Question: When did Peter Hirsch work under an Australian-born British physicist and X-ray crystallographer?

Context paragraphs:
Gerard Kleywegt: Gerard Jacob Kleywegt (born 5 June 1962, Rozenburg) is a Dutch X-ray crystallographer and the former team leader of the Protein Data Bank in Europe at the EBI; a member of the Worldwide Protein Data Bank.

Michael Eisen: Born in Boston, Eisen and his brother Jonathan were raised in a family of scientists.  Their grandfather was an x-ray crystallographer, their father, Howard Eisen a physician, and mother, Laura a biochemist.  They moved to Bethesda, Maryland when Eisen was four or five years old.  The brothers spent summers in Long Island with their grandparents.  Eisen states that he loved frogs and salamanders '"Even more than I have a frog fetish, I have a swamp fetish.  I really like being in swamps."'  He was also very interested in math and was captain of the high school math team.  Eisen graduated from Walt Whitman High School in 1985.  Intending to major in mathematics at Harvard University, he realized that there [he may encounter] other more brilliant math students, it was a "Good Will Hunting" moment and he decided that he did not want to major in mathematics, '"You don't want to be Salieri to Mozart."'  During his years at Harvard, Eisen worked on "unlocking the three-dimensional structures of proteins."  He was shown a DNA microarray which taught him a '"new way of doing biology"'.

Rosalind Franklin: Rosalind Elsie Franklin (25 July 192016 April 1958) was an English chemist and X-ray crystallographer who made contributions to the understanding of the molecular structures of DNA (deoxyribonucleic acid), RNA (ribonucleic acid), viruses, coal, and graphite.  Although her works on coal and viruses were appreciated in her lifetime, her contributions to the discovery of the structure of DNA were largely recognised posthumously.

Photograph 51 (play): Photograph 51 is an award-winning play by Anna Ziegler.  "Photograph 51" opened in the West End of London in September 2015.  The play focuses on the often-overlooked role of x-ray crystallographer Rosalind Franklin in the discovery of the double helix structure of DNA while working at King's College London.  This play won the 3rd "STAGE" International Script Competition in 2008.  The title comes from "Photo 51", the nickname given to an X-ray diffraction image taken by Raymond Gosling in May, 1952, under the supervision of Rosalind Franklin.  The one-act play runs for 95-minutes with no intermission.

David Hall (chemist): David Hall (15 February 1928 – 15 June 2016) was a New Zealand chemist, best known as an X-ray crystallographer.

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.  He was joint winner (with his father, William Henry Bragg) of the Nobel Prize in Physics in 1915: ""For their services in the analysis of crystal structure by means of X-ray"", an important step in the development of X-ray crystallography.

Douglas M. C. MacEwan: Dr Douglas MacLean Clark MacEwan FRSE (1917-2000) was a Scottish physicist and x-ray crystallographer.  In authorship he is often referred to as D. M. C. MacEwan.

Arthur Lindo Patterson: Arthur Lindo Patterson (23 July 1902, Nelson, New Zealand - 6 November 1966, Philadelphia, Pennsylvania) was a pioneering British X-ray crystallographer.  Patterson was born to British parents in New Zealand in 1902.  Shortly afterwards the family moved to Montreal, Canada and later to London, England.  In 1920 Patterson moved to Canada for college at McGill University, Montreal.  Firstly he concentrated on Mathematics and but then changed his major to Physics.  He received his bachelor's degree in 1923 and a master's in 1924.  His master's thesis was on the production of hard X-rays by interaction of radium β rays with solids.

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.  Hirsch attended the Sloane School, Chelsea and St Catharine's College, Cambridge.  In 1946 he joined the Crystallography Department of the Cavendish to work for a PhD on work hardening in metals under Lawrence Bragg.  He subsequently carried out work, which is still cited, on the structure of coal.

Kedareswar Banerjee: Kedareswar Banerjee (15 September 1900 – 30 April 1975) was an X-ray crystallographer and director of the Indian Association for the Cultivation of Science, Kolkata.  Early in his career he determined the structures of naphthalene and anthracene.  In 1931, he worked with Sir William Henry Bragg and developed one of the first direct methods of crystal structure determination.  He was Professor of Physics at the Indian Association for the Cultivation of Science from 1943 to 1952 and Director of the Association from 1959 until his retirement in 1965.  Between 1952 and 1959 he was Head of the Department of Physics at Allahabad University.  His interests in crystallography were widespread and, with his death, India has lost a renowned teacher.  K. Banerjee joined the research group of Sir C. V. Raman at the Indian Association for the Cultivation of Science (IACS), Calcutta, a premier Indian research institute of India.  He worked in various institutions including IACS, the India Meteorological Department, University of Dhaka and Allahabad University and finally retired as the Director of IACS, Calcutta in 1965.  Prof. Banerjee explained some points of crystal research to Homi J. Bhabha (21 Dec 1956) also .

Supporting paragraphs: Peter Hirsch William Lawrence Bragg
Answer: 1946