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Digital portable X-ray scanner working in quantum regime based on bulk undoped semi-insulating GaAs radiation detectors

František Dubecký 1Pavol Ščepko 2Bohumír Zako 1Vladimír Sekerka 2Vladimír Nečas 3

1. Slovak Academy of Sciences, Institute of Electrical Engineering (IEE SAS), Dubravska cesta 9, Bratislava 841 04, Slovakia (Slovak Rep.)
2. T&N System Ltd., Severná 8, Banská Bystrica 97401, Slovakia (Slovak Rep.)
3. Slovak University of Technology, Faculty of Electrical Engineering, Department of Nuclear Physics and Technique (FEE SUT), Ilkovičova 3, Bratislava 81219, Slovakia (Slovak Rep.)


In the present work developed digital portable X-ray scanner is demonstrated. The scanner operates in "quantum" imaging mode ("single photon counting") with potential improvement of dynamic range in contrast of the observed X-ray images (e.g. [1]). "Heart" of the scanner - detection unit - is based on semi-insulating (SI) GaAs monolithic strip line detectors. Detector chip based on "SAMO" [2] topology is mounted onto flexible PCB support directly connected to the input of readout module through micro-connector. Detectors with pitch 0.25 mm and absorption length of strip 1.25 or 2.5 mm are arranged in the "edge on" irradiation configuration with an active area 0.25x0.22 mm2. Detection efficiency of the SI GaAs detector reaches a value over 60 % of the theoretical one (75 %) for detection of 60 keV photons at a bias of 200 V. Readout electronics consists of 20 modules with 24 readout channels each fabricated using a progressive SMD technology with automatic assembling of electronic devices. Scanner line is 12 cm long having 480 readout channels and trace length is 15 cm. Position of detection module and position motion controller board are programmable controlled using PC through USB interface. System has the finest step 0.085 mm. Signals from counters included in digital parts of the modules are collected in the PC via USB and evaluated by custom developed software allowing X-ray image reconstruction. Collected data were used for creation of the first X-ray "quantum" images of various test objects using the developed imaging software. General technical properties of the scanner and future work-plan are discussed.

[1] B. Mikulec, Nucl. Instr. And Meth. A 510 (2001) 1.
[2] F. Dubecký, et al. Nucl. Instr. And Meth. A 458 (2001) 152.


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Presentation: oral at E-MRS Fall Meeting 2004, Symposium D, by František Dubecký
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-08-18 14:05
Revised:   2009-06-08 12:55