By utilizing lithium spherical shell transmission and multiplication measurements, the Li7(n,n'y)Li7 and the He6-production cross sections, it is possible to deduce that the 14-Mev Li (n,n'a)T cross section is 325 ± 75 mb. A spectrum for neutrons degraded in energy between 0 and 12 Mev is also given.

The following report calculates how many neutrons are produced by the O-16([alpha]-n) reaction in a thin and uniform polonium oxide layer.

"This report gives briefly a rather simple method for fabricating foils from uranium buttons. Two log sheets one of a U-238 run and one of a U-255 run are given."

Abstract: "A theoretical and experimental investigation is made of the diffraction pattern produced by a slit, whose aperture varies uniformly from a constant value A to zero. The results of this investigation are applied to a proposed high speed camera. It is shown that diffraction effects are very serious and cannot be neglected. It seems, unless the suggested design of this high speed camera is changed, the camera will be of little use for accurate measurements, and photographs will show too much blue to give details."

Abstract: "This report describes work done to improve the casting characteristics of methyl methacrylete resin under CMR-6-18 authorization. The experimental program was initiated with the objectives of decreasing casting time, bubble formation and shrinkage. It has been found that by use of a common solvent for monomer and polymer concentration in monomer can be attained greater than any previously reported in preparation of a methacrylate casting resign. Incorporation of this greater amount of polymer has produced the desired effects. A bibliography of relevant literature is included to which reference is made in the text."

The following report examines the fission counter, fission plates and activation results of the neutron energy distribution in the center of the Los Alamos plutonium reactor.

The following report describes procedures taken to utilize the photelometer to procure the most rapid and reliable determinations, but the goal of the tests presented was to create satisfactory dispersions of particles to analyze.

The operation of the Fast Reactor is considered in terms of normal equilibrium conditions and normal shut-down. The proposed loading, control rod adjustment and subsequent "floating" operation are discussed. Safety devices and interlocks are described. Temperature and reactivity changes are examined with respect to various system failures, phase changes, and "flashing" of the reactor. Slow changes due to faulty slug cooling are also considered. The calculations were initially based upon 10 kw operation. Performance tests of the mercury system now indicate that 20-kw operation may be feasible.

This report records two samples of Xe-135 that have been isolated with activities sufficient for the measurement of the cross section of Xe by the velocity spectrometer technique.

This is a summarizing and reviewing report in which almost all the experimental data representing Project work done prior to 1949 on the corrosion of pure uranium are brought together and analyzed. New data obtained in this laboratory on corrosion rates in laboratory atmosphere and on the identification of corrosion products by electron diffraction are included. The data for corrosion in each of several different media have been plotted according to logarithm-of-the-rate versus reciprocal-temperature coordinates; and from these plots values for the energies and entropies of activation of the corrosion reactions have been obtained. By theoretical treatment of the role of oxygen as a negative catalyst, it is shown that this element may be expected to "poison" the corrosion rection and then act as a corrosion inhibitor. A practical significance of these data analyses is that they explain why machined uranium parts stored in inert atmospheres (helium or argon) containing only very small amounts of water vapor will corrode relatively rapidly with the formation of loose powdery oxide, whereas similar parts may be kept in dry air almost indefinitely with formation on their surface of only a discoloring, but adhered, oxide coating.

From abstract: "The present report describes experimental work performed to establish a procedure for the production of uranium metal wire. In all cases, the size of the initial rod was 1/2 inch diameter. Three materials were used: hot extruded tuballoy rod, high purity cast tuballoy rod, and cast U-235 rod."

Abstract: "The thermal and electrical conductivities of a series of Pu-Al alloys have been determined in the range 0.12 atomic percent Pu. The conductivities are approximately proportional to the volume of free aluminum."

