Hemispherical Detector Research Articles

Overview of the use of CdTe detectors for the verification of nuclear material in nuclear safeguards

Abstract CdTe detectors are uniquely suited for international safeguards verification measurements of nuclear material in the field. The paper gives an overview of the use of CdTe detectors for various safeguards verification tasks. Characteristic features of the detection systems primarily developed under Member State Technical Support Programmes to IAEA Safeguards and typical measurement results are described. Presently available planar and hemispherical detectors have a resolution of 1–4% for 137Cs and can be used to verify items that are difficult to access with larger more bulky detectors. Examples are described covering the verification of spent fuel items stored under water and fresh fuel assemblies in dense storage geometries. Considerable effort was also put into the development of appropriate miniature preamplifiers and pulse processors which are needed to take full advantage of the CdTe detectors. Considerations for future development of CdTe detectors and the associated pulse processing electronics are given that would further enhance the application of these systems for international safeguards and other radiation monitoring tasks.

Surface extended electron loss fine structure: dependence on incident electron energy and collection solid angle

Reflected electron energy loss fine structure above the M 2,3 core excitation edge of Cu is measured using two dissimilar electron detection systems, a cylindrical mirror analyzer and an hemispherical grid detector, at primary energies ranging from 700 to 2000 eV. We find slight differences in the loss structures measured by the two detector systems, but the radial and pseudo-radial distribution functions calculated by an EXAFS type analysis of the extended fine structure show agreement in the first peak position to within ±0.02 Å for all primary energies above 800 eV. Core-loss and fine-structure signals from sub-monolayers of C and O were observed. No fine structure was measurable for core-loss signals of single monolayer coverages of Na, K, Cs, or S.