AlGaAs/GaAs Quantum Well Infrared Photodetectors

In this article, we present an overview of a focal plane array (FPA) with 640 × 512 pixels based on the AlGaAs quantum well infrared photodetector (QWIP). The physical principles of the QWIP operation and their parameters for the spectral range of 8–10 μm have been discussed. The technology of the manufacturing FPA based on the QWIP structures with the pixels 384 × 288 and 640 × 512 has been demonstrated. The parameters of the manufactured 640 × 512 FPA with a step of 20 μm have been given. At the operating temperature of 72 K, the temperature resolution of QWIP focal plane arrays is less than 35 mK. The number of defective elements in the matrix does not exceed 0.5%. The stability and uniformity of the FPA have been demonstrated

Electron and hole injection barriers between silicon substrate and RF magnetron sputtered In2O3 : Er films

In2O3 : Er films have been synthesized on silicon substrates by RF magnetron sputter deposition. The currents through the synthesized metal/oxide/semiconductor (MOS) structures (Si/In2O3 : Er/In-contact) have been measured for n and p type conductivity silicon substrates and described within the model of majority carrier thermoemission through the barrier, with bias voltage correction to the silicon potential drop. The electron and hole injection barriers between the silicon substrate and the film have been found to be 0.14 and 0.3 eV, respectively, by measuring the temperature dependence of the forward current at a low sub-barrier bias. The resulting low hole injection barrier is accounted for by the presence of defect state density spreading from the valence band edge into the In2O3 : Er band gap to form a hole conduction channel. The presence of defect state density in the In2O3 : Er band gap is confirmed by photoluminescence data in the respective energy range 1.55–3.0 eV. The band structure of the Si/In2O3 : Er heterojunction has been analyzed. The energy gap between the In2O3 : Er conduction band electrons and the band gap conduction channel holes has been estimated to be 1.56 eV

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Construction of the Integrated Method to Model a System for Measuring the Density of Infrared Radiation Flows

We have constructed an integrated method to model the system of measuring the density of flows of infrared radiation based on solving the inverse problems of dynamics using the Volterra equation of the first kind and focusing on solving the problem on dynamic correction. Solving a problem on the structural correction of the dynamic characteristics of the system for measuring the density of flows implies the construction and application in a transforming channel or a circuit in the system of a certain unit. This unit, owing to its specially formed dynamic properties, ensures the best dynamic characteristics of the entire system.We have experimentally verified the technique for the compensation for a dynamic error. To this end, the experiments were conducted to measure the density of a non-stationary flow of infra-red radiation with the assigned law of change, which is characteristic of the practical working conditions for receivers. A change in the density of the incident flow of infrared radiation was achieved at the expense of the receiver's rotation around the axis that passes through the middle of its receiving surface, in the flow of the stationary emitter. The result of the experiment is the derived nonlinear approximation of the experimentally obtained transitional characteristic in the form of the receiver's response to the sinusoidal flow of infrared radiation.It should be specifically noted that the results of numerical simulation and the experiment show a satisfactory convergence, which allows us to argue about the correct choice of the model. The developed algorithms are capable to provide a numerical implementation of integrated models and serve as the basis for constructing high-performance specialized microprocessor systems to work in real time. That has made it possible to successfully implement the dynamic correction of the system for measuring flows of infrared radiation and to significantly increase its accuracy. A combined application of the devised method for solving mathematical problems and computer tools would provide an opportunity to improve the efficiency of processes to synthesize and design computational devices for correcting means of measuremen

Electron and hole injection barriers between silicon substrate and RF magnetron sputtered In2O3 : Er films

In2O3 : Er films have been synthesized on silicon substrates by RF magnetron sputter deposition. The currents through the synthesized metal/oxide/semiconductor (MOS) structures (Si/In2O3 : Er/In-contact) have been measured for n and p type conductivity silicon substrates and described within the model of majority carrier thermoemission through the barrier, with bias voltage correction to the silicon potential drop. The electron and hole injection barriers between the silicon substrate and the film have been found to be 0.14 and 0.3 eV, respectively, by measuring the temperature dependence of the forward current at a low sub-barrier bias. The resulting low hole injection barrier is accounted for by the presence of defect state density spreading from the valence band edge into the In2O3 : Er band gap to form a hole conduction channel. The presence of defect state density in the In2O3 : Er band gap is confirmed by photoluminescence data in the respective energy range 1.55–3.0 eV. The band structure of the Si/In2O3 : Er heterojunction has been analyzed. The energy gap between the In2O3 : Er conduction band electrons and the band gap conduction channel holes has been estimated to be 1.56 eV

Manipulation of gravitational quantum states of a bouncing neutron with the GRANIT spectrometer

The bouncing neutron is one of the rare system where gravity can be studied in a quantum framework. To this end it is crucial to be able to select some specific gravitational quantum state (GQS). The GRANIT apparatus is the first physics experiment connected to a superthermal helium UCN source. We report on the methods developed for this instrument showing how specific GQS can be favored using a step between mirrors and an absorbing slit. We explore the increase of GQS separation efficiency by increasing the absorber roughness amplitude, and find it is feasible but requires a high adjustment precision. We also quantify the transmission of the absorbing slit leading to a measurement of the spatial extension of the neutron vertical wave function $z_0 = \hbar^{2/3}\left(2m^2g\right)^{-1/3} = 5.9\pm0.3\,\mu$m.Comment: 5 pages, 3 figure

A Possible Neutron-Antineutron Oscillation Experiment at PF1B at the Institut Laue Langevin

International audienceWe consider a possible neutron–antineutron (n−n¯) oscillation experiment at the PF1B instrument at Institut Laue Langevin. It can improve the best existing constraint on the transition rate and also allow the testing of the methods and instrumentation which would be needed for a later larger-scale experiment at ESS. The main gain factors over the most competitive experiment, performed earlier at PF1 instrument at ILL, are: a more intense neutron beam and a new operating mode based on coherent n and n¯ mirror reflections. The installation of such an experiment would need a temporary replacement of the existing ballistic neutron guide by a specially designed n/n¯ guide with a gradually increasing cross section and a specially selected coating as well as the development and construction of an advanced n¯ annihilation detector with a high efficiency and low background. The overall gain factor could reach up to an order of magnitude and depends on the chosen experiment configuration

Manipulation of gravitational quantum states of a bouncing neutron with the GRANIT spectrometer

The bouncing neutron is one of the rare system where gravity can be studied in a quantum framework. To this end it is crucial to be able to select some specific gravitational quantum state (GQS). The GRANIT apparatus is the first physics experiment connected to a superthermal helium UCN source. We report on the methods developed for this instrument showing how specific GQS can be favored using a step between mirrors and an absorbing slit. We explore the increase of GQS separation efficiency by increasing the absorber roughness amplitude, and find it is feasible but requires a high adjustment precision. We also quantify the transmission of the absorbing slit leading to a measurement of the spatial extension of the neutron vertical wave function $z_0 = \hbar^{2/3}\left(2m^2g\right)^{-1/3} = 5.9\pm0.3\,\mu$m