A comparison of the simple impact theories of line broadening by electrons with the detailed computations of Kivel, Bloom, and Margenau.

During this period a prototype gamma ray detection system was assembled and data was obtained on samples of beryllium salts on filter paper under a variety of conditions. Ordinarily either a scaler-register combination or the CRM-recorder combination would be sufficient for obtaining data. Both units have been used here in order to utilize the particular advantages of each system. The scaler-register unit was employed for obtaining precise data over short intervals while the CRM-recorder was used to maintain a check on stability over longer intervals of time.

A generalization of the Fermi-Thomas model for application of mixtures. This study attempts to determine the equation of state of water up to pressure of 10,000 megabars and temperatures of several thousand electron-volts.

There was considerable disagreement between results obtained by early investigators who studied the interaction of ionizing radiations with solid nitrates. It was thought worthwhile, therefore, to extend their work and to make certain that reproducible results were being obtained. It was expected that the nitrite ion and oxygen would be found in equivalent amounts in the irradiated samples. Four measurements of nitrite ion and oxygen indicate that the decomposition of barium nitrate by gamma rays probably proceeds by more than one path.

A method to determine the correction to Grüneisen's law corresponding to the effect of the electrons at high pressure. It is assumed that the lattice contribution to the pressure is small and that the equation of state of the solid can be approximated by results of the statistical Thomas-Fermi atom model for the electron pressure.

A pulsed 931-A photomultiplier and TW-10 traveling wave oscilloscope have been used to measure the scintillation decay times of (a) transtilbene, (b) terphenyl-in-toluene, and (c) polystyrene plastic containing one percent terphenyl, 0.03% α-NPO, and 0.01% zinc stearate. The times for 1/e decay are (a) 4±1×10-9 sec, (b) 2.2±0.3×10-9 sec, and (c) 2.2±0.3×10-9 sec. The behavior of the multiplier with large collector currents was studied, using a synchronized flash lamp. Linear currents up to 1.5 amperes and maximum currents up to 15 amperes were obtained. Currents in the ampere range can give rise to an oscillation which may limit the application of pulsed photomultipliers.

The role of endogenous infections was investigated as a contributory cause of death in mice irradiated with doses of 400 to 800 r x radiation and 480 to 616 rem of thermal column radiation. Results indicate a direct relationship between mortality and bacteremia following exposure to both types of radiation.

Equipment has been designed and constructed for the purpose of leaching pure uranium minerals in both acidic and basic circuits. This equipment provides a means for removal of a series of samples during any one run, control over speed of agitation, indication of gas over pressure, and automatic temperature control. These units may be operated up to 1500 p.s.i. Solid UO2 samples were prepared by sintering under hydrogen to 1800 degree C. Preliminary results of the leaching of sintered UO2 in a basic Na2CO3-NaHCO3 circuit resulted in the formation of an insoluble yellow precipitate (probably Na2UO4) for low concentrations of Na2-NaHCO3. At higher carbonate concentrations no insoluble precipitate was formed and the rate of leaching was found to increase vary rapidly above 300 p.s.i. oxygen over pressure.

Ceramic investigators often find it desirable to know the weight of reactants either immediately after a given heating period or while the specimen is still at the elevated reacting temperature. The conventional gravimetric methods render either of these goals difficult if not actually impossible. Specimens often gain weight through adsorption of water or other reactions upon cooling to room temperature. Desiccators are employed but are not completely satisfactory. Repeated heating and weighing are necessary before a "constant weight" value is obtained. Research in the field of rates for various ceramic reactions, as for example, dehydration of clays, has been hampered by the lack of a simple continuous method of obtaining the required data. While the differential thermal analysis methods have proven somewhat effective for some applications there still remain ample areas for improvements. it was for the above reasons that this research was undertaken.

The object of this project is to conduct studies on the coating of metals and alloys by the gas plating process. Coatings to be studied consist of chromium on copper; alloys of nickel chromium on copper; molybdenum on stainless steel and Inconel; chromium on stainless steel and Inconel; and tungsten and molybdenum and their carbides on stainless steel and Inconel.

The object of the work done during the month of June has been to assure that deposition of chemically pure chromium metal by gas plating, both by itself, or as a component of nickel-chronium and/or other alloys.

The object of the work performed under this contract was to investigate the possibility of gas plating copper base metal with (a) pure chromium metal from chromium hexacarbonyl vapor; (b) chromium-nickel plating from a mixture of chromium hexacarbonyl and nickel tetracarbonyl. The object of the work performed during the final month was to confirm the fact that the gas plating of chromium metal and chromium-nickel laminates free from nitrides, oxides and carbides was practical.

Three groups of balloon flights carrying unshielded boron trifluoride counters were made from geomagnetic latitudes 10.1°N, 55.1°N, and 88.6°N. From the data obtained, curves of slow-neutron intensity versus atmospheric depth for depths less than 700 millibars are plotted. The mean absorption lengths for neutrons in the equilibrium portion of the atmosphere were found to be [formula]. The depths of the neutron intensity maxima were found to be [formula]. From these results and those of other investigators, the variation of the mean absorption coefficient and the depth of the neutron intensity maximum are plotted as functions of the geomagnetic latitude. A family of curves of neutron intensity versus atmospheric depth is drawn for geomagnetic latitudes at 10-degree intervals between 0° and 90°N, and from this the low-energy neutron capture per square centimeter per second by the N14(n,p) reaction in the atmosphere is calculated and plotted as a function of geomagnetic latitude. It is found that the observed neutron intensity varies by about 420% from 0° to 90°N. A value of 5.8×10(18) sec-1 is obtained for the total number of low-energy neutrons captured in the atmosphere.

