Te) > 3.1 x 1024 y
mbb < meV (*)
(*) using NME from Rodin et al, Nucl. Phys. A 776 (2006) and erratum arXiv::nucl-th/
Cuoricino demonstrates the feasibility of a large scale bolometric detector with good energy resolution
Background reduction is being worked on for scaled up CUORE

10. The Constraint from Cosmology Competitive
Model Dependent ! G.L. Fogli et al, hep-ph/
Cosmological Data Set S (at 2s)
CMB < 1.19 eV
CMB+HST+SN-Ia < 0.75 eV
CMB+HST+SN-Ia+BAO < 0.60 eV
CMB+HST+SN-Ia+BAO+Lya < 0.19 eV
CMB – WMAP 5-year, ACBAR, VSA, CBI, BOOMERANG
HST – Hubble Space Telescope h=
SN-Ia – SNLA (The SuperNova Legacy Survey)
BAO – Baryonic Acoustic Oscillation (WMAP)
Lya – Small Scale Primordial Spec from Lyman-a forest coulds

11. Candidate for Double beta Decays
Q (MeV) Abund.(%)
48Ca48Ti
4.271
0.187
76Ge76Se
2.040
7.8
82Se82Kr
2.995
9.2
96Zr96Mo
3.350
2.8
100Mo100Ru
3.034
9.6
110Pd110Cd
2.013
11.8
116Cd116Sn
2.802
7.5
124Sn124Te
2.228
5.64
130Te130Xe
2.533
34.5
136Xe136Ba
2.479
8.9
150Nd150Sm
3.367
5.6

12. Major 0nbb Experiments (scalable to ~1 ton now or planned)
-- CUORE 130Te
-- MAJORANA/GERDA 76Ge
-- EXO 136Xe
Essential to Measure 0nbb for Several
Elements !!

13. Underground National Laboratory
US-Italy Collaboration
LNGS
CUORE R&D (Hall C)
Underground National Laboratory
of Gran Sasso
L'Aquila – ITALY
3500 m.w.e.
CUORICINO - CUORE
(Hall A)

14. 19 CUORICINO-like towers with 13 planes of 4 crystals each
CUORE
CUORE: Cryogenic Underground Observatory for Rare Events will be a tightly packed array of 988 Bolometers - M ~ 200 kg of 130Te
80 cm
19 CUORICINO-like towers with 13 planes of 4 crystals each
Operated at Gran Sasso laboratory
Special cryostat built w/ selected materials
Cryogen-free dilution refrigerator
Shielded by several lead shields

15. Bolometer TeO2 Bolometer: Source = Detector Heat sink: ~8-10 mK
Thermal coupling: Teflon
Thermometer: NTD Ge thermistor
Absorber: TeO2 crystal
TeO2 Bolometer: Source = Detector

16. Signal from NTD Ge Thermistor

17. Energy resolution of a TeO2 crystal of
5x5x5 cm3 (~ 760 g )
Energy [keV]
Counts
210Po a line
0.8 keV FWHM @ 46 keV
1.4 keV FWHM @ MeV
2.1 keV FWHM @ MeV
2.6 keV FWHM @ MeV
3.2 keV FWHM @ MeV
the best a spectrometer so far

18. Scaling CUORE from CUORICINO

19. Background Reduction is the Key
CUORICINO – Surface Related Background
CUORE --
Crystal Production
-- TeO2 Material QA for Crystal Production
-- Crystal Processing QA
-- Improved Surface Cleaning Procedure
Crystal Support Structure (Cu)
-- New/Improved Surface Cleaning Procedure
Note – CUORICINO/CUORE Has Excellent
Shielding (Roman Lead)

20. Expected Sensitivity of the CUORE Experiment
APS Neutrino Study 2004

22. General Comments CUORE-- 130Te
-- Excellent Energy Resolution (FWHM 0.3%)
-- Cost Effective
-- Background Elimination Challenging
-- Data-Taking Early 2011
GERDA/MAJORANA -- 76Ge
-- Ultra-Low Background Possible
-- Detector Segmentation and Pulse Shape
Analysis Possible
-- Very Costly !
EXO Xe
-- Easy to Scale Up
-- Ba+ Tagging Challenging / FWHM ~3.4%

