The Cs-137 / Zn-65 mixed solid disk sources are designed for use as reference sources. Half-lives are: 30.08 years for CS-137, and 243.9 days for Zn-65 . Each source is constructed using a Plexiglas disk. Standard size is 1.0 x 0.125 inches .

All disk sources have an uncertainty of ± 20% of the labeled activity (unless calibrated - for an additional cost). The small quantity of radioactive material is sealed in the plastic with epoxy to prevent leakage and contamination. The transmission window is sufficiently thin to transmit beta and gamma emissions without undue absorption.

The activities are:

Cs-137.....0.5 uci
Zn-65......1.0 uci