There is a need in the x-ray imaging community for phosphors with short persistence (I/I₀ < 0.1-0.01% in less than 0.5 ms). Persistence limits a detector's performance by defining the minimum x-ray exposure discernable for a given time after a previous exposure, by ghosting of previous images, and by limiting the dynamic range. The description of the luminescence decay time for any particular phosphor is tedious since the decay time is usually a complicated function of the excitation intensity, the exposure time, the phosphor temperature, and the impurity concentration, as well as the manufacturing procedure. We have characterized commercially available and specially synthesized gadolinium oxysulfide (Gd₂O₂S) phosphors with a variety of activators in terms of persistence, and relative light output, and discussed their possible usefulness for particular x-ray imaging experiments. We have found that the level of long-term persistence for Gd₂O₂S x-ray phosphors can differ by more than an order of magnitude solely due to changes in the exposure time. The persistence of these phosphors is characterized as a function of x-ray intensity, exposure time, and, when possible, imppurity concentrations.

Date Published: 15 June 1995
PDF: 7 pages
Proc. SPIE 2519, X-Ray and Ultraviolet Sensors and Applications, (15 June 1995); doi: 10.1117/12.211910

Published in SPIE Proceedings Vol. 2519:
X-Ray and Ultraviolet Sensors and Applications
Richard B. Hoover; Mark Bennett Williams, Editor(s)