"In the past ten years quantities of alpha-, beta-, gamma- and neutron-emitting isotopes handled in enclosures have increased from microcuries to kilocuries. Contaminated-atmosphere problems have increased accordingly. Developments at Berkeley are reviewed with particular emphasis on recent equipment, viz: a multiple-purpose gas scrubber and a total-capture system for slug-dissolver off gas."

Abstract. An analysis is made of a proposal to obtain neutrons of 15-25 Kev energy by moderating fast neutrons in aluminum and then reflecting off titanium. The fluxes calculated do not significantly exceed those obtainable from a standard antimony-beryllium photoneutron source. Two appendices treat aspects of the transport of neutrons through a slab of finite thickness.

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.