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SCATTERING OF A VELOCITY SELECTED POTASSIUM BEAM BY NEON, ARGON, AND XENON GASES AT DIFFERENT TEMPERATURES

Description: A thermal K beam was velocity selected, and scattered by Ne, Ar, and Xe gases. The dependence of the total cross section on relative velocity is approximately v/sup -0.4/ for K--Ar and K--Xe, and v/sup 0.8/ for K--Ne. The average relative velocity ranges were 400 to 1430 m/sec for Ne, 480 to 1350 m/sec for Ar, and 380 to 1320 m/sec for Xe. The dependence of the cross section on relative velocity was obtained by removing the cross section from the collision frequency integral. For the v/sup -0.4/ dependences, this gives results correct to 3%. For the v/sup -0.8/ dependences, the error is most likely greater. Three gas temperatures were used: liquid air, room, and 200 deg C. The results for a given gas at different temperatures are consistent with kinetic theory predictions. (auth)
Date: January 1, 1962
Creator: Brown, Jr, H H; Lulla, K & Bederson, B
Partner: UNT Libraries Government Documents Department

REACTIVE COLLISIONS IN CROSSED MOLECULAR BEAMS

Description: The distribution of velocity vectors of reaction products is discussed with emphasis on the restrictions imposed by the conservation laws. The recoil velocity that carries the products away from the center of mass shows how the energy of reaction is divided between internal excitation and translation. Similarly, the angular distributions, as viewed from the center of mass, reflect the partitioning of the total angular momentum between angular momenta of individual molecules and orbital angular momentum associated with their relative motion. Crossed-beam studies of several reactions of the type M + RI yields R + MI are described, where M = K, Rb, Cs, and R = CH/sub 3/, C/sub 3/H/sub 5/, etc. The results show that most of the energy of reaction goes into internal excitation of the products and that the angular distribution is quite anisotropic, with most of the MI recoiling backward (and R forward) with respect to the incoming K beam. (auth)
Date: January 1, 1962
Creator: Herschbach, D.R.
Partner: UNT Libraries Government Documents Department

INTERMEDIATE PHASES IN BINARY SYSTEMS OF TECHNETIUM-99 WITH SEVERAL TRANSITION ELEMENTS

Description: An exploratory survey was made of the intermediate phases formed when Tc/ sup 99/ is alloyed with the Sc, Ti, V, Cr, Mn, and Fe-group elements. A total of nineteen intermediate phases were identified and found to be isomorphous with the Cr/sub 3/O-type, CsCl-type, MgZn/sub 2/-type, gamma -phase, or sigma -phase structure. The alloying characteristics of Tc are rationalized in terms of periodic table relationships. (auth)
Date: December 1, 1962
Creator: Darby, Jr, J. B.; Lam, D. J.; Norton, L. J. & Downey, J. W.
Partner: UNT Libraries Government Documents Department

NEUTRON RADIOGRAPHY: A 1962 PROGRESS REPORT

Description: The possibility of improved detection discrimination between selected materials; the high absorption of several 1ight materials such as hydrogen, lithium, and boron; and the relatively low absorption of many heavy materials are some characteristics which make neutron radiographic inspection attractive as a complementary technique to xradiography. A study of neutron radiography is reported in which the emphasis has been placed upon determining many of the characteristics of various techniques for detecting neutron images. Characteristics of photographic detectors for thermal neutron images are outlined. (R.J.S.)
Date: August 17, 1962
Creator: Berger, Harold
Partner: UNT Libraries Government Documents Department

DEVELOPMENT AND EVALUATION OF LARGE VOLUME SCINTILLATION DETECTORS AND THEIR APPLICATION TO RADIOISOTOPE PROCESS CONTROL

Description: Large-volume scintillation detectors are being developed for radioisotope control of unit processes. In the development work, mirror-finished aluminum foil reflectors were better than diffuse reflectors, argon flushing to remove dissolved oxygen from liquid scintillators improves the pulse amplitude, and liquid scintillators are superior to plastics. Dimethyl POPOP was found to be an excellent primary solute; optimum concentration is 2.5 g/l in toluene with argon flushing and no secondary solute. A test loop was constructed for testing the detectors in process control applications. Among the systems being tested are one using a solid-state magnetic comparator-control relay and an inexpensive solenoid valve as the final control element, at approximates 25% of the cost of a conventional system. (D. L.C.)
Date: January 1, 1962
Creator: Perry, J K
Partner: UNT Libraries Government Documents Department

