STUDIES ON THE SURFACE-CHARGE DISTRIBUTION OF RADON EXPOSED ELECTRETSWITHIN AN ELECTRET IONIZATION-CHAMBER

For studying the processes inside an electret ionisation chamber the c harge distribution on the electret surface was measured using an autom atic scanning device constructed using a non-contacting voltmeter. A s eries of such measurements of electrets exposed to radon within an ele ctret ionisation chamber shows a changing shape of the charge distribu tion. The initial shape of the charge distribution depends on the meth od of electret charging, whereas the discharging processes depends on the chamber design and the electric field. Investigations have also be en made in how far small areas charged with opposite sign affect the r eadings of radon concentration. The data are used to calculate the rec ombination loss inside the chamber and to optimise the chamber design.