Vol. XVI (1957)
Fasc. 1–2, pages 3–169
On Transient Radiation of a Dipole Inside a Wave Guide (II)
Acta Phys. Pol. 16, 3 (1957)
abstract
A dipole situated inside a wave guide of an arbitrary cross section starts oscillating, its moment being \(M1(t)\sin \omega _0t\). Asymptotic formulae valid far from the front of the forerunner, are derived for the electric and magnetic fields of different modes. An analysis of the pulse propagation leads to the conclusion that, on account of the pulse becoming diffused, a theoretical limit exists for shortening the pulse width.
The Role of the Emitter Shape in Cold Emission Research
Acta Phys. Pol. 16, 25 (1957)
abstract
Observations were made of the changes of electron patterns from iron and nickel points, these changes taking place under the influence of changes of temperature and voltage. It was established that the emission of electrons from weakly heated points takes place from the corners and edges of the monocrystalline point. As a result of surface migration or plastic deformation, there occurs on the corners a piling up, which causes a local increase in the electric field intensity. As a result, the distribution of the current in the electron pattern maps the shape of the surface of the monocrystal forming the end of the point. The observed effect permits one to assume that the different values for the work function obtained from the surfaces of the monocrystal by various authors result from various degrees of rounding of the point.
Point Sources for X-Rays
Acta Phys. Pol. 16, 35 (1957)
abstract
An X-ray tube with adjustable focus of the order of 20 to 70 \(\mu \) was built. The electrode beam is collimated by means of an electrostatic lens. The different focus sizes are obtained by changing the position of the cathode filament with respect to the grid diaphragms and by changing the grid potential with respect to that of the cathode. The tube wave has an original design.
On the Induced Reverse Response of the Oxidized Aluminium G–M Counter to Visible Light, the Joshi Effect, and the Geiger Counter Sensitivity to the Air-flux
Acta Phys. Pol. 16, 49 (1957)
abstract
A study was made of the induced emission of photoelectrons from aluminium oxide. It was found that the aluminium counters with an oxide layer on the cathode, heated to 500\(^\circ \)C for few hours in atmospheric air, showed a counting rate run up effect under visible light illumination after a preceding ‘excitation’. This effect is ascribed to the generation of colour centres in the aluminium oxide during the continuous discharge ‘excitation’ period and to the positive charge (ions) on the surface of the oxide layer.
Decay of Phosphorescence of Rigid Solutions
Acta Phys. Pol. 16, 63 (1957)
abstract
An investigation was made of the decay curves of the intensity of phosphorescence components parallel and perpendicular to the direction of vibration of the electric vector of the linearly polarized light exciting gelatin phosphors dyed either with acridine orange or with acridine yellow. The decay curves appeared to be, in agreement with Jabłoński’s theory, a superposition of exponential functions with different decay constants. Different lifetimes correspond to different groups of luminescence centres with different limiting degrees of polarization. Changes of the degree of polarization of the total phosphorescence during the further stages of the decay (longer than \(10^{-6}\) sec. after the interruption of the excitation) are conditioned by the emission of light from successive groups of centres playing an essential part in the phosphorescence.
Theoretical Considerations on the Possibility of a New Method for Separating Mixtures and Isotopes
Acta Phys. Pol. 16, 79 (1957)
abstract
In this paper a new way for separating mixtures and isotopes is proposed. This method is based on the superposition and mutual intensification of the thermal diffusion (the boundary conditions being different from the usual ones) and distillation processes. The phenomenological theory of proposed method is set up. A numerical example based on the theory presented shows that there exists a possibility of increasing by several times (mean — 15 times) the degree of separation in an isotope mixture at equilibrium as compared with the separation obtained under similar conditions when using thermo-gravitational or distillation methods alone.
Neutron Polarization and Angular Distributions in (p,n) Reactions and Nuclear Optical Model
Acta Phys. Pol. 16, 93 (1957)
abstract
The neutron polarization and angular distribution of the neutrons produced in a (\(p,n\)) reaction are calculated with the assumption of the direct mechanism of the reaction. The cloudy crystal ball potential modified by a spin–orbit coupling is assumed as the neutron–nucleus interaction. The Coulomb effect of the incident proton wave results in a flattening of the angular distributions and gives smaller absolute values for the polarization. The model is applied to the reaction \(^{29}\)Si(\(p,n)^{29}\)P for \(E_p=6\) and 6.5 MeV. The maximum negative polarization \(\sim -65\)% appear for the c.m. scattering angle \(\theta \sim 100^\circ \). Further extensions of the model are discussed.
