&lt;title&gt;Room temperature semiconductor detectors for hard x-ray astrophysics&lt;/title&gt;

Parsons, A.; Stahle, C. M.; Lisse, C. M.; Babu, R. Sachidananda; Gehrels, N.; Teegarden, B. J.; Shu, P.

doi:10.1117/12.187260

Cited by 8 publications

(3 citation statements)

References 1 publication

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“…These instruments are the PoRTIA (Piggyback Room Temperature Instrument for Astronomy) (Parsons et al, 1994) on board the GRIS (Gamma-Ray Imaging Spectrometer) mission that flew in Alice Springs and HEXIS (High Energy X-ray Imaging Spectrometer) (Slavis et al, 2000) that flew in Palestine, Texas, USA. Both are based on CdZnTe detection elements.…”

Section: Polarimetric Q Factor For a Crab Like Source Superimposed Tomentioning

confidence: 99%

Cipher, A Polarimeter Telescope Concept for Hard X-Ray Astronomy

Bahmanabadi

Ghomi

Samimi

et al. 2003

Experimental Astronomy

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Abstract. The polarisation of astrophysical source emission in the energy range from a few tens of keV up to the MeV region is an almost unexplored field of high-energy astrophysics. Till date, polarimetry in astrophysics-in the energy domain from hard X-rays up to soft γ -rays-has not been pursued due to the difficulties involved in obtaining sufficient sensitivity. Indeed for those few instruments that are capable of performing this type of measurement (e.g. the COMPTEL instrument on the Compton Gamma-ray Observatory and the IBIS instrument on INTEGRAL), polarimetry itself plays a secondary role in the mission objectives, as the efficiencies (0.5% and 10% maximum, respectively) and polarimetric Q factors (0.1 and 0.3, respectively) are relatively limited. In order to perform efficient polarimetric measurements for hard X-ray and soft gamma-ray sources, with an instrument of relatively robust and simple design, a CdTe based telescope (CIPHER: Coded Imager and Polarimeter for High Energy Radiation) is under study. This instrument is based on a thick (10 mm) CdTe position-sensitive spectrometer comprising four modules of 32 × 32 individual pixels, each with a surface area of 2 × 2 mm 2 (about 160 cm 2 total detection area). The polarimetric performance and design optimisation of the CIPHER detection surface have been studied by use of a Monte Carlo code. This detector, due to its intrinsic geometry, can allow efficient polarimetric measurements to be made between 100 keV and 1 MeV. In order to predict the polarimetric performance and to optimise the design and concept of the CIPHER detection plane, a Monte Carlo code based on GEANT4 library modules was developed to simulate the detector behaviour under a polarised photon flux. The Compton double event efficiency, as well bi-dimensional double event distribution maps and the corresponding polarimetric modulation factor will be presented and discussed. Modulation Q factors better than 0.50 and double event total efficiencies greater than 10% were calculated in the energy range between 100 keV and 1 MeV. Herein we will present and discuss the general problems that affect polarimetric measurements in space, such as the inclination of the source with respect to the telescope optical axis and background radiation. Q factor calculations for several beam inclinations as well as for background together with simulated astronomical sources will be presented and discussed.

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Section: Polarimetric Q Factor For a Crab Like Source Superimposed Tomentioning

confidence: 99%

Cipher, A Polarimeter Telescope Concept for Hard X-Ray Astronomy

Bahmanabadi

Ghomi

Samimi

et al. 2003

Experimental Astronomy

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“…As this is precisely the geometry required for a position-sensitive detector, pixellated arrays of CdZnTe for X-ray astronomy have enjoyed intense scrutiny in recent years. 3,4,5 Our work in particular has been motivated by the need for a large-area hard X-ray survey telescope, such as the Energetic X-ray Imaging Survey Telescope (EXIST or EXIST-LITE) concept, 6,7 designed to be sensitive between 20 and 600 keV. Thus we have focused our study on relatively thick (5 mm) CdZnTe detectors fashioned with various types of pixellated arrays, and with these devices we have measured a typical energy resolution of ∼ 4% at 60 keV.…”

Section: Introductionmentioning

confidence: 99%

<title>CdZnTe background measurement at balloon altitudes with an active BGO shield</title>

Bloser¹,

Grindlay

Narita

et al. 1998

EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy IX

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We report results of an experiment conducted in May 1997 to measure CdZnTe background and background reduction schemes in space flight conditions similar to those of proposed hard X-ray astrophysics missions. A 1 cm 2 CdZnTe detector was placed adjacent to a thick BGO anticoincidence shield and flown piggybacked onto the EXITE2 scientific balloon payload. The planar shield was designed to veto background counts produced by local gamma-ray production in passive material and neutron interactions in the detector. The CdZnTe and BGO were partially surrounded by a Pb-Sn-Cu shield to approximate the grammage of an X-ray collimator, although the field of view was still ∼ 2π sr. At an altitude of 127000 feet we find a reduction in background by a factor of 6 at 100 keV. The non-vetoed background is 9 × 10 −4 cts cm −2 s −1 keV −1 at 100 keV, about a factor of 2 higher than that of the collimated (4.5 • FWHM) EXITE2 phoswich detector. We compare our recorded spectrum with that expected from simulations using GEANT and find agreement within a factor of 2 between 30 and 300 keV. We also compare our results with those of previous experiments using passive lead and active NaI shields, and discuss possible active shielding schemes in future astronomy missions employing large arrays of CdZnTe detectors.

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“…However, it has been found [2] that employing a grid of pixels small relative to the detector thickness creates an internal electric field favorable for the collection of only one polarity of charge carrier; if used to collect electrons, the easily-trapped holes are no longer important (this is often called the small pixel effect). As this is precisely the detector geometry required for hard X-ray telescope detectors, pixellated arrays of CZT have enjoyed intense scrutiny in recent years [3][4][5][6]. Here we describe initial results of our program to develop imaging CZT array detectors specialized for use in a hard X-ray survey telescope.…”

Section: Introductionmentioning

confidence: 99%

Prototype Imaging CD-ZN-TE Array Detector

et al. 1997

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We describe initial results of our program to develop and test Cd-Zn-Te (CZT) detectors with a pixellated array readout. Our primary interest is in the development of relatively thick CZT detectors for use in astrophysical coded aperture telescopes with response extending over the energy range ∼ 10 − 600 keV. The coded aperture imaging configuration requires only relatively large area pixels (1-3 mm), whereas the desired high energy response requires detector thicknesses of at least 3-5 mm. We have developed a prototype detector employing a 10 x 10 x 5 mm CZT substrate and 4 x 4 pixel (1.5 mm each) readout with gold metal contacts for the pixels and continuous gold contact for the bias on the opposite detector face. This MSM contact configuration was fabricated by RMD and tested at Harvard for uniformity, efficiency and spatial as well as spectral resolution. We have developed an ASIC readout (IDE-VA-1) and analysis system and report results, including ∼ 4% (FWHM) energy resolution at 60 keV. A prototype design for a full imaging detector array is discussed.

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<title>Room temperature semiconductor detectors for hard x-ray astrophysics</title>

Cited by 8 publications

References 1 publication

Cipher, A Polarimeter Telescope Concept for Hard X-Ray Astronomy

Cipher, A Polarimeter Telescope Concept for Hard X-Ray Astronomy

<title>CdZnTe background measurement at balloon altitudes with an active BGO shield</title>

Prototype Imaging CD-ZN-TE Array Detector

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