The following report investigates cross sections for the absorption of slow neutrons of heavy isotopes. The purpose of these measurements was to determine the cross section of an isotope of element 94 for the process of fission by the absorption of a slow neutron, relative to the cross section of U235 for the same process, that is, to measure R.

Abstract: Fifty-four spectral lines of curium are listed together with estimated intensities. A brief description of the manner of taking the spectra and of measuring the lines are given.

Technical report includes three reports of research progress: 1) Range Measurements on 190 Mev Deuterons, M. Stephan; 2) Meson measurements, C. Lattes; and 3) N-P Scattering, R. Christian.

Technical report includes three reports of research progress: 1)Meson Mass Determination by Grain Counting, W. H. Barkas; 2) The Magnetic Beta Ray Lens Spectrograph, A. C. Helmholz; 3) Anthracene Counters, E. Martinelli.

Technical report includes three reports of research progress: 1)Neutron scattering by A. Bratenahl; 2) Nuclear Cross Sections, Norman Knable.

Abstract: The rate of extraction of PuIV in either direction between benzene-TTA and aqueous HNO3 solutions is shown in the present study to be fast enough so that application of the chelate process to continuous operation should be feasible. This conclusion is based on two primary considerations: 1. The mechanism limiting the rate of extraction appears to be diffusion and not chemical-reaction-limiting. 2. The extraction may be controlled by adjustment of the system conditions to give almost any desired specifications of rate and/or equilibrium. A continuous process involving multiple extraction stages with a controlled pH gradient is proposed for obtaining maximum decontamination and plutonium recovery.

This summary of the research progress meeting on June 3, 1948 discusses the following topics: (1) Photomultipliers (L. Wouters); (2) Positive mesons (C.M.G. Lattes); and (3) Background work in 184-inch program (W. Panofsky).

This summary of the research progress meeting on June 10, 1948 discusses the following topics: (1) 184-inch cyclotron (J. Vale); (2) Slow neutrons in the shielding of the 184-inch cyclotron (W. Benson); and (3) Fission of thorium with alpha particles (A. Newton).

This summary of the research progress meeting on June 17, 1948 discusses the following topics: (1) Potassium 43 (R. Overstreet); (2) Recoils (A. Ghiorso); (3) M.I.T. accelerator conference (W. Panofsky); and (4) Cosmic rays (Prof. Louis Le prince - Ringuet, France)

This summary of the research progress meeting on June 24, 1948 discusses the following topics: (1) Spectrographic analysis of alpha active materials (J. Conway); and (2) Range energy determinations (Dr. R.L. Thornton, Mr. Walter Stephan and Mr. Walter Aron).

The following report is a quarterly report done by the Physics Division of the University of California's Radiation Laboratory, covering the period of February 1, 1948 to May 1, 1948. This report discusses general physics research and the development and operation of the accelerator.

Abstract: The purpose of this report is to outline the work done at the Radiation Laboratory toward the development of a magnetic field measuring device using the phenomenon of nuclear resonance. While the work described here is far from complete, it has served to indicate the limitations of the method as well as some of its possibilities. For reasons which will become apparent, the project is being discontinued. It is hoped that this report will serve as a starting point should the work be continued at some later time and that some of the mistakes already made need not be repeated.

A quarterly report consisting of reports published on Transuranic Elements from the University of California Radiation Laboratory. Each report is a brief one to two page summaries of the article submitted for publication during the months of September-November, 1948.

Abstract: Part I: A series of extraction experiments has been performed to determine the distribution coefficient of uranium(VI) between dilute perchloric acid and benzene solutions of TTA. The data are interpreted to show that the principal species in the acid phase is a doubly charged ion, UO2++. The discrepancies revealed in previous work(1) were not found. Part II: The spectrophotometric method of analysis developed for use in Part I has shown the existence of previously unreported species of uranium(VI) in the presence of TTA: UO2K2-HK in benzene, and UO2K+ in dilute acid. The absorption spectra of all the principal species are reported.

