Search

The paper reviews our understanding of the properties of gases and their multicomponent mixtures with particular emphasis on transport properties. The review amounts to a systematic comparison between the results of kinetic theory (Boltzmann and Wang Chang‐Uhlenbeck equations) and the best experimental data.Rather than concentrate on a search for suitable potentials, the paper explores the extent to which the existing body of theory can be put to practical use without an explicit knowledge of the intermolecular force potential for any gas. The organizing principle consists in the formulation of an extended law of corresponding states. This proves to be as accurate as the best measurements of all properties for monatomic gases and for certain properties of the polyatomic gases. Thus, instead of a potential, the formulation presents its empirically determined universal functionals together with suitable scaling factors for pure components and mixtures.

Magnetic printing is quite similar to electrostatic printing. The basic steps consist of recording a magnetic latent image, development of the recording with a magnetic ink and finally transferring the ink to a sheet of paper. Since papers on magnetic printing were first published in 1951, each step of this process has become highly developed. Impactless magnetic printers have been displayed at several conferences during the past few years. This review of the work on magnetic printers shows that printing speeds and print quality equal to electrostatic and ink jet printers can be achieved.

The recent development of Rare Earth permanent magnets requires a revision of the application possibilities of permanent magnets in rotating machinery. This paper contributes some ideas on how to make the best use of their characteristics. The two important areas of application, the stationary magnet structure and rotating magnet structure, are discussed separately. Electrically excited machines are compared to those with permanent magnet excitation of both the conventional magnet and the new magnet types. The results of these considerations are twofold depending upon whether the magnets are used in stationary magnet structures or in rotating magnet structures. Many of the electromagnetic design concepts, which have been developed for ceramic magnet motors, also apply for the new magnets when they are used in stationary magnets (1) provide more than twice the flux densities at higher coercive forces, (2) will withstand more than twice the demagnetization forces, and (3) show much improved thermal properties. New design concepts will have to be developed for the application of Rare Earth magnets in rotating field structures. Present design concepts have mainly been worked out for Alnico 5–7, a material with an extremely high remanence flux density but a very low coercive force. They do not fit the Rare Earth magnets. One possible design concept is outlined in the paper. The significant difference between an Alnico magnet design and a Rare Earth magnet design lies in the volume of the magnets. The new magnets allow more rotor volume to be used for the mechanical structure resulting for a more reliable and stronger rotor construction. It is expected that the new magnets significantly broaden the range of applications for permanent magnets in rotating machinery.

The scope of the present paper is three‐fold: to review the status of the detection of cosmic ray muon neutrinos of atmospheric origin, to make an estimate of the cosmic ray background in the Brookhaven Solar Neutrino Experiment and to briefly examine the possibility of detecting neutrinos from supernovae and collapsing stars in the Galaxy.

The basic question raised in this paper is the relationship between group theoretical and physical notions. In particular the physical significance of the mathematical entities occurring in group‐representations is examined in detail. For this reason a brief outline is presented of the mathematical definitions and status of non‐linear realizations of groups. Special non‐linear realizations of the Lorentz and Poincare groups are exhibited. The possible physical meaning of these realizations is discussed. It is shown that there is a fundamental interpretation question involved, which indicates that the identical formalism can describe a wide variety of physical phenomena. The classical (Wigner) theory of the representations of the Poincare group, allows the description of many‐particle systems in terms of elements and operators in tensor products of Hilbert space. An appropriate adaptation of this procedure suggests that the utilization of the non‐linear realization of the Poincare group, describes a relativistic many‐particle system in interaction. General requirements such as causality are shown to be compatible with the formalism of the non‐linear realizations.

Recently it has been proposed by Tucciarone that the relative magnitude of photoinduced dichroism in YIG(Si) can be calculated by imposing axial symmetry on the electric‐dipole photodetachment cross section. By means of this method, the polarization dependence of the dichroism induced by linearly and circularly polarized light was calculated, and, while the former case was found to be uniquely determined by symmetry alone in the framework of the model, the latter effect was found to be particularly sensitive, by means of a “shape parameter” r, to the details of the excitation process. In this paper we apply the same method to the calculation of the temperature dependence of the dichroism induced by both linearly and circularly polarized light. We find that the temperature variation of the magnitude of the dichroism depends on the strength of the trigonal field, while the temperature dependence of the shape parameter r is strongly coupled to the spin‐orbit constant. In case the trigonal field is assigned the values recently proposed by Alben et al., the calculated magnitude of the dichroism is practically constant between 0°K and nitrogen temperature, if the relaxation time of the effect is neglected.

