Basic Standards and Calibrations

The two 8 in (20.32 cm) × 4 in (10.16 cm) NaI(Tl) well detectors are withdrawn from the 30 in (76.2 cm)  × 20 in (50.8 cm) surrounding anticoincidence plastic shield ready for source insertion. In the counting configuration, the top NaI(Tl) slides down the rods to form a 4 steradian enclosure, which itself slides into the center of the shield. The calibration of cascading gamma-ray emitting radionuclides such as ^166mHo are accurately and efficiently performed with this system.

Another aspect of the apparatus showing the relationship to the preworld war battleship iron cave which reduces the background typically by a factor of 10. The system is also used for sum-peak counting.

Reference: Sum-Peak Counting with Two Crystals, J.M.R. Hutchinson, W.B. Mann, and P.A. Mullen, First International Summer School on Radionuclide Metrology, Herceg Novi, Yugoslavia, Nucl. Instr. Meth., 112 187 (1973).

Inquiries or comments: lisa.karam@nist.gov
Online: November 1997   -   Last update: March 1999