Part I of this report covers critical-mass determinations for pseudospheres of oralloy hydride composition (approximating UH3) in 8"-thick Tu and Ni tampers and in the Tu tamper with Ni liner. The critical mass of a hydride cube in the thick Tu also is given. Data on weight and dimensional changes of hydride pieces during the period of use are included. In Part II are presented the results of Rossi time-scale measurements on the hydride assemblies. Values of alpha at delayed critical and its variation with mass in the neighborhood of delayed critical are given. Measurements on the activation of various detectors within the hydride assemblies are described in Part III. Results as a function of radial position are given for Au, for Au shielded by Au and by Cd, for S and for fission catchers with U235 and U238. Reactivity changes resulting from the introduction of foreign materials into the hydride assemblies are discussed in Part IV. Apparent regularities with respect to Z and qualitative interpretations of variations with radius are pointed out. From data for various radial positions, changes in critical mass corresponding to small changes in composition and density are computed.

Measurements have been at the Pajarito remote control laboratory to determine the effect of change of shape on system reactivity for oralloy cylinders. Systems tested include cylindrical configurations with various height-to-diameter ratios ranging from slabs to rods. Each system reactivity is referred to that of a sphere in the same tamper. Reactivity tests were made on bare (untamped) Oy configurations, as well as on systems In tuballoy tampers 1.12,1.87,and 8.0 thick. The amount of reactivity change associated with a particular cylinder height-to-diameter ratio is feud to be a function of tamper thickness, and is greatest for very thin tampers.

This investigation was begun as a result of a mass spectrometric measurement of two samples of tritium which had been stored for several months in Pyrex glass bulbs using stopcocks. The first of these was originally supposed to be of extremely high isotopic and chemical purity. What was observed at this time was 1.45 H had accumulated, and that tritiated methane, CT4, was also present to the extent of 0.18%. A consistent attempt had been made in this sample to protect the gas from contact with the grease by covering the stopcock with mercury. the second sample was a composite of T2 samples of various degrees of enrichment with an isotopic analysis of 92% T. No protection had been attempted during its storage, and 0.86% CT4 to be present.

Tests made on the Oy-Tu reacting assembly at Pajarito indicate that the lateral displacement of two halves of the active material within the assembly can be used as a control mechanism on this type of reacting assembly. This report describes a reacting assembly using a rotary control mechanism based on this principle and indicates the sensitivity of control possible with such a device.

Uranium has been successfully forged using a Lobdell-Nazel forging hammer and a forging temperature range of 500 to 650 degrees centigrade. Using standard forging techniques, the metal readily flowed at the temperature chosen. A noticeable increase in tensile strength, yield strength and percent elongation was obtained in forged metal as compared with cast metal. To obtain complete recrystallization and uniform grain size, a minimum of approximately 75 percent reduction in cross section by forging followed by an anneal within the range of 500 to 600 degrees C is required.

Uranium can be rolled from cast metal or forged ingot to sheet satisfactory for cupping, deep drawing, and similar fabrication procedures by a combination of hot breakdown in the neighborhood of 600 deg C and warm finishing at 225 to 325 deg C. Sheet may also be obtained by hot rolling alone and by warm rolling alone. However, it is difficult to secure a uniform, controlled grain size by hot rolling only and warm rolling is time consuming because of the limited reduction per pass obtainable. The combination of hot and warm rolling afforded best and most practical method to secure good quality sheet in the quantity required. The percent reduction by hot working does not appear to be critical, but at least 60% warm reduction is desirable to obtain complete and controlled grain size by recrystallization with high ductility and strength properties. Except for research investigation, rolling of uranium below 225 deg C is not recommended. In the temperature range considered (below 225 deg C), reduction is difficult and must be limited to one to two percent if edge cracking is to be avoided. Hot rolling of unplated uranium from the as-cast or as-forged surface is recommended, using a …

This technical report presents results of nuclear plate work carried out to determine the neutron energy distribution inside the Los Alamos fast reactor. Most of the distributions which were investigated are valid over the energy region from 0.4 to 6 Mev. The results show that at the center of the reactor pot about 65% of the neutrons are located below 1 Mev in a rather narrow energy region which has a maximum in the neighborhood of 0.5 to 0.6 Mev. Above 2 Mev the energy distribution is similar to that of a plutonium fission neutron spectrum, i.e. the spectrum decreases exponentially, diminishing by a factor of 10 in intensity over an energy range of about 4 Mev. The leading geometry of the reactor pot does not seem to appreciably affect the spectrum at the center of the pot. However, spectra determined outside the pot can be significantly altered by the particular viewing geometry employed to examine the neutrons coming from the center of the reactor.

