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An investigation of the inelastic and elastic reactions between high- energy neutrons nnd He nuclei was conducted with a cloud chamber filled with He and operating in a pulsed magnetic field of 21,700 gauss. Neutrons produced by bombardment of a 1/2-in. LiD target with 340-Mev protons in the 184-in. synchrocyclotron were collimated and passed through the 22-inch expansion cloud chamber, which was filled with He gas to a total pressure of 89.8 cm Hg. Exclusive of meson-producing reactions, the possible reactions are: Inelastic, He/ sup 4/(n,pn)t, He/sup 4/(n,d)t, He/sup 4/(n,2np)d, He/sup 4/(n, dn)d, He/sup 4/ (n,2n2p) n, He/sup 4/(n, 2n) He/s up 3/; and Elastic, He/sup 4/(n,n)He/sup 4/. The total number of events, for incident neutrons above 160 Mev, was normalized to the interpolated n-He/sup 4/ total cross section at 300 Mev, and absolute cross sections for the various processes were established. Energy and angular distributions of the reaction products were compared with available theoretical predictions and other experiments. A few cases of meson production were noted. (auth)

A comparative study was made of the growth of yeast in various media at the optimum temperature (30 ) and at supraoptimum temperatures. It was found that at elevated temperatures there is a decrease in the ability of yeast to grow, which may be alleviated by increasing the percentage of yeast extract in the medium, adding oleic acid to the medium, or using an inoculum of cells that have previously been grown at the elevated temperature. Because of these findings, it is believed that growth at elevated temperatures results in an increased nutrient requirement which may be eliminated by induced adaptation. When yeasts were grown at elevated temperatures or exposed for a short time to lethal temperatures it was found that there was a great increase in the fraction of respiratory-deficient mutants (petites). It was shown that the increase of mutants did not arise because of selection, but that the elevated temperatures actually induced the mutation. From the results of various genetic analyses it is shown that these respiratorydeficient mutants are very similar, if not identical. to vegetative petites occurring spontaneously or induced by acriflavine. The kinetics of this mutation is discussed, with possible theoretical interpretations. (auth)

The products from the flssion of U induced by charged particles were studied in a mass spectrometer. Both U/sup 238/ and U/sup 235/ were bombarded with 45.7- and 24-Mev helium ions, and U/sup 238/ was also bombarded with 730-Mev protons and 100-Mev carbon ions. Tbe total chain-yields in the region of the rare-earth elemerts (mass 140 to mass 155) for most of the above bombardments and a thermal-neutron bombardment of U/sup 235/ were studied by using the isotopicdilution technique. Independent yields were measured for all the above bombardnnents for several shielded nuclides. (auth)

A manipulator or mechanical arm involves an upper and a lower arm, with a variable angle between them. Cables used to transmit motion and force from the upper to the lower arms pass over a pulley at the joint or elbow. A pulley, axiaily fixed with respect to the joint, imposes a change in length of the cable as the angle between the arms varies. Manipulation design requires a cable of constant length during this variation; this constant length may be achieved by guiding the center of the pulley along the proper path. Acceptable solutions were obtained in terms of variables such as the lengths of each arm, the radius of the pulley, and the angle between the arms. In one design the pulley center is moved along a straight line with respect to the lower arm, while in the other solution the pulley center is moved along a circular arc with respect to the upper amn. Practical and economical mechanisms based on these solutions were investigated for use in manipulator design. (auth)

The range and range straggling of 96.8-kev Ra/sup 224/ recoil atoms produced by alpha decay of Th/sup 228/ have been measured in H/sub 2/, D/sub 2/, He, N/sub 2/, Ne, and Ar by a charged, parallelplate, collection technique. The range and range straggling of 725-kev Th/sup 226/ recoii atoms produced by bombardments of Ra/sup 226/ with 41.6-Mev helium ions have been measured in D/sub 2/, He, N/sub 2/, and Ar by this same technique. Experimental results seem to indicate that the range-energy relation for the stopping of heavy recoils by nuclear collisions is not linear, as is theoretically predicted by Bohr. The distribution of ranges about the mean range appears to be Gaussian. Various factors contributing errors to the measured range stragglings are discussed in detail P coil efflciencies of the heavy recoils produced in the (d,) (d,2n), (d,3n), and (d,p) reactions of Bi/sup 209/ have been measured at incident deuteron energies of 15 0 to 23.6 Mev for Bi/sup 209/ targets of 0 6 to 42.5 mu g/cm. The recoil effic encies of the different reaction products have been compared on the basis of probable nuclear-reaction mechanism by which they are produced. Mean ranges for Po/sup 208/ in Bi/sup …

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The cycle of cesium-134 (2 mu c) in white oak trees on four sites differing soil type and moisture was followed. Gains, losses, and transfers were estimated by sampling from inoculated trees, understory, litter, and soil. With rapid translocation into leaves from initial trunk inoculations in the spring, white oak leaves contained 10/sup 5/ to 10/sup 6/ dpm per g dry weight by early June. This represented a total transfer of about 40% of the original input. From rains, loss from leaves continued throughout the growing season until September, by which time a total loss of 15% of the observed maximum concentration in leaves had occurred. Approximately 70% of this rain-induced loss reached the mineral soil by September, the remainder located in litter and understory vegetation. Radiocesium transferred from trees via annual leaf fall was two times greater than the quantity exported by rain. With subsequent leaching over the winter months, the litter lost about half of its radiocesium to the mineral soil. Soils on wet sites had significantly greater percentages at lower depths down to 12 in. However, 92% of the total soil radiocesium remained in the top 4 in. on year and seven months after tree inoculation. A …

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Transport solutions to the monoenergetic plane, spherical, and cylindrical critical problems with isotropic scattering are developed by the method of singular expansion modes. The results are given in the form of exact expressions for the neutron distributions and criticality conditions. These expressions depend on expansion coefficients that are shown to satisfy Fredholm integral equations of the second kind. Successive approximations on the coefficients lead to the asymptotic results of diffusion theory as well as to easily accessible transport corrections. The expansions for the neutron distributions are derived by two different, but equivalent, methods. In the first method a three-dimensional expansion for the angular density is developed from the elementary solutions of the transport equation and then specialized to the desired geometry. For problems with plane symmetry, the resulting expression are used directly to determine the expansion coefficients, whereas in spherical and cylindrical geometries the specialization of the three-dimensional solutions yields a variety of representations for the respective angular densities. The second method consists of replacing the angular distributions by suitable density transforms and then determining the transforms completely with the aid of the integral equations for the neutron densities. In plane geometry this method leads to the conversion of the …

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