Unfolding first and second order diffracted radiation when using synchrotron radiation sources: a technique.

A technique is presented of using a single calibrated XUV detector for radiometric measurements of synchrotron radiation after the radiation passes through a monochromator that produces a mixture of first and second order diffracted radiation. Irradiance measurements are made with the synchrotron source operating at two different energies for the orbiting electrons. The known change in the spectral distribution produced by the electron energy change is used to calculate the flux in both first and second order. The dependence of the precision of these determinations on the two detected currents and on the detector calibration at both first and second order wavelengths is calculated. Experimental results using the National Bureau of Standards synchrotron (SURF-I) are presented, and anticipated results for the new NBS electron storage ring (SURF-II) are calculated.