Uranium has been successfully impact extruded into typical cylindrical shapes of conventional design. Extrusion was carried out in the "gamma" region by heating cast uranium slugs to a temperature of approximately 1050 degrees C. Protection against oxidation was afforded by surrounding the slugs during heating with an inert atmosphere of argon gas. Impact extruded shapes possessed physical properties which are better than the properties of as-cast metal. Also, extruded shapes show a uniform internal structure with flow lines characteristic of commercial impact extruded pieces formed from other metals. Impact extrusion, as a fabricating processes for uranium, maybe applied successfully to produce complicated shapes or forms not practical by casting or where savings in metal and machining time is desired. The process would not appear to be commercial unless a large quantity of pieces was required.

A search for gamma-ray activities with period 1-100 msec from thermal neutron fission of U235 gave negative results. 0.43 +- 0.03 sec was the shortest observed. The period of B12 was found to be 27 +- 3 msec. The cyclotron beam was pulsed to supply 1-10 msec neutron bursts. coincidence scintillation deters were employed.

A spectrophotometric method for the determination of plutonium wing sodium alizarin sulfonate has been developed. The red plutonium-alizarin sulfonate color is developed in solutions having a pH of about three in the presence of a formic acid-sodium formate buffer, and the resulting absorption is measured at 530 millimicrons. Most interfering cations, particularly iron(III), are removed from the plutonium solutions by means of electrolysis using a mercy cathode. Aluminum(III), in quantities up to 3 percent of the plutonium content, may be tolerated in this procedure. Chloride and nitrate ions produce no interference over the concentration range studied, while tartrate, citrate, oxalate, and fluoride ions cause low results. The analysis of a large series of pure plutonium solutions, ranging from about 25 to 150 micrograms of plutonium in 10 milliliters, have a standard deviation of 0.92 percent for the determined plutonium content.

Experimental techniques are described for the spectral measurement of a collimated fast neutron beam. A hydrogen filled cloud chamber, proton recording nuclear plates, and threshold fission foils were used as neutron detectors in the measurements. As an application of the above technique, the energy distribution and absolute flux of the fast neutron beam emerging from port 5W of the Los Alamos fast rector has been measured from 0.1 Mev to 18 Mev. The result show a spectral curve possessing a maximum between 9.25 and 0.30 Mev and having an exponential decrease at energies above 1.5 Mev. The mass energy of the distribution is at 0.55 Mev and the slope of the exponential section is 3.1 - 0.1 Mev per decade of intensity decrease.

A tentative nickel-plutonium constitutional diagram was based on data obtained by thermal analysis, metallography, and x-ray-diffraction techniques. The systema is a complex one with the following important features. Nickel is soluble in epsilon plutonium, extending the epsilon field to 4.3 at.% nickel at 465 deg C. Nickel and plutonium form six intermetallic compounds, PuNi, EnNi/sub 2/, PuNi/sub 3/, PuNi/sub 4/, PuNi/sub 5/, and PuNi/sub 9/. The compound PuNi/ sub 5/ forms congruently from the melt at approximately l300 deg C, whereas the other compounds form peritectoidally. The extended epsilon field terminates in a eutectoid reaction at 415 deg C and l.5 at.% nickel. Epsilon plutonium and the compound PuNi form a eutectic system at 465 deg C with a eutectic composition of l2.5 at,% nickel. Nickel and the compound PuNi/sub 9/ form a eutectic system at l2l0 deg C with a eutectic composition of 92 at.% nickel. Plutonium forms a limited solid solution with nickel.