"The properties of the muon have been studied for many years and much is now known about this particle. Very accurate measurements of its mass and magnetic moment gave values in the relationship predicted by the Dirac equation and quantum electrodynamics. Experimental evidence indicating that the muon spin is 1/2 is obtained from comparison of precession measurements of the muon bound in certain mesic atoms and from observation of muonium precession. To all appearances, one would conclude that the muon behaves as an unstable electron, but as 206.76 times the mass of that electron. A study of the interaction of the muon with nuclear matter may throw more light on this problem of muon-electron equivalence."

"Progress is reported on Phase II of a program for the development of a mixed fission product fueled thermoelectric generator. Materials studies are described in which bonded assemblies of bismuth telluride were life tested up to 3000 hours at 350 to 400 deg F hot junction temperature. Data were too inconsistent to define any satisfactory long-life bonding process. Further work is needed to eliminate the process variables. Insulation studies aimed at determining the thermal conductivity of various insulations with different fill gases under reduced pressures are described. Opacified aerogel powder appears to be very promising as an insulation medium for a diffuse heat source. A full- scale simulated test generator aimed at proving out the concept of a diffuse heat source for power generation is described. Progress on the construction of this electrically heated generator and its thermoelectric power converter is related.

"The influence of compressive creep on the self-diffusivity of α-iron has been measured in the temperature range of 742-885°C. the diffusivity is enchanced in proportion to the strain rate, but this dependence decreases with increasing temperature. The magnitude of the strain is relatively unimportant in this connection. Strain rates from 0 to -2 x 10¯³ sec¯¹ were investigated with a corresponding increase in diffusivity up to 3 x 10³ times. The results are analyzed in terms of vacancy diffusion and the excess vacancies introduced during deformation. It is concluded that grain boundaries are the main vacancy sinks in polycrystalline iron and that the vacancy lifetime is therefore dependent on the grain size."