CUORE is a tonne-scale cryogenic detector operating at the Laboratori Nazionali del Gran Sasso (LNGS) that uses tellurium dioxide bolometers to search for neutrinoless double-beta decay of 130 Te. CUORE is also suitable to search for low energy rare events such as solar axions or WIMP scattering, thanks to its ultra-low background and large target mass. However, to conduct such sensitive searches requires improving the energy threshold to 10 keV. In this paper, we describe the analysis techniques developed for the low energy analysis of CUORE-like detectors, using the data acquired from November 2013 to March 2015 by CUORE-0, a single-tower prototype designed to validate the assembly procedure and new cleaning techniques of CUORE. We explain the energy threshold optimization, continuous monitoring of the trigger efficiency, data and event selection, and energy calibration at low energies in detail. We also present the low energy background spectrum of CUORE-0 below 60keV . Finally, we report the sensitivity of CUORE to WIMP annual modulation using the CUORE-0 energy threshold and background, as well as an estimate of the uncertainty on the nuclear quenching factor from nuclear recoils inCUORE-0.

United States

C. Alduino

K. Alfonso

Italy

D.R. Artusa

F.T. Avignone

O. Azzolini

G. Bari

J.W. Beeman

F. Bellini

G. Benato

A. Bersani

M. Biassoni

A. Branca

C. Brofferio

C. Bucci

A. Camacho

A. Caminata

L. Canonica

China

X.G. Cao

S. Capelli

L. Cappelli

L. Cardani

P. Carniti

N. Casali

L. Cassina

D. Chiesa

N. Chott

M. Clemenza

S. Copello

C. Cosmelli

O. Cremonesi

R.J. Creswick

J.S. Cushman

A. D’Addabbo

D. D’Aguanno

I. Dafinei

C.J. Davis

S. Dell’Oro

M.M. Deninno

S. Di Domizio

M.L. Di Vacri

A. Drobizhev

D.Q. Fang

M. Faverzani

E. Ferri

F. Ferroni

E. Fiorini

M.A. Franceschi

S.J. Freedman

B.K. Fujikawa

A. Giachero

L. Gironi

France

A. Giuliani

L. Gladstone

P. Gorla

C. Gotti

T.D. Gutierrez

E.E. Haller

K. Han

E. Hansen

K.M. Heeger

R. Hennings-Yeomans

H.Z. Huang

R. Kadel

G. Keppel

Yu. G. Kolomensky

A. Leder

C. Ligi

K.E. Lim

Y.G. Ma

M. Maino

L. Marini

Spain

M. Martinez

R.H. Maruyama

Y. Mei

N. Moggi

S. Morganti

P.J. Mosteiro

T. Napolitano

M. Nastasi

C. Nones

E.B. Norman

V. Novati

A. Nucciotti

T. O’Donnell

J.L. Ouellet

C.E. Pagliarone

M. Pallavicini

V. Palmieri

L. Pattavina

M. Pavan

G. Pessina

G. Piperno

C. Pira

S. Pirro

S. Pozzi

E. Previtali

C. Rosenfeld

C. Rusconi

M. Sakai

S. Sangiorgio

Low energy analysis techniques for CUORE

The Cryogenic Underground Observatory for Rare Events (CUORE) is designed to search for neutrinoless double beta decay of 130 Te with an array of 988 TeO 2 Â bolometers operating at temperatures around 10 mK. The experiment is currently being commissioned in Hall A of Laboratori Nazionali del Gran Sasso, Italy. The goal of CUORE is to reach a 90% C.L. exclusion sensitivity on the 130 Te decay half-life of 9 Ã 10 25 years after 5Â years of data taking. The main issue to be addressed to accomplish this aim is the rate of background events in the region of interest, which must not be higher than 10 -2 Â counts/keV/kg/year. We developed a detailed Monte Carlo simulation, based on results from a campaign of material screening, radioassays, and bolometric measurements, to evaluate the expected background. This was used over the years to guide the construction strategies of the experiment and we use it here to project a background model for CUORE. In this paper we report the results of our study and our expectations for the background rate in the energy region where the peak signature of neutrinoless double beta decay of 130 Te is expected.

