[Triumf-seminars] TRIUMF Technical Seminar today at 16:00

[TRIUMF Seminars]

Date/Time: Mon 2011-08-15 at 16:00

Location:  Auditorium          

Speaker:   Karim S. Karim (University of Waterloo)

Title:     Large area radiation detectors for digital imaging applications

Abstract: Amorphous selenium is a direct X-ray detection photoconductor that has found recent application for high spatial resolution, static mammography imaging.  However, incomplete charge collection due to poor electron mobility in amorphous selenium (a-Se) X-ray radiation detectors results in depth-dependent signal variations. The slow signal rise-time for the portion of the induced charge due to electron-movement towards the anode and significant electron trapping cause ballistic deficit. In this work, we report on recent efforts on embedding a Frisch-grid into an amorphous selenium photodetector to significantly improve the detector's transient response.  We analyze the impact of using a unipolar photodetector design on (a) photon count-rates and spectral performance of amorphous selenium radiation detectors and (b) x-ray sensitivity, detective quantum efficiency (DQE), modulation transfer function (MTF), and image lag of integrating-mode a-Se radiation detectors. Theory and measured results are presented and the use of the unipolar detector technology for high resolution, hard X-ray digital imaging applications is discussed.



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