The Transition Curve of the Electron–Photon Component of Extensive Air Showers in Lead Absorber of Thicknesses Between 0 and 25 cm
Acta Phys. Pol. 16, 119 (1957)
abstract
Measurements of the absorption curves of extensive shower particles have been performed with an apparatus containing a normal extensive shower detector composed of three counter trays and a telescope consisting of three large area counter trays. There have been registered simultaneously 8 kinds of coincidences with good statistics for two positions of the lead absorber relative to the trays of the telescope. The thickness of the absorber was changed from 0 to 25 cm. Analysis of the results has made possible the evaluation of the ratio \(p/e\), i.e. the ration of the number of photons to the number of electrons in extensive air showers. The value found for this ratio is less than 1 and is equal to \(0.70\pm 0.15\). This value has been determined with greater accuracy than in measurements of other authors. All results of measurements obtained by different authors in connection with the determination of the ratio \(p/e\) are analysed. It is shown that large numbers of penetrating low energy photons are amongst the particles leaving the lead absorber several centimeters thick, and that they may be registered by single trays of the telescope, but not by a telescope composed of two or three trays. The registration takes place according to the mechanism suggested by Greisen.
Multi-plate Ionization Chamber for the Detections of Slow Neutrons
Acta Phys. Pol. 16, 135 (1957)
abstract
The authors describe the design of a multi-plate ionization chamber with electron pulses designed for the detection of slow neutrons. The electrodes of the ionization chamber, made in the shape of a multi-plate condenser, are coated with natural boron 3 mg/cm\(^2\) thick. The chamber is filled with argon at a pressure of 1 atm. The chamber efficiency for thermal neutrons is about 2%.
Survey of the Hyperfragment Experimental Data
Acta Phys. Pol. 16, 139 (1957)
abstract
All the available cases (about 120) interpreted as hyperfragment decays underwent a selection in effect of which 72 cases were considered to be hyperfragment decays, whereas in the remaining ones there is a possibility of the existence of other interpretations. On the basis of such a “pure sample” of hyperfragments certain statistical conclusions in regard to the production, decay, binding energy, structure, and life-time of light hyperfragments was reached. Tables facilitating the estimation of the binding energy of the \({\mit \Lambda }^0\) hyperon in light hyperfragments have been drawn.
Measurements of the Intensity of Transient Magnetic Fields by the Faraday Effect
Acta Phys. Pol. 16, 151 (1957)
abstract
Transient magnetic fields were produced by discharging a battery of capacitors through a coil. The magnetooptic Faraday effect was used for measuring the intensity of transient magnetic fields. The change in light intensity produced by a rotation of the plane of polarization was recorded using a photo-multiplier and cathode ray oscillograph. Magnetic fields of intensities of about 100 kOe were measured; CS\(_2\), CCl\(_4\) and H\(_2\)O were used as optical media.
On the 3D Electron Band in Body Centered Structure
Acta Phys. Pol. 16, 157 (1957)
abstract
The tight binding method can serve in energy band calculations as an interpolating scheme in the manner indicated by Slater and Koster (1954). In the very detailed discussion given by these authors for the 3d electron band in body centered structure the nearest neighbour interactions are taken into account. When one assumes the two-centre approximation and takes nearest and next nearest neighbour interactions into account one has more parameters, while the secular equation can still be solved analytically in several directions in the Brillouin zone. These directions of high symmetry will be enumerated below. The notation of Slater and Koster will be followed ...
On the Width of the 3D Electron Band in Iron
Acta Phys. Pol. 16, 161 (1957)
abstract
The simplified tight binding or LCAO method with two-centre approximation has been used to discuss the energy hand of 3d electrons in body-centered iron. The discussion is closely analogous to the one given by Slater and Koster (1954) for body-centered structure. Here the nearest and next nearest neighbour interactions are taken into account. The values of the energy integrals have been computed (1956) in Fletcher’s ...
