Alexander V. St. John
Tata Institute of Fundamental Research
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Featured researches published by Alexander V. St. John.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1990
P.N. Bhat; Alexander V. St. John; S.S. Upadhyaya
Abstract An experiment is being conducted at Pachmarhi (MP) to search for TeV gamma rays from celestial sources like: Cygnus X-3, Crab Pulsar, Cas-γ, Her X-1 etc. The detection of an extensive air shower intiated by TeV γ-rays or more abundant cosmic-ray photons in the Earths atmosphere is through the Cherenkov light from the secondaries (e + and e − ). It is identified by multiplicity logic of the signals from an array of parabolic mirrors (or a group of mirrors called a bank) at the foci of which a fast (RCA 8575) phototube is placed. Whenever such an event occurs, we record the time of occurrence correct to a microsecond, the scalers which record various counting rates, the latch information signifying which mirrors or banks have triggered during the event, the pulse height in each phototube to be read from a CAMAC ADC module and the relative time delays between various mirrors or banks from a CAMAC TDC module. The event rate is in the range of 2–20 Hz. This is accomplished by an indigenously designed hardware system built around a Q-bus-based PDP 11/23 processor through a general-purpose 16-bit parallel I/O interface, viz. DRV-11. High-priority interrupt (INTA) is used for the event while lower-priority interrupt (INTB) is used by the monitor interrupt generator (MIG). A versatile software package called HEGROSOFT has been developed to control the above hardware acquisition system. It is designed to meet the following objectives with four-level task priorities: (a) to acquire the γ-ray event data with a recording dead time of ∼ 1 ms; (b) monitor the various counting rates and print them out at regular intervals; (c) attend to the operator interrupt service requests from the console; (d) provide services for a low-priority job queue to make use of the idle time of the processor. The complete acquisition system and its design philosophy are explained in detail.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1995
B. S. Acharya; P.N. Bhat; Alexander V. St. John; S.G. Khairatkar; B. K. Nagesh; M.R. Rajeev; K. Shobha Rao; M.V.S. Rao; V.A. Reddy; Kondagunta Umamaheswaram Sivaprasad; S. Sinha; A.J. Stanislaus; P. Unnikrishnan; S. S. Upadhya; B.L. Venkateshmurthy; P. R. Vishwanath; K. Viswanathan
Abstract A computerised on-line data acquisition system has been implemented to acquire data and monitor all the detectors in an extensive air shower experiment at Kolar Gold Fields, India, designed to search for point sources of Ultra High Energy gamma rays. It is based on the LSI-11 microcomputer, which has a powerful instruction set and a daisy chained vectored interrupt facility. Two personal computers are linked with LSI-11 through a 16-bit communication bus, to transfer data for a quick analysis. While the system performs this function in the background, it can be interrupted, at different priority levels, by several foreground functions, such as event data acquisition, detector monitoring, etc. The hardware and software features of the data acquisition system are described in detail.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 2005
Sourendu Gupta; Yuri Aikawa; N. V. Gopalakrishnan; Y. Hayashi; Noriaki Ikeda; N. Ito; A. Jain; Alexander V. St. John; S. Karthikeyan; S. Kawakami; T. Matsuyama; Deepak Mohanty; P.K. Mohanty; S.D. Morris; T. Nonaka; A. Oshima; B.S. Rao; K. C. Ravindran; M. Sasano; K. Sivaprasad; B. V. Sreekantan; Hiroyuki Tanaka; S. C. Tonwar; K. Viswanathan; T. Yoshikoshi
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 2005
Y. Hayashi; Yuri Aikawa; N. V. Gopalakrishnan; Sourendu Gupta; Noriaki Ikeda; N. Ito; A. Jain; Alexander V. St. John; S. Karthikeyan; S. Kawakami; Haruo Kojima; T. Matsuyama; Deepak Mohanty; P.K. Mohanty; S.D. Morris; T. Nonaka; A. Oshima; B.S. Rao; K. C. Ravindran; M. Sasano; K. Sivaprasad; B. V. Sreekantan; Hiroyuki Tanaka; S. C. Tonwar; K. Viswanathan; T. Yoshikoshi
Archive | 2005
T. Nonaka; Sourendu Gupta; Y. Hayashi; N. Ito; A. Jain; Alexander V. St. John; S. Karthikeyan; S. Kawakami; H. Kojima; Keigo Matsumoto; Yuji Matsumoto; Tomoyuki Matsuyama; Deepak Mohanty; P. K. Mohanty; S.D. Morris; Takeshi Okuda; A. Oshima; B.S. Rao; K. C. Ravindran; Masaki Sasano; K. Sivaprasad; B. V. Sreekantan; Hiroyuki Tanaka; S. C. Tonwar; K. Viswanathan; T. Yoshiyoshi
Archive | 2003
T. Nonaka; Y. Hayashi; Yoshihisa Ishida; N. Ito; S. Kawakami; A. Oshima; Satoshi Tamaki; Hirohisa Tanaka; T. Yoshikoshi; Kiyoshi Fujimoto; Haruo Kojima; Sourendu Gupta; A. Jain; Alexander V. St. John; Deepak Mohanty; P. K. Mohanty; S.D. Morris; K. C. Ravindran; K. Sivaprasad; B. V. Sreekantan; S. C. Tonwar; K. Viswanathan
Bulletin of the Astronomical Society of India | 2005
P. K. Mohanty; Sourendu Gupta; Yuri Aikawa; N. V. Gopalakrishnan; Y. Hayashi; N. Ito; Anand Iyer; A. Jain; P. Jagadeesan; Alexander V. St. John; S. Karthikeyan; Tomoyuki Matsuyama; Deepak Mohanty; S.D. Morris; T. Nonaka; A. Oshima; B. P. C. Rao; K. C. Ravindran; K. Sivaprasad; B. V. Sreekantan; Hirohisa Tanaka; S. C. Tonwar; K. Viswanathan; T. Yoshikoshi
Archive | 2005
Hirohisa Tanaka; Sourendu Gupta; Y. Hayashi; N. Ito; A. Jain; Alexander V. St. John; S. Karthikeyan; S. Kawakami; Haruo Kojima; Keigo Matsumoto; Yuji Matsumoto; T. Matsutama; Deepak Mohanty; P. K. Mohanty; S.D. Morris; T. Nonaka; Takeshi Okuda; A. Oshima; B. P. C. Rao; K. C. Ravindran; K. Sivaprasad; B. V. Sreekantan; S. C. Tonwar; K. Viswanathan; T. Yoshikoshi
Archive | 2005
S.K. Gupta; Y. Hayashi; N. Ito; A. Jain; Alexander V. St. John; S. Karthikeyan; T. Yoshikoshi
Archive | 2003
S. C. Tonwar; Sourendu Gupta; Y. Hayashi; Yoshihisa Ishida; N. Ito; Atul Jain; Alexander V. St. John; S. Kawakami; H. Kojima; Tomoyuki Matsuyama; Deepak Mohanty; P. K. Mohanty; S.D. Morris; T. Nonaka; A. Oshima; K. C. Ravindran; Masaki Sasano; K. Sivaprasad; B. V. Sreekantan; Satoshi Tamaki; Hiroyuki Tanaka; K. Viswanathan