NBS Ionization Chamber for Beta Emitters

This ionization chamber was constructed at the National Bureau of Standards in 1953.

During the 1950s, beta emitting radiation sources from the NBS were shipped around the world. More often than not, they were quantified with this instrument.

The spherical detector chamber (ca. 6" in diameter), purchased at a local hardware store, was nothing more than a gold-plated ball intended for the top of a flagpole. The collecting electrode is a short 1/8 " brass rod. The chamber's high voltage connection can be seen projecting out from the back of the chamber in the photo.

The beta-emitting sample to be quantified is introduced into the bottom of the chamber via a scissors lift.

The current from the chamber (related to the sample activity) is evaluated with the Lindemann-Ryerson electrometer located in the brass box on top of the chamber. The horizontally mounted microscope is used to view the electrometer fiber.

This design was based on an instrument developed by Gino Failla at Columbia University.

Reference

Seliger, H. and Schwebel, A. Standardization of Beta Emitting Nuclides (Nucleonics July 1954, p.54).