Along with other members of the Feynman team , Ashkin produced technical reports while at Los Alamos . These were classified at the time but have since been made public . One example gives an idea of the work carried out by the group . It is '' The Calculation of Critical Masses Including the Effects of the Distribution of Neutron Energies '' , by Feynman , R.P. ; Welton , T.A. ; Ashkin , J. ; Ehrlich , R. ; Peshkin , M. ; and Reines , F. Report LA-524 ( Del. ) January 21 , 1947 ( extract from abstract : " Convenient approximate methods are developed for the calculation of critical sizes and multiplication rates of spherical , active cores surrounded by infinite tampers . Special attention is given to those problems arising from the fact that neutrons of different velocities have different properties . The methods consist essentially of approximating the neutron densities at each velocity by fundamental mode shapes for each velocity . " ) On July 16 , 1945 Ashkin was present at the first-ever explosion of a nuclear bomb at the Trinity test site , Alamogordo . Only a few of the many scientists were permitted to witness this unspeakably dramatic culmination of their work . Ashkin was probably there because of his work on radiation poisoning , begun at Met Lab and probably continued afterward
Trinity test site
Trinity (nuclear test)
Julius Ashkin