Summary: The activity coefficient of Pu(Cl04)4 was measured in perchloric acid solutions. The procedure used was to measure the extraction of the neutral plutonium(IV)-TTA chelate into benzene-TTA solutions at different perchloric acid concentrations. Equations are presented which show the relation of the extraction coefficients, obtained in the above manner, to the activity coefficient of plutonium(IV) per-chlorate. The activity coefficient of Pu(Cl0~)4 is similar to that of a strong acid, e.g., perchloric acid, in that its value increases rapidly when the perchloric acid concentration becomes greater than 2M. The distribution coefficient of TTA between benzene and aqueous perchloric acid solutions was found first to decrease slightly and then to increase two fold as the perchloric acid was varied from 0.01 to 6M. The activity coefficient of the uranous-TTA chelate in benzene was calculated from the results of solubility measurements. The values of the activity coefficient of UK4 are,within experimental error, identical with the values of the activity coefficient of TTA itself.

Abstract: Magnetic susceptibilities per gram atomic weight of elements 92 to 95 in most of their oxidation states were measured at 20°C on 0.1 ml of solution which was 0.005 to 0.09M in heavy element. The values obtained (all paramagnetic) in units × 106 were: U(IV), 3690; Np(VI), 2060; Np(V), 4120; Np(IV), 4000; Pu(IV), 1610; Pu(III), 370; Am(III), 720. The results could be interpreted only on the basis of electronic configurations 5fn, even though susceptibilities were generally lower than the theoretical values and lower than experimental values for corresponding lanthanide 4fn cations. The lower values should be expected as a result of the Stark effect produced by electric fields of anions and of water dipoles. Failure of the Russell‐Saunders approximation to the coupling between electrons may account for some of the error in the theoretical calculations. That the susceptibilities of Pu(III) and Am(III) are manyfold lower than those of Sm(III) and Eu(III), respectively, is attributed to wider multiplet splitting in the actinide atoms.

In H measurements, the measured flux-linkage change represents twice the value of H to be plotted. In B measurements the bucking coil links flux equal to the air-flux in the B-measuring coils. The measured flux change therefore corresponds to twice the flux of intrinsic magnetization in the sample.

In programming the sequence of events in the operational cycle of the bevatron, certain devices must be triggered at specific values of magnetic field strength in the gap. It is desirable that the time-jitter, which corresponds to field jitter, of the tirggering pulses be small. In the synchrotron this is done with peaking strips which are located in the fringing field of the gap.

The thermal decomposition of the higher oxides of praseodymium and americium have been investigated.

The recovery of plutonium has been demonstrated in a laboratory countercurrent horizontal extractor using the TTA process. Using three extractive stages and two washing stages in each step, a recovery of 91 percent has been obtained in the chelation step and a recovery of 99.9+ percent in the de-chelation step. With five extractive stages, recoveries of 94-98 percent have been found for the chelation step.

The flux standard is a device which will give a known flux-linkage change to be used as a calibration. At the Radiation Laboratory, two types of flux standards are used, a stationary type and a portable type.

The absolute excitation functions for the production of fission by charged particle bombardment in several substances were investigated at both high and low energies. The low energy work was done at the 60-inch Crocker cyclotron with alpha particles and deuterons, while the high energy work was done at the 184-inch cyclotron with alpha particles, deuterons, and protons.

Positive and negative mesons produced in a common target in the cyclotron are received in two photographic plates. In the magnetic field of the cyclotron, negatives are deflected to one plate, positives to the other. The mesons must pass through an absorber before entering the plates in order to be observable.

The basic experiment consists of causing a beam of protons to impinge upon an accumulation of relatively stationary protons (hydrogen gas) and to measure the number of protons scattered as a function of the scattering angle. A description of the arrangement and alignment of equipment with the 32-Mev beam of the Berkeley linear accelerator is included. The data have been analyzed statistically and results have been indicated.