Following the shutdown of the B Pile in March 1946 a method was devised for monitoring the sub-critical reactivity such that any significant change in neutron flux would be detected. This report summarizes the status of the unit until its start up in July 1948.

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 …

The fission distribution of fission of thorium with alpha particle of average energy 37.5 Mev has been measured by the chemical method. The distribution found shows that the characteristic dip in the fission yield mass spectrum has been raised to within a factor of two of the peaks compared to a factor of 600 in slow neutron fission of U{sup 235}. The raise in the deip has caused a corresponding lowering in fission yield of these elements at the peaks. The cross section for fission of thorium with 37.5 Mev alphas was found to be about 0.6 barn, and the threshold for fission was found to be 23 to 24 Mev.

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The production of U{sup 232} by the sum of {alpha},4n and {alpha},p 3n reactions on thorium has been studied. The cross section at an average energy of 37.5 Mev was 0.013 barns and the threshold for the reaction was about 30 Mev.

At the end of the war it became apparent that the teamwork of government and scientific institutions, which had been so effective in wartime work, must somehow be perpetuated in order to insure the continued progress of nuclear science in peace time. The enormous expense of the tools needed to pursue the next steps in this research -- nuclear reactors and high energy accelerators -- and the shortage of scientifically trained personnel pointed towards the establishment of a cooperative laboratory. Such a laboratory, using government funds, could carry out a comprehensive research program that would benefit the many interested research groups throughout the country. As a result of the wartime programs under the Manhattan District, centers of research in nuclear science were already active at the Radiation Laboratory in Berkeley, California, at Los Alamos in New Mexico, at the Clinton Laboratories in Oak Ridge, Tennessee and at the Argonne Laboratory in Chicago. No analogous nuclear research laboratories, however, had developed in the Northeast, and since so much of the nation's scientific talent and industrial activities are concentrated in the northeastern states, it was proposed that a new laboratory be established near New York City. As a result of this plan, …

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This report considers the work done during the year ending June 30, 1948, present work being done and future plans on the determination of formulas, methods of preparation, and properties of as many compounds of postum as possible. An experimental approach to such a research problem on the element postum requires that procedures which may be used deal with ultramicro quantities of material. Such procedures on an ultramicro or gamma scale require special techniques by personnel trained in manipulating these small quantities of radioactive material. Equipment which may be used varies with the experiment considered. Often new apparatus must be developed or equipment previously developed and used in some other experiment must be modified. This generalized research problem is subdivided in the {open_quotes}Research Problems Outline{close_quotes}. The presentation of a survey of these research problems with reference to the outline for the year ending June 30, 1948 is a critical review of the work done by the Gamma Scale Chemistry Group as well as a consideration of future plans. The course which these future plans may follow will depend upon information which may be obtained when carrying out planned experiments.

This document details gamma scale chemistry activities at Mound Laboratory during the month of April 1948.

Attempts for preparation and x-ray diffraction studies of postum (polonium 210) bromide and dioxide are described. Surrogate parallel studies employing parallel compounds of tellurium and thorium are also related.

Preparation and analytical chemistry of postum (Polonium 210) dibromide and tetrabromide by bromination of metallic postum are described.

An attempt has been made to prepare a compound of postum (Polonium 210) analogous to K{sub 2}{sup TeBr}{sub 6}. A preliminary experiment indicates possible preparation of bromides of postum and that these bromides are analogous to the chloride of postum. Photomicrographs of two crystalline forms of a product resulting from the reaction of bromine and postum are included in this report together with procedure used to form these crystals. Intermediate compounds formed in the attempted preparation of potassium postum bromide include a white residue from nitric acid containing postum and a yellow material formed on the ignition of this white residue. This yellow residue was identical in appearance to the yellow dioxide of postum. A red crystalline precipitate resulted when the yellow residue, which may well be QO{sub 2}, was treated with solution of hydrobromic acid and potassium bromide. Investigation of the use of titanium trichloride as a reducing agent to titrate, quantitatively tellurium dioxide has not yielded concordant results. An effort is being made to determine the best conditions for such a titration potentiometrically. Variations in concentrations, temperature of titration, electrode surface, acid concentration, and degree of agitation are in suspect.

This report details gamma scale chemistry activities at Mound Laboratory during the month of November1948.

This document details gamma scale chemistry activities at Mound Laboratory during the month of October 1948.

This document details gamma scale chemistry activities at Mound Laboratory during the month of November 1948.

This document is a de-classified July 1948 General Chemistry Progress Report from Monsanto Chemical`s Mound facility. Detailed discussions of numerous studies of Postum compounds are included in this report, and experimental data on various chemical and physical properties of these compounds are given.

This document is a de-classified August 1948 General Chemistry progress report from Monsanto Chemical`s Mound facility. General chemical properties of Postum compounds are discussed, and experimental data on these properties are presented.

Decomposition potentials of bismuth solutions of 1.037 and 0.509 grams of the metal per 100 ml. of 1.5 nitric acid were found to be -0.06 and -0.09 volts to N.C.E. These results confirm previous values and indicate that bismuth will not be reduced from production solutions at the potential of the normal calomel electrode. A summary of research in progress, completed, or anticipated is given.

Three studies are described: diffusion of postum (Polonium 210), measurement of standard potential of postum, and polarography with the cathode controller.

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This report outlines plans for tests of the graphite stack during lay up in the pile structures. Measurements are planned upon completion of layers 20, 60, and 102, which will require not more than 16 hours each. The test method will require restriction of Construction personnel from the areas immediately adjacent to the pile. Precise boundaries will be set up in collaboration with H I Division personnel prior to the test.

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