Introduction: "In connection with conducting neutron experiments in a pit with earth and concrete walls, it was proposed that the background flux of neutrons might be reduced by lining the walls of the pit with a neutron absorber such as boron. To determine how much liner material would be desirable and what diminution in the neutron background could be expected, the following measurements were undertaken."

Bismuth metal was irradiated with 340 Mev protons in the circulating beam of the 184-inch Berkeley cyclotron. Nuclides formed as fission products during the course of the bombardment were separated and studied through the use of radiochemical techniques.

The total number of neutrons emitted from various targets bombarded by high energy deuterons and protons was measured by using a solution of MnSO<sub>4 to thermalize and capture the neutrons. The methods of monitoring the number of particles striking the target and of calibrating the neutron detecxting apparatus are discussed in detail. Deuterons of energies to 230 Mev and protons of energies to 345 Mev were used. Targets ranging from lithium to uranium were used and were backed by secondary targets of uranium and thorium. The yields are expressed in terms of the number of neutrons emitted per incident particle. Uranium targets gave the highest yield.

Research progress on projects: Landau Effect with 32 Mev Protons, n - p Scattering of "300" Mev Neutrons, Geologic History of the Earth's Magnetic Field.

A graph plotting pulse height analyzer of compact size and moderate cost is described. The operation is simple and flexible, and the instrument is easy to maintain.

The angular distribution of charged pions from 100 = 30 Mev neutron bombardment of C12 and Be9 has been measured. These data may be used to infer, by subtraction, the identity, within limits, of the [formula] and [formula] angular distributions.