The LUCIFER project aims at deploying the first array of enriched scintillating bolometers for the investigation of neutrinoless double-beta decay of Se-82. The matrix which embeds the source is an ...array of ZnSe crystals, where enriched Se-82 is used as decay isotope. The radiopurity of the initial components employed for manufacturing crystals, that can be operated as bolometers, is crucial for achieving a null background level in the region of interest for double-beta decay investigations. In this work, we evaluated the radioactive content in 2.5 kg of 96.3 % enriched Se-82 metal, measured with a high-purity germanium detector at the Gran Sasso deep underground laboratory. The limits on internal contaminations of primordial decay chain elements of Th-232, U-238 and U-235 are respectively: <61,<110 and <74 mu Bq/kg at 90 % C.L. The extremely low-background conditions in which the measurement was carried out and the high radiopurity of the Se-82 allowed us to establish the most stringent lower limits on the half-lives of the double-beta decay of Se-82 to 0(+)(1), 2(2)(+) and 2(1)(+) excited states of Kr-82 of 3.4.10(22), 1.3.10(22) and 1.0.10(22) y, respectively, with a 90 % C.L.
The CUPID-0 experiment searches for double beta decay using cryogenic calorimeters with double (heat and light) read-out. The detector, consisting of 24 ZnSe crystals 95
enriched in
Se and two ...natural ZnSe crystals, started data-taking in 2017 at Laboratori Nazionali del Gran Sasso. We present the search for the neutrino-less double beta decay of
Se into the 0
, 2
and 2
excited states of
Kr with an exposure of 5.74 kg
yr (2.24
10
emitters
yr). We found no evidence of the decays and set the most stringent limits on the widths of these processes:
(
Se
Kr
)8.55
10
yr
,
(
Se
Kr
)
yr
,
(
Se
Kr
)8.25
10
yr
(90
credible interval).
Over the last few years, kinetic inductance detectors (KIDs) became the object of increasing interest as photon and phonon detectors. From this perspective, the pulse response of such detectors ...deserves an in-depth study. In most applications, the sensitivity of the KID is ultimately limited by the white noise from the cryogenic amplifier, which is reduced by increasing the power supplied to the device. On the other hand, a high readout power leads to a nonlinear response of the microresonator, originating from the dependence on the current acquired by the kinetic inductance. This paper describes a model for the response to optical pulses of a KID driven to the nonlinear regime, taking into account not only the electrical effects but also the thermal ones induced by power absorption. The model has been validated on data collected using an aluminium resonator developed within the CALDER project (
http://www.roma1.infn.it/exp/calder/
).
The production of ultra-pure raw material is a crucial step to ensure the required background level in rare event searches. In this work, we establish an innovative technique developed to produce ...high-purity (99.999%) granular zinc. We demonstrate the effectiveness of the refining procedure by measuring the internal contaminations of the purified zinc with a high-purity germanium detector at the Laboratori Nazionali del Gran Sasso. The total activity of cosmogenic activated nuclides is measured at the level of a few mBq/kg, as well as limits on naturally occurring radionuclides are set to less than mBq/kg. The excellent radiopurity of the zinc sample allows us to search for electron capture with positron emission and neutrinoless double electron capture of
64
Zn, setting the currently most stringent lower limits on their half-lives,
T
1
/
2
ε
β
+
>
2.7
×
10
21
year
(90% CI), and
T
1
/
2
0
ν
2
ε
>
2.6
×
10
21
year
(90% CI), respectively.
Non-equilibrium quasiparticles can deteriorate the performance of superconducting qubits by reducing their coherence. We are investigating a source of quasiparticles that has been too long neglected, ...namely radioactivity: cosmic rays, environmental radioactivity and contaminants in the materials can all generate phonons of energy sufficient to break Cooper pairs and thus increase the number of quasiparticles. In this contribution, we describe the status of the project and its perspectives.
Fabrication of the CALDER light detectors Colantoni, I.; Bellini, F.; Cardani, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Letnik:
824
Journal Article
Recenzirano
CALDER (Cryogenic wide-Area Light Detectors with Excellent Resolution) is a project for the development of large area phonon mediated KIDs (Kinetic Inductance Detectors), for the detection of ...Cherenkov radiation emitted in TeO2 bolometers to search for neutrinoless double beta decay (0νββ). The KIDs are superconducting detectors made of high quality factor superconducting resonators, which are coupled to a transmission line for signal readout. We designed and fabricated KIDs using aluminum. The Al thin films (40nm) were evaporated on Si(100) high resistivity silicon wafers using an electron beam evaporator in a HV chamber. In this work we report the steps of the fabrication process. All devices are made in direct-write using Electron Beam Lithography (EBL), positive tone resist poly-methyl methacrylate (PMMA) and lift off process. In order to improve the sensitivity of the detectors we have started recently to use sub-stoichiometric TiN deposited by means of DC magnetron sputtering and we will optimize a different fabrication process.
In the field of fundamental particle physics, the neutrino has become more and more important in the last few years, since the discovery of its mass. In particular, the ultimate nature of the ...neutrino (if it is a Dirac or a Majorana particle) plays a crucial role not only in neutrino physics, but also in the overall framework of fundamental particle interactions and in cosmology. The only way to disentangle its ultimate nature is to search for the neutrinoless double beta decay. The idea of LUCIFER is to combine the bolometric technique proposed for the CUORE experiment with the bolometric light detection technique used in cryogenic dark matter experiments. The bolometric technique allows an extremely good energy resolution while its combination with the scintillation detection offers an ultimate tool for background rejection. The goal of LUCIFER is not only to build a background-free small-scale experiment but also to directly prove the potentiality of this technique. Preliminary tests on several detectors containing different interesting DBD emitters have clearly demonstrated the excellent background rejection capabilities that arise from the simultaneous, independent, double readout of heat and scintillation light.
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