A method for location of the peaks in step-scan measured Bragg reflexions

A method for location of the peak in a step-scan-measured Bragg reflexion profile is described. It leads to a ratio between the standard deviation of the intensity and the intensity, σ(I)/I, which is near minimum. The method is based on the observation that if σ(I)/I is calculated for all possible peak widths for a given profile then σ(I)/I is minimum near the true value of the peak width, and minimal σ(I)/I can thus be used as a criterion for correct location of the peak. The intensity determined this way is however in general slightly underestimated, and the bias as well as possible corrections are discussed. In addition a simple function resembling σ(I)/I, which has proved to be useful for practical applications, is given.