The High Energy Telescope on EXIST

Proceedings of SPIE - The International Society for Optical Engineering (Impact Factor: 0.2). 09/2009; DOI: 10.1117/12.826540
Source: arXiv

ABSTRACT The Energetic X-ray Imaging Survey Telescope (EXIST) is a proposed next generation multi-wavelength survey mission. The primary instrument is a High Energy telescope (HET) that conducts the deepest survey for Gamma-ray Bursts (GRBs), obscured-accreting and dormant Supermassive Black Holes and Transients of all varieties for immediate followup studies by the two secondary instruments: a Soft X-ray Imager (SXI) and an Optical/Infrared Telescope (IRT). EXIST will explore the early Universe using high redshift GRBs as cosmic probes and survey black holes on all scales. The HET is a coded aperture telescope employing a large array of imaging CZT detectors (4.5 m^2, 0.6 mm pixel) and a hybrid Tungsten mask. We review the current HET concept which follows an intensive design revision by the HET imaging working group and the recent engineering studies in the Instrument and Mission Design Lab at the Goddard Space Flight Center. The HET will locate GRBs and transients quickly (<10-30 sec) and accurately (< 20") for rapid (< 1-3 min) onboard followup soft X-ray and optical/IR (0.3-2.2 micron) imaging and spectroscopy. The broad energy band (5-600 keV) and the wide field of view (~90 deg x 70 deg at 10% coding fraction) are optimal for capturing GRBs, obscured AGNs and rare transients. The continuous scan of the entire sky every 3 hours will establish a finely-sampled long-term history of many X-ray sources, opening up new possibilities for variability studies. Comment: 10 pages, 6 figures, 3 tables, SPIE conference proceedings (UV, X-ray, and Gamma-Ray Space Instrumentation for Astronomy XVI, 7435-9)

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Available from: J. E. Grindlay, Sep 26, 2015
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    • "Currently we are in the middle of the design and layout work for the readout electronics boards for ProtoEXIST2 & 3 ( §3.2-3.5). See also Grindlay et al (2010) [1] for the EXIST mission overview and Hong et al (2009) [4] for a more in-depth overview of the design concept and expected performance of the HET. For the detailed flight performance of the ProtoEXIST1 telescope, see Hong et al (2010) [5] and for the telescope integration and assembly, see Allen et al (2010) [6] [7]. "
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    ABSTRACT: The hard X-ray sky now being studied by INTEGRAL and Swift and soon by NuSTAR is rich with energetic phenomena and highly variable non-thermal phenomena on a broad range of timescales. The High Energy Telescope (HET) on the proposed Energetic X-ray Imaging Survey Telescope (EXIST) mission will repeatedly survey the full sky for rare and luminous hard X-ray phenomena at unprecedented sensitivities. It will detect and localize (<20", at 5 sigma threshold) X-ray sources quickly for immediate followup identification by two other onboard telescopes - the Soft X-ray imager (SXI) and Optical/Infrared Telescope (IRT). The large array (4.5 m^2) of imaging (0.6 mm pixel) CZT detectors in the HET, a coded-aperture telescope, will provide unprecedented high sensitivity (~0.06 mCrab Full Sky in a 2 year continuous scanning survey) in the 5 - 600 keV band. The large field of view (90 deg x 70 deg) and zenith scanning with alternating-orbital nodding motion planned for the first 2 years of the mission will enable nearly continuous monitoring of the full sky. A 3y followup pointed mission phase provides deep UV-Optical-IR-Soft X-ray and Hard X-ray imaging and spectroscopy for thousands of sources discovered in the Survey. We review the HET design concept and report the recent progress of the CZT detector development, which is underway through a series of balloon-borne wide-field hard X-ray telescope experiments, ProtoEXIST. We carried out a successful flight of the first generation of fine pixel large area CZT detectors (ProtoEXIST1) on Oct 9, 2009. We also summarize our future plan (ProtoEXIST2 & 3) for the technology development needed for the HET. Comment: 10 pages, 13 figures, 2 tables, SPIE Conference "Astronomical Telescopes and Instrumentation 2010"; to appear in Proceedings SPIE (2010)
    Proceedings of SPIE - The International Society for Optical Engineering 09/2010; DOI:10.1117/12.857713 · 0.20 Impact Factor
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    ABSTRACT: The EXIST Mission is a proposed multi-wavelength observatory to carry out the most sensitive hard X-ray survey and census of SMBH as well as the most powerful follow-up of Gamma Ray Bursts (GRBs). This mission will carry a large area (4.5m 2) CdZnTe modular detector with an angular resolution of ∼ 2arcmin, sensitive in the energy range 5-600 keV, and a near infrared telescope with cooled mirror with outstanding sensitivity and capability of measuring onboard the redshift of many GRBs. Italy will contribute to EXIST with the provision of a soft X-ray telescope sensitive in the energy range 0.1-10 keV with an effective area approximately equivalent to one mirror module of XMM-Newton. We will describe hereafter the characteristics and performance of this instrument together with its capability of performing serendipitous surveys.
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    ABSTRACT: The primary instrument of the proposed EXIST mission is a coded mask high energy telescope (the HET), that must have a wide field of view and extremely good sensitivity. It will be crucial to minimize systematic errors so that even for very long total integration times the imaging performance is close to the statistical photon limit. There is also a requirement to be able to reconstruct images on-board in near real time in order to detect and localize gamma-ray bursts. This must be done while the spacecraft is scanning the sky. The scanning provides all-sky coverage and is key to reducing systematic errors. The on-board computational problem is made even more challenging for EXIST by the very large number of detector pixels. Numerous alternative designs for the HET have been evaluated. The baseline concept adopted depends on a unique coded mask with two spatial scales. Monte Carlo simulations and analytic analysis techniques have been used to demonstrate the capabilities of the design and of the proposed two-step burst localization procedure.
    Proceedings of SPIE - The International Society for Optical Engineering 02/2010; DOI:10.1117/12.830184 · 0.20 Impact Factor
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