Temperature stabilization of a field instrument for uranium enrichment measurements

Enrichment measurements with sodium iodide (NaI) detectors are hampered with a number of problems related to the temperature behavior of NaI crystals and the associated electronics. This problem is of particular concern in applications requiring the use of fixed regions of interest; such applications are used by the International Atomic Energy Agency (IAEA) in Vienna. The Canberra IMCA is a new portable instrument for such applications which can use either a NaI or a Ge detector. In developing the IMCA to meet the IAEA requirements for NaI detectors, Canberra has designed a system with a new temperature stabilization method capable of maintaining the detector stability at 0.5% over a temperature range of -10 to +50/spl deg/C. This paper includes a detailed description of this IMCA temperature stabilization system, as well as test results for a range of temperatures using uranium standards.