Automated construction of detector models for efficiency interpolation in gamma-ray spectrometry.
A method was developed for automated construction of detector models in gamma-ray spectrometry, which can be used in Monte Carlo calculations of efficiency calibration curves. Full-energy peak efficiencies were first measured for different gamma-ray energies and for a given sample-detector arrangement and then calculated by the Monte Carlo method. For these calculations a detector model was employed along with a computer algorithm, which seeks agreement between the experimental efficiencies and the calculated ones by automatically determining the parameters of the model. The resulting agreement of the calculated data with the experimental one was within the relative uncertainty of the latter (3-4%) and the parameters of the detector models obtained were close to the values specified by the manufacturers. The detector models thus constructed can then be used for interpolation of calibration curves.
Spline techniques for fitting efficiency curves in gamma-ray spectrometry
Abstract Low order spline functions are used in a least-squares fitting procedure to establish full-energy peak efficiency curves for different kinds of semiconductor photon detectors (Ge(Li), Si(Li), HPGe) in the energy range from 2 keV to 3 MeV. The algorithm allows discontinuities in the efficiency curves due to absorption edges of the detector material to be represented. Uncertainties of the calculated efficiencies are evaluated from the covariance matrix of the experimental data, taking into account correlated data uncertainties.
EFFECT OF SAMPLE PREPARATION ON WATER TREE RESISTANCE OF XLPE/SEBS BLENDS
The effects of an aromatic polymer, such as poly[styrene-b-(ethylene-co-butylene)b-styrene] (SEBS), and its preparation processes on water tree resistance, morphology, crystallinity, dielectric constant and dielectric loss tangent of crosslinked polyethylene (XLPE)/SEBS and XLPE/SEBS/ethylene vinyl acetate (EVA) blends were investigated. The XLPE/SEBS samples were characterized by means of differential scanning calorimetry, scanning electron microscopy, dielectric spectral analysis and the accelerated water treeing experiment. The results clearly showed that although SEBS was partially compatible with LDPE and it was dispersed evenly in XLPE matrix, the blends demonstrated excellent dielectric performances, such as dielectric constant and dissipation factor. The crystallinity of XLPE/SEBS blends was decreased with increase in SEBS content and it was further decreased with the addition of EVA. SEBS could effectively improve the water-tree resistance of XLPE and both SEBS and EVA were found to improve the water tree resistance of XLPE synergistically as expected. The differences in sample preparation processes could change the phase morphology and dielectric performance of the blends, and could also influence the dispersion of SEBS in XLPE matrix as well as the crystallinity of the blends. Different preparation processes led to different water tree resistance behaviours of the samples. The improvement of SEBS dispersion in XLPE matrix helped to improve the water tree resistance of XLPE.