Lawrence Livermore National Laboratory (LLNL) and EG and G ORTEC have
jointly developed a portable ambient-temperature detection system that
can be used in a number of application scenarios. The detection syste
m uses a planar cadmium zinc telluride (CZT) detector with custom-desi
gned detector support electronics developed at LLNL and is based on th
e recently released MicroNOMAD multichannel analyzer (MCA) produced by
QRTEC. Spectral analysis is performed using software developed at LLN
L that was originally designed for use with high-purity germanium (HPG
e) detector systems. In one application, the CZT detection system dete
rmines uranium enrichments ranging from less than 3% to over 75% to wi
thin accuracies of 20%. The analysis was performed using sample sizes
of 200 g or larger and acquisition times of 30 min. We have demonstrat
ed the capabilities of this system by analyzing the spectra gathered b
y the CZT detection system from uranium sources of several enrichments
. These experiments demonstrate that current CZT detectors can, in som
e cases, approach performance criteria that were previously the exclus
ive domain of larger HPGe detector systems.