-_— THYAC (ALPHA CONVERTED) The converted thyac with circuit changes to increase the trigger period and integration constant seems to be a very good field unit. It has not shown itself to be moisture or temperature sensitive. The probe must be handled gently and a rather high photo multiplier mortality rate has been notede A guard ring should be added as further protection of the very thin mylar windowe The probe may be used for short periods of time in any desired position due to the high viscosity of the silicone coupling compound and shape of its cavity in the light pipe. The unit is capable of calibration to provide ly readings with reasonable ageuracye ' Due to our lack of range in alpha sources they have only been checked at 00, 1800, 8800 and 3320 d/me , |