Calibration

To analyse the recorded spectra the spectrometer needs to be calibrated. The three main calibration parameters are the velocity scale, the center point of the spectrum and the alinearity of the velocity/time profile of the oscillation compared to a standard reference. The calibration is performed using a spectrum recorded from an $\alpha$ -iron foil at room temperature and fitted with the ``FCal'' subroutine.

The velocity scale is calibrated using the well defined line positions of the sextet from $\alpha$ -iron, which occur at $\pm5.312\ensuremath{\unskip\,\mathrm{\nicefrac{mm}{s}}}$ , $\pm3.076\ensuremath{\unskip\,\mathrm{\nicefrac{mm}{s}}}$ and $\pm0.840\ensuremath{\unskip\,\mathrm{\nicefrac{mm}{s}}}$ .[16] The center of this $\alpha$ -iron spectrum at room temperature is taken as the reference point ( $0.0\ensuremath{\unskip\,\mathrm{\nicefrac{mm}{s}}}$ ) for isomer shift values of sample spectra.

Dr John Bland, 15/03/2003