21 research outputs found
Discovery of the Eu decay
We report on the first compelling observation of decay of Eu
to the ground state of Pm. The measurement was performed using a 6.15 g
LiEu(BO) crystal operated as a scintillating bolometer. The Q-value
and half-life measured are: Q = 1948.9 keV, and
T y . The
half-life prediction of nuclear theory using the Coulomb and proximity
potential model are in good agreement with this experimental result
Validation of techniques to mitigate copper surface contamination in CUORE
In this article we describe the background challenges for the CUORE
experiment posed by surface contamination of inert detector materials such as
copper, and present three techniques explored to mitigate these backgrounds.
Using data from a dedicated test apparatus constructed to validate and compare
these techniques we demonstrate that copper surface contamination levels better
than 10E-07 - 10E-08 Bq/cm2 are achieved for 238U and 232Th. If these levels
are reproduced in the final CUORE apparatus the projected 90% C.L. upper limit
on the number of background counts in the region of interest is 0.02-0.03
counts/keV/kg/y depending on the adopted mitigation technique.Comment: 10 pages, 6 figures, 6 table
Search for 14.4 keV solar axions from M1 transition of Fe-57 with CUORE crystals
We report the results of a search for axions from the 14.4 keV M1 transition
from Fe-57 in the core of the sun using the axio-electric effect in TeO2
bolometers. The detectors are 5x5x5 cm3 crystals operated at about 10 mK in a
facility used to test bolometers for the CUORE experiment at the Laboratori
Nazionali del Gran Sasso in Italy. An analysis of 43.65 kg d of data was made
using a newly developed low energy trigger which was optimized to reduce the
detectors energy threshold. An upper limit of 0.63 c kg-1 d-1 was established
at 95% C.L.. From this value, a lower bound at 95% C.L. was placed on the
Peccei-Quinn energy scale of fa >= 0.76 10**6 GeV for a value of S=0.55 for the
flavor-singlet axial vector matrix element. Bounds are given for the interval
0.15 < S < 0.55.Comment: 14 pages, 6 figures, submitted to JCA
Neutrinoless double-beta decay search with CUORE and CUORE-0 experiments
The Cryogenic Underground Observatory for Rare Events (CUORE) is an upcoming experiment designed to search for the neutrinoless double-beta decays. Observation of the process would unambiguously establish that neutrinos are Majorana particles and provide information on their absolute mass scale hierarchy. CUORE is now under construction and will consist of an array of 988 TeO2 crystal bolometers operated at 10 mK, but the first tower (CUORE-0) is already taking data. The experimental techniques used will be presented as well as the preliminary CUORE-0 results. The current status of the full-mass experiment and its expected sensitivity will then be discussed
Initial performance of the CUORE-0 experiment
CUORE-0 is a cryogenic detector that uses an array of tellurium dioxide
bolometers to search for neutrinoless double-beta decay of ^{130}Te. We present
the first data analysis with 7.1 kg y of total TeO_2 exposure focusing on
background measurements and energy resolution. The background rates in the
neutrinoless double-beta decay region of interest (2.47 to 2.57 MeV) and in the
{\alpha} background-dominated region (2.70 to 3.90 MeV) have been measured to
be 0.071 \pm 0.011 and 0.019 \pm 0.002 counts/keV/kg/y, respectively. The
latter result represents a factor of 6 improvement from a predecessor
experiment, Cuoricino. The results verify our understanding of the background
sources in CUORE-0, which is the basis of extrapolations to the full CUORE
detector. The obtained energy resolution (full width at half maximum) in the
region of interest is 5.7 keV. Based on the measured background rate and energy
resolution in the region of interest, CUORE-0 half-life sensitivity is expected
to surpass the observed lower bound of Cuoricino with one year of live time.Comment: 8 pages, 5 figures, version 2 as published in Eur. Phys. J.