When one writes into a continuous planar film memory or a wire memory, the stray field from the pole distribution is generally comparable to or in some regions greater than the applied field from the striplines. In this paper, it is shown that if a keeper is used or if the poles are confined to a narrow strip, the problem can be reduced (via a Taylor series) to a local linear differential equation solvable by hand. The theory is used to calculate the hard axis component of magnetization along a plated wire and to calculate the locus of the domain wall in a planar oligatomic film memory as a function of word and digit fields. The length of the domain is compared with Lorentz microscope data.

Prompting this study was the possible use of a time‐varying electrical current within the magnetic alloy material of large interconnected memory arrays to simplify the wiring needed for coincident current switching and for nondestructive readout. This paper reports details on the following effects of low‐frequency current in the direction of magnetization in 50% Ni–Fe tape: (1) The reduction in average frictional field of a major domain wall, as caused by the cross‐field of the current, is found to decrease with depth from the tape surface as expected. The electron drift itself did not measurably affect the wall friction. (2) The measured Rayleigh hysteresis effect, shown to suffer a reduction in restoring field with cross‐field interaction, is compared with a revised form of Baldwin's theoretical model to give further understanding of the mechanism for the interaction. (3) The threshold for low‐field switching (H

A survey is presented of the behavior of transport properties near the gas‐liquid critical point of one component fluids and near the critical mixing point of binary liquids. The paper deals specifically with the shear viscosity and those transport properties, thermal conductivity and thermal diffusivity of gases and binary diffusion coefficient of liquid mixtures, that are related to the critical slowing down of the fluctuations in the order parameter. The experimental data are compared with current theoretical predictions.

This paper discusses the tolerances imposed on certain imperfections in the TRIUMF magnetic field by the resonances νx = 1/1, 2/2, 3/2 and 6/4, νz = 1/2 and νx − νz = 1, and by the height of the equilibrium orbit. A method of calculating harmonic coil settings to centre a beam of wide phase width is described.

The present paper is devoted to a study of TE surface modes along a ferrite‐dielectric interface, the ferrite magnetization being parallel to the interface. For a transverse propagation with respect to magnetization, two TE‐modes can be found. These unidirectional modes are respectively forward and reverse. The “magnetostatic mode” includes the Damon‐Eshbach mode. The “dynamic mode”, which presents a very wide bandwidth, includes the mode recently described by Hines. Our investigation, carried out on a schematic configuration, gives simple results, which clearly point out the physical behaviour of these very interesting modes.

The high‐intensity beam of LAMPF requires careful control of beam loss to minimize activation of the beam channel. This paper describes a beam‐spill control system now in operation which limits the average beam loss to an amount allowed by activation criteria, without severely restricting accelerator tune‐up and diagnostics work. This average loss is maintained by downward modulation of the beam‐pulse width and repetition rate until the loss‐producing fault is corrected. Binary and analog signals describing the action are sent to the Central Control Computer where decisions regarding corrective measures can be made by either the operator or the computer. The computer can test all beam‐spill monitors simultaneously while the machine is in operation.

High speed transportation vehicles (trains) carrying superconducting magnets can be levitated by repulsion from diamagnetic currents induced in a conducting track. In a paper by Richards and Tinkham submitted to J. Appl. Phys., various approximate methods are presented for calculating the lift and drag forces for such magnetic suspensions. Fourier analysis of periodic train magnet fields is used to study “image force” and “hybrid null flux” systems which involve homogeneous conducting sheet tracks. A lumped circuit analysis is used to discuss the “null flux” principle and related systems with structured tracks. The stability and efficiency of linear induction and linear synchronous motor propulsion systems are studied using related methods.

