Ionizing Radiation Division

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Basic Standards and Calibrations

NaI(Tl) x-ray counting system

The large-area-defined solid angle NaI(Tl) x-ray counting system consists of a 0.079 cm thick, 2.46 cm diameter NaI(Tl) detector which is placed at accurately calibrated distances from a platform form which is vertically moveable over 35.56 cm. Large area x-ray sources of 238Pu are routinely calibrated using this instrument. The detector is thick enough that all impinging U L-x-rays following the decay of Pu are absorbed except those which are lost in the 0.013 cm Be window.

Reference: Construction and Calibration of the NIST Large-Area Source X-Ray Counting Systems, J.M.R. Hutchinson, M.P. Unterweger, and P.A. Hodge. J. Res. Natl. Inst. Stand. Technol. 96, 693 (1991).

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Online: November 1997   -   Last update: March 1999