Eine Neue Gesetzmässigkeit auf dem Gebiete der Plastischen Deformation
Acta Phys. Pol. 16, 165 (1957)
abstract
Diese wurden an flachen Nickelbändern kommerzieller Reinheit durchgeführt, die ein einheitliches Ausmass von \(100 \times 2 \times 0,1\) mm hatten. Die Bänder wurden zuvor in technischem Wasserstoff bei etwa 780 Grad C geglüht und sodann jeweils einer definierten plastischen Deformation im Bereiche von 0 bis etwa 30% unterworfen. Letzterer Wert war die Bruchdehnung. Nach der Dehnung wurde an jedem Muster die Anfangspermeabilität in einem Felde von 0,045 Oe gemäss Bild 1 und sodann die Koerzitätskraft gemäss Bild 2 gemessen. Leztgenanntes Messgerät stellt ein von uns entworfenes neuartiges Magnetometer mit magnetischer Sonde dar ...
Domain Formation in Ferroelectrics
Acta Phys. Pol. 16, 169 (1957)
abstract
The dielectric properties of ferroelectrics depend on the domain structure and domain dynamics. The formation and movement of domains have been studied by various authors: Forsbergh (1949), Merz (1954), Little (1955). Our main aim is to find how the formation of the c domain of BaTiO depends on the electric field ...Fasc. 3, pages 177–235
The Equations of Motion in General Relativity Theory and the Action Principle
Acta Phys. Pol. 16, 177 (1957)
abstract
This paper deals with the formulation of the equations of motion for \(p\) bodies, assuming: (1) the field equations of General Relativity Theory, (2) the fact that the energy-momentum tensor is different from zero only along certain world lines; this means that this tensor depends linearly on Dirac’s \(\delta \)-functions. It can be shown that from these simple assumptions the proper Lagrangian can be found almost without tedious calculation. It will give the equations of motion up to the post-Newtonian order. Also the connection between these equations and those of the “geodetic lines” is elucidated.
On the Free-electron Theory of Absorption Spectra of Some Linear Conjugated Systems
Acta Phys. Pol. 16, 211 (1957)
abstract
The AS FEMO method was applied in this work to calculate the absorption maxima in the spectrum of symmetrical cyanine dyes and polyenes. The results were discussed in comparison with experimental data and these of the simple free-electron model. In the case of cyanines considerable improvement of the theoretical values is obtained by introducing the resonance barrier in the FE model. The height of this barrier is determined by the stabilization energies of the cyanine nuclei. The effect of the energy states obtained by the introduction of the barrier to the simple FE model is discussed in detail and the correspondence between the results of resonance theory for cyanines and those of a FE model with a barrier was indicated.
Domain Formation in Ferroelectrics
Acta Phys. Pol. 16, 227 (1957)
abstract
The dielectric properties of ferroelectrics depend on the domain structure and domain dynamics. The formation and movement of domains have been studied by various authors: Forsberg (1949), Merz (1954), Little (1955). Our main aim is to find how the formation of the c domain of BaTiO\(_3\) depends on the electric field.
Note on the \(^{12}\)C(d,p)\(^{13}\)C Reaction Near the 4 MeV Resonance
Acta Phys. Pol. 16, 231 (1957)
abstract
Recently several observations have been performed for the stripping reactions in the vicinity of an isolated resonance of the compound nucleus. A calculation scheme for these reactions is outlined in the present note in its most simple version for the case of the \(^{12}\)C(d,p)\(^{13}\)C reaction near the 4 MeV resonance investigated experimentally by Bonner et al. (1956a). We adopt their values: \(J=3^+\) and the width \({\mit \Gamma }_\mathrm {lab}=0.15\) MeV of the excited level in \(^{14}\)N.
Appendix IV to the Paper Neutron Polarization and Angular Distribution in (p,n) Reactions
Acta Phys. Pol. 16, 235 (1957)
abstract
Derivation of the Final State of the Outgoing Neutron Eq. (3) represents the “equivalent” outgoing state of the neutron scattering in a spin–orbit potential its radial partial waves being proportional to ...Fasc. 4, pages 237–299
Investigation of Lead Sulphide Layers by the Electric Field Pulse Method
Acta Phys. Pol. 16, 237 (1957)
abstract
A number of microcrystal layers of evaporated lead sulphide in vacuum envelopes were investigated. The previously developed method (H. Rzewuski, L. Sosnowski 1955) of investigating semi-conductor layers by applying, in a condenser-like arrangement, a pulsed electric field to the layer is discussed extensively. On the basis of the above method, the following were determined (a) the type of layer investigated, (b) the type of barrier layer, (c) the concentration of the majority carriers, (d) the mobility of the majority carriers, (e) the minimum density of the surface states, (f) the relaxation time of the barrier, (g) the kinetic changes of the barrier layer conductivity are discussed. Finally the accuracy of the pulse method used to investigate the type of semi-conductor layer, as well as possibilities of its application, is discussed.
