Affiliations: Struttura Dipartimentale di Matematica e Fisica,
Università di Sassari, 07100, Sassari, Italy | Istituto di Struttura della Materia, CNR, Rome,
Italy | INFN, Sezione di Cagliari, Cagliari, Italy
Note: [] Corresponding author: A. Brunetti, Struttura Dipartimentale di
Matematica e Fisica, Università di Sassari, Via Vienna 2, I-07100 Sassari,
Italy. E-mail: brunetti@uniss.it
Abstract: In Energy Dispersive X-Ray diffraction measurements, the estimate of
momentum transfer q, on which the diffracted intensity depends, should be as
accurate as possible. Since q, in turn, depends on both the energy and the
scattering angle, an error on the latter due to an incorrect positioning of the
sample, to the asymmetric angular spread induced by the collimation slits or,
in general, to any uncertainty on the geometric setup, results in an
uncertainty on the q value. Here, a new self calibration method to correct such
errors, based on a genetic algorithm is presented. It is robust, fast and
completely automatic. Results obtained by carrying out Energy Dispersive X-Ray
Diffraction measurements on reference samples are reported and discussed. They
show how the application of such genetic algorithm may provide a fast esteem of
the two parameters required when multiple angle pattern collection is
performed, namely the effective starting angle and the angular step. In this
way, reliable q-values of all the diffraction pattern features (Bragg peaks for
crystalline, and diffused bumps for non-crystalline samples) are obtained.
