Faster Background Determination - a method for gaining time coverage and flux measurement accuracy with Cherenkov telescopes

An improved way of taking off-source data for background determination in Cherenkov telescope observations is proposed. Generalizing the traditional concept of taking on-source/off-source observations of equal duration (e.g. 30 minutes ON followed by 30 minutes OFF), Faster Background Determination (FBD) permits an off-source observation with the same zenith angle distribution as the on-source observation to be obtained within less time. The method permits the on-source observation time to be maximized without compromising the quality of the background determination. It also increases the signal significance for strong sources. The only modification necessary in the data acquisition is a small change to the tracking algorithm. The only modification necessary in the data analysis is to introduce a time normalization which does not increase the systematic errors. The method could become the normal observing mode for Cherenkov telescopes when observing strong sources.Comment: LaTeX, 13 pages, 4 figures, Astropart. Phys., in pres

Flux Sensitivity of VERITAS

VERITAS is a new major ground-based gamma-ray observatory with an array of seven 10 m optical reflectors to be built at the Whipple Observatory in southern Arizona, USA. It will consist of an array of imaging Cherenkov telescopes designed to conduct critical measurements of AGNs and SNRs in the energy range of 50 GeV - 50 TeV. The design of the array has been optimized for the highest sensitivity to point sources in the 100 GeV - 10 TeV band when the stereoscopic imaging technique is employed. Maximum versatility of the array has been another major optimization criterion. We present the flux sensitivity of the baseline VERITAS configuration.Comment: 5 pages, 1 figure, presented at VERITAS Workshop on TeV Astrophysics of Extragalactic Sources, Cambridge, MA, Oct. 23-24, 1998. In press, Astroparticle Physics, ed. M. Catanese, J. Quinn, T. Weeke

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

Acknowledging Ralph Pred

At the time of his death in May of 2012, Ralph Pred was working on a critical social theory inspired by process philosophy. In the book manuscript he left unfinished, Syntax and Solidarity, he develops a “radically empirical” sociology that enables him to identify and critically evaluate the different forms that social solidarity has taken in the history of civilization. The purpose of this paper is to draw attention to the importance of his unfinished project. The executors of Pred’s literary estate would be happy to see his project, with due acknowledgment, publicized and continued. Keywords: Active Voice Bias, Concrescence, Middle Voice, Sociogeny, Solidarity, Substanc

On design studies for the future 50 GeV arrays of imaging air Cherenkov telescopes

Arrays of imaging air Cherenkov telescopes (IACTs) like VERITAS, HESS have been recently proposed as the instruments of the next generation for ground based very high energy gamma-ray astronomy invading into 50-100 GeV energy range. Here we present results of design studies for the future IACT arrays which have been performed by means of Monte Carlo simulations. We studied different trigger strategies, abilities of cosmic ray rejection for arrays of 4 and 16 telescopes with 10 m reflectors, equipped with cameras comprising 271 and 721 pixels of 0.25 and 0.15 degree, respectively. The comparative analysis of the performance of such telescope arrays has been done for both camera options, providing almost the same field of view of 4.3 degree. An important issue is the choice of the optimum spacing between the telescopes in such an array. In order to maximize the signal-to-noise ratio in observations at the small zenith angles of 20 degree as well as at large zenith angles of 60 degree, different arrangements of IACT array have been examined. Finally, we present a major recommendations regarding the optimum configuration.Comment: 5 pages, presented at the VERITAS Workshop on TeV Astrophysics of Extragalactic Sources, eds. M. Catanese, J. Quinn, and T. Weekes, to be published in Astroparticle Physic