Ludwig Boltzmann's H‐theorem of 1872, commemorated at this Seminar, is only one of the major steps in his long struggle to grasp the full meaning of the second law of thermodynamics. This paper describes some of the stages in Boltzmann's development of a statistical mechanics, emphasizing his intellectual debt to James Clerk Maxwell.

Contributed papers to the session on hadronic spectroscopy are reviewed. The relationship of these contributions to existing knowledge on the R‐S‐T‐U meson states is discussed.

High performance rare earth‐cobalt permanent magnets are being incorporated in an increasing number of devices. The translation of laboratory powder metallurgical processes into methods of volume manufacturing is described in this paper. The crucial nature of each processing step is considered and the relationship to the intrinsic magnetic properties, property uniformity and performance characteristics of finished magnets is discussed.

Strip domains resulting from hard bubbles in a reduced bias field demonstrate a variety of shapes and complex rotational behavior. This paper describes some observations on dumbbell‐shaped, S‐shaped, and C‐shaped domains when excited by time dependent bias‐aiding and bias‐opposing fields.

Motion of magnetic domain walls in magnetic bubble domain materials is discussed in this paper. A steady‐state solution for wall velocity in a magnetic material with orthorhombic anisotropy is used to obtain the conventional expression for the domain wall mobility. After reviewing the experimental situation, it is concluded that the mobility depends in a predictable way on wall width but that its detailed behavior otherwise is not well understood. Limiting wall velocities, nonlinear velocity‐field behavior, and wall inertial effects are considered, and important consequences of the orthorhombic anisotropy appear here; supporting experimental results for these effects are reviewed. Wall motion damping due to anisotropic energy levels in several of the magnetic rare earths is shown to be a limiting factor in obtaining high mobility materials. Other factors which have been shown to be significant, such as surface smoothness, thermal annealing, and irradiation with X‐rays, are also discussed. Finally, express...

It is well known that the Mn ion in tin tellurides exists approximately as Mn++ with spin of 5/2. The ions exhibit ferromagnetic coupling 1 with a paramagnetic curie temperature which increases linearly with the magnetic impurity. In this paper we present the complete data of the superconducting transition temperature Tc as a function of paramagnetic ions for various carrier densities. The study showed a strong dependence of TC on the carrier concentration n and also on the spin density Ns. Finally interpretation of the experimental data is made on the basis of the theories of Abrikosov, 2 Benneman 3 and Benneman and Garland. Preliminary superconducting results on the system (SnTe–EuTe) indicate that the system remains superconducting for the impurity concentration as large as 5 atomic percent. Other 3d elements, e.g., Cr, Ni, Co are successively dissolved in the matrix of SnTe. X‐ray diffraction results show that at least 3 atomic percent of solute can be dissolved while retaining a single phase Bl struc...

This paper examines the dynamic effects of magnetization fluctuations in polycrystalline films on their uniform mode resonance behavior. The dynamic interactions of the non‐uniform components with the spatially averaged magnetization M⇒0 is first treated as a perturbation correction on the susceptibility χ(ω) when the interaction is small. When the interaction is large such that phenomenological damping is neglected it is shown that the fluctuations introduce regions of damped behavior. Illustrative numerical calculations are made on a model whose spatial variation is described by a single wave vector.

This paper describes the conceptual design of a highly reliable 108‐Bit Bubble Domain Memory for the Space Program. The Memory has random access to blocks of closed‐loop shift registers, and utilizes self‐contained bubble domain chips with on‐chip decoding. Tradeoff studies show that the highest reliability and lowest power dissipation is obtained when the memory is organized on a bit‐per‐chip basis. The final design, has 800 bits/register, 128 registers/chip, 16 chips/plane, and 112 planes, of which only seven are activated at a time. A word has 64 data bits +32 checkbits, used in a “16‐adjacent” code to provide correction of any combination of errors in one plane. 100 KHz maximum rotational frequency keeps power low (≤ 25 watts) and also allows asynchronous operation. Data rate is 6.4 megabits/sec, access time is 200 μsec to an 800‐word block and an additional 4 msec (average) to a word.

