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      Permanent link:
      https://www.ias.ac.in/article/fulltext/joaa/042/0068

    • Keywords

       

      Space vehicles: instruments; instrumentation: detectors; X-rays: detectors; X-rays: analysis.

    • Abstract

       

      The Cadmium Zinc Telluride (CZT) Imager onboard AstroSat consists of pixelated CZT detectors, which are sensitive to hard X-rays above 20 keV. The individual pixels are triggered by ionising events occurring in them, and the detectors operate in a self-triggered mode, recording each event separatelywith information about its time of incidence, detector co-ordinates, and channel that scales with the amount of ionisation. The detectors are sensitive not only to photons from astrophysical sources of interest, but also prone to a number of other events like background X-rays, cosmic rays, and noise in detectors or theelectronics. In this work, a detailed analysis of the effect of cosmic rays on the detectors is made and it is found that cosmic rays can trigger multiple events which are closely packed in time (called ‘bunches’). Higher energy cosmic rays, however, can also generate delayed emissions, a signature previously seen in the PICsIT detector on-board INTEGRAL. An algorithm to automatically detect them based on their spatial clustering properties is presented. Residual noise events are examined using examples of Gamma Ray Bursts as target sources.

    • Author Affiliations

       

      D. PAUL1 2 A. R. RAO1 3 A. RATHEESH1 4 5 N. P. S. MITHUN6 S. V. VADAWALE6 A. VIBHUTE3 D. BHATTACHARYA3 P. PRADEEP7 S. SREEKUMAR7

      1. Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India.
      2. Gubbi Labs LLP, No: 2-182, 2nd Cross, Extension, Gubbi, Tumkur 572 216, India.
      3. Inter University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411 007, India.
      4. Department of Physics, Tor Vergata University of Rome, Via della Ricerca Scientifica 1, 00133 Rome, Italy.
      5. INAF-IAPS, Via Fosso del Cavaliere 100, 00133 Rome, Italy.
      6. Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, India.
      7. Vikram Sarabhai Space Centre, Kochuveli, Thiruvananthapuram 695 022, India.
    • Dates

       
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