465 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
Development of Lumped Element Kinetic Inductance Detectors for the W-Band
We are developing a Lumped Element Kinetic Inductance Detector (LEKID) array
able to operate in the W-band (75-110 GHz) in order to perform ground-based
Cosmic Microwave Background (CMB) and mm-wave astronomical observations. The
W-band is close to optimal in terms of contamination of the CMB from Galactic
synchrotron, free-free, and thermal interstellar dust. In this band, the
atmosphere has very good transparency, allowing interesting ground-based
observations with large (>30 m) telescopes, achieving high angular resolution
(<0.4 arcmin). In this work we describe the startup measurements devoted to the
optimization of a W-band camera/spectrometer prototype for large aperture
telescopes like the 64 m SRT (Sardinia Radio Telescope). In the process of
selecting the best superconducting film for the LEKID, we characterized a 40 nm
thick Aluminum 2-pixel array. We measured the minimum frequency able to break
CPs (i.e. ) obtaining
GHz, that corresponds to a critical temperature of 1.31 K. This is not suitable
to cover the entire W-band. For an 80 nm layer the minimum frequency decreases
to 93.2 GHz, which corresponds to a critical temperature of 1.28 K; this value
is still suboptimal for W-band operation. Further increase of the Al film
thickness results in bad performance of the detector. We have thus considered a
Titanium-Aluminum bi-layer (10 nm thick Ti + 25 nm thick Al, already tested in
other laboratories), for which we measured a critical temperature of 820 mK and
a cut-on frequency of 65 GHz: so this solution allows operation in the entire
W-band.Comment: 16th International Workshop on Low Temperature Detectors, Grenoble
20-24 July 2015, Journal of Low Temperature Physics, Accepte
Clustering or scattering? The spatial distribution of cropland in a metropolitan region, 1960-2010
This article presents empirical results of a multivariate analysis run with the aim to identify (apparent and latent) socioeconomic transformations that shape the distribution pattern of cropland in a metropolitan region of southern Europe (Athens, Greece) over a sufficiently long time interval spanning from 1960 to 2010. The study area is representative of monocentric cities expanding in an unregulated fashion and experiencing sequential cycles of economic growth and recession. Percent share of cropland in total municipal area increased moderately over time. A non-linear relationship with the distance from downtown Athens was also observed, indicating that the highest rates of cropland were observed at a distance ranging between 20 and 30 km from the inner city. A multivariate regression was run by decade at each municipality of the study area using 11 predictors with the aim to identify the factors most associated with cropland decline along urban fringes. Distance from downtown Athens, soil and climate quality, population growth rate, and competing land use were the most relevant factors correlated with cropland expansion (or decline) in the study area. Competing land use was particularly important for cropland decline in a first urbanization phase (1960-1980), while population growth rate-and hence an increased human pressure-was positively associated with agricultural areas in a subsequent phase (1990-2010). In these regards, per capita urban land had a non-linear spatial behavior, being correlated negatively with cropland in 1960 and 1970 and positively in 2010, possibly indicating a moderate change from a monocentric model towards a more dispersed metropolitan configuration impacting distribution of agricultural areas. Empirical findings of this study suggest that effective strategies supporting peri-urban agriculture require a comprehensive knowledge of the local socioeconomic context and relevant biophysical conditions-specifically focusing on the dominant soil and climate attributes
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
Predictive factors of hospitalization related to the caregiver burden in older adults presenting to the emergency department
Background
Long-term care for the elderly by their family members represents a serious burden in Italy. The physical and psychological health of informal caregivers is a growing public health issue. Old patients often seek urgent medical attention in the Emergency Department (ED) and hospitalisation is frequent event among the elderly.
Aim
Aim of the study was (1) to investigate the burden of care among the caregivers of old patients; (2) to examine the influence of the burden experienced by the caregivers on ED and hospital admissions of the elderly.
Methods
We conducted a descriptive study of patients aged 75 years or older and their caregiver admitted to the ED from 10/1/15 to 6/10/15 (77 patient-caregiver pairs). The caregivers were evaluated using the Caregiver Burden Inventory (CBI). A case manager collected the patient's data.
Results
CBI score is the highest among patients seeking ED evaluation due to caregiver's concern. The majority of the elderly admitted to the ED whose caregiver shows elevated emotional burden at the CBI do not present with serious or urgent medical condition and are not hospitalised. Emotional burden is the highest among the caregivers of demented subjects who share the same house.
Conclusion
Our findings indicate that the burden experienced by caregiving family members plays a role in elderly people avoidable ED visits
Phonon and light read out of a Li 2MoO 4 crystal with multiplexed kinetic inductance detectors
Molybdenum based crystals such as Li 2MoO 4 and CaMoO4 are emerging as leading candidates for next generation experiments searching for neutrino-less double beta decay with cryogenic calorimeters (CUPID, AMoRE). The exquisite energy resolution and high radio-purity of these crystals come at the cost of a potentially detrimental background source: the two neutrinos double beta decay of 100Mo. Indeed, the fast half-life of this decay mode, combined with the slow response of cryogenic calorimeters, would result in pile-up events in the energy region of interest for neutrino-less double beta decay, reducing the experimental sensitivity. This background can be suppressed using fast and high sensitivity cryogenic light detectors, provided that the scintillation time constant itself does not limit the time resolution. We developed a new detection technique exploiting the high sensitivity, the fast time response and the multiplexing capability of Kinetic Inductance Detectors. We applied the proposed technique to a 2 × 2 × 2 cm3Li 2MoO 4 crystal, which was chosen as baseline option for CUPID. We measured simultaneously both the phonon and scintillation signals with KIDs. We derived the scintillation time constant of this compound at millikelvin temperatures obtaining tscint= 84.5 ± 4.5 (syst) ± 1.0 (stat) µs, constant between 10 and 190 mK
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