A High-Speed Readout for Multi-Channel Pulse-Height Analyzers

Description: From American Nuclear Society Meeting, New York, Nov. 1963. In computer-coupled automated activation analysis such as in the Mark II system, conventional methods of data readout impose a serious restriction on the minimum handling time per sample. A data coupler for operating between the data accumulation system and the computer tape unit was developed which contributes nothing to the handling time per sample, does not distort the data, and prepares the data for direct computer entry. In addition to activation analysis, the coupler may be used to obtain successive spectra separated in time by 0.16 sec in the study of short-lived isotopes. (D.L.C.)
Date: January 1, 1962
Creator: Wilkins, W. W.; Fite, L. E. & Wainerdi, R. E.
Partner: UNT Libraries Government Documents Department

EPSILON HYPERONS IN THE REACTION K- + P -->+ K+

Description: No Description Available.
Date: June 5, 1962
Creator: Alvarez, Luis W.; Berge, J. Peter; Kalbfleisch, George R.; Button-Shafer, Janice; Solmitz, Frank T.; Stevenson, M. Lynn et al.
Partner: UNT Libraries Government Documents Department

THE IMPURITY OF SCIENCE

Description: Science is impure in two ways. There is not a 'pure' science. By this I mean that physics impinges on astronomy, on the one hand, and chemistry on biology on the other. And not only does each support its neighbors but derives sustenance from them. The same can be said of chemistry. Biology is, perhaps, the example par excellence today of an 'impure' science. Beyond this, there is no 'pure' science itself divorced from human values. The importance of science to the humanities and the humanities to science in their complementary contribution to the variety of human life grows daily. The need for men familiar with both is imperative. We are faced today with a social decision resulting from our progress in molecular genetics at least equal to, and probably greater than, that required of us twenty years ago with the maturity of nuclear power.
Date: April 19, 1962
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

FACTORS IN RADIOGRAPHY AT ENERGIES BELOW 400 kvp

Description: From 1963 American Society of Metals/Metals and Materials Show, Cleveland, Oct. 1963. 23rd National Convention of the Society for Nondestructive Testing. The factors which affect the attainment of optimum results in radiography are radiation source, specimen, filmscreen combination, film processing, and their mutual relationships. A general review is presented of radiographic practice and the effects of variations in the factors, at energies below 400 kvp, on radiographic contrast and sensitivity. (D.L.C.)
Date: January 1, 1962
Creator: McClung, R W
Partner: UNT Libraries Government Documents Department

HELIUM THREE

Description: A review is given of the present state of knowledge concerning the condensed phases of He{sup 3}. Attention is confined to the pure substance, and emphasis is placed upon the theoretical understanding of the material.
Date: September 11, 1962
Creator: Sessler, Andrew M.
Partner: UNT Libraries Government Documents Department

PERTURBATION-THEORY RULES FOR COMPUTING THE SELF-ENERGY OPERATOR IN QUANTUM STATISTICAL MECHANICS

Description: Highly convenient rules are given for the general term in the time-independent perturbation-theory expansion for the self-energy operator of quantum statistical mechanics. The rules are derived by starting from the usual formalism involving time-dependent Green's functions. The well-known formulas for thermodynamic quantities in terms of the self-energy operator are included for completeness.
Date: December 17, 1962
Creator: Baym, Gordon & Sessler, Andrew M.
Partner: UNT Libraries Government Documents Department

The Effect of Ionizing Radiation on the Optical and Electrical Properties of the Alkali Halides

Description: Various mechanisms for the formation of point defects in ionic crystals are considered. Their probable importance as a function of the energy of the ionizing radiation and the temperature at which the irradiation takes place is discussed. Complex centers formed from aggregates of simple point defects are reviewed and their occurrence considered in terms of the expected spatial distribution of the point defects. The effect of high energy x rays and protons on the ionic conductivity is discussed in terms of a new interpretation of the conductivity curve as a function of temperature, and it is suggested that radiation-enhanced diffusion may be important in explaining the experimental data. (auth)
Date: January 1, 1962
Creator: Royce, B S.H.
Partner: UNT Libraries Government Documents Department

