Early in the design of the Mark I accelerator it was decided to install magnetic lenses in the drift tubes. A number of model magnets were constructed and tested to determine the best design for these lenses. This report includes only the results of the tests on the final models of the magnets that are designed for Mark I.

The change in the simple [formula] distribution of neutrons in a spherical lump of uranium caused by the distribution in velocities of thermal neutrons is calculated. If the calculated curve is fitted as well as possible by a simple [formula] curve, it is shown that the value of [formula] obtained in this way is a function of [formula], the radius of the sphere. For small radii the [formula] obtained in this manner will be as much as 25% greater than the [formula] corresponding to average velocity neutrons. The change in the thermal utilization caused by the distribution in velocities is discussed. The flux of neutrons into a sphere is calculated taking into account the velocity distribution and this is compared with the usual theory.

This report analyzes two high-current linear accelerators, the A-54--a 48.5 megacycle resonant cavity accelerator--and the A-48, that is under construction during the time this report is written.

"Characteristics of a pulsed, occluded-gas ion source, operating in a magnetic field, have been investigated. Mass spectra of hydrogen- and deuterium-loaded sources are presented. Constructional details of the source and its operating characteristics are discussed."

"Dust and gas masks and respirators have been an effective method under certain environmental conditions to reduce the inhalation of toxic aerosols. Under many conditions, however, their efficacy has been seriously questioned. It is the purpose of this study to evaluation over-all respirator performance on fine aerosols and to develop equipment whereby a greater degree of respiratory protection may be assured with reliability for highly toxic atmospheres."

"This report presents some of the theory of operation of the Mirror Machine, and summarizes the experimental work which has been carried out...The modus operandi of the Mirror Machine is to create, heat and control a high temperature plasma by means of externally generating magnetic fields."

Abstract: The thermal distortion of a Y-shaped hafnium control rod heated by arrays of individually controlled radiation heaters was studied. The large axial and radial temperature gradients specified for this control rod were easily obtained with the radiation-heating method. The distortion, as measured with dial indicators, amounted to a 2-mil movement of the free end of the rod in the direction of the coolest blade.