GEOFFREY WILKINSON, RICHARD M. DIAMOND, and EUGENE G. ROCHOW Hamard University, Cambridge, Massachusetts
HARVARD'S first cyclotron went to war early. AS re- clear and radiochemical studies has been set up in the corded in the Smythe report, that cyclotron was trans- Department of Chemistry, and a program of research planted to Los Alamos in 1943. In the immediate has been started in which the Harvard synchrocypostwar years. a new and larger cyclotron, with bet- clotron and a variety of radioactive tracers are being ter instrumentation and control, was constructed in applied to problems in inorganic and physical chemisa new nuclear laboratory adjacent to the departments try. The laboratory facilities a t hand include equipof chemistry and physics. For six years this new in- ment for Geiger, proportional, and scintillation countstrument has been in active use on the problems of ing, in addition to customaly radiochemical protecnuclear physics. tion and monitoring equipment, and present an exWithin the same postwar years nuclear chemistry cellent basis for a wide range of research interests. has undergone a particularly rapid development as a The Harvard 95-inch synchrocyclotron is available broad field of scientific endeavor, not only directly in for use in bombardment and radiochemical studies. the study of nuclear phenomena hut indirectly in the It has a unique feature that makes the cyclotron of further use of radioactive tracers in the solution of unusual utility from the chemist's point of view. This chemical problems. With this development has come feature is a tantalum scattering device by means of the recognition of nuclear chemistry as an individual which the circulating proton beam can be deflected discipline in courses of instruction. Nuclear and back into the magnetic field of the cyclotron. These radiochemical research and teaching in other insti- deflected protons are focused by the field in positions tutions has been discussed before in THIS JOURNAL;' dependent upon their energy, and in consequence beams in this note we should like to point out the potential of protons of accurately known energy range are availof the chemistry department a t Harvard University for able. Thus protons from 15 to 100 m. e. v. can be ohresearch in nuclear chemistry for students who wish tained where, for small targets, the energy resolution is better than 0.5 m. e. v.; t,his contrasts strikingly with to do work in the field for the Ph.D. degree. During the past three years a laboratory for nu- most other cyclotrons, in which beams are usually obwith a several-m. e. v. spread in energy. The ' Symposium on Teaching Nuclear Chemistry, J. CREM. tained Harvard cyclotron is hence a unique instrument for preEDWC., 28.2-14 (1951): R. T. OVERMAN, H. M. CLARK, W. M. HAMILL, R. R. WILLIAMS, JR.. R. H. SCWLA,I. PERLMAN. G. T. cise studies on the yields of nuclear reactions as a function of proton energy. Such studies of excitation func-
SEPTEMBER, 1954
tion areof great importance in providing data for a better understanding of the mechanisms of nuclear reactions and of the range of validity of proposed models (such as the formation of compound nuclei a t low bombarding energies and the knock-on process at high energies). Another advantage of the Harvard cyclotron in this type of work is that its energy range (up to 110 m. e. v.) bridges the gap between ordinary cyclotrons (
