I’ve just been told by the writer Henry Nicholls, who interviewed him in 2009, that the engineer Tony Broad died last week at the age of 93. It is one of my sins of omission as a writer that I did not interview Broad myself when I undertook my research for Max Perutz and the Secret of Life, though I did acknowledge his critical role in the solution of the first protein structures.
Broad was recruited to the Cavendish Laboratory in Cambridge by Sir Lawrence Bragg to build X-ray tubes for Perutz and his fellow crystallographers in the MRC Unit for Research on the Molecular Structure of Biological systems (later to become the Laboratory of Molecular Biology). These tubes produce X-rays by focusing a beam of electrons from a cathode to an anode, generating intense heat as well as X-rays. The heat tends to damage the anode, limiting the power of the tube. Broad made an improved tube with an anode in the form of a rotating drum that could sweep past the beam of electrons, so limiting the heat damage and making it possible to increase the tube’s power. The crystals of haemoglobin and myoglobin that Perutz and his colleague John Kendrew were using for their studies of protein structure were very tiny, and needed powerful X-ray sources to produce data-rich diffraction patterns. The rotating anode tube gave them a global advantage in their quest to become the first to solve protein structures at atomic resolution, for which they were awarded the Nobel Prize for Chemistry in 1962. Broad’s contribution, though acknowledged in histories of the LMB such as Soraya de Chadarevian’s Designs for Life and John Finch’s A Nobel Fellow on Every Floor, seems otherwise entirely unrecognised. When I scanned the web for this post, his name barely featured: Wikepedia’s detailed entries on rotating anode tubes do not mention him at all. I infer, though I have no evidence, that he was a self-effacing man who put his energies into building technological solutions rather than drawing attention to himself. I have written this post from a position of greater ignorance (both biographical and technological) than I feel comfortable with, and hope that others who know more will fill out the picture.
Update: I am indebted to Colin Robertson, who worked with Broad tubes when they were developed commercially at Elliott’s in the 1960s, both for supplying the more accurate image above, and for the following comment on the significance of Tony Broad’s innovation: ‘in my opinion the main value of Tony’s work lay in the engineering design of the bearing and sealing arrangements that allowed the rotating anode drum (not a disc) to be driven and water-cooled reliably from outside the continuously evacuated enclosure of the tube itself. This resulted in a tube capable of providing much higher outputs for very long continuous periods that crystallographers needed for the advanced work they were doing. The tube is “demountable”. It can be dismantled and its parts can be replaced or exchanged as required, for example to use anodes with various target materials having different characteristic radiation properties. The design was covered by UK Patent No.854,363.’