Development of an on-demand beam pulsing system for Pixe-analysis of thick targets
This work concerns the developnent of a proton irnuced X-ray
emission (PIXEl analysis system and a multi-sample scattering chamber
The characteristics of the beam pulsing system and its counting
rate capabilities were evaluated by observing the ion-induced X- ray
operation. The characteristic X-rays were detected with a high
resolution 5i(Li) detector ocoupled to a multi-channel analyser.
The removal of the pile-up continuum by the use of the on-demand
beam pulsing is clearly demonstrated in this work . This new on-demand
pu1sing system with its counting rate capability of 25, 18 and 10 kPPS
corresponding to 2, 4 am 8 used main amplifier time constant
respectively enables thick targets to be analysed more readily.
Reproducibility tests of the on-demand beam pulsing system
operation were checked by repeated measurements of the system throughput
curves, with and without beam pulsing . The reproducibility of the
analysis performed using this system was also checked by repeated
measurements of the intensity ratios from a number of standard binary
alloys during the experimental work.
A computer programme has been developed to evaluate the
calculations of the X-ray yields from thick targets bombarded by
protons, taking into account the secondary X-ray yield prproduction due to
characteristic X- ray fluorescence from an element energetically higher
than the absorption edge energy of the other element present in the
target. This effect was studied on metallic binary alloys such aa Fe/Ni
and Cr /Fe .
The quantitative analysis of Fe/Ni and Cr/Fe alloy samples to
determine their elemental composition taking into account the
enhancement has been deIronstrated in this work. Furthermore , the
usefulness of the Rutherford backscattering (R.B.S .) technique to obtain
the depth profiles of the elements in the upper micron of the sample is