Jordan Model CG 50 Ion Chamber (ca. 1955-1960)

Jordan Model CG-50 Ion Chamber

This ion chamber was manufactured by Jordan Electronics (a division of the Victoreen Instrument Company) of Alhambra, California.

It was only capable of responding to gamma rays, hence the G in the model designation. The Model CGB-50, not in the ORAU collection, had a thin window and was capable of detecting betas as well as gammas. 

The CG-50 employs a Neher-White design with a floating grid. The resulting output (current) is a logarithmic function of gamma intensity. A nice advantage of this approach is that no guard ring or high meg resister is required! The electrometer tube is hermetically sealed inside the chamber.

Fill gas: Argon (200 psi)

Active volume: ca. 820 cc

Sensitivity: ca. 15 microamps per decade from 0.01 mR/hr to 10,000R/hr

Size: ca. 11" tall and 4" in diameter

Kindly donated by Chuck Abraham.


AEC Radiation Measuring Instruments, RIB-8 (supplement 2) July 1, 1954. Page BIC-19A,B.