This report is a progress report detailing operations and ongoing projects at the Brookhaven National Laboratory. The report describes new developments with buildings and progress regarding ongoing experiments. The report includes photographs showing progress in the construction of the reactor and other images and figures that accompany the descriptions of projects.

While investigating the relative yields for the many reactions resulting from the irradiation of antimony with 200-Mev deuterons in the Berkeley 184-inch cyclotron several previously unreported isotopes of tellurium and antimony were encountered. The tellurium fraction when followed on a thin mica window counter could be resolved into half-life periods of 2.5 hrs, 6.0 days and a small amount of a long-lived component. The 2.5 hour period has not been further characterized with respect to mass number or mode of decay other than to note that the radiation is predominantly electrons. The 6.0-day period is accompanied by positrons which were shown to be due to a 3.5 minute antimony daughter which is undoubtedly the same activity assigned to Sb{sup 118} by Risser, Lark-Horowitz and Smith. The positron energy was found to be 3.1 {+-} 0.2 Mev by absorption in berylllum and from the end point of the energy distribution curve taken with a low-resolution beta-ray spectrometer. Gamma activity is also present with this period. The 6.0-day tellurium showed a high abundance of x-rays, little or no conversion electrons and some gamma-ray activity which could be due to the 3.5 minute antimony daughter. The tellurium fraction contained another component of 4.5-day …

The theory of high energy nuclear stars depends on a theory of nuclear transparency and on a theory of nuclear evaporation. The transparency can be computed on the basis of a model proposed by R. Serber as soon as the interactions between the nucleons and the incident particle are known. The evaporation can be computed on the basis of the statistical model of the nucleus as soon as the nuclear entropy and binding energies of the evaporated particles are known. The calculations have been formulated with approximate values for the above interactions, entropies, and binding energies; and by means of various mathematical methods: a method of averages, a method of reaction integrals, and one using diffusion equations. Probability distributions have been obtained for the number of prongs per star, and distributions are being computed for the energy and angle of a prong. The results are in qualitative agreement with the observations on photographic emulsions described in Part I.

The effects of backscattering upon self-absorption correction curves are demonstrated. Data are given for the backscattering powers of several substances for the beta radiations from C{sup 14}, and for se1f-absorption of samples of barium carbonate and wax, containing C{sup 14}, mounted on aluminum.

This report gives a short summary of the work done in the following fields for the month of January 1948: (1) 184-inch cyclotron; (2) 60-inch cyclotron; (3) synchrotron; (4) linear accelerator; (5) experimental physics; (6) theoretical physics; (7) isotope research; (8) chemistry; (9) medical physics; and (10) health physics and chemistry.

Map of the United States and surrounding areas with time zones marked and labeled in red. Bodies of water are marked, with depth marked by hatchures, as well as state lines and major cities..

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The major problems in this determination are the extraction of X from the sample and the isolation of the extracted X. The application of various analytical methods to these two problems indicates that the current method of analysis yields values which may be as much as 15% high. The current method of analysis is subject to positive and negative errors. The magnitude of these errors varies with techniques and with sample composition. The recommend method, although longer, is believed to be free of these errors, but a radical change, say 100 fold, in the composition of the sample would certainly require further investigation.

The authors have observed tracks which they believe to be due to mesons in photographic plates placed near a target bombarded by 380 Mev alpha particles. For a 10-minute exposure in the cyclotron, about 50 meson tracks are found along the 3-inch edge of a photographic plate. The mass has been determined by measuring the bending in the magnetic field and the range in emulsion. From the first 50 meson tracks measured they find a mass of 313 {+-} 16 electron masses. It is highly probable that these mesons are the heavy mesons described by Lattes, Occhialini, and Powell.