Abstract
A time-of-flight mass spectrometer has been crossed with atomic beams of Ca and Sr and a source of monochromated synchrotron radiation in order to obtain the ratio of double-to-single photoionisation cross sections in the region of the 3p (or 4p) ionisation thresholds, between 25 and 35 eV. Attempts are made to correlate the structure observed in both elements with recently published photoabsorption, photoelectron and ejected-electron spectra.