In this paper the results of numerical investigation of transverse motion influence on time duration of the ion bunch in the isochronous cyclotron are reported. The requirements to the control degree of transverse motion parameters at beam extraction from the isochronous radius and from the region with dropping magnetic field are formulated. The ion entry into the additional bunching dee operating at the highest harmonic compared with the accelerating voltage of the main dee has been investigated. In conclusion the results of numerical modelling of the beam acceleration in the ring isochronous cyclotron with double‐acceleration system at the beam extraction from radial stability boundary are given.

This paper presents the major highlights of past experimental work and current knowledge on the superconducting critical temperatures of the transition elements, their alloys and compounds. The survey includes materials such as: the solid solution alloys of the d‐band transition metals; intermetallic compounds of the sigma, alpha‐manganese and Laves phases; superconducting compounds of ferromagnetic elements and Group 3 elements; and high critical temperature materials of the sodium chloride and β‐tungsten structures.

In the basic tokamak experiment, the copper shell is a highly‐satisfactory feedback control device. For certain extensions of the tokamak operation — for example, to compression heating — it is, however, convenient to remove the copper shell. External feedback control of the equilibrium position is then a natural substitute. A more complex problem is the feedback stabilization of MHD modes. The interchange instabilities, against which linear magnetic feedback is ineffective, are fortunately stabilized by the minimum‐average‐B property of the toroidal tokamak. Feedback stabilization of a type of thermal instability that results in major‐radius shifts is the principal topic of this paper.

This paper describes the 80 MeV (protons) cyclotron built for the University of Louvain. The machine features variable energy and can also accelerate deuterons, 3He and alpha particles. Design and construction were completed within 40 months and first operational results are reported.

This paper will report on a new type of cylindrical magnetic domain. This domain, called a “hard” bubble (HB) can have markedly different properties from a “normal” bubble (NB). A NB has a diameter range from run‐out to collapse of about 3:1 and a bias field change of about 0.10(4πM), whereas some HB's have a diameter ratio of 10:1 and exist over a bias range of 0.23(4πM). HB's transport with a velocity component perpendicular to a magnetic field gradient as well as the normal parallel component. HB's have been observed with a parallel velocity of 16 cm/sec and a perpendicular velocity of 144 cm/sec, whereas a NB in the same materials and at the identical gradient drive of 1 Oe/micron has a parallel velocity of 1500 cm/sec. There also exists a range of “intermediate” bubbles (IB) with properties between those of NB's and HB's. A model for IB's and HB's consisting of a domain wall that has many Bloch to Neel transitions along the circumference of the bubble has explained both the static and dynamic properties of these bubbles. The different IB's correspond to a varying number of these transitions while a HB has the maximum number. Films that are free from IB's or HB's, which are a necessity for devices, have been made using two magnetic layers or a single layer that has been ion implanted on one side.

The storage of information in present day computer systems is shared between high‐speed, high‐cost memories and low‐speed, low‐cost mechanical storage devices. With the advent of cheap bulk memory technology one can envision a storage hierarchy with three levels of storage: buffer, memory, and a mechanical backing store. The individual cost and performance characteristics of the three technologies involved affect the overall computer system cost‐performance. In fact, it is the judicious selection of technologies and system configurations which leads to a well designed storage system. This paper first describes the automatic management of information in a three level storage system where the objective is to keep current information in the fastest device and the rest of the information in the slower devices. Then the evaluation of the storage systems is described for a multiprogramming environment where total system dollars per instruction executed is the criterion for system cost‐performance. Finally, two ...

Spin‐polarized methods of multiple scattering are applied to study the magnetic properties of condensed systems. The material is represented as a collection of spin‐polarized scatterers, an exact calculation is made for clusters of such scatterers including boundary conditions to represent the rest of the material. The condition for the existence of spin‐polarized waves are related to enhancement, micromagnetism and ferromagnetism and to the dependance of those properties on the relative concentration in alloys. It is concluded that this one electron theory with local exchange and *“correlation” approximation, successfully includes features of both localized electron and free wave theories. Many magnetic properties can be described in terms of the self consistency conditions for the multiple scattered wave. The method is thought to be particularly useful to study amorphous solids and liquids. In principle we only need to know the scattering properties of a representative part of the system and a modified free space Green function for an scattered wave where all the information about the rest of the system is included1. The point of view adopted in this paper is a cluster method approach2 where we compute exactly the scattering properties of a selected set of clusters representative of the material and use some approximations to the boundary conditions the rest of the system impose on the wave functions. This method allows the direct calculation of the density of states, the total energy (in the statistical exchange approximation), etc. With this technique we can follow changes in local order, composition, in the pair correlation functions, etc. Computer programs have been written and currently applied to some typical alleys and pure metals. Some results are discussed.

