High efficiency NbN nanowire superconducting single photon detectors fabricated on MgO substrates from a low temperature process

We demonstrate high-performance nanowire superconductingsingle photon detectors (SSPDs) on bN thin films grown at a temperaturecompatible with monolithic integration. NbN films ranging from 150nmto 3nm in thickness were deposited by dc magnetron sputtering on MgOsubstrates at 400◦C. SSPDs were fabricated on high quality NbN films ofdifferent thickness (7 to 3nm) deposited under optimal conditions. Electricaland optical characterizations were performed on the SSPDs. The highestQE value measured at 4.2K is 20% at 1300nm

Extended investigation of superdeformed bands in 151,152^{151,152}Tb nuclei

A detailed study of known and new SD bands in Tb isotopes has been performed with the use of the EUROBALL IV -ray array. The high-statistics data set has allowed for the extension of known SD bands at low and high spins by new -ray transitions. These transitions, as it turns out, correspond to the rotational frequencies where the principal superdeformed gaps (Z=66,N=86) close giving rise to up- or down-bending mechanisms. This enables to attribute the underlying theoretical configurations with much higher confidence as compared to the previous identifications. Five new SD bands have been discovered, three of them assigned to the 152Tb and the two others to the 151Tb nuclei. Nuclear mean-field calculations have been used to interpret the structure of known SD bands as well as of the new ones in terms of nucleonic configurations

Evolution of the use of corticosteroids for the treatment of hospitalised COVID-19 patients in Spain between March and November 2020: SEMI-COVID national registry

Objectives: Since the results of the RECOVERY trial, WHO recommendations about the use of corticosteroids (CTs) in COVID-19 have changed. The aim of the study is to analyse the evolutive use of CTs in Spain during the pandemic to assess the potential influence of new recommendations. Material and methods: A retrospective, descriptive, and observational study was conducted on adults hospitalised due to COVID-19 in Spain who were included in the SEMI-COVID- 19 Registry from March to November 2020. Results: CTs were used in 6053 (36.21%) of the included patients. The patients were older (mean (SD)) (69.6 (14.6) vs. 66.0 (16.8) years; p < 0.001), with hypertension (57.0% vs. 47.7%; p < 0.001), obesity (26.4% vs. 19.3%; p < 0.0001), and multimorbidity prevalence (20.6% vs. 16.1%; p < 0.001). These patients had higher values (mean (95% CI)) of C-reactive protein (CRP) (86 (32.7-160) vs. 49.3 (16-109) mg/dL; p < 0.001), ferritin (791 (393-1534) vs. 470 (236- 996) µg/dL; p < 0.001), D dimer (750 (430-1400) vs. 617 (345-1180) µg/dL; p < 0.001), and lower Sp02/Fi02 (266 (91.1) vs. 301 (101); p < 0.001). Since June 2020, there was an increment in the use of CTs (March vs. September; p < 0.001). Overall, 20% did not receive steroids, and 40% received less than 200 mg accumulated prednisone equivalent dose (APED). Severe patients are treated with higher doses. The mortality benefit was observed in patients with oxygen saturation </=90%. Conclusions: Patients with greater comorbidity, severity, and inflammatory markers were those treated with CTs. In severe patients, there is a trend towards the use of higher doses. The mortality benefit was observed in patients with oxygen saturation </=90%

High quality superconducting NbN thin films on GaAs

A very promising way to increase the detection efficiency of nanowire superconducting single-photon detectors (SSPDs) consists in integrating them with advanced optical structures such as distributed Bragg reflectors (DBRs) and optical waveguides. This requires transferring the challenging SSPD technology from the usual substrates, i.e.sapphire and MgO, to an optical substrate like GaAs, on which DBRs and waveguides can be easily obtained. Therefore, we optimized the deposition process of few-nm thick superconducting NbN films on GaAs and AlAs/GaAs-based DBRs at low temperatures (substrate temperature T S = 400 °C), in order to prevent As evaporation. NbN films ranging from 150 to 3nm in thickness were then deposited on single-crystal MgO, GaAs, MgO-buffered GaAs and DBRs by current-controlled DC magnetron sputtering (planar, circular, balanced configuration) of Nb in an Ar+N2 plasma. 5.5nm thick NbN films on GaAs exhibit TC = 10.7K, ¿T C = 1.1K and RRR = 0.7. The growth of such high quality thin NbN films on GaAs and DBRs has never been reported before. © 2009 IOP Publishing Ltd

Single-photon detection at the nanoscale with superconducting nanowires

We evidence the nanoscale nature of photodetection in superconducting nanowire single-photon detectors by a spatially-resolved efficiency measurement. A novel nanoscale detector, with 100×100 nm2 active area, is also demonstrated using an artificial constrictio

NbN nanowire superconducting single photon detectors fabricated on MgO substrates

High sensitivity ultrafast nanowire superconducting single photon detectors (SSPD) in the near infrared wavelength range have been fabricated with ultrathin (3.5nm) NbN films grown on R-plane sapphire substrates by dc reactive magnetron sputtering in Ar+N2 mixture. These results show for the first time that high performance NbN SSPDs can be realized on different substrates and at lower deposition temperature than previously reported, and opens the way to integration with advanced solid state optical structures. SSPDs have been fabricated by a two mask process using electron beam lithography and reactive ion etching on 3.5nm thick NbN films deposited under optimal conditions on MgO

Characterization of superconducting single photon detectors fabricated on MgO substrates

Electrical and optical characterization has been performed on several superconducting single photon detectors (SSPDs) consisting of meanders made of ultrathin NbN films. The NbN films, with thickness ranging from 150 nm to 3 nm, were deposited by dc magnetron sputtering on MgO substrates kept at temperature T=400°C. This deposition process carried out at low temperature opens the way of monolithic integration with other photonic devices. The superconducting properties of NbN films and the critical design parameters that affect the quantum efficiency (QE) have been optimized. In particular, by measuring the switching current distribution of each stripe of the meander the process uniformity has been studied. Optical measurements on the fabricated SSPDs showed a QE ˜20% at 4.2 K for photons with a wavelength of 1300 nm

Characterization of superconducting single photon detectors fabricated on MgO substrates

Electrical and optical characterization has been performed on several superconducting single photon detectors (SSPDs) consisting of meanders made of ultrathin NbN films. The NbN films, with thickness ranging from 150 nm to 3 nm, were deposited by dc magnetron sputtering on MgO substrates kept at temperature T=400°C. This deposition process carried out at low temperature opens the way of monolithic integration with other photonic devices. The superconducting properties of NbN films and the critical design parameters that affect the quantum efficiency (QE) have been optimized. In particular, by measuring the switching current distribution of each stripe of the meander the process uniformity has been studied. Optical measurements on the fabricated SSPDs showed a QE ˜20% at 4.2 K for photons with a wavelength of 1300 nm