Rare event physics demands very detailed background control, high-performance detectors, and custom analysis strategies. Cryogenic calorimeters combine all these ingredients very effectively, ...representing a promising tool for next-generation experiments. CUPID-0 is one of the most advanced examples of such a technique, having demonstrated its potential with several results obtained with limited exposure. In this paper, we present a further application. Exploiting the analysis of delayed coincidence, we can identify the signals caused by the 220Rn-216Po decay sequence on an event-by-event basis. The analysis of these events allows us to extract the time differences between the two decays, leading to a new evaluation of 216Po half-life, estimated as (143.3±2.8) ms.
In this paper we describe the current status of the CALDER project, which is developing ultra-sensitive light detectors based on superconductors for cryogenic applications. When we apply an AC ...current to a superconductor, the Cooper pairs oscillate and acquire kinetic inductance, that can be measured by inserting the superconductor in a LC circuit with high merit factor. Interactions in the superconductor can break the Cooper pairs, causing sizable variations in the kinetic inductance and, thus, in the response of the LC circuit. The continuous monitoring of the amplitude and frequency modulation allows to reconstruct the incident energy with excellent sensitivity. This concept is at the basis of Kinetic Inductance Detectors (KIDs) that are characterized by natural aptitude to multiplexed read-out (several sensors can be tuned to different resonant frequencies and coupled to the same line), resolution of few eV, stable behavior over a wide temperature range, and ease in fabrication. We present the results obtained by the CALDER collaboration with 2×2cm2 substrates sampled by 1 or 4 Aluminum KIDs. We show that the performances of the first prototypes are already competitive with those of other commonly used light detectors, and we discuss the strategies for a further improvement.
The background induced by the high penetration power of the radiation is the main limiting factor of the current radio-guided surgery (RGS). To partially mitigate it, a RGS with β(+)-emitting ...radio-tracers has been suggested in literature. Here we propose the use of β(-)-emitting radio-tracers and β(-) probes and discuss the advantage of this method with respect to the previously explored ones: the electron low penetration power allows for simple and versatile probes and could extend RGS to tumours for which background originating from nearby healthy tissue makes probes less effective. We developed a β(-) probe prototype and studied its performances on phantoms. By means of a detailed simulation we have also extrapolated the results to estimate the performances in a realistic case of meningioma, pathology which is going to be our first in-vivo test case. A good sensitivity to residuals down to 0.1 ml can be reached within 1 s with an administered activity smaller than those for PET-scans thus making the radiation exposure to medical personnel negligible.
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.
CYGNO is a project realising a cubic meter demonstrator to study the scalability of the performance of the optical approach for the readout of large-volume, GEM-equipped TPC. This is part of the ...CYGNUS proto-collaboration which aims at constructing a network of underground observatories for directional Dark Matter search. The combined use of high-granularity sCMOS and fast sensors for reading out the light produced in GEM channels during the multiplication processes was shown to allow on one hand to reconstruct 3D direction of the tracks, offering accurate energy measurements and sensitivity to the source directionality and, on the other hand, a high particle identification capability very useful to distinguish nuclear recoils. Results of the performed R&D and future steps toward a 30-100 cubic meter experiment will be presented.
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.
► The ZnMoO4 crystals permit alpha discrimination from the pulse shape analysis. ► ZnMoO4 crystals show an excellent energy resolution. ► ZnMoO4 crystals are extremely radiopure. ► A medium sized ...(30kg) tower-like double beta experiment based on ZnMoO4 will show a zero background in the ROI.
We investigate the performances of two ZnMoO4 scintillating crystals operated as bolometers, in view of a next generation experiment to search the neutrinoless double beta decay of 100Mo. We present the results of the α vs β/γ discrimination, obtained through the scintillation light as well as through the study of the shape of the thermal signal alone. The separation obtained at the 2615keV line of 208Tl is 8σ, using the heat-light scatter plot, while it exceeds 20σ using the shape of the thermal pulse alone. The achieved FWHM energy resolution ranges from 2.4keV (at 238keV) to 5.7keV (at 2615keV). The internal radioactive contaminations of the ZnMoO4 crystals were evaluated through a 407h background measurement. The obtained limit is <32μBq/kg for 228Th and 226Ra. These values were used for a Monte Carlo simulation aimed at evaluating the achievable background level of a possible, future array of enriched Zn100MoO4 crystals.
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.
Purpose
Few examples of the involvement of a single gene in idiopathic short stature have been described until now. Our aim was to identify the causative gene of proportionate short stature in a ...large family showing co-segregation of the phenotype with the reciprocal translocation t(10;15)(q22;q24).
Methods
FISH mapping was carried out with BACs and long-range PCR probes to identify the smallest genomic regions harboring the translocation breakpoints. Real-Time RT-PCR was performed in blood after pre-amplification of target genes cDNA.
Result
The affected family members presented with a final height of between − 2.41 and − 4.18 SDS and very mild skeletal dysmorphisms. Growth rates of the proband and of her cousin, whose childhood and pre-pubertal bone age corresponded to the chronological age, showed a poor growth spurt during treatment with rhGH. However, their adult height was greater than that of their untreated mothers, suggesting efficacy of GH therapy. Breakpoint mapping revealed that the translocation t(10;15)(q22.3;q26.1) disrupts, on 15q, the
ACAN
gene at intron 1, decreasing its transcriptional expression.
Conclusions
This is the first description of a chromosome rearrangement disrupting
ACAN
and leading to its haploinsufficiency.
ACAN
loss of function should be considered a potential underpinning of short patients who display a poor growth spurt and belong to families with autosomal dominant segregation of proportionate short stature. Besides this core phenotype, literature review suggests that advanced bone age, early onset osteochondritis dissecans, osteoarthritis, intervertebral disc disease as well as craniofacial dysmorphisms can be important suggestive phenotypes in affected families.
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