The ac‐anhysteretic process is the elementary process of recording. In an earlier paper, the author has presented a mean field theory that relates the anhysteretic remanence curve Mar(H) to the material structural properties.1 In particular, at temperature T=0, the initial slope of Mar(H), Xar, may be finite only for certain material structures and is then determined by the dynamic rather than the static interaction fields. This concept is now extended to T>0, using a result of Jaep. In principle, the assumed mechanism may be described in terms of a feedback control process with the interaction fields acting as feedback link. The control function is a step function at T=0; it becomes continuous for T>0. The theory yields in considerable detail the characteristic features of the experimental data. The most important difference between the author's view and other theories appears to be that the latter either ignore or oversimplify the role of the dynamic interaction fields and thereby lose most of the relat...

Particle accelerators have been used for some time in materials science to study the effects of irradiation damage and to implant impurity atoms to well defined concentrations. In the past the majority of this work has been of a fairly fundamental nature but recently important technological problems in connection with fast reactor development, have been highlighted. This paper will review the use of cyclotrons to study a variety of materials problems and in particular the Harwell Variable Energy Cyclotron to study the phenomenon of void formation in irradiated materials. It will illustrate how simulation experiments can help to provide an understanding of an important technological problem and furthermore provide data which can be used together with that from fast neutron irradiation to select the most suitable materials for the design of fast reactors.

This paper describes the fabrication and operation of a 52‐bit bubble domain memory chip designed to test the concept of on‐chip magnetic decoding. Access to one of the chip's four shift registers for the read, write, and clear functions is by means of bubble domain decoders utilizing the interaction between a conductor line and a bubble. All other functions are performed by a permalloy overlay driven by an external rotating field. The metallurgy consists of 200 A evaporated permalloy for magnetoresistive sensors. 4000 A electroplated permalloy for propagation etc., and 6000 A electroplated copper for control lines.

This paper describes transport measurements on the magnetic semiconductors Gd3−xvxS4. The vacancies, v, are randomly distributed throughout the lattice and lead to fluctuating repulsive potentials and band tailings. Furthermore, since our largest measured carrier concentrations are small compared to the maximum number of vacancies (∼2.3×1021cm−3), a rigid band model should be applicable. This is in contrast to ordinary semiconductors where the energy dependence of the density of states is generally a strong function of the dopant concentration. Recent transport measurements in Eu doped EuS, which demonstrate the applicability of a model for transport in a band tail of localized states will also be reviewed. The two systems will be compared and discussed in terms of a model first suggested by Cutler and Mott for paramagnetic Ce3−xvxS4, and modified here to include magnetic interactions.

Stabilization of an electrostatic flute‐type instability occurring in a simple magnetic mirror by feedback techniques is discussed. In the first part of the paper a diffuse plasma is considered. The effect of varying the locations of the sensing and suppressing systems is found to alter the stability threshold significantly. In the second part a sharp‐boundary plasma is considered and phase shift and frequency response are included in the feedback terms.

At tricritical points thermodynamic functions scale with respect to three independent field variables. Such points have been called critical points of the third order. We present, in this paper, a general scaling hypothesis for such critical points and demonstrate how the concept of invariant spaces leads naturally to the prediction of data collapsing from volumes to lines in terms of “double‐power scaling functions”.

The composition of epitaxial Y3−yGdyGaxFe5−xO12 films on GGG substrates was determined by quantitative microprobe analysis. The paper discusses practical aspects concerning the measurements and their evaluation and presents data on the film composition and corresponding magnetic properties versus initial melt formulation of eight melt compositions.

