"Head of lab" is not appropriate. The Cavendish Laboratory (which Bragg indeed headed) is/was the equivalent of a whole department or institute (of experimental

"Head of lab" is not appropriate. The Cavendish Laboratory (which Bragg indeed headed) is/was the equivalent of a whole department or institute (of experimental physics, chemistry and biology). The head of the actual lab that they worked for, who was Watson postdoctoral mentor and Crick's PhD advisor, was Max Perutz.