engleski

Effects of in-target Compton-scattering in lanthanum fluorescence spectra

A study of the continuum adjacent to the Ka1 and Ka2 peaks (the "shoulder") in lanthanum fluorescence spectra has been made. The fluorescence was induced by 59.537 keV gamma- rays of 241Am. The spectra were observed with a Lantanum oxide-loaded parafine target (the "La- target"). To limit the observations to the scattering in the target, a collimator was used in front of the germanium detector which strongly reduced the near-detector scattering. Changes in the shoulder spectra have been observed when attaching additional mass to the La-target and by changing its orientation with respect to the detector-to-target centre-line. The measurements clearly show that the main cause of the shoulder spectra is due to the in- target Compton scattering. Different distribution of mass in vicinity of the fluorescing atoms with respect to the detector- to-target centre-line results in a different distribution of scattering angles. Since the energy of secondary Compton photons is directly related to the scattering angles, different distribution of mass causes the change of the shoulder spectrum. Comparison of the calculated and measured shoulder spectra show a fair agreement on absolute scale.

Fluorescence spectra ; lanthanum ; germanium detector ; response function ; shoulder

nije evidentirano