617 research outputs found
RON-BEAM DEBUG AND FAILURE ANALYSIS OF INTEGRATED CIRCUITS
A current research project at IMAG/TIM3 Laboratory aims at an integrated test system
combining the use of the Scanning Electron Microscope (SEM), used in voltage contrast
mode, with a new high-level approach of fault location in complex VLSI circuits, in order
to reach a complete automated diagnosis process.
Two research themes are induced by this project, which are: prototype validation of
known circuits, on which CAD information is available, and failure analysis of unknown
circuits, which are compared to reference circuits.
For prototype validation, a knowledge-based approach to fault location is used.
Concerning failure analysis, automatic image comparison based on pattern recog-
nition techniques is performed.
The purpose of the paper is to present these two methodologies, focusing on the
SEM-based data acquisition process
Overview of the Far Ultraviolet Spectroscopic Explorer Mission
The Far Ultraviolet Spectroscopic Explorer satellite observes light in the
far-ultraviolet spectral region, 905 - 1187 A with high spectral resolution.
The instrument consists of four coaligned prime-focus telescopes and Rowland
spectrographs with microchannel plate detectors. Two of the telescope channels
use Al:LiF coatings for optimum reflectivity from approximately 1000 to 1187 A
and the other two use SiC coatings for optimized throughput between 905 and
1105 A. The gratings are holographically ruled to largely correct for
astigmatism and to minimize scattered light. The microchannel plate detectors
have KBr photocathodes and use photon counting to achieve good quantum
efficiency with low background signal. The sensitivity is sufficient to examine
reddened lines of sight within the Milky Way as well as active galactic nuclei
and QSOs for absorption line studies of both Milky Way and extra-galactic gas
clouds. This spectral region contains a number of key scientific diagnostics,
including O VI, H I, D I and the strong electronic transitions of H2 and HD.Comment: To appear in FUSE special issue of the Astrophysical Journal Letters.
6 pages + 4 figure
Argon milling induced decoherence mechanisms in superconducting quantum circuits
The fabrication of superconducting circuits requires multiple deposition,
etch and cleaning steps, each possibly introducing material property changes
and microscopic defects. In this work, we specifically investigate the process
of argon milling, a potentially coherence limiting step, using niobium and
aluminum superconducting resonators as a proxy for surface-limited behavior of
qubits. We find that niobium microwave resonators exhibit an order of magnitude
decrease in quality-factors after surface argon milling, while aluminum
resonators are resilient to the same process. Extensive analysis of the niobium
surface shows no change in the suboxide composition due to argon milling, while
two-tone spectroscopy measurements reveal an increase in two-level system
electrical dipole moments, indicating a structurally altered niobium oxide
hosting larger two-level system defects. However, a short dry etch can fully
recover the argon milling induced losses on niobium, offering a potential route
towards state-of-the-art overlap Josephson junction qubits with niobium
circuitry.Comment: Main text: 6 pages, 3 figures, 1 table. 5 appendices, with 6
additional figures and 3 additional tables. 62 reference
An Initial Survey of White Dwarfs in the Sloan Digital Sky Survey
An initial assessment is made of white dwarf and hot subdwarf stars observed
in the Sloan Digital Sky Survey. In a small area of sky (190 square degrees),
observed much like the full survey will be, 269 white dwarfs and 56 hot
subdwarfs are identified spectroscopically where only 44 white dwarfs and 5 hot
subdwarfs were known previously. Most are ordinary DA (hydrogen atmosphere) and
DB (helium) types. In addition, in the full survey to date, a number of WDs
have been found with uncommon spectral types. Among these are blue DQ stars
displaying lines of atomic carbon; red DQ stars showing molecular bands of C_2
with a wide variety of strengths; DZ stars where Ca and occasionally Mg, Na,
and/or Fe lines are detected; and magnetic WDs with a wide range of magnetic
field strengths in DA, DB, DQ, and (probably) DZ spectral types. Photometry
alone allows identification of stars hotter than 12000 K, and the density of
these stars for 15<g<20 is found to be ~2.2 deg^{-2} at Galactic latitudes
29-62 deg. Spectra are obtained for roughly half of these hot stars. The
spectra show that, for 15<g<17, 40% of hot stars are WDs and the fraction of
WDs rises to ~90% at g=20. The remainder are hot sdB and sdO stars.Comment: Accepted for AJ; 43 pages, including 12 figures and 5 table
The USNO-B Catalog
USNO-B is an all-sky catalog that presents positions, proper motions,
magnitudes in various optical passbands, and star/galaxy estimators for
1,042,618,261 objects derived from 3,643,201,733 separate observations. The
data were obtained from scans of 7,435 Schmidt plates taken for the various sky
surveys during the last 50 years. USNO-B1.0 is believed to provide all-sky
coverage, completeness down to V = 21, 0.2 arcsecond astrometric accuracy at
J2000, 0.3 magnitude photometric accuracy in up to five colors, and 85%
accuracy for distinguishing stars from non-stellar objects. A brief discussion
of various issues is given here, but the actual data are available from
http://www.nofs.navy.mil and other sites.Comment: Accepted by Astronomical Journa
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