title: Suppression of Afterglow in Microcolumnar CsI:Tl by Codoping With Sm: Recent Advances.
abstract: Microcolumnar CsI:Tl remains a highly desirable sensor for digital X-ray imaging due to its superior spatial resolution, bright emission, high absorption efficiency, and ready availability. Despite such obvious advantages, two characteristic properties of CsI:Tl undermine their use in clinical and high speed imaging: a persistent afterglow in its scintillation decay, and a hysteresis effect that distorts the scintillation yield after exposure to high radiation doses.In our earlier work we have discovered that the addition of 0.05 to 0.5 mol percent of Sm(2+) to crystals of CsI:Tl suppresses their afterglow by a factor of up to 50, even when subjected to a very high exposure of 120 R. This additive also diminishes hysteresis by an order of magnitude, which is a major accomplishment. Consequent- ly, our work is now focused on developing codoped microcolumnar CsI:Tl, Sm films that can potentially combine excellent properties of the current state-of-the-art CsI:Tl films with the reduced afterglow and hysteresis observed in codoped crystals. While our earlier attempts in CsI:Tl, Sm film fabrication, reported at the previous IEEE meeting, demonstrated obvious advantages of the approach, the recent work has succeeded in producing films that show improvement by at least a factor of 7 in afterglow and 150% in brightness compared to the standard CsI:Tl films. We report these important results in this paper, along with other recent advances in film growth and new imaging results.
authors.affiliation: Radiation Monitoring Devices, Inc., Watertown, MA 02472 USA. ( VNagarkar@rmdinc.com ;  VGaysinskiy@rmdinc.com ;  LOvechkina@rmdinc.com ;  SMiller@rmdinc.com ;  SCool@rmdinc.com ;  SThacker@rmdinc.com .).
authors.forename: Vivek V
authors.initials: VV
authors.lastname: Nagarkar
authors.forename: Samta C
authors.initials: SC
authors.lastname: Thacker
authors.forename: Valeriy
authors.initials: V
authors.lastname: Gaysinskiy
authors.forename: Lena E
authors.initials: LE
authors.lastname: Ovechkina
authors.forename: Stuart R
authors.initials: SR
authors.lastname: Miller
authors.forename: Steven
authors.initials: S
authors.lastname: Cool
authors.forename: Charles
authors.initials: C
authors.lastname: Brecher