1) The technical details of controlled experiments with iontophoresis of thorium X solutions are described. 2) Experiments carried out on living human skin in situ demonstrate that Iontophoresis of weak solutions of thorium X will increase its biologic effects as judged by erythema and pigmentation, and cause greater penetration as shown by autoradiography. 3) The possible relationship between increased penetration of thorium X and increased clinical biologic effects is discussed. 4) Some possible clinical applications of the Iontophoresis of thorium X to enhance its therapeutic effectiveness are mentioned.

Part A. The major effort during the past year has been the construction of a suitable vacuum furnace for studying the effects of temperature and pressure on the wettability of metals by glass. A systems was completed that was capable of subjecting test combinations up to temperatures of 1400 degree C at a working pressure of 1 x 10(-5) mm. of Hg. Part B. A compound, identified by X-ray analysis as sodium meta tantalate (na2Ta2O6), was found at the interface between a sodium silicate glass and tantalum metal which had been heated in vacuum to 1000 degree C. thermodynamic calculations, followed by further experimental evidence, were used to determine the chemical reaction between tantalum and sodium silicate which resulted in the formation of Na2Ta3O6. the compound was synthesized by other methods, and its structure investigated.

The Lindemann assumption of direct contact of neighboring atoms at fusion is replaced by the criterion that melting occurs when the root-mean-square amplitude of thermal vibration reaches a critical fraction ρ, presumed the same for all isotropic monatomic solids, of the distance of separation of nearest-neighbor atoms. The Debye-Waller theory of the temperature dependence of the intensity of Bragg reflection of x-rays is used, without further assumptions, to derive a generalized Lindemann law. In contrast to the Lindemann form, all physical quantities involved in this formulation are evaluated at the fusion point, and departure of the average energy of an atomic oscillation from the equipartition value is taken into account by the quantization factor of the Debye-Waller theory. If the Grüneisen constant γm of the solid at fusion is evaluated by its definition from the Debye frequency of the solid, use of the generalized Lindemann law and Clapeyron's equation permits one to express γm in terms of the bulk modulus of the solid at melting and the latent heat and volume change of fusion. By means of Grüneisen's law applied to the solid at fusion, γm can be expressed likewise in terms of the corresponding bulk modulus, thermal expansion, volume, …

A generalization of the Lindemann law is used in connection with the Murnaghan equation of state for a solid to derive theoretically the empirical Simon equation for the fusion curve. For the alkali metals it is shown that experimental values of the temperature exponent in the Simon equation are quantitatively compatible with the theoretical evaluation given, and, furthermore, that the theory can predict approximate values of the experiment, in practice.

The gamma radiations of In107 have been investigated with a scintillation spectrometer . The In107 was produced in a cyclotron by a (d,n) reaction on electromagnetically enriched Cd106. Beta-gamma and y-y coincidence experiments showed in addition to the annihilation radiation, only one y ray of 0.22 Mev associated with the 2.2 Mev positron.

A wet collection system for aerosols has been developed using fibrous media. Tests show the performance to be in accord with recently developed theory of collection by fibrous media. The effects of varying aerosol particle size, particle density, and gas velocity have indicated that inertial impaction is the primary collection mechanism. Three-year operating experience on several full scale plant installations shows reliable performance.

The first highly productive phase in the development of organic scintillation detectors found physicists exploring the excitation and light emission properties of easily available organic chemicals. The second phase of this work which is now in progress can be characterized by the active participation of organic chemists in synthesizing new compounds for sturdy and setting standards of purity leading to the recognition by some chemical manufactures of a "scintillation grade".

To obtain a better understanding of the mechanism involved in scaling behavior of zirconium, kinetic studies were made of the weight pickup in air after the following pretreatments; (1) exposure to oxygen or nitrogen, (2) exposure to air, oxygen or nitrogen and removal of the resulting surface compounds.

Knowledge of the potential dangers of exposure to radioactive substances and the institution of proper safety precautions have helped to reduce accidental exposures to radioactive substances. In the following technical report we shall review briefly carcinogenesis in man by naturally occurring and artificially produced radioactive substances, the lung cancer problem in miners, the development of bone tumors in luminous dial painters and in patients treated with radium-containing nostrums, and the development of cancers in patients who received thorotrast (ThO2) as a diagnostic procedure several decades ago.

Recent instrumental developments and theoretical speculation have indicated a need for more information concerning the excited electronic states of polyatomic molecules and ions in the elucidation of mass spectra. A theoretical description of these states is necessary for the proper interpretation of existing data and in laying a firm basis for the planning of future experiments. For the above reasons the energies of a number of the excited electronic states of methane have been calculated in a approximate fashion and the results applied to a discussion of the behavior of the methane ion.

There is at present a large collection of data giving the relative abundances of ions formed when molecules, especially hydrocarbons, are bombard with electrons and collected as positives ions in a mass spectrometer. This data per se gives us little insight into the kinetic processes occurring until it is combined with thermodynamic data and subject to a theoretical treatment based upon an assumed model for the kinetic processes taking place in the mass spectrometer. In accordance with our desire to learn more about these kinetic processes and in this way to shed some light on problems of molecular structure we have continued to explore the possible kinetic paths which propane ions take during their decomposition, with special reference to the effect of the substitution of deuterium for hydrogen.