title: Design and feasibility of active matrix flat panel detector using avalanche amorphous selenium for protein crystallography.
abstract: Protein crystallography is the most important technique for resolving the three-dimensional atomic structure of protein by measuring the intensity of its x-ray diffraction pattern. This work proposes a large area flat panel detector for protein crystallography based on direct conversion x-ray detection technique using avalanche amorphous selenium (a-Se) as the high gain photoconductor, and active matrix readout using amorphous silicon (a-Si:H) thin film transistors. The detector employs avalanche multiplication phenomenon of a-Se to make the detector sensitive to each incident x ray. The advantages of the proposed detector over the existing imaging plate and charge coupled device detectors are large area, high dynamic range coupled to single x-ray detection capability, fast readout, high spatial resolution, and inexpensive manufacturing process. The optimal detector design parameters (such as detector size, pixel size, and thickness of a-Se layer), and operating parameters (such as electric field across the a-Se layer) are determined based on the requirements for protein crystallography application. The performance of the detector is evaluated in terms of readout time (<1 s), dynamic range (approximately 10(5)), and sensitivity (approximately 1 x-ray photon), thus validating the detector's efficacy for protein crystallography.
authors.affiliation: Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. asultana@venus.uwaterloo.ca
authors.forename: Afrin
authors.initials: A
authors.lastname: Sultana
authors.forename: Alla
authors.initials: A
authors.lastname: Reznik
authors.forename: Karim S
authors.initials: KS
authors.lastname: Karim
authors.forename: J A
authors.initials: JA
authors.lastname: Rowlands
mesh_terms: D018360:Crystallography, X-Ray / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D011506:Proteins / Q000648:ultrastructure*; D015203:Reproducibility of Results; D012643:Selenium; D012680:Sensitivity and Specificity; D014173:Transistors, Electronic; D014963:X-Ray Intensifying Screens
chemical_list: D011506:Proteins; D012643:Selenium