Demonstration of the ultrafast nature of laser produced betatron radiation

This Letter aims to demonstrate the ultrafast nature of laser produced betatron radiation and its potential for application experiments.An upper estimate of the betatron x-ray pulse duration has been obtained by performing a time-resolved x-ray diffraction experiment: The ultrafast nonthermal melting of a semiconductor crystal ͑InSb͒ has been used to trigger the betatron x-ray beam diffracted from the surface.An x-ray pulse duration of less than 1 ps at full width half-maximum ͑FWHM͒ has been measured with a best fit obtained for 100 fs FWHM.