547 research outputs found
High sensitivity phonon-mediated kinetic inductance detector with combined amplitude and phase read-out
The development of wide-area cryogenic light detectors with good energy
resolution is one of the priorities of next generation bolometric experiments
searching for rare interactions, as the simultaneous read-out of the light and
heat signals enables background suppression through particle identification.
Among the proposed technological approaches for the phonon sensor, the
naturally-multiplexed Kinetic Inductance Detectors (KIDs) stand out for their
excellent intrinsic energy resolution and reproducibility. To satisfy the large
surface requirement (several cm) KIDs are deposited on an insulating
substrate that converts the impinging photons into phonons. A fraction of
phonons is absorbed by the KID, producing a signal proportional to the energy
of the original photons. The potential of this technique was proved by the
CALDER project, that reached a baseline resolution of 1547 eV RMS by
sampling a 22 cm Silicon substrate with 4 Aluminum KIDs. In this
paper we present a prototype of Aluminum KID with improved geometry and quality
factor. The design improvement, as well as the combined analysis of amplitude
and phase signals, allowed to reach a baseline resolution of 824 eV by
sampling the same substrate with a single Aluminum KID
New application of superconductors: high sensitivity cryogenic light detectors
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 2x2 cm2 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
Characterization of the KID-Based Light Detectors of CALDER
The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution
(CALDER) project is the development of light detectors with active area of
cm and noise energy resolution smaller than 20 eV RMS,
implementing phonon-mediated kinetic inductance detectors. The detectors are
developed to improve the background suppression in large-mass bolometric
experiments such as CUORE, via the double read-out of the light and the heat
released by particles interacting in the bolometers. In this work, we present
the characterization of the first light detectors developed by CALDER. We
describe the analysis tools to evaluate the resonator parameters (resonant
frequency and quality factors) taking into account simultaneously all the
resonance distortions introduced by the read-out chain (as the feed-line
impedance and its mismatch) and by the power stored in the resonator itself. We
detail the method for the selection of the optimal point for the detector
operation (maximizing the signal-to-noise ratio). Finally, we present the
response of the detector to optical pulses in the energy range of 0-30 keV
Energy resolution and efficiency of phonon-mediated Kinetic Inductance Detectors for light detection
The development of sensitive cryogenic light detectors is of primary interest
for bolometric experiments searching for rare events like dark matter
interactions or neutrino-less double beta decay. Thanks to their good energy
resolution and the natural multiplexed read-out, Kinetic Inductance Detectors
(KIDs) are particularly suitable for this purpose. To efficiently couple
KIDs-based light detectors to the large crystals used by the most advanced
bolometric detectors, active surfaces of several cm are needed. For this
reason, we are developing phonon-mediated detectors. In this paper we present
the results obtained with a prototype consisting of four 40 nm thick aluminum
resonators patterned on a 22 cm silicon chip, and calibrated with
optical pulses and X-rays. The detector features a noise resolution
eV and an (182) efficiency.Comment: 5 pages, 5 figure
Pion Polarizabilities and Volume Effects in Lattice QCD
We use chiral perturbation theory to study the extraction of pion
electromagnetic polarizabilities from lattice QCD. Chiral extrapolation
formulae are derived for partially quenched QCD, and quenched QCD simulations.
On a torus, volume dependence of electromagnetic observables is complicated by
SO(4) breaking, as well as photon zero-mode interactions. We determine finite
volume corrections to the Compton scattering tensor of pions. We argue,
however, that such results cannot be used to ascertain volume corrections to
polarizabilities determined in lattice QCD with background field methods.
