When did Peter Hirsch work under an Australian-born British physicist and X-ray crystallographer?
Peter Hirsch: Sir Peter Bernhard Hirsch HonFRMS FRS (born 16 January 1925) is a figure in British materials science who has made fundamental contributions to the application of transmission electron microscopy to metals. Peter Hirsch:  In 1946 he joined the Crystallography Department of the Cavendish to work for a PhD on work hardening in metals under Lawrence Bragg. William Lawrence Bragg: Sir William Lawrence Bragg (31 March 1890 – 1 July 1971) was an Australian-born British physicist and X-ray crystallographer, discoverer (1912) of Bragg's law of X-ray diffraction, which is basic for the determination of crystal structure.
1946