Electron Correlation in Molecules. I. The Ethylene Molecule
Acta Phys. Pol. 16, 257 (1957)
abstract
The excitation energies of the ethylene molecule were calculated using in the interaction integrals of the \(\pi \)-electrons wave functions depending explicitly on the mutual electron separation. The resulting energies are in satisfactory agreement with experimental values.
Electron Correlation in Molecules. II. The Benzene Molecule
Acta Phys. Pol. 16, 267 (1957)
abstract
The energy levels of benzene were calculated by an extended molecular orbital method. In the interaction integrals, between electrons having opposite spins and belonging to the same pair, wave functions depending explicitly on the mutual electron separation were used. An assignment of the \(^1B_{1\mu }\leftarrow {^1A}_{1g}\) transition for the experimental band at 6.2 eV was suggested.
On a Screw Model of Particles in Isospace
Acta Phys. Pol. 16, 279 (1957)
abstract
A model of hot particles in isospace is investigated enabling a physical interpretation of charge, isobaric spin, attribute (strangeness), and mass in terms of rotations in isospace. This model possesses some analogies with the hydrogen atom: the particle possesses a spinning centre, a spinning outer point, an orbital angular momentum, and a size. The particle (antiparticle) possesses also a property of a right (left) screw. The spin of the centre is interpreted as isobaric spin. Strangeness is replaced by a more physical attribute being an extremum component of the angular momentum of the outer point. This angular momentum, together with the radius of the particle, determines the rest mass. A privileged “third axis” is no more a property of isospace but of the particle itself. The algebraic additivity of the attributes is secured by means of a generalized postulate of contact interaction. Conservation of the total angular isomomentum holds for strong as well as for weak interactions between hot particles. A new “particle” — isotrino is suggested.
An Automatic Timing and Recording Circuit for Use with a Neutron Crystal Spectrometer
Acta Phys. Pol. 16, 293 (1957)
abstract
Apparatus is described for the automatic control and recording of the measurements on a crystal neutron spectrometer. The angular position, time of measurement and intensity of the primary and scattered neutron beams are registered and recorded on an electric desk adding machine. The circuits ensure the most economic use of the measurement time available by relating the time duration and angular frequency of measurement points to the scattered beam intensity.
On the One-centre Interaction Integrals in the Molecular Orbital Method
Acta Phys. Pol. 16, 299 (1957)
abstract
It is well known that the standard molecular orbital method is not very successful when used to calculate the excitation energies of molecules. Moffitt (1951) and Pariser (1953) have pointed out that a major source of error in these calculations is the inaccuracy of the energies of asymptotic dissociation products of molecular states, and the above authors have also given the ways of eliminating this error ...Fasc. 5, pages 305–389
Asymptotic Behaviour of Higher Factorial Moments of Electron–Photon Cascades at Large Depths
Acta Phys. Pol. 16, 305 (1957)
abstract
In this paper the behaviour of the higher factorial moments of electron–photon cascades at large depths is investigated in approximation “A”. The differential cross sections satisfying the conditions of homogeneity are positive, and, in addition, are arbitrary functions. It is assumed that the Bremsstrahlung cross section is greater than the pair formation cross section. The main results of this paper are: 1) The main factor determining the development of the cascades at large depths is the product of the total number of particles and the threshold energy. Systems with a smaller value of this variable are privileged. 2) Photons, as primary particles, are “stronger’” than electrons — generalization of the conclusions of Stachowiak (1956) for moments of any order. 3) Privileged configurations of electrons and photons were obtained. It turns out that configurations containing an even number of electrons different from zero are privileged. The weakest configuration for \(N\) particles is \(N\) photons and zero electrons when \(N \gt 1\).
