1,379 research outputs found
Postdoctoral Narrative - Life After Passing
This presentation outlines the journey to completing a PhD and the subsequent career path
An application of the operational code to Eric Williams, Prime Minister of Trinidad and Tobago.
Dept. of History, Philosophy, and Political Science. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1974 .W33. Source: Masters Abstracts International, Volume: 40-07, page: . Thesis (M.A.)--University of Windsor (Canada), 1974
An LED-based Flasher System for VERITAS
We describe a flasher system designed for use in monitoring the gains of the
photomultiplier tubes used in the VERITAS gamma-ray telescopes. This system
uses blue light-emitting diodes (LEDs) so it can be operated at much higher
rates than a traditional laser-based system. Calibration information can be
obtained with better statistical precision with reduced loss of observing time.
The LEDs are also much less expensive than a laser. The design features of the
new system are presented, along with measurements made with a prototype mounted
on one of the VERITAS telescopes.Comment: Accepted for publication in Nuclear Instruments and Methods in
Physics Research
An Overview of The VERITAS Prototype Telescope And Camera
VERITAS (the Very Energetic Radiation Imaging Telescope Array System) is the
next generation ground-based gamma-ray observatory that is being built in
southern Arizona by a collaboration of ten institutions in Canada, Ireland, the
U.K. and the U.S.A. VERITAS is designed to operate in the range from 50 GeV to
50 TeV with optimal sensitivity near 200 GeV; it will effectively overlap with
the next generation of space-based gamma-ray telescopes. The first phase of
VERITAS, consisting of four telescopes of 12 m aperture, will be operational by
the time of the GLAST launch in 2007. Eventually the array will be expanded to
include the full array of seven telescopes on a filled hexagonal grid of side
80 m. A prototype VERITAS telescope with a reduced number of mirrors and signal
channels has been built. Its design and performance is described here. The
prototype is scheduled to be upgraded to a full 499 pixel camera with 350
mirrors during the autumn of 2004.Comment: 8 pages, 6 figures, Proceedings of the Conference "The
Multiwavelength Approach to Unidentified Sources", to appear in the journal
Astrophysics and Space Scienc
Detection Techniques of Microsecond Gamma-Ray Bursts using Ground-Based Telescopes
Gamma-ray observations above 200 MeV are conventionally made by
satellite-based detectors. The EGRET detector on the Compton Gamma Ray
Observatory (CGRO) has provided good sensitivity for the detection of bursts
lasting for more than 200 ms. Theoretical predictions of high-energy gamma-ray
bursts produced by quantum-mechanical decay of primordial black holes (Hawking
1971) suggest the emission of bursts on shorter time scales. The final stage of
a primordial black hole results in a burst of gamma-rays, peaking around 250
MeV and lasting for a tenth of a microsecond or longer depending on particle
physics. In this work we show that there is an observational window using
ground-based imaging Cherenkov detectors to measure gamma-ray burst emission at
energies E greater than 200 MeV. This technique, with a sensitivity for bursts
lasting nanoseconds to several microseconds, is based on the detection of
multi-photon-initiated air showers.Comment: accepted for publication in the Astrophysical Journa
TOPSAN: a dynamic web database for structural genomics
The Open Protein Structure Annotation Network (TOPSAN) is a web-based collaboration platform for exploring and annotating structures determined by structural genomics efforts. Characterization of those structures presents a challenge since the majority of the proteins themselves have not yet been characterized. Responding to this challenge, the TOPSAN platform facilitates collaborative annotation and investigation via a user-friendly web-based interface pre-populated with automatically generated information. Semantic web technologies expand and enrich TOPSAN’s content through links to larger sets of related databases, and thus, enable data integration from disparate sources and data mining via conventional query languages. TOPSAN can be found at http://www.topsan.org
Detection of Cherenkov light from air showers with Geiger-APDs
We have detected Cherenkov light from air showers with Geiger-mode APDs
(G-APDs). G-APDs are novel semiconductor photon-detectors, which offer several
advantages compared to conventional photomultiplier tubes in the field of
ground-based gamma-ray astronomy. In a field test with the MAGIC telescope we
have tested the efficiency of a G-APD / light catcher setup to detect Cherenkov
light from air showers. We estimate a detection efficiency, which is 60% higher
than the efficiency of a MAGIC camera pixel. Ambient temperature dark count
rates of the tested G-APDs are below the rates of the night sky light
background. According to these recent tests G-APDs promise a major progress in
ground-based gamma-ray astronomy.Comment: 4 pages, 5 figures, to appear in the proceedings of the 30th
International Cosmic Ray Conference, Merida, July 200
TeV Gamma-ray Astronomy: The Story So Far
A snapshot is presented of the present status of our knowledge of the TeV
gamma-ray universe. Emphasis is put on observations made using the imaging
atmospheric Cherenkov technique. The capabilities of the present generation of
telescopes is listed. Progress has been dramatic and several features have been
different from what was anticipated. The catalog of sources includes some 78
objects and these are tabulated as extragalactic sources (24), supernovae
remnants (11), pulsar wind nebulae (10), binaries (4), miscellaneous (9),
diffuse high energy sources (3) and unidentified sources (20). Some comments
are made on the factors influencing the past and future development of the
field.Comment: Submitted to Proceedings of "4th Heidelberg International Symposium
on High Energy Gamma-Ray Astronomy 2008
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