In the focus of attention at the present time are the new rare earth‐cobalt‐based magnet alloys. This paper is primarily a qualitative review of the physical phenomena controlling their behavior and of the materials problems these magnets have posed. It also provides an outlook at possibilities for the development of still better or cheaper permanent magnets which current research on rare earth‐ transition metal alloys appears to provide. The origins of the magnetic moments and the crystal anisotropy of rare earth‐transition metal phases are discussed. Alternative concepts of the causes of coercivity in powders and sintered bodies are analyzed. Some basic aspects of the sintering of R‐Co compacts and the magnetic hardening of R–Co–Cu alloys in the massive state are reviewed. Specific problems related to particular alloys and applications of the magnets are pointed out. The conclusion is drawn that the new family of permanent magnets now emerging rivals in complexity both the Alnicos and the ferrites together. There are many development opportunities for the future, and we can expect that, eventually, magnets based on high‐anisotropy alloys containing rare earths will be offered in a variety of grades, covering a wide range of properties and prices, and that they will be produced by several drastically different methods.

This paper examines the effects of static magnetization dispersion in polycrystalline films on their low field, uniform mode resonance behavior. The quasistatic interaction of the disperse local magnetization with the average magnetization M⇒0, enters the description of FMR through modified initial conditions and through the internal field. The initial nonuniform state alone modifies the low field resonance behavior. In addition, quasistatic free energy minimization yields a dependence of the mean planar equilibrium angle on nonlinear interactions. This causes changes of the resonance frequency and susceptibility magnitude and, under certain conditions, the occurrence of a double resonance.

Macroscopic and x‐ray volume expansivity measurements have, in recent years, yielded information about the formation energies and entropies of atomic vacancies in several crystalline solids. Such vacancy data may now be utilized in conjunction with the great amount of volume expansivity, heat capacity, and elastic constant data that has become generally available to ascertain the relative contribution of thermally‐generated vacancies to various thermodynamic properties. The present paper reports the results of an endeavor of this sort for neon, argon, krypton, aluminum, lead, copper, silver, and gold. Critical evaluation of data in the literature is required. It is shown, for the solids investigated, that among the ordinary thermodynamic properties, the one most sensitive to the presence of thermal vacancies is the coefficient of thermal expansion. Heuristic justification is thus obtained for the use of thermal expansion methods (in preference to other methods) for determining the properties of this type of thermal defect. Comparisons are also made with published analyses by other authors.

In this paper we present a self‐consistent treatment of the effect of the exchange interaction on the dielectric response of each spin band of an itinerant electron system. Our equation gives a simple physical picture for the role of exchange interaction, as well as that of the direct Coulomb interaction, in the dielectric responses both for the paramagnetic and ferromagnetic state. In the ferromagnetic state, the self‐consistent inclusion of the exchange interaction effect leads to a rather drastic result in which the electrons of one spin band can be repelled by a positive point charge while the electrons of the opposite spin band can be attracted.

According to the increasing demands for magnetic tape printing especially for video tape, the magnetic tape duplication using a contact process is one of the most attractive solutions. There are two major methods, i. e. anhysteretic transfer and thermal transfer. The coercivity of the master tape should be 2.5 times higher than the slave by computer simulation for anhysteretic transfer, but is not important for thermal transfer. The highest coercivity of the slave tape will be decided by the master tape which, in turn, is limited by the recording head saturation for anhysteretic transfer, however, the thermal characteristics of coercivity and magnetic induction under Tc are more dominant for thermal transfer. The tape surface roughness as well as the coercivity is very important for short wavelength printing. In this paper, the properties of the master and slave tapes for anhysteretic and thermal transfer are discussed with theoretical and experimental results.

In this paper, the authors study the quasi‐static (1 kHz) parallel reversible susceptibility (μ−1)∥ in toroǐdal samples, with respect to the grain size Dm. One can obtain a highly useful characteristic reduced curve (μ−1)∥/Dm = f (H.Dm). A concept of mechanisms of the parallel reversible susceptibility is introduced from an earlier proposed model. The values of the internal field acting on the wall, given by the analysis of (μ−1)∥, are in good agreement with those given by the analysis of the initial magnetization.

