The Ising model, a system of atoms arranged on a lattice with simple nearest neighbor interactions, provides a more or less realistic description of many physical systems. The state of each atom is specified by a two-valued variable, which may be identified with: (1) its spin (up or down), if one wishes to describe a magnetic system; (2) its identity (A or B), if one wishes to describe a a mixture of two kinds of atoms; or (3) its presence or absence (atom or hole), if one is dealing with a lattice gas. In all three cases it is assumed that the energy of a configuration of the system, aside from the energy of interaction with external fields, is simply a sum of energies of nearest-neighbor pairs, the energy of a pair being zero if the two atoms are similar, and the sum if they are different. In describing the calculations, we shall use the terminology appropriate to (2), but the results will be general statements about the model.

This paper is primarily intended to give an account of a few of the diagnostic techniques that have been applied to a highly ionized, steady-state helium plasma at the Lawrence Radiation Laboratory. However, to establish a proper perspective it will first be well to describe briefly the system in which the plasma is generated and studied.

Abstract. Monte Carlo methods using importance sampling and splitting are proposed for estimating the effectiveness of neutron shields. As usual, the aim is to increase the number of particles that go through or around the shield, this increase being compensated by a decrease in the weights of these particles. With suitable modifications, the ideas are applicable to to other Monte Carlo problems. One way of using splitting and Russian roulette is to require that the weight of each particle be approximately equal to a specified function of the coordinate; one such function is given in equation. The proposed form of importance sampling uses a cross-section for particle collisions that is the product of the neutron cross-section (or its square root) with a linear function of the cosine of the angle between the particle direction and some preferred direction. The probability density of this cosine itself is taken proportional to the reciprocal of this same linear function. This function is adjustable on both a regional and an overall basis.

Since the discoveries by the early U. S. and Russian satellites of the great radiation belts which surround the earth a considerable amount of effort has been expended to determine the nature, flux, and energy distribution of the trapped particles. This is done for serval reasons. First, it is important for purely geophysical and geomagnetic purposes to understand the source of these particles as well as the magnetic trapping phenomena and loses mechanisms. Secondly, it is imperative, if one is to travel through space to have knowledge of the radiation present there so that he may shield himself sufficiently and avoid bodily harm from over-exposure to radiation.

Among the thermodynamic variables, which include temperature (T), energy per unit mass (E), volume per unit mass (V), pressure (p), and others any two may be selected as independent, and on this pair will depend, in principle, every other variable, each such relationship constituting an "equation of state". Thus, the common choice of V and T as independent variables implies that E is given by a function E(V,T), p by a function p(V,T), and similarly for the other variables. Occasionally, it is desirable to select V and E as independent variables rather than V and T, and to define the functions. The concern of this paper will be with the relationship between the two functions p(V,E) and T(V,E) since these have considerable utility. Two illustrative cases will be examined, namely, that of a "perfect gas" and that of a model representing a real substance.

Abstract. The polarization of the recoil nucleon in pion-nucleon scattering is studied from the point of view of providing a means of distinguishing among the various angular momentum assignments proposed for the higher pion-nucleon resonances. It is shown that polarization in this reaction is just as useful a guide as polarization in photoproduction. In particular, a measurement of the polarization at and in the neighborhood of 90 degrees in the energy range between the first and third resonances should give a fairly convincing verification of one or the other of the prevailing assignments.

As we might suspect, the propellant problems for electrical propulsion systems are quite different than those of chemical or nuclear propulsion schemes. In those cases, two of the most important parameters were the propellant temperature and mean molecular weight. Here we are sidestepping the temperature requirement entirely by using electrical energy for the energy source rather than chemical or thermal energy. Of course, mission analysis have demonstrated that the energy per unit weight requirements are so large as to rule out all except nuclear or solar sources for this energy. As a result, nearly all the weight of the propulsion system is in the electrical power supply. Consequently, the efficiency of the thrust system in converting this electrical energy into directed mechanical energy of the propellant is one of its most important parameters. In addition, it must have exceedingly long operating life, say a year or so, and its electrical characteristics must match those of the power source.

Investigations of the electrical response of diffused p-n junctions in silicon to charged particles were made on detectors obtained from two sources.

Abstract. An extensive activity at the University of California Lawrence Radiation Laboratory is the design and construction of elaborate electronic systems for instrumentation and control of test and research facilities. Design and construction of these large scale electronic systems is guided by principles and practices of standardization which reduce system cost and completion time. A summary of these standardization principles and practices is presented.

