JINST 13 (2018) P01010 CUORE - the Cryogenic Underground Observatory for Rare Events - is an
experiment searching for the neutrinoless double-beta ($0\nu\beta\beta$) decay
of $^{130}$Te with an array ...of 988 TeO$_2$ crystals operated as bolometers at
$\sim$10 mK in a large dilution refrigerator. With this detector, we aim for a
$^{130}$Te $0\nu\beta\beta$ decay half-life sensitivity of $9\times10^{25}$ y
with 5 y of live time, and a background index of $\lesssim 10^{-2}$
counts/keV/kg/y. Making an effort to maintain radiopurity by minimizing the
bolometers' exposure to radon gas during their installation in the cryostat, we
perform all operations inside a dedicated cleanroom environment with a
controlled radon-reduced atmosphere. In this paper, we discuss the design and
performance of the CUORE Radon Abatement System and cleanroom, as well as a
system to monitor the radon level in real time.
Phys. Rev. Lett. 124, 022502 (2020) The $^7$H system was populated in the $^2$H($^8$He,$^3$He)$^7$H reaction with
a 26 AMeV $^8$He beam. The $^{7}$H missing mass energy spectrum, the $^{3}$H
energy ...and angular distributions in the $^7$H decay frame were reconstructed.
The $^7$H missing mass spectrum shows a peak which can be interpreted either as
unresolved $5/2^+$ and $3/2^+$ doublet or one of these states at 6.5(5) MeV.
The data also provide indications on the $1/2^+$ ground state of $^7$H located
at 2.0(5) MeV with quite a low population cross section of $\sim 10$ $\mu$b/sr
within angular range $\theta_{\text{cm}} \simeq 6^{\circ} - 30^{\circ}$.
The CUORE experiment is the world's largest bolometric experiment. The detector consists of an array of 988 TeO2 crystals, for a total mass of 742 kg. CUORE is presently taking data at the Laboratori ...Nazionali del Gran Sasso, Italy, searching for the neutrinoless double beta decay of 130Te. A large custom cryogen-free cryostat allows reaching and maintaining a base temperature of about 10 mK, required for the optimal operation of the detector. This apparatus has been designed in order to achieve a low noise environment, with minimal contribution to the radioactive background for the experiment. In this paper, we present an overview of the CUORE cryostat, together with a description of all its sub-systems, focusing on the solutions identified to satisfy the stringent requirements. We briefly illustrate the various phases of the cryostat commissioning and highlight the relevant steps and milestones achieved each time. Finally, we describe the successful cooldown of CUORE.
CUORE is a cryogenic experiment searching primarily for neutrinoless double decay in \(^{130}\)Te. It will begin data-taking operations in 2016. To monitor the cryostat and detector during ...commissioning and data taking, we have designed and developed Slow Monitoring systems. In addition to real-time systems using LabVIEW, we have an alarm, analysis, and archiving website that uses MongoDB, AngularJS, and Bootstrap software. These modern, state of the art software packages make the monitoring system transparent, easily maintainable, and accessible on many platforms including mobile devices.
The extremely neutron-rich system \(^{6}\)H was studied in the direct \(^2\text{H}(^8\text{He},{^4\text{He}})^{6}\)H transfer reaction with a \(26 A\) MeV secondary \(^{8}\)He beam. The measured ...missing mass spectrum shows a broad bump at \(\sim 4-8\) MeV above the \(^3\)H+\(3n\) decay threshold. This bump can be interpreted as a broad resonant state in \(^{6}\)H at \(6.8(5)\) MeV. The population cross section of such a presumably \(p\)-wave state (or may be few overlapping states) in the energy range from 4 to 8 MeV is \(d\sigma/d\Omega_{\text{c.m.}} \simeq 190^{+40}_{-80}\) \(\mu\)b/sr in the angular range \(5^{\circ}<\theta_{\text{c.m.}}<16^{\circ}\). The obtained missing mass spectrum is practically free of the \(^{6}\)H events below 3.5 MeV (\(d\sigma/d\Omega_{\text{c.m.}} \lesssim 5\) \(\mu\)b/sr in the same angular range). The steep rise of the \(^{6}\)H missing mass spectrum at \(\sim 3\) MeV allows to derive the lower limit for the possible resonant-state energy in \(^{6}\)H to be \(4.5(3)\) MeV. According to the paring energy estimates, such a \(4.5(3)\) MeV resonance is a realistic candidate for the \(^{6}\)H ground state (g.s.). The obtained results confirm that the decay mechanism of the \(^{7}\)H g.s.\ (located at 2.2 MeV above the \(^{3}\)H+\(4n\) threshold) is the "true" (or simultaneous) \(4n\) emission. The resonance energy profiles and the momentum distributions of fragments of the sequential \(^{6}\)H\( \,\rightarrow \, ^5\)H(g.s.)+\(n\, \rightarrow \, ^3\)H+\(3n\) decay were analyzed by the theoretically-updated direct four-body-decay and sequential-emission mechanisms. The measured momentum distributions of the \(^{3}\)H fragments in the \(^{6}\)H rest frame indicate very strong "dineutron-type" correlations in the \(^{5}\)H ground state decay.
