1. Daniel Lenz, University of Wisconsin, Madison 11/05/2010 - APS DNP Cryogenic search for neutrinoless double beta decay Daniel Lenz on behalf of the CUORE collaboration

2. Daniel Lenz, University of Wisconsin, Madison 11/05/2010 - APS DNP Motivation – 0νββ ν ≠ ν ν = ν 0νββ is only experimentally feasible way to distinguish Dirac vs. Majorana neutrinos if 0νββ observed: ? lepton number violation ΔL = 2 Schechter-Valle theorem ν = ν hint for seesaw type 1 m ν = m D 2 / M R << mD possible to determine absolute ν mass scale and ν hierarchy np n ν = νν = ν e-e- e-e- p 0 νββ -decay 0νββ 2νββ n e-e- e-e- p n p ν ν 2 νββ -decay 1

3. Daniel Lenz, University of Wisconsin, Madison 11/05/2010 - APS DNP Bolometric Approach rise time: ~ 50 ms total pulse length several seconds G E decay constant: ~ 200 ms several techniques employed to search for 0νββ here: bolometric approach several isotopes can be used large masses all energy measured in form of heat source = detector no event topology 2 typical pulse shape parameters for large bolometers: ΔT = E/C pulse shapes help identifying fake signals, e.g. electronics noise

4. Daniel Lenz, University of Wisconsin, Madison CUORE Experiment 3m 80cm Cryogenic Underground Observatory for Rare Events LNGS it is all about reducing background: only radiopure material copper, teflon goal: reach a flat bkg of 0.01 cts/(keV kg y) in ROI at least 36cm lead shields array of 988 bolometers 19 towers, 13 planes 4 bolometers /plane /tower 3 Borated polyethylene neutron shield located in Hall A of Gran Sasso National Lab (LNGS) overburden of ~3100 m.w.e. (relative to flat overburden) Phys.Rev. D73 053004 total detector mass 741kg M( 130 Te) ~200 kg ( 130 Te: 0νββ candidate isotope) 300 K 40 K 4 K lead shield 0.7 K 70 mK 10 mK lead shield + external lead shield (not shown) lead shield cryogen-free dilution refrigerator 11/05/2010 - APS DNP demonstrated within factor 2 - 4

5. Daniel Lenz, University of Wisconsin, Madison 11/05/2010 - APS DNP large bolometers 5 x 5 x 5 cm made from natural Te0 2 130 Te abundance ~ 34 % (no enrichment) FWHM ~ 5 keV @2528 keV CUORE Bolometers Temperature sensor: NTD Ge thermistor resistance change converted into voltage pulse non-linear energy response 4 Resolution: high purity copper & Teflon holder structure Q-value ( 130 Te) = 2528 keV 511 keV e + e - 583 keV 208 Tl 911 keV 228 Ac 965 + 969 keV 228 Ac 1588 228 Ac + 1593 keV DEP 2104 keV SEP 2615 keV 208 Tl 2528 keV 0νββ Phys. Rev. C 80 025501 Phys. Rev. Lett. 102, 212502

6. Daniel Lenz, University of Wisconsin, Madison 11/05/2010 - APS DNP CUORE Calibration System see also poster 123 by Ian Guinn 12 source strings move under own weight 300K to 10mK without shifting detector base temperature 300 K 40 K 4 K lead shield 0.7 K 70 mK 10 mK lead shield 5 heat load requirements very strict: sources need to be at 4K dedicated thermalization mechanism currently tested Kevlar string copper capsules with Telfon solenoid linear actuator pushing blade iso view calibration is big challenge slow detector response requires low activity sources (~100mBq) large shielding & good self shielding requires sources inside detector array for bkg reasons sources have to be stored outside the cryostat each string has 30 copper crimps housing 232 Th wire, calibrating 500keV - 3000keV kevlar string PTFE copper capsule thoriated tungsten wire

7. Daniel Lenz, University of Wisconsin, Madison 11/05/2010 - APS DNP Cuoricino 6 T 0v 1/2 ( 130 Te) > 2.8 x 10 24 y (90% C.L.) (presented @ Neutrino 2010) m ββ < 300 -700 meV (depending on choice of NME) M(Te0 2 ) = 40.7 kg => 130 Te = 11.3 kg 44 crystals: 5cm x 5cm x 5cm (CUORE-type) Total exposure 19.75 kg y 18 crystals: 3cm x 3cm x 6cm located at LNGS Hall Asmaller cryostat, single tower Cryostat will be further used for CUORE-like tower assembly tests: CUORE-0 b(ROI) = 0.169 ± 0.01 cts / (keV kg y) predecessor of CUORE using same experimental technique 4 are enriched FWHM ~ 6 keV FWHM ~ 10 keV FWHM ~ 14 keV two independent analyses, US and Italy: (very similar, agreeing, results) 0νββ expected

8. Daniel Lenz, University of Wisconsin, Madison CUORE Experiment - Status CUORE experimental hut finished cryostat main support in place 450 bolometers ready and stored underground at LNGS; tests ongoing 12/2010 outer cryostat vessels delivery US bolometer production started early 2011 cryostat 4K tests 12/2010 partial calibration system delivery 7 2013 CUORE data taking 11/05/2010 - APS DNP fall 2011 CUORE-0 data taking CUORE hut cryostat main support now : mid 2011 delivery dilution unit bolometers packaged

9. Daniel Lenz, University of Wisconsin, Madison 11/05/2010 - APS DNP Projected Sensitivity 8 m ββ = 41 – 96 meV (depending on NME) start probing inverted hierachy T 0ν 1/2 = 1.5 x 10 26 y at 1σ CUORE Sensitivity at 1σ: 5 years live time and bkg of b = 0.01 cts/ (keV kg y) Cuoricino 1σ result CUORE-0 – 0.06 cts/(keV kg y) Combined Cuoricino + CUORE-0 CUORE – 0.01 cts/(keV kg y)

10. Daniel Lenz, University of Wisconsin, Madison 11/05/2010 - APS DNP Summary 0νββ is only experimentally feasible way to distinguish Dirac vs. Majorana neutrinos CUORE uses bolometers made of natural Te0 2 to search for 0νββ of 130 Te Goal of background in ROI of 0.01 cts/(keV kg y); demonstrated within factor 2-4 Good progress being made: CUORE-0 data-taking starts fall 2011 CUORE data-taking 2013 CUORE sensitivity at 1σ T 0ν 1/2 = 1.5 × 10 26 y => m ββ = 41-96 meV start probing inverted hierarchy calibration is challenging: 12 strings with 30 sources brought into cryostat from 300K to 10mK, without changing detector base temperature 9