In the Plowshare Program many calculations of the effects of underground explosions are made. Usually these are done on high-speed digital computers. The effects are calculated for ranges up to hundreds of meters from the explosion; at these ranges pressures become less than one kilobar. In order to make these calculations, information about the properties of the materials involved is required. Benedick [13] has developed a low-pressure, plane-wave lens using nitroguanidine. It was decided to use a similar lens in the Plowshare Program. A number of lenses were built using Benedick's technique. This report is of a study of simultaneity and pressure uniformity of these lenses, with some attempts at development of a reflection pressure vs particle velocity curve for them.

Abstract. The cross section of photoneutron production in Be9 at energies of 1.692, 1.720, and 1.78 Mev has been investigated using radioisotope gamma-ray sources. Neutron counting was by manganous sulfate bathe and a long counter. Gamma-ray counting was by a scintillation spectrometer consisting of a NaI(T1) scintillation crystal and a 256 channel pulse-height analyzer. A theoretical treatment of the P [right arrow] S transition near threshold using square-well potentials is also presented.

Critical mass experiments to be conducted at HAPO will require dilute and concentrated plutonium solutions. Since very high plutonium concentrations (~2,000 g/l) cannot be attained in pumpable solutions, solid plutonium compounds will be utilized for this phase of the work. Mixtures of plutonium oxide and polyethylene, methyl methacrylate or paraffin compacted in containers have been considers for use in highly-concentrated plutonium systems of known hydrogen to plutonium atomic ratio (H/Pu).