Karl Canter, a pioneer of experimental positron physics and a professor at Brandeis University. At Brandeis, Professor Canter served as department chair and also as a member of the Faculty Senate. ollowing a post-doctoral position at University College, London, he came to Brandeis University in 1972 and began a long and productive collaboration with Stephan Berko (deceased) and Allen P. Mills (now at U.C. Riverside). Canter's crucial contribution was a practical way of slowing down the high energy positrons emitted by radioactive sources to make a focused and controlled beam of slow positrons.