Introduction. With the development of fission and subsequently of thermonuclear explosives, a very large source of cheap energy has become available. The problem of using this energy for peaceful purposes safely and economically presents itself as one of the most interesting and important of our time. In explosions the energy is released very suddenly. Conversion of this sudden release of energy at extremely high temperature and pressure into the form of useful work, either mechanical or chemical or thermal, must be accomplished in order for such explosions to have nonmilitary uses. The technical feasibility of such conversions in a number of different instances will be described in this article. At the same time one must be able to control nuisance effects. Examples of these are seismic effects, the blast and heat which at least in the atmosphere always accompany such explosions, and the problem of radioactivity. Even given the technical feasibility of these accomplishments, which in some cases seems quite clear from what is known already, one must prove economic feasibility. That is to say, one must show that the cost of certain nonmilitary undertakings will be considerably less by the use of nuclear explosions than by conventional methods.

The pion-pion interaction is of great theoretical importance and must be understood before the other and more familiar interactions can be systematically analyzed. Therefore, various experiments to verify the existence of a P resonance in the w w system are proposed.

Report discussing part of a study that aims to understand plasma stability and confinement in mirror geometries.

The following report describes the injection and trapping of high current electron beams in order to construct an electron gun and the first 2 Mev section of the accelerator.

Abstract. The preparation and properties of a new explosive, liquid over the range -65 degrees F to +165 degrees F, are presented. This explosive, called NTN, is a 5/1/1 mole ration of nitromethane, tetranitromethane, 1 -nitropropane. The sensitivity and stability of NTN meet military requirements.

The following document aims to analyze the dynamics of a pinch tube, including the reaction back on the energy source.

Introduction. A survey has been made of the image converter tubes generally available in this country and Europe. Ultraviolet and infrared types using photocathodes were included, buy x-ray and solid state types were omitted. Since this is the first time that this list has been compiled, it may have errors and omissions. The author will appreciate any corrections or suggestions, and it is hoped that revised lists will be published from time to time.

Abstract. A systematic procedure for preparing purchase specification on electronic instrumentation or control systems has been developed. This procedure results in preparation of specifications which: 1) make it possible to find any particular specification requirement quickly; and 2) insure that no important requirement has been omitted. Details of this systematic specification preparing procedure presented.

A digital computer program called KICK (K-meson Interaction Coplanarization and Kinematics), which carries out the analysis of complete bubble chamber events, is described.

Abstract. An IBM-650 computer code for the detailed unfolding of [gamma]-ray spectra obtained from NaI scintillation counters has been developed. The procedure is set up to remove analyzer scale dependence and to largely remove energy dependences. Computer time is about 1 minute per [gamma]-ray.

Introduction. The Lawrence Radiation Laboratory of the University of California has developed a series of reactor neutronic programs for an IBM 709 Data Processing System.. This paper presents a brief outline of these codes and includes the results of one- and two-dimensional diffusion calculations used to interpret data from a series of enriched-uranium beryllium-oxide moderated critical measurements. These were performed for the specific purpose of evaluating the computer programs. The time-independent neutron diffusion theory criticality codes are 9ZOOM, a one-dimensional multigroup program; and 9ANGIE, a two-dimensional multigroup program. A series of codes, named SOPHIST, are described which prepare neutronic input data for the criticality codes. Examples of modification of the data to account for disadvantage factors, anisotropic scattering and for the (n,2n) reaction of Be9 are given. The critical assemblies include bare and graphite-reflected systems, using atomic BeO/U235 ratios from 247/1 to 7660/1, arranged in simple one- and two-dimensional rectangular parallelepiped arrays. All of the assemblies utilized heterogeneous arrangements of moderator and thin uranium foils. These systems are not truly thermal and are in a range where critical mass is extremely sensitive to size. The constants used in the multigroup (18 energy groups were used) calculations are presented in tabular …

Abstract. The Tory II-A reactor is a small, air cooled, high power-density reactor which is to operate at quite high temperatures. Design of the reactor is essentially complete. First operation is scheduled for late 1960 at the Nevada Test Site of the Atomic Energy Commission. Since the reactor is unshielded, the control room which houses the recording and indicting equipment is located approximately two miles from the test bunker. Signals from reactor and facility transducers are amplified in the test bunker and transmitted by cable to the control point. The kinds of quantities measures include neutron flux level, temperatures, pressures, vibration amplitudes, strain and air mass flow rate. The recording and indicating system is centered around 258 channels of 1.5 cycle per second, pulse-width modulation tape recording equipment and 72 channels of 120 cps, analogue strip-chart records. In addition, there is a number of the usual meters, scalers and slow-response strip-chart recorders.

A variable-length vacuum-insulated liquid hydrogen transfer line is described. The vacuum system is semi-permanent, and segments of the line are assembled with only threaded vacuum fittings. Thermal stress calculations are presented for a statically indeterminate union coupling.

The probabilities for nine electronic transitions among the low lying excited states in the C2 molecule are calculated by the dipole moment operator method and are given in the form of oscillator strength (or f values).

Abstract. The region where exact thermodynamic description of the state of matter at high pressure and high temperature is possible is located. In the remaining region various approximate theories and empirical relations are discussed. These considerations are applied to hydrogen to locate the density and pressure at which the diatomic bond collapses. Also the approximate conditions are determined at which no bound electron states exist.