Advanced tab of energy calibration window

On the advanced tab, you can revise the equations of the current energy calibration. If the additive nonlinearity correction is not used for a given calibration, then a simple

formula is used. In case of nonlinearity correction, the

formula will be applied, where NonlinShift is computed from the polynomial of nonlinearity curve for a given channel value.

This should result in much better agreement of the measured peak positions throughout the whole measurement range.

The calibration chart will also significantly change: calibration points will scatter randomly around the calibration line, and the differences between the points and the line become much smaller, thus resulting in much more precise peak position determination.

Advancedtab displays the energy calibration function in two forms.

The upper part contains the exact and numerically stable representation, which utilizes orthogonal polynomials. This solution, however, may seem uncommon.

The lower part displays the very same function as a regular polynomial, whose computation is more straightforward. It may be used in external applications, where the simplicity has higher priority than numerical stability.

This page also makes it possible the computation of any energy value and its uncertainty from arbitrary channel values: just enter the position in channels into Position edit box, and possibly its absolute 1σ uncertainty. Upon clicking Calculate button, the corresponding energy value will be displayed, together with its absolute uncertainty value.