24. Interdisciplinary Sciences
Three Overarching Themes
-- APS multidivisional neutrino study
Neutrino Matrix – physics/
Neutrinos and the New Paradigm
-- neutrino masses, Dirac/Majorana and CP violation
beyond the Standard Model
2) Neutrinos and the Unexpected
-- Many discoveries in recent years, what surprises and
extraordinary properties ahead?
3) Neutrinos and Cosmos
-- # of neutrinos, neutrino masses – large structures
CP violation – matter/anti-matter asymmetry

25. CUORE Collaboration Universita’ di Milano-Bicocca5
C. Arnaboldi, C. Brofferio, S. Capelli, M. Carrettoni, M. Clemenza,
E. Fiorini, S. Kraft, C. Maiano, C. Nones, A. Nucciotti, M. Pavan,
D. Schaeffer, M. Sisti, L. Zanotti
Sezione di Milano dell’INFN
F. Alessandria, L. Carbone, O. Cremonesi, L. Gironi, G. Pessina,
S. Pirro, E. Previtali
Politecnico di Milano
R. Ardito, G. Maier
Laboratori Nazionali del Gran Sasso
M. Balata, C. Bucci, P. Gorla, S. Nisi, E. L. Tatananni, C. Tomei, C. Zarra
Universita’ di Firenze and Sezione di Firenze dell’INFN
M. Barucci, L. Risegari, G. Ventura
Universita’ dell’Insubria5
E. Andreotti, L. Foggetta, A. Giuliani, M. Pedretti, C. Salvioni
Universita di Genova
S. Didomizio6, A. Giachero7, P. Ottonello6, M. Pallavicini6
Laboratori Nazionali di Legnaro
G. Keppel, P. Menegatti, V. Palmieri, V. Rampazzo
Universita di Roma La Sapienza and Sezione di Roma dell’INFN
F. Bellini, C. Cosmelli, I. Dafinei, R. Faccini, F. Ferroni, C. Gargiulo,
E. Longo, S. Morganti, M. Olcese, M. Vignati
Universita’ di Bologna and Sezione di Bologna dell’INFN
M. M. Deninno, N. Moggi, F. Rimondi, S. Zucchelli
University of Zaragoza
M. Martinez
Kammerling Onnes Laboratory, Leiden University
A. de Waard, G. Frossati
Shanghai Institute of Applied Physics
(Chinese Academy of Sciences)
X. Cai, D. Fang, Y. Ma, W. Tian, H. Wang
5also Sezione di Milano dell’INFN
6also Sezione di Genova dell’INFN
7also LNGS
University of California at Berkeley
A. Bryant2, M.P. Decowski2 , M.J. Dolinski3 , S.J. Freedman2,
E.E. Haller2, L. Kogler2, Yu.G. Kolomensky2
University of South Carolina
F.T. Avignone III, I. Bandac, R. J. Creswick, H.A. Farach,
C. Martinez, L. Mizouni, C. Rosenfeld
Lawrence Berkeley National Laboratory
J. Beeman, E. Guardincerri, R.W. Kadel, A.R. Smith, N. Xu
Lawrence Livermore National Laboratory
K. Kazkaz, E.B. Norman4, N. Scielzo
University of California, Los Angeles
H. Z. Huang, S. Trentalange, C. Whitten Jr.
University of Wisconsin, Madison
L.M. Ejzak, K.M. Heeger, R.H. Maruyama, S. Sangiorgio
California Polytechnic State University
T.D. Gutierrez
2also LBNL
3also LLNL
4also UC Berkeley

26. Full estimated range of M0n within QRPA framework and comparison with NSM
(higher order currents now included in NSM) – P. Vogel

27. Double Beta Decay Candidates
Normal beta-decay is energetically forbidden, while
double beta-decay from (A,Z)  (A, Z+2) is energetically
allowed:
(A=even, Z=even)
A, Z+1
A, Z+3 0+
A, Z bb 0+
A, Z+2
Some candidates:
48Ca, 70Zn, 76Ge, 80Se, 86Kr, 96Zr, 100Mo, 116Cd, 130Te, 136Xe, 150Nd

28. CUORE Array of 988 TeO2 crystals 19 Cuoricino-like “towers”
13 levels, 4 crystals each
5x5x5 cm3 (750 g each)
Low conductance Teflon insulators
OFHC Cu structure
Crystals equipped with NTDs
Suspended from cold stage
Mechanically isolated
OGHC-Oxygen Free High Conductivity
NTD-Neutron Transmutation Doped

29. Neutrino Masses and Hierarchy
Normal
Inverted

30. Cosmogenic Co from Te