OPERATING CHARACTERISTICS OF GAS-FILLED PROPORTIONAL COUNTERS WITH A NONSOLID CATHODE.

Gas-filled proportional ionizing-radiation counters with cathodes made from metal filaments or meshes have a low background level, are not readily contaminated by radioactive materials, and permit effective recording of beta radiation from solid sources. These advantages result from a reduction in the effective thickness and area of the cathode and ″pulling in″ of secondary electrons from the source into the counter volume. The latter effect and many other operating features of nonsolid-cathode counters are a consequence of the penetration of the electrostatic field through the mesh cathodes. Depending on the measurement task, the extraction of electrons may affect the counting characteristics in different ways.