Connection is lacking because momentum expansions are not permitted in finite
volume. Our argument also applies to form factors. Volume effects for
electromagnetic moments cannot be deduced from finite volume form factors.Comment: 5 figs., 19p
Physical investigations on (In2S3)x(In2O3)y and In2S3-xSex thin films processed through In2S3 annealing in air and selenide atmosphere
In2S3-xSex and (In2S3)x(In2O3)y thin films have been prepared on glass substrates using appropriate heat treatments of In evaporatedt hin films. X-ray analysis shows that In thin films which were annealed under sulfur atmosphere at 350°C were mainly formed by In2S3. A heat treatment o fthis binary in air at 400°C during one hour leads to (In2S3)x(In2O3)y ternary material which has a tetragonal structure with a preferred orientation of the crystallites along the (109) direction. Similarly, a heat treatment of In2S3
in selenium atmosphere at 350°C during six hours leads to a new In2S3-xSex ternary material having tetragonal body centered structure with a preferred orientation of the crystallites along the (109) direction.Optical band gap,refractive index and extinction coefficient values of In2S3-xSex and (In2S3)x(In2O3)y thin films have been reached. Moreover, correlations between optical conductivity, XRD, AFM and Urbach energy of such ternary thin films have been discussed. Finally, the recorded formation disparity between the quaternary (In2S3)x(In2O3)y and ternary In2S3-xSex compounds has been discussed in terms of the Simha–Somcynsky and Lattice Compatibility theories
CALDER - Neutrinoless double-beta decay identification in TeO bolometers with kinetic inductance detectors
Next-generation experiments searching for neutrinoless double-beta decay must
be sensitive to a Majorana neutrino mass as low as 10 meV. CUORE, an array of
988 TeO bolometers being commissioned at Laboratori Nazionali del Gran
Sasso in Italy, features an expected sensitivity of 50-130 meV at 90% C.L, that
can be improved by removing the background from radioactivity. This is
possible if, in coincidence with the heat release in a bolometer, the Cherenkov
light emitted by the signal is detected. The amount of light detected
is so far limited to only 100 eV, requiring low-noise cryogenic light
detectors. The CALDER project (Cryogenic wide-Area Light Detectors with
Excellent Resolution) aims at developing a small prototype experiment
consisting of TeO bolometers coupled to new light detectors based on
kinetic inductance detectors. The R&D is focused on the light detectors that
could be implemented in a next-generation neutrinoless double-beta decay
experiment.Comment: 8 pages, 3 figures, added reference to first result
Found in Complexity, Lost in Fragmentation: Putting Soil Degradation in a Landscape Ecology Perspective
The United Nations Convention to Combat Desertification (UNCCD) assumes spatial disparities in land resources as a key driver of soil degradation and early desertification processes all over the world. Although regional divides in soil quality have been frequently observed in Mediterranean-type ecosystems, the impact of landscape configuration on the spatial distribution of sensitive soils was poorly investigated in Southern Europe, an affected region sensu UNCCD. Our study proposes a spatially explicit analysis of 16 ecological metrics (namely, patch size and shape, fragmentation, interspersion, and juxtaposition) applied to three classes of a landscape with different levels of exposure to land degradation (‘non-affected’, ‘fragile’, and ‘critical’). Land classification was based on the Environmentally Sensitive Area Index (ESAI) calculated for Italy at 3 time points along a 50-year period (1960, 1990, 2010). Ecological metrics were calculated at both landscape and class scale and summarized for each Italian province—a relevant policy scale for the Italian National Action Plan (NAP) to combat desertification. With the mean level of soil sensitivity rising over time almost everywhere in Italy, ‘non-affected’ land became more fragmented, the number of ‘fragile’ and ‘critical’ patches increased significantly, and the average patch size of both classes followed the same trend. Such dynamics resulted in intrinsically disordered landscapes, with (i) larger (and widely connected) ‘critical’ land patches, (ii) spatially diffused and convoluted ‘fragile’ land patches, and (iii) a more interspersed and heterogeneous matrix of ‘non affected’ land. Based on these results, we discussed the effects of increasing numbers and sizes of ‘critical’ patches in terms of land degradation. A sudden expansion of ‘critical’ land may determine negative environmental consequences since (i) the increasing number of these patches may trigger desertification risk and (ii) the buffering effect of neighboring, non-affected land is supposed to be less efficient, and this contains a downward spiral toward land degradation less effectively. Policy strategies proposed in the NAPs of affected countries are required to account more explicitly on the intrinsic, spatio-temporal evolution of ‘critical’ land patches in affected regions
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