4,486 research outputs found
Influence of material quality and process-induced defects on semiconductor device performance and yield
An overview of major causes of device yield degradation is presented. The relationships of device types to critical processes and typical defects are discussed, and the influence of the defect on device yield and performance is demonstrated. Various defect characterization techniques are described and applied. A correlation of device failure, defect type, and cause of defect is presented in tabular form with accompanying illustrations
The beamformer and correlator for the Large European Array for Pulsars
The Large European Array for Pulsars combines Europe's largest radio
telescopes to form a tied-array telescope that provides high signal-to-noise
observations of millisecond pulsars (MSPs) with the objective to increase the
sensitivity of detecting low-frequency gravitational waves. As part of this
endeavor we have developed a software correlator and beamformer which enables
the formation of a tied-array beam from the raw voltages from each of
telescopes. We explain the concepts and techniques involved in the process of
adding the raw voltages coherently. We further present the software processing
pipeline that is specifically designed to deal with data from widely spaced,
inhomogeneous radio telescopes and describe the steps involved in preparing,
correlating and creating the tied-array beam. This includes polarization
calibration, bandpass correction, frequency dependent phase correction,
interference mitigation and pulsar gating. A link is provided where the
software can be obtained.Comment: 10 pages, 6 figures, accepted for publication in Astronomy and
Computin
What kind of Brexit do voters want? Lessons from the Citizens’ Assembly on Brexit
The Citizens’ Assembly on Brexit was a major exercise in deliberative public engagement conducted in autumn 2017. It brought together fifty randomly selected members of the public for two carefully structured weekends of listening, learning, reflecting and discussing. Assembly Members considered what post-Brexit arrangements the UK should pursue, focusing on trade and migration. On trade, most Members wanted the UK to pursue a bespoke arrangement with the EU and rejected the option of leaving the EU with no deal. On migration, most wanted the UK to maintain free movement of labour while using already available policy levers to reduce immigration numbers. These findings provide unique insight into informed public opinion on vital, pressing policy questions. The Assembly also illustrates the valuable role that such deliberative exercises could play in UK democracy. We suggest they could be particular helpful for unlocking progress on issues, such as the future of social care, that are often felt to be ‘too difficult’ to handle
A search for X-ray emission from rich clusters, extended halos around clusters, and superclusters
The all-sky data base acquired with the HEAO A-2 experiment was searched for X-ray emission on a variety of metagalactic size scales which were either predicted or previously detected. Results in the 0.2-60 keV energy range are presented. The optically richest clusters, including those from which a microwave decrement were observed, appear to be relatively underluminous in X-rays. Observations of Abell 576 show its luminosity to be less than earlier estimates, and moreover less than the luminosity predicted from its microwave decrement, unless the intracluster gas is a factor of approximately 10 hotter than in typical clusters. Near SC0627 there are two X-ray sources, and the identification of the dominant source with SCO627 is probably incorrect. New spectral observations of Abell 401 and 2147, possible superclusters, reveal that they have typical cluster spectra with iron line emission
Probing the Local Interstellar Medium with Scintillometry of the Bright Pulsar B1133+16
The interstellar medium hosts a population of scattering screens, most of unknown origin. Scintillation studies of pulsars provide a sensitive tool for resolving these scattering screens and a means of measuring their properties. In this paper, we report our analysis of 34 yr of Arecibo observations of PSR B1133 + 16, from which we have obtained high-quality dynamic spectra and their associated scintillation arcs, arising from the scattering screens located along the line of sight to the pulsar. We have identified six individual scattering screens that are responsible for the observed scintillation arcs, which persist for decades. Using the assumption that the scattering screens have not changed significantly in this time, we have modeled the variations in arc curvature throughout the Earth's orbit and extracted information about the placement, orientation, and velocity of five of the six screens, with the highest-precision distance measurement placing a screen at just pc from the Earth. We associate the more distant of these screens with an underdense region of the Local Bubble
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