Electromechanically cooled germanium radiation detector system

We have successfully developed and fielded an electromechanically cooled ge rmanium radiation detector (EMc-HPGe) at Lawrence Livermore National Labora tory (LLNL). This detector system was designed to provide optimum energy re solution, long lifetime, and extremely reliable operation for unattended an d portable applications, For most analytical applications, high purity germ anium (HPGe) detectors are the standard detectors of choice, providing an u nsurpassed combination of high energy resolution performance and exceptiona l detection efficiency. Logistical difficulties associated with providing t he required liquid nitrogen (LN) for cooling is the primary reason that the se systems are found mainly in laboratories. The EMC-HPGe detector system d escribed in this paper successfully provides HPGe detector performance in a portable instrument that allows for isotopic analysis in the field. It inc orporates a unique active vibration control system that allows the use of a Sunpower Stirling cycle cryocooler unit without significant spectral degra dation from microphonics. All standard isotopic analysis codes, including M GA and MGA + + [1], GAMANL[2], GRPANL[3] and MGAU[4], typically used with H PGe detectors can be used with this system with excellent results. Several national and international Safeguards organisations including the Internati onal Atomic Energy Agency (IAEA) and U.S, Department of Energy (DOE) have e xpressed interest in this system. The detector was combined with custom sof tware and demonstrated as a rapid Field Radiometric Identification System ( FRIS) for the U.S. Customs Service [5]. The European Communities' Safeguard s Directorate (EURATOM) is field-testing the first Safeguards prototype in their applications. The EMC-HPGe detector system design, recent application s, and results will be highlighted. (C) 1999 Elsevier Science B.V. All righ ts reserved.