Comments on Neutrinoless Double Beta Decay Experiments Huan Zhong Huang (黄焕中) Department of Physics and Astronomy University of California, Los Angeles 90095 huang@physics.ucla.edu OCPA Underground Sciences Workshop Hong Kong, July 21-23 2008 Thanks to F. Avignone, S.J. Freedman, E. Fiorini, R. Maruyama

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?

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

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

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 !

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> =

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

The Cuoricino experiment 62 TeO2 bolometers Total detector mass: M ~ 11 kg 130Te ~ 5x1025 130Te nuclides Deep underground in the Gran Sasso Laboratory (Italy) (3500 m.w.e.) Started in 2003, currently the largest operated bolometric experiment

Cuoricino Results Neither Support Nor Rule Out Heidelberg-Moscow Claim Background in bb region 0.18  0.01 c/keV/kg/y Average resolution @ 2615keV ~ 8keV PRELIMINARY Updated Aug 2007 Tot exposure = 15.53 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 < 200 - 680 meV (*) (*) using NME from Rodin et al, Nucl. Phys. A 776 (2006) and erratum arXiv::nucl-th/0706.4304 Cuoricino demonstrates the feasibility of a large scale bolometric detector with good energy resolution Background reduction is being worked on for scaled up CUORE

The Constraint from Cosmology Competitive Model Dependent ! G.L. Fogli et al, hep-ph/0805.2517 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=0.75+-0.07 SN-Ia – SNLA (The SuperNova Legacy Survey) BAO – Baryonic Acoustic Oscillation (WMAP) Lya – Small Scale Primordial Spec from Lyman-a forest coulds

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

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

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

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

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

Signal from NTD Ge Thermistor

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 @ 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

Scaling CUORE from CUORICINO

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)

Expected Sensitivity of the CUORE Experiment APS Neutrino Study 2004

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 -- 136Xe -- Easy to Scale Up -- Ba+ Tagging Challenging / FWHM ~3.4%

Interdisciplinary Sciences Three Overarching Themes -- APS multidivisional neutrino study Neutrino Matrix – physics/0411216 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

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

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

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

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

Neutrino Masses and Hierarchy Normal Inverted

Cosmogenic Co from Te