A thermostable high pressure xenon gamma-ray detector for monitoring concentration of KCl during fertilizer manufacturing

The abundance of 40K isotope in natural K is about 10-4. Therefore, measurements of the intensity of the 1.46 MeV gamma line from 40K allows to estimate the concentration of KCl in various mixtures and solutions. However, during the technological procedure it is necessary to carry out the measurements at a relatively high temperature, typically at about 120 deg. C, where traditional detectors cannot be used. A high pressure xenon gamma-detector has been developed for these kinds of measurements. The detector is a cylindrical ionization chamber with a sensitive volume of 5 l. The pressure of xenon gas inside the chamber is 40 atm. A special charge sensitive amplifier capable to operate at high temperatures up to 200 deg. C was designed for these measurements. The detector test under real industrial conditions at 'Silvinit' - a company located in the North East of European part of Russia - proved that the concentration of KCl can be measured directly during the manufacturing process with an accuracy better than 1% in the temperature between 15 deg. C and 120 deg. C