Providing a background discrimination tool is crucial for enhancing the sensitivity of next-generation experiments searching for neutrinoless double- beta decay. The development of high-sensitivity ...(< 20 eV RMS) cryogenic light detectors allows simultaneous read-out of the light and heat signals and enables background suppression through particle identification. The Cryogenic wide- Area Light Detector with Excellent Resolution (CALDER) R&D already proved the potential of this technique using the phonon-mediated Kinetic Inductance Detectors (KIDs) approach. The first array prototype with 4 Aluminum KIDs on a 2 \(\times\) 2 cm2 Silicon substrate showed a baseline resolution of 154 \(\pm\) 7 eV RMS. Improving the design and the readout of the resonator, the next CALDER prototype featured an energy resolution of 82 \(\pm\) 4 eV, by sampling the same substrate with a single Aluminum KID.
Molybdenum based crystals such as Li\(_2\)MoO\(_4\) and CaMoO\(_4\) 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 \(^{100}\)Mo. 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 \(2\times2\times2\) cm\(^3\) Li\(_2\)MoO\(_4\) 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 \(\tau_{scint} = 84.5\pm4.5\rm{(syst)}\pm1.0\rm{(stat)}\) \(\mu\)s, constant between 10 and 190 mK.
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\(^2\)) 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 154\(\pm\)7 eV RMS by sampling a 2\(\times\)2 cm\(^2\) 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 82\(\pm\)4 eV by sampling the same substrate with a single Aluminum KID.
Controversial results come from spot measurements of plasma atrial natriuretic peptide (ANP) in compensated cirrhotic patients. Moreover, either blunted or exaggerated natriuresis has been described ...after maneuvers increasing plasma ANP. This does not make it possible to delineate the ANP effectiveness. Plasma ANP, renin activity (PRA) and aldosterone and hematocrit were serially measured (7 AM, 9 AM, 6 PM, and 11 PM) in nine preascitic cirrhotic outpatients and in nine healthy subjects on normal sodium diet (150 mmol/day) and carrying on their usual activities (mobile from 7 AM to 10 PM). Daily natriuresis was monitored the day before and during the study. In both groups, ANP peaked at the end of the recumbence period (7 AM) and declined on the assumption of the upright position, so that both ANP values of the standing period were significantly lower than the mean daily level. These fluctuations were reciprocal to PRA and hematocrit changes. Patients showed steadily elevated plasma ANP and reduced PRA (ANP mean daily level: 33.3 ± 3.8 vs. 15.5 ± 3.2 pg/mL,
P = .004; PRA: 0.76 ± 0.23 vs. 1.66 ± 0.21 ng/mL/hr,
P = .003). Aldosterone fluctuations and mean daily level were similar in the two groups (mean daily level: 122 ± 11 vs. 119 ± 9 pg/mL). Natriuresis was well adapted to the sodium intake and similar in healthy subjects (day 1: 152 ± 11 mmol; day 2: 138 ± 12.5 mmol) and patients (143 ± 15 mmol; 148 ± 29 mmol). Preascitic cirrhotic patients on a normal salt intake and carrying on their usual activities develop a new steady state requiring increased ANP levels to maintain a sodium balance. In addition to a reduced renal sensitivity to ANP, several subtle abnormalities of the antinatriuretic forces may yield the renal hyporesponsiveness to the peptide.
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. \(h\nu=2\Delta\left(T_{c}\right)=3.5k_{B}T_{c}\)) obtaining \(\nu=95.5\) 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.
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.
The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of \(5\times5\) cm\(^2\) 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.
Background/Aims: We studied the effects of ascites apheress, concentration and reinfusion, a new form of treatment for tense or refractory ascites, on systemic hemodynamics and renal function.
...Methods: Twelve patients with advanced cirrhosis (two belonging to Child-Pugh's class B and the remainder to class C) were monitored. They were evaluated under baseline conditions, just after the treatment, and 24 and 48 h after baseline assessment. In addition to systemic hemodynamics — as evaluated by Doppler echocardiography — and renal function, indirect markers of effective volemia, such as atrial natriuretic factor, plasma renin activity and aldosterone concentration, and plasma norepinephrine were also measured.
Results: The technique led to significant changes in systemic hemodynamics, such as an increase in stroke volume and cardiac output. However, due to a striking reduction in peripheral vascular resistance, mean arterial pressure also declined. The hemodynamic changes were associated with a parallel increase in atrial natriuretic factor. Despite the reduction in arterial pressure, plasma renin activity also significantly declined, while plasma norepinephrine did not undergo significant changes. Although an improvement in glomerular filtration rate and renal sodium excretion occurred, neither change reached statistical significance. All the hemodynamic, renal and neuro-humoral changes described above subsided almost entirely after 48 h, when no significant changes with respect to baseline values were any longer detectable with the exception of a slight reduction in mean arterial pressure.
Conclusions: In advanced cirrhosis ascites apheresis, concentration and reinfusion enhance central volemia, but an exaggerated peripheral vasodilation largely wastes the potential favourable effect on arterial volemia. As a result, no significant improvement in renal perfusion and sodium excretion can ensue.
