Excitation functions have been measured, using a 38-Mev alpha-beam and a 19-Mev deuteron beam for the following reactions: Bi({alpha},2n)At{sup 211}, Bi({alpha},3n)At{sup 210}, Bi(d,p)Ra E, Bi(d,n)Po{sup 210}, and Bi(d,3n)Po{sup 209}. The results are summarized in Figs. 4 and 5 and Tables I and II. A new isotope of astatine, At{sup 210}, has been identified; this isotope has a half life of 8.3 hr., decaying by K-capture to Po{sup 210} with the emission of a 1.0-Mev gamma-ray and a few conversion electrons.

In the course of a rather cursory examination of the elution of tetra-positive ions from the cation exchange resin Dowex 50 with hydrochloric acid solutions, the authors have discovered a very effective method of separating zirconium from hafnimu. In view of the great labor involved in preparing even reasonably pure hafnium compounds by existing methods, they feel that this procedure will prove very valuable to those interested in obtaining hafnium compounds free of zirconium. Although the conditions which give satisfactory separation were first worked out using microgram amounts of material and the radioactive tracer technique, the run described here, involving milligrams of material, illustrates the applicability of the method to the production of significant amounts of pure hafnium and zirconium.

This report summarizes the radioactive contamination measured at the Hanford Works and immediate plant areas for the quarter April, May, and June, 1948. Topics discussed are: Meteorology; airborne contamination; contamination in the Columbia and Yakima Rivers; and contamination in rain, drinking water, vegetation, and in Hanford Wastes.

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In connection with the problem of eliminating contamination of the atmosphere by the exhaust from the 221 Building ventilation air stacks, sand filters were previously recommended. Construction of a sand filter in West Area is about completed and construction of a filter in East Area is well underway. This report summarizes the status, technical findings, and comments and suggestions since the writer`s last Interim Report, dated August 6, 1948, was issued.

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Soon after the discovery of fission, Meitner, Bretscher and Cook found differences in the decay of various chemical fractions separated from uranium irradiated with slow neutrons and thorium irradiated with fast neutrons respectively and suggested that a difference existed in the distribution of fission products in the two cases. In 1940, Turner suggested that the distribution in various modes of fission should be investigated. The fact that elements such as tin, cadmium, palladium, and silver were found in fast neutron and deuteron fission of uranium and thorium before they were found in slow neutron fission of uranium suggested that the middle region of the distribution was raised as the energy of the incident particle was increased. Since the compound nucleus formed in the fission of thorium with alpha particles is U{sup 236}, the same compound nucleus formed in the fission of U{sup 235} with neutrons, it is of interest to study the fission of thorium with alphas and compare the resulting distribution of fission products with that found with uranium with slow and thorium with fast neutrons. Any difference between the various results where the same compound nucleus is formed must be due to differences in energy content and possible …

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This letter itemizes the miscellaneous equipment and supplies not previously specified which should be ordered to equip the 234-5 Chemical Development Laboratory. Equipment currently carried in store stock is not included in this list. The vendor is given only to identify the item or as a suggested source of supply.

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Investigation report of new artificial heavy nuclides conducted at the laboratory.

This report provides the regional radiation surveys for the months of October and November of 1948.

This report summarizes the preparations made for reactivation of the 100-B pile and the operational activities associated with the reactivation and subsequent operation up to the time of reaching desired power level. The period covered is from approximately June 1, 1948 until July 16, 1948.

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Difficulty encountered in the preparation of a pure postum sample for vapor pressure measurements with the quartz sickle gauge is tentatively ascribed to the existence of lead postumide. The modifications which have been made since June 1, 1948 in the apparatus for the measurement of vapor pressure by effusion are discussed. The apparatus in its new form is essentially complete and awaits the delivery of a Dewar flask before measurements are begun. In the preparation of a sample for the determination of the purity of postum with the vacuum balance, difficulties similar to those in Section 1 above were encountered. Resistivity of Postum - No progress. Ninety-one neutron counts were made for other groups. A specially shaped postum sample has been prepared for use in the attempts to flatten the response of the lead-geometry gamma counter. Patterns obtained from the recently acquired sample of elemental postum show the slight increase in unit cell size previously reported; however, the formation of the PbQ compound was detected much earlier than with the older sample.

This report contains a summary of biological information on distribution, excretion, and toxicity of polonium; a comparison of results obtained when maximum permissible exposure rates for man are calculated from available data by different methods; and a critical evaluation of the present status of Po tolerance estimates. A maximum permissible body content of the order of 0.2 {mu}c/70 Kg man is obtained by two methods. Applying an urinary excretion rate of 0.1% of body content/day, effective half-life of 34 days, and certain corrections for the non-exponential nature of Pb excretion, maximum permissible air and water concentrations and urinary excretion rates have been computed. Extrapolation from present data to calculations of tolerance levels in man is still difficult, and there appears to be no substitute for actual long term experiments. On the other hand, permissible exposure levels quoted herein appear to be, to a large extent, consistent with conservative practice.