A General Equation for Scattering Amplitudes of Particles in the Field Theory
Acta Phys. Pol. 16, 327 (1957)
abstract
In this note a formally exact relation in the field theory is obtained for the elements of the S matrix corresponding to two given numbers of particles. All elements with other numbers of particles are eliminated. Low’s general equation derived in a previous paper (Królikowski, 1957) is a special case, when both distinguished numbers of particles are identical. If the two numbers of particles, say \(N_1\) and \(N_2\) are different, then the equation obtained here connects the transition \(N_1\to N_2\) with the transition \(N_1\to N_1\), e.g. the photoproduction of pions with the Compton effect on nucleons. If the transition amplitude for the process \(N_1\to N_1\) is known, then that for the process \(N_1\to N_2\) satisfies a linear equation.
Estimation of the Height of the Potential Barrier of Hindered Rotation in the CH\(_3\)SH Molecule by Means of Thermal Neutron Scattering
Acta Phys. Pol. 16, 335 (1957)
abstract
In this paper the potential barrier height \(H\) of internal hindered rotations of methyl mercaptan molecules was estimated by means of a method based on the scattering of thermal neutrons with a Maxwellian energy distribution (mean neutron energy \(E=0.037\) eV). The cross section of CH\(_3\)SH molecules measured by thermal neutron scattering was a (\(194.5 \pm 5\)) barns. This was determined by the method of relative attenuation of the beam. Water was used as a standard liquid (\(\sigma _\mathrm {H_2O}=91\) barns). The cross section for rigid CH\(_3\)SH molecules calculated on the basis of the theory of Sachs and Teller was \(\sigma _\mathrm {rig}=258\) barns. Assuming a potential barrier height of \(H = 705\) cal/mol and taking into account the hindered rotation and the vibration of the atoms, the authors calculated the cross section of the CH\(_3\)SH molecules. The result obtained was \(\sigma _\mathrm {theor} =\) 202 barns. The cross section for collisions that are elastic with regard to hindered rotation was also calculated under the assumption that \(H = 1460\) cal/mol, this value being obtained by thermodynamical methods. The discussion of the results leads to the conclusion that a height of 705 cal/mol found by microwave spectroscopic methods should be ascribed to the potential barrier in the methyl mercaptan molecule rather than the value obtained by thermodynamic methods.
The Application of the Tight Binding Method to the Investigation of Energy Bands in Hexagonal Close-packed Structure. I
Acta Phys. Pol. 16, 343 (1957)
abstract
Tables for reduction of the matrix components of energy in the tight binding method have been prepared for hexagonal close-packed lattices.
Pi–Sigma Interaction in the Free-electron Model. I. Theory
Acta Phys. Pol. 16, 369 (1957)
abstract
The method of antisymmetrized molecular orbitals for the three-dimensional free-electron model was developed here for the case of linear conjugated molecules. In this model the \(\pi \) and \(\sigma \) electrons are assumed to form a gas in one cylindrical box extending along the molecular core, and both groups of electrons are characterized according to the classification given originally by Nikitine and Komoss. Then the whole \(\pi \)–\(\sigma \) interaction can be treated directly, contrary to the treatment of this problem in the Goeppert–Mayer–Sklar scheme. The values of the electronic repulsion integrals presented by the author in an earlier work for the case of the so called “one-dimensional” free-electron model, were verified as corresponding to the integrals of the present scheme when the radius of the box tends to zero.
On Nuclear Magnetic Resonance in Flowing Liquid
Acta Phys. Pol. 16, 381 (1957)
abstract
An investigation was made of nuclear magnetic resonance in a stream of flowing liquid. The dependence of the amplitude of the absorption lines on the rate of flow was investigated. It was established that the flowing liquid method allows a simultaneous determination of the saturation factor and the longitudinal relaxation time; in this connexion, the relaxation time measurement may be made for any (not too small) degree of saturation. It was also shown that the limit of applicability of the method can, in comparison with the limit of applicability given by Suryan, be shifted considerably in the direction of long relaxation times.
