The Cd-109 disk sources are designed for use as reference sources. The half-life is 453 days. Each source is constructed using a Plexiglas disk. Standard size is 1.0 x 0.125 inches. The small quantity of radioactive material is sealed in radioactive isotope check source the plastic with epoxy to prevent leakage and contamination. The transmission window is sufficiently thin to transmit gamma emissions without undue absorption.

The Cd-109 source is available in these activities:

1 microCurie
5 microCuries
10 microCuries