Laboratory coded-aperture imaging experiments: radial hole coded masks and depth-sensitive CZT detectors

Hong, Jaesub; Vadawale, S.; Zhang, M.; Bellm, Eric C.; Yousef, Amr; Noss, James; Grindlay, Jonathan E.; Narita, T.

doi:10.1117/12.559650

Cited by 9 publications

(7 citation statements)

References 9 publications

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“…In the case of mask design, the wide energy band width (10 -600 keV) and the fine angular resolution for the mission require a relatively large aspect ratio of mask elements (≥ 5 mm thick, 2.5 mm pixel pitch), which introduces self-collimation at large off-axis angles. We have introduced the radial hole imaging scheme to alleviate the selfcollimation problem of relatively thick masks, 3,4 and we will verify the performance of radial hole masks using ProtoEXIST. The mask will be made of laser-etched multi-layer tungsten plates (5 layers, 1 mm thick each) with a varying pitch (on average, ~5 mm for ProtoEXIST1 and ~2.5 mm for ProtoEXIST2) to orientate the holes in radial directions as done in our first prototype tests.…”

Section: Shield and Maskmentioning

confidence: 99%

“…The mask will be made of laser-etched multi-layer tungsten plates (5 layers, 1 mm thick each) with a varying pitch (on average, ~5 mm for ProtoEXIST1 and ~2.5 mm for ProtoEXIST2) to orientate the holes in radial directions as done in our first prototype tests. 3 A URA pattern will be employed to optimize the imaging performance.…”

Section: Shield and Maskmentioning

confidence: 99%

“…For example, we will verify the performance of new imaging schemes we have developed for coded-aperture imaging with maximum sensitivity, such as radial hole imaging and scanning. 3,4 These new imaging schemes may be essential to achieve the EXIST science goals and some of the techniques can also be applied to the LETs. In section 2, we will review the ProtoEXIST concept and the development plan.…”

Section: Introductionmentioning

confidence: 99%

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Detector and telescope development for ProtoEXIST and fine beam measurements of spectral response of CZT detectors

et al. 2005

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We outline our plan to develop ProtoEXIST, a balloon-borne prototype experiment for the Energetic X-ray Imaging Survey Telescope (EXIST) for the Black Hole Finder Probe. EXIST will consist of multiple wide-field hard X-ray coded-aperture telescopes. The current design of the EXIST mission employs two types of telescope systems: high energy telescopes (HETs) using CZT detectors, and low energy telescopes (LETs) using Si detectors. With ProtoEXIST, we will develop and demonstrate the technologies required for the EXIST HETs. As part of our development efforts, we also present recent laboratory measurements of the spectral response and efficiency variation of imaging CZT detectors on a fine scale (~0.5 mm). The preliminary results confirm the need for multi-pixel readouts and small inter-pixel gaps to achieve uniform spectral response and high detection efficiency across detectors.

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Section: Shield and Maskmentioning

confidence: 99%

Section: Shield and Maskmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Detector and telescope development for ProtoEXIST and fine beam measurements of spectral response of CZT detectors

et al. 2005

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“…4 and listed in Table 2 for several energies. The effective area falls to about 0.35 of the maximum when the polar angle is 45 or 135 degrees due primarily to effect of projection, plus a small amount of collimation by the slits of the coded mask, which can be minimized 31 . Figure 3.…”

Section: Effective Areamentioning

confidence: 99%

Large-angle observatory with energy resolution for synoptic x-ray studies (LOBSTER-SXS)

Gorenstein

2011

SPIE Proceedings

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The soft X-ray band hosts a larger, more diverse range of variable sources than any other region of the electromagnetic spectrum. They are stars, compact binaries, SMBH's, the X-ray components of Gamma-Ray Bursts, their X-ray afterglows, and soft X-ray flares from supernova. We describe a concept for a very wide field (~ 4 ster) modular hybrid X-ray telescope system that can measure positions of bursts and fast transients with as good as arc second accuracy, the precision required to identify fainter and increasingly more distant events. The dimensions and materials of all telescope modules are identical. All but two are part of a cylindrical lobster-eye telescope with flat double sided mirrors that focus in one dimension and utilize a coded mask for resolution in the other. Their positioning accuracy is about an arc minute. The two remaining modules are made from the same materials but configured as a Kirkpatrick-Baez telescope with longer focal length that focuses in two dimensions. When pointed it refines the hybrid telescope's arc minute positions to an arc second and provides larger effective area for spectral and temporal measurements. Above 10 keV the mirrors act as an imaging collimator with positioning capability. For short duration events this hybrid focusing/coded mask system is more sensitive and versatile than either a 2D coded mask or a 2D lobster-eye telescope. Very wide field X-ray telescopes have become feasible as the ability to fabricate large area arrays of CCD and CMOS detectors has improved. This instrument's function in the soft X-ray band is similar to that of Swift in hard X-ray band and there are a greater variety of fast transients in the soft X-ray band. An instrument with considerably more sensitivity than current wide field X-ray detectors would be compatible with a modest NASA Explorer mission.

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“…The coded-aperture imaging technique started with space exploration and then moved into X-ray and gamma ray imaging, which have imaging process characteristics similar to each other [3][4][5][6]. The coded-aperture approach to radiation detection is from the development of the pinhole collimator for X-ray and gamma ray imaging.…”

Section: Introductionmentioning

confidence: 99%

Implementation of a Coded Aperture Imaging System for Gamma Measurement and Experimental Feasibility Tests

Kim¹,

Lee²,

Jang³

et al. 2017

IEIE Transactions on Smart Processing and Computing

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Radioactive materials are used in medicine, non-destructive testing, and nuclear plants. Source localization is especially important during nuclear decommissioning and decontamination because the actual location of the radioactive source within nuclear waste is often unknown. The coded-aperture imaging technique started with space exploration and moved into X-ray and gamma ray imaging, which have imaging process characteristics similar to each other. In this study, we simulated 21x21 and 37x37 coded aperture collimators based on a modified uniformly redundant array (MURA) pattern to make a gamma imaging system that can localize a gamma-ray source. We designed a 21x21 coded aperture collimator that matches our gamma imaging detector and did feasibility experiments with the coded aperture imaging system. We evaluated the performance of each collimator, from 2 mm to 10 mm thicknesses (at 2 mm intervals) using root mean square error (RMSE) and sensitivity in a simulation. . In experimental results, the full width half maximum (FWHM) of the point source was 5.09° at the center and 4.82° at the location of the source was 9°. We will continue to improve the decoding algorithm and optimize the collimator for high-energy gamma rays emitted from a nuclear power plant.

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Laboratory coded-aperture imaging experiments: radial hole coded masks and depth-sensitive CZT detectors

Cited by 9 publications

References 9 publications

Detector and telescope development for ProtoEXIST and fine beam measurements of spectral response of CZT detectors

Detector and telescope development for ProtoEXIST and fine beam measurements of spectral response of CZT detectors

Large-angle observatory with energy resolution for synoptic x-ray studies (LOBSTER-SXS)

Implementation of a Coded Aperture Imaging System for Gamma Measurement and Experimental Feasibility Tests

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