Evaluation of the utilization of flat ionization chamber as monitor chamber

Abstract

This work continues the study initiated in 2003 of the PTW 77335 ionization chamber, showing their performance and functionality to be used as transmission chamber. Those chambers have the same characteristic of monitor chamber. They are flat kind with 112cm3 of volume, graphite window with thickness of 170µm and polarizing voltage of 100V. The chambers were named A and B, and they were connected to an electrometer Unidos also of PTW, and a 14C as a check source. The repeatibility test consists in 10 measurements in fix and repeated conditions. This test shows the behaviour of the ionization chamber in short time. To verify their long time stability, this test was made for 6 months. The results showed a good performance of the chamber model 77335 to be used as transmission chamber, as published before. The stability test showed that the chamber A (s. 1870) had a variation of 0.16 % and the chamber B (s.1868) 0.20%. The long time measurements showed a variation of +/- 1.8 % for chamber A and +/-1.6 for chamber B. The values showed the functionality of the chamber to be used as transmission chamber. The results showed good performance of the studied chambers, therefore, the continuing evaluation is needed to guarantee the quality of the results showed until now.