Absolute intensity calibration of a grazing-incidence spectrograph in the wavelength region 10-120 $Aring$

A method is described for determining the absolute sensitivity of a grazing-incidence spectrograph. This makes use of an x-ray source of discrete K-lines, the intensity of which is monitored by a flow proportional counter, acting as an absolute photon flux detector. Experimental results are given for Ilford Q2 emulsion used with a two-metre 600 lines per mm platinum coated blazed grating at an angle of incidence of 88°. The resultant curve compares well with a relative calibration obtained by using the radiation from a 335 MeV electron beam in a synchrotron.