Investigation of Operating Conditions of a Dielectric Resonant Amplifier
Acta Phys. Pol. 16, 389 (1957)
abstract
The authors investigated the operating conditions of a dielectric resonant amplifier and the dielectric properties of (Ba–Sr)TiO\(_3\) ferroelectric condensers employed in the amplifier. Curves of the relative permittivity variation versus the DC field at various temperatures were obtained. The following characteristics of the dielectric amplifier under investigation were measured: output voltage versus signal voltage and signal frequency, and voltage amplification coefficient versus temperature. The largest voltage amplification value was obtained within the Curie point region. The temperature being constant, this amplification value remained practically constant over the entire audio frequency range. The measurements proved that it is possible to determine the optimal operating conditions of the dielectric amplifier from the graphs showing the dependence of the permittivity of the ferroelectric material on the DC field and on the temperature.Fasc. 6, pages 399–481
Sur une Modification de Lorentz-Invariant Formalisme dans la Théorie de Fusion
Acta Phys. Pol. 16, 399 (1957)
abstract
Dans ce travail une modification de Lorentz-invariant formalisme dans la théorie de la fusion de M. de Broglie est présentée pour le cas de deux fermions de spin 1/2. Ces fermions ne doivent pas être particules de Dirac, ils peuvent être aussi les particules de Majorana. Le formalisme proposé se distingue par la facilité des calculs.
Théorie de Fusion de Deux Particules de Majorana
Acta Phys. Pol. 16, 407 (1957)
abstract
Dans ce travail la théorie de fusion de M. de Broglie sous la forme Lorentz-invariante (Średniawa 1957) est appliquée aux particules de Majorana. On trouve que les fonctions d’ondes de la particule de spin maximum 1 et aussi las grandeurs \(I_1, A,E,H, \dots \) des champs “maxwelliens” et “non maxwelliens” sont réelles. Pour l’énergie de l’interaction entre ces particules de masse évanouissante et les électrons on trouve une expression ordinaire de la théorie semiclassique de radiation au lieu des expressions de de Broglie avec les champs complexes.
The Organization of Triple Alloys as Cooperative Phenomenon
Acta Phys. Pol. 16, 415 (1957)
abstract
It is first shown that the partition function of a triple alloy can be reduced to an Ising partition function only in the case of a linear lattice. This case is briefly considered in §2. In §3 and §4 some simple conclusions about triple alloys in the three-dimensional case are drawn by the matrix method under the assumption of a long-range order, but it is pointed out that if is impossible at present to obtain more definite results as (i) the partition function cannot be directly reduced to the Ising type and (ii) to each lattice point there correspond three and not two configurations. Thus, the mathematical apparatus which played such a prominent role in the study of the organization of binary alloys cannot be used.
Lagrange Function for the Motion of Charged Particles in General Relativity Theory. II
Acta Phys. Pol. 16, 423 (1957)
abstract
The Lagrange function is given for non-Newtonian equations of motion of charged particles in general relativity theory.
On Inversions of Space and Time
Acta Phys. Pol. 16, 435 (1957)
abstract
In this paper the transformation properties of spinors and pseudospinors with respect to inversions of space and time are investigated in some detail. In particular the various possible two-component theories are investigated. A purely geometrical approach to the theorem of Lüders and Pauli is pointed out.
The Application of the Tight Binding Method to the Investigation of Energy Bands in Hexagonal Close-packed Structure, II
Acta Phys. Pol. 16, 447 (1957)
abstract
In this work are given these terms in the matrix components of energy for hexagonal close-packed lattice, which contain E-integrals for the neighbour atoms from the second to the fourth.
Decay of Photoluminescence of Solutions
Acta Phys. Pol. 16, 471 (1957)
abstract
Several factors may cause the decay of photoluminescence to deviate from simple exponential law. Influence of some factors (depolarizing chocs in the case of gases, thermal rotations of luminescent molecules, quenching and self-depolarization of photoluminescence in the case of solutions) were studied in earlier papers. In the present theory a further factor is taken into account, this factor being the change produced by neighbouring like molecules of the probability of transition involved in emission of phosphorescence. Such changes occur in certain organophosphors investigated by Frąckowiak. The model of a luminescent centre, adopted in the present considerations, is the simplest one — a luminescent molecule, primarily excited by absorption of light, with some unexcited like molecules within its active sphere, the distribution of which among the centres being that of Smoluchowski. It is believed that the results may be a good approximation also in the case, in which the centres are in reality complexes of very loosely bound luminescent molecules mutually oriented at random. Expressions are obtained describing the decay of photoluminescence as well as those describing the decay time dependence of its polarization.
Abhängigkeit der Spinwellendispersion von der Magnetischen Struktur des Antiferromagnetischen Raumgitters
Acta Phys. Pol. 16, 481 (1957)