A technique for improving the rate of convergence of the solution of field problems by the method of finite differences called SER (successive extrapolated relaxation) has been developed. Sufficient saving in computing time is obtained by the method so that it is feasible to solve three‐dimensional field problems. This method uses conventional overrelaxation for every three iterations and then extrapolates simultaneously to the solution using a modification of Aitken's formula. In this paper, this method is applied to obtain the field in three dimensions from “T bar” circuits used for propagating magnetic bubbles. Symmetry considerations have been used so that the analysis is required over only one half of the propagating period. The permalloy circuit is idealized for these calculations.

This paper discusses recent experiments related to e+e− ⇒ hadrons. Subjects discussed include hadron form factors, the total hadronic cross section, multiplicities and some specific channels.

The experimental value of the constant α= −(32/5)e2 (l−R)Q(βHex)2 〈r−3〉(2E1 + E2)/(E12E2 h) (1) was derived by Streever & Caplan (Phys. Rev. B, 3, 2910 (1971) from the quadrupolar contribution to their nuclear resonance measurements in EuIG. They obtained −54 MHz, whereas the value calculated from (1) was −108MHz. This discrepancy does not seem justified by uncertainty in the parameters appearing in (1); and two attempts to remove it are made in the present paper. In the first, which is unsuccessful, a more precise nuclear Hamiltonian is used, together with large values of the anisotropic exchange parameters. In the second, the discrepancy is removed by adding a biquadratic exchange term to the nuclear Hamiltonian. However the ratio of the required biquadratic to conventional linear exchange is nearly an order of magnitude larger than the usual theoretical estimates.

This paper discusses spin excitation effects in superconductors with an emphasis on experiment. First, a review is presented of the superconductivity in dilute alloy systems which exhibit localized spin fluctuations associated with resonant impurity states. It is shown that when the localized spin fluctuation temperature is much larger than superconducting temperatures; (1) the transition temperature falls off rapidly with impurity concentration following a modified exponential, and (2) the thermodynamic properties (e.g., the specific heat jump at the transition and the critical field) obey the BCS law of corresponding states. A comparison is made to a recent theory by Kaiser of superconductivity in the presence of nonmagnetic resonant impurity states. Next, experiments on La and La intermetallic compounds with Ce impurities which simultaneously exhibit superconductivity and the Kondo effect are reviewed. Finally, pressure‐induced magnetic‐nonmagnetic transitions of Ce impurities in superconductors are discussed and compared with certain theoretical models.

This paper discusses the system developed to control the 2 MW 23 MHz RF system at TRIUMF. Included are means of pulsing through the multipactoring region; RF accelerating voltage amplitude and phase control; provision of self‐excited and driven modes of operation; fine tuning of the resonators; phase and amplitude control of third harmonic voltage for flat‐topping of the RF waveform. Results obtained with a prototype control system on the central region cyclotron are included.

The Magneplane1, a large‐gap high speed vehicle concept, has an integrated magnetic suspension‐propulsion system. Two aspects of the system study are discussed in this paper: (a) lift and drag force calculations, and (b) magnet design for the scale model. The first task is to derive general force laws and to develop techniques for analyzing general guideway configurations. Both analytical approaches and computer methods of solution have been investigated. These techniques will be discussed. The second task relates to the verification of the theoretical predictions of system performance using a 1/24 scale model. In order to provide an adequate magnetic field for the 12″ gap, five superconducting coils are required in a full scale vehicle. In the 1/24 scale model permanent magnets are used to give magnetic fields for the 1/2″ gap. Both Alnico and Samarium Cobalt magnets are considered. The design of the magnets made use of the computer program MAGNET2.

The paper begins with a lightning review of the principal features of π–π scattering and of the generally accepted theoretical picture (using current algebra and smoothness) which accounts for most of these features. This is followed by a brief look into the future, in which it is argued that P‐wave π–π scattering will continue to play a prominent role in experiment and theory at energies above 1 GeV, just as it does at lower energies. Finally, calculations are presented which indicate that the theoretical picture of low energy π–π P‐wave scattering and the pion form factor is not noticeably modified by the inelastic states which will be prominent at higher energies. This result depends on the use of current algebra constraints for inelastic scattering and is not necessarily true of I=0, S‐wave scattering, since the current algebra provides less stringent constraints for I=0 inelastic scattering.