20 research outputs found
Radio Pulses from Cosmic Ray Air Showers
The first experiment in which radio emission was detected from high energy
particles is described. An array of dipoles was operated by a team of British
and Irish physicists in 1964-5 at the Jodrell Bank Radio Observatory in
conjunction with a simple air shower trigger. The array operated at 44 MHz with
2.75 MHz bandwidth. Out of 4,500 triggers a clear bandwidth-limited radio pulse
was seen in 11 events. This corresponded to a cosmic ray trigger threshold of
5x10^16 eV and was of intensity close to that predicted. The early experiments
which followed this discovery and their interpretation is described.Comment: 11 pages, 4 figures. Proceedings of the First International Workshop
on Radio Detection of High Energy Particles, UCLA, Nov 16-18, 2000, to be
published by the AI
Revealing the Dark TeV Sky: The Atmospheric Cherenkov Imaging Technique for Very High Energy Gamma-ray Astronomy
The Atmospheric Cherenkov Imaging Technique has opened up the gamma-ray
spectrum from 100 GeV to 50 TeV to astrophysical exploration. The development
of the technique (with emphasis on the early days) is described as are the
basic principles underlying its application to gamma-ray astronomy. The current
generation of arrays of telescopes, in particular, VERITAS is briefly
described.Comment: To be published in the Proceedings of the International Workshop on
"Energy Budget in the High Energy Universe", Kashiwa, Japan, February 22-24,
200
Very High Energy Gamma Ray Extension of GRO Observations
The membership, progress, and invited talks, publications, and proceedings made by the Whipple Gamma Ray Collaboration is reported for june 1990 through May 1994. Progress was made in the following areas: the May 1994 Markarian Flare at Whipple and EGRET (Energetic Gamma Ray Experiment Telescope) energies; AGN's (Active Galactic Nuclei); bursts; supernova remnants; and simulations and energy spectra
Study of MeV/GeV/Sources. TeV Extension of First CGRO EGRET Catalogue Sources Multiwavelength Blazar Studies: A Search for TeV Emission from Bursts Detected by BATSE
The Whipple Gamma Ray Collaboration was formed in 1982 with the aim of improving the sensitivity of the ground-based atmospheric Cherenkov technique by the use of imaging cameras on large optical detectors. The approach was successful and the discipline of ground-based TeV astronomy was established. The first confirmed galactic source was discovered by the Whipple Collaboration as were the first two extragalactic sources. The technique has now matured and several new and important astrophysical results have been produced. The gamma-ray group of the Smithsonian Astrophysical Observatory is a key component of the Whipple Gamma Ray Collaboration. With all its members resident in Arizona, all its activities are devoted to research in ground-based gamma-ray astronomy
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
Genomic epidemiology of SARS-CoV-2 in a UK university identifies dynamics of transmission
AbstractUnderstanding SARS-CoV-2 transmission in higher education settings is important to limit spread between students, and into at-risk populations. In this study, we sequenced 482 SARS-CoV-2 isolates from the University of Cambridge from 5 October to 6 December 2020. We perform a detailed phylogenetic comparison with 972 isolates from the surrounding community, complemented with epidemiological and contact tracing data, to determine transmission dynamics. We observe limited viral introductions into the university; the majority of student cases were linked to a single genetic cluster, likely following social gatherings at a venue outside the university. We identify considerable onward transmission associated with student accommodation and courses; this was effectively contained using local infection control measures and following a national lockdown. Transmission clusters were largely segregated within the university or the community. Our study highlights key determinants of SARS-CoV-2 transmission and effective interventions in a higher education setting that will inform public health policy during pandemics.</jats:p