The extremely neutron-rich system \(^{7}\)H was studied in the direct \(^2\)H(\(^8\)He,\(^3\)He)\(^7\)H transfer reaction with a 26 AMeV secondary \(^{8}\)He beam Bezbakh et al., Phys. Rev. Lett. 124 ...(2020) 022502. The missing mass spectrum and center-of-mass (c.m.) angular distributions of \(^{7}\)H, as well as the momentum distribution of the \(^{3}\)H fragment in the \(^{7}\)H frame, were constructed. In addition to the investigation reported in Ref. Bezbakh et al., Phys. Rev. Lett. 124 (2020) 022502, we carried out another experiment with the same beam but a modified setup, which was cross-checked by the study of the \(^2\)H(\(^{10}\)Be,\(^3\)He\()^{9}\)Li reaction. A solid experimental evidence is provided that two resonant states of \(^{7}\)H are located in its spectrum at 2.2(5) and 5.5(3) MeV relative to the \(^3\)H+4\(n\) decay threshold. Also, there are indications that the resonant states at 7.5(3) and 11.0(3) MeV are present in the measured \(^{7}\)H spectrum. Based on the energy and angular distributions, obtained for the studied \(^2\)H(\(^8\)He,\(^3\)He)\(^7\)H reaction, the weakly populated 2.2(5) MeV peak is ascribed to the \(^7\)H ground state. It is highly plausible that the firmly ascertained 5.5(3) MeV state is the \(5/2^+\) member of the \(^7\)H excitation \(5/2^+\)-\(3/2^+\) doublet, built on the \(2^+\) configuration of valence neutrons. The supposed 7.5 MeV state can be another member of this doublet, which could not be resolved in Ref. Bezbakh et al., Phys. Rev. Lett. 124 (2020) 022502. Consequently, the two doublet members appeared in the spectrum of \(^{7}\)H in Bezbakh et al., Phys. Rev. Lett. 124 (2020) 022502 as a single broad 6.5 MeV peak.
CUORE - the Cryogenic Underground Observatory for Rare Events - is an experiment searching for the neutrinoless double-beta (\(0\nu\beta\beta\)) decay of \(^{130}\)Te with an array of 988 TeO\(_2\) ...crystals operated as bolometers at \(\sim\)10 mK in a large dilution refrigerator. With this detector, we aim for a \(^{130}\)Te \(0\nu\beta\beta\) decay half-life sensitivity of \(9\times10^{25}\) y with 5 y of live time, and a background index of \(\lesssim 10^{-2}\) counts/keV/kg/y. Making an effort to maintain radiopurity by minimizing the bolometers' exposure to radon gas during their installation in the cryostat, we perform all operations inside a dedicated cleanroom environment with a controlled radon-reduced atmosphere. In this paper, we discuss the design and performance of the CUORE Radon Abatement System and cleanroom, as well as a system to monitor the radon level in real time.
The \(^7\)H system was populated in the \(^2\)H(\(^8\)He,\(^3\)He)\(^7\)H reaction with a 26 AMeV \(^8\)He beam. The \(^{7}\)H missing mass energy spectrum, the \(^{3}\)H energy and angular ...distributions in the \(^7\)H decay frame were reconstructed. The \(^7\)H missing mass spectrum shows a peak which can be interpreted either as unresolved \(5/2^+\) and \(3/2^+\) doublet or one of these states at 6.5(5) MeV. The data also provide indications on the \(1/2^+\) ground state of \(^7\)H located at 2.0(5) MeV with quite a low population cross section of \(\sim 10\) \(\mu\)b/sr within angular range \(\theta_{\text{cm}} \simeq 6^{\circ} - 30^{\circ}\).