T.I. Banks

L. Carbone

G. Fernandes

K.P. Hickerson

V. Pettinacci

The projected background for the CUORE experiment

We report a study of the CUORE sensitivity to neutrinoless double beta ( 0Î½Î²Î² ) decay. We used a Bayesian analysis based on a toy Monte Carlo (MC) approach to extract the exclusion sensitivity to the 0Î½Î²Î² decay half-life ( T1/20Î½ ) at 90% Â credibility interval (CI) â i.e. the interval containing the true value of T1/20Î½ with 90% probability â and the 3Ï discovery sensitivity. We consider various background levels and energy resolutions, and describe the influence of the data division in subsets with different background levels. If the background level and the energy resolution meet the expectation, CUORE will reach a 90% Â CI exclusion sensitivity of 2Â·1025 Â year with 3 months, and 9Â·1025 Â year with 5Â years of live time. Under the same conditions, the discovery sensitivity after 3Â months and 5Â years will be 7Â·1024 Â year and 4Â·1025 Â year, respectively.

CUORE sensitivity to 0νββ decay

We present the performances of two 92% enriched 130 TeO 2 crystals operated as thermal bolometers in view of a next generation experiment to search for neutrinoless double beta decay of 130 Te. The crystals, 435 g each, show an energy resolution, evaluated at the 2615 keV γ -line of 208 Tl, of 6.5 and 4.3 keV FWHM. The only observable internal radioactive contamination arises from 238 U (15 and 8 μBq/kg, respectively). The internal activity of the most problematic nuclei for neutrinoless double beta decay, 226 Ra and 228 Th, are both evaluated as &lt;3.1 μBq/kg for one crystal and &lt;2.3 μBq/kg for the second. Thanks to the readout of the weak Cherenkov light emitted by β/γ particles by means of Neganov–Luke bolometric light detectors we were able to perform an event-by-event identification of β/γ events with a 95% acceptance level, while establishing a rejection factor of 98.21% and 99.99% for α particles.

L. Dumoulin

Z. Ge

P. de Marcillac

S. Marnieros

S. Nagorny

S. Nisi

E. Olivieri

D. Orlandi

L. Pagnanini

Ukraine

D.V. Poda

K. Schäffner

N.D. Scielzo

Y. Zhu

Enriched TeO 2 bolometers with active particle discrimination: Towards the CUPID experiment

We report on the measurement of the two-neutrino double-beta decay half-life of 130 Te with the CUORE-0 detector. From an exposure of 33.4Â kgÂ year of TeO 2 , the half-life is determined to be T1/22Î½ = [8.2 Â± 0.2 (stat.) Â± 0.6 (syst.)] Ã 10 20 Â year. This result is obtained after a detailed reconstruction of the sources responsible for the CUORE-0 counting rate, with a specific study of those contributing to the 130 Te neutrinoless double-beta decay region of interest.

J. Feintzeig

X. Liu

F. Orio

Measurement of the two-neutrino double-beta decay half-life of 130 Te with the CUORE-0 experiment

A search for Pauli-exclusion-principle-violating K Î± electron transitions was performed using 89.5Â kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8Ã1030 Â s at 90%Â C.L. was set by looking for a peak at 10.6Â keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8Ã1030 Â s at 90%Â C.L. It is estimated that the Majorana Demonstrator , a 44Â kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of 76 Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.

N. Abgrall

I.J. Arnquist

Russia

A.S. Barabash

F.E. Bertrand

A.W. Bradley

JINR

V. Brudanin

M. Busch

M. Buuck

A.S. Caldwell

Y.D. Chan

C.D. Christofferson

P.H. Chu

C. Cuesta

J.A. Detwiler

C. Dunagan

Yu. Efremenko

Japan

H. Ejiri

S.R. Elliott

P. S Finnerty

A. Galindo-Uribarri

T. Gilliss

G.K. Giovanetti

J. Goett

M.P. Green

J. Gruszko

I.S. Guinn

V.E. Guiseppe

R. Henning

E.W. Hoppe

S. Howard

M.A. Howe

B.R. Jasinski

K.J. Keeter

M.F. Kidd

S.I. Konovalov

R.T. Kouzes

B.D. LaFerriere

J. Leon

J. MacMullin

Canada

R.D. Martin

R. Massarczyk

S.J. Meijer

S. Mertens

J.L. Orrell

C. O’Shaughnessy

A.W.P. Poon

D.C. Radford

J. Rager

K. Rielage

R.G.H. Robertson

E. Romero-Romero

B. Shanks

M. Shirchenko

A.M. Suriano

D. Tedeschi

J.E. Trimble

R.L. Varner

S. Vasilyev

K. Vetter

Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector