Calendar: 1963-1964 Page 446

ANNUAL REPORT group is developing techniques for investigating the optical and electrical properties of diamond and other crystals Considerable progress has been made in the interpretation of the processes involved The theoretical group under Professor Domb continues to pursue its studies of cooperative phenomena and lattice dynamics New techniques based on the application of the Pade approximant to series expansions have been successfully applied to number of different problems including the statistical mechanics of isotopic mixtures the Ising and Heisenberg models and percolation processes The nuclear physics group operating at the Harwell under Dr Burge has used the proton linear accelerator at 50 MeV in order to extend their existing measurements with the slit scattering apparatus Optical model computations for separated isotopes have been completed The atmospherics research group under Dr Chapman has con- tinued investigations in radiophysics on the propagation of and electromagnetic waves between the ground and ionosphere New developments of importance include the detection of the electro- magnetic resonant frequencies of the cavity formed between the ground and the ionosphere new theoretical treatment of these results has led to determination of the attenuation of radio waves at frequencies ranging from sec to 100 sec The results on the polarization of radio atmospheric amplitude frequency components have been success- fully explained in terms of the ground-ionosphere waveguide theory Automatic conversion of the experimental observations to form suitable for direct application to the University digital computer is in progress Conferences visits lectures etc Professor Price presented papers at the First International Conference on Vacuum Ultraviolet Spectroscopy Los Angeles the Spectroscopy Conference of the Institute of Petroleum and the Photo Electric Spectrometry Group He also gave the opening lecture to course on Developments in Modern Physics at the North- East Technical College Professor Champion Dr Dean and Dr Male presented papers at the Cambridge Diamond Conference on The interpretation of edge absorption edge excitation and radiative recombination in diamond and Birefringence and luminescence patterns in semi-conducting diamond Professor Domb gave an advanced course of lectures on Statistical Mechanics in the intercollegiate postgraduate series and he lectured on Lattice Dynamics to the eighth International Conference on Low Temperature Physics Dr Μ Fisher lectured on Lattice Statistics to the conference on the thermodynamics and statistical mechanics of phase transitions He also lectured at the Bell Telephone Laboratory Harvard University Bristol and Newcastle Dr Danielian lectured on Antiferromagnetic Susceptibilities at the University of Man- Chester