PERTURBATION THEORY OF MANY-BOSON SYSTEMS

Description: A noncanonical transformation of the boson creation and annihilation operators is performed in order to obtain a Hamiltonian which can be treated by the standard methods of field-theoretic perturbation theory. The standard results of Belyaev (with a slight modification) are rederived by this technique. (auth)
Date: December 15, 1962
Creator: Kromminga, A.J. & Bolsterli, M.
Partner: UNT Libraries Government Documents Department

Secondary Isotope Effects in Molecular Structure

Description: A study was made to determine whether secondary iso tope effects also occur in molecular structure. Electron diffraction studies were carried out on ethane and deuteroethane. In C/sub 2/H/sub 6/ the mean C-C and C-H bond lengths found agreed very closely with values determined for other paraffin hydrocarbons, and the C--H bond showed a normal primary isotope effect (~ 0.005 A) similar to that found in methane when H is replaced by O. The output of the leastsquares analysis suggested that the mean C-- C bond length in C/sub 2/D/sub 6/ is shorter than in C/sub 2/H/sub 6/ and by about 0.004 A. Th e decrease seemed to be real for the apparent uncertainty was not much greater than 0.001 A. (M.C.G.)
Date: June 15, 1962
Creator: Bartell, L. S.
Partner: UNT Libraries Government Documents Department

Recent Developments in Multichannel Pulse-Height Analysis

Description: The state of the pulse-height analyzing art is reviewed with particular emphasis on the developments of the past two years. The discussion includes consideration of multidimensional instruments, calibration-stabilizing techniques, and some of the auxiliary features that are becoming increasingly available on commercial instruments. Possible future developments with respect to resolving time and memory organization is discussed briefly. (auth)
Date: June 1, 1962
Creator: Chase, R.L.
Partner: UNT Libraries Government Documents Department

THERMAL STUDY OF CRYSTAL FIELD SPLITTINGS IN ERBIUM ETHYLSULFATE

Description: The heat capacities of erbium and yttrium ethylsulfates were measured in the range 12-300 deg K. The magnetic contribution of the erbium ion was evaluated with the help of an assumption concernlng the difference in lattice contributions between the erbium and yttrium salts. The contribution agrees, to within experimental error, with the experimental energy level scheme for the /sup 4/I/ sub 15/2/ state previously published. (auth)
Date: December 1, 1962
Creator: Gerstein, B.C.; Penney, C.J. & Spedding, F.H.
Partner: UNT Libraries Government Documents Department

Electrical and Magnetic Properties of Holmium Single Crystals

Description: Magnetic moment measurements are made on holmium single crystals (hcp) from 1.3 to 300 deg K in magnetic fields from 250 to 18,000 Oe, with the field applied along the c axis, the a axis, and a (1010) direction. The STA1010! direction is the direction of easy magnetization with an extrapolated effective moment per atom at saturation of 10.34 Bohr magnetons. Basal plane measurements show antiferromagnetism below the Neel temperature of 132 deg K with basal plane anisotropy occurring below 80 deg K. Below the Neel point, an anomalous type of transition to ferromagnetic behavior upon application of sufficient field is observed. Magnetization curves for the c axis are linear down to 60 deg K, while measurements below 20 deg K show an initial magnetization of approximately 1.7 Bohr magnetons followed by nearly linear magnetization curves. Electrical resistivity measurements are made from 4.2 to 300 deg K. For the a axis, the resistivity changes slope slightly at 20 deg K. A larger change in slope occurs at the Neel temperature of 132 deg K. For the c axis, the resistivity changes slope slightly at 20 deg K, reaches a peak at 120 deg K, goes through a minimum at 132 deg K, and remains constant until approximately 150 deg K, after which it increases linearly with increasing temperature. (auth)
Date: September 15, 1962
Creator: Strandburg, D. L.; Legvold, S. & Spedding, F. H.
Partner: UNT Libraries Government Documents Department

Laboratory-Scale Demonstration of the Fused Salt Volatility Process

Description: The feasibility of processing enriched irradiated zirconium--uranium alloy fuel by the fused salt-fluoride volatility procedure has been demonstrated in laboratory tests with fuel having a burnup of over 10%. Uranium recoveries were greater than 99% and decontamination factors for radioactive fission products were 10/sup 6/ to 10/sup 6/. The UF/sub 6/ product contained significant quantities of nonradioactive impurities; additional work in this area is needed. (auth)
Date: August 1, 1962
Creator: Cathers, G.I.; Jolley, R.L. & Moncrief, E.C.
Partner: UNT Libraries Government Documents Department