bluuebunny/crossref_metadata_2025 huggingface dataset:
THE CALCULATION OF THE ELECTRON–ION MATRIX ELEMENT BY THE SPHERICAL CELLULAR METHOD: Na
Authors: Taylor Rogert , Moore R. A. , Vosko Seymour H.
Published: April 2011

An accurate method is developed for the calculation of the "Schrodinger" part (in the ilotation of Vosko et al. 1965) of the electron–ion matrix element in the Wigner–Seitz spherical cell model. The rigid-ion model is used and the potential in the zero-order Hamiltonian is the sum of the free-ion potentials and the Hartree field of the conduction electrons. The Bloch wave function in a single cell is expanded in spherical waves and the matrix element is expressed as the product of an angular factor and an integral involvirlg the radial parts of the wave function, which for energy-conserving transitions may be expressed in terms of their values at the cell boundary. The radial parts of the wave functions are obtained by two methods: (1) the Kohn (1954) variational method and (2) A power series in k (Brooks 1958). The methods are applied to Na and converge to the same values, though the former converges considerably faster. The results indicate that the single orthogonalized plane-wave method gives a good representation of this matrix element in Na, while the Bardeen (1937) approximation does not, as is also demonstrated by explicit evaluation of the higher-order (in k) contributions neglected by Bardeen. The effective electron–ion matrix element is also calculated. In the course of the calculations a new theoretical value of the Fermi electron density at the nucleus (PF = 0.439a0−3) is obtained which is in closer agreement with recent experiments than previous theoretical estimates.
STRUCTURE OF THE BAND SPECTRUM OF THE CuI MOLECULE: II. ROTATIONAL STRUCTURE OF THE C AND D SYSTEMS OF 63Cu127I
Authors: Rao P. Ramakoteswara , Apparao K. V. S. R.
Published: April 2011

The C and D band systems of 63Cu127I, lying in the region 4 100–4 800 Å, have been photographed in emission under high resolution. Rotational analysis of the (0–0), (0–1), and (0–2) bands of the C system and the (0–0), (0–1), (0–2), and (0–3) bands of the D system has been made. The C and D systems are found to involve 1Σ (C1Σ)–1Σ(X1Σ)and 1Π(D1Π)–1Σ(X1Σ) transitions respectively. The Λ-type splitting in the D1Π state is small. The rotational constants obtained are as follows (cm−1 units):[Formula: see text]
RESOLUTION OF CLASSICAL CAPACITY PROBLEMS BY MEANS OF A DIGITAL COMPUTER
Authors: Greenspan Donald
Published: April 2011

A completely general, yet easy to follow, numerical method is developed for estimating the capacity of an arbitrary surface S. The essence of the method is to first apply inversion to an associated exterior Dirichlet problem and then to estimate the solution at the origin of the resulting interior Dirichlet problem. This estimate is an approximation of the capacity of S and is obtained on a digital computer by a currently popular numerical technique. Estimates of capacities of cubes, ellipsoids, lenses, and toroids are obtained, and, whenever possible, comparisons are made with results obtained by other methods.
HIGH-TEMPERATURE HALL EFFECT IN GaSb
Authors: Woolley J. C.
Published: April 2011

The anomalous high-temperature Hall data for GaSb are explained in terms of the effect of electrons in the [Formula: see text] conduction-band minima. By making reasonable assumptions about the mobility and effective mass of these electrons, values are determined for the zero-temperature energy separation of the [Formula: see text] and [Formula: see text] conduction-band minima and the temperature coefficient of the energy separation.
THE DETERMINATION OF METEOR MASS DISTRIBUTION FROM RADAR ECHO COUNTS
Authors: McIntosh B. A.
Published: April 2011

In relating the frequency distribution of the durations of radar echoes from meteor trails to the mass distribution of the meteoroid flux, two major effects must be taken into account. Because bright meteors tend to be observable by radar from any angle, the rate of long-duration echoes is enhanced relative to short-duration echoes. This effect is particularly pronounced for the Ottawa radar which has wide-beam antennas. On the other hand, the effect of electron attachment is to suppress the long-duration echo count, particularly for low-velocity meteors, which produce ionized trails at lower altitudes.The influence of both these effects on the observational results from the Ottawa meteor radar is examined quantitatively.
INDUCED INFRARED ABSORPTION OF DEUTERIUM IN DEUTERIUM – FOREIGN GAS MIXTURES
Authors: Pai S. T. , Reddy S. Paddi , Cho C. W.
Published: April 2011

The pressure-induced fundamental infrared absorption band of deuterium was studied in deuterium–helium, deuterium–argon, and deuterium–nitrogen mixtures at pressures up to 1 200 atm at room temperature. The enhancement absorption profile of each mixture shows a well-resolved splitting of the Q branch into two components QP and QR. While the enhancement contours of deuterium–helium mixtures do not exhibit any absorption peaks corresponding to the O and S branches, those of the other two binary mixtures show a pronounced S(2) peak and an indication of several other O and S peaks of the band. Integrated absorption coefficients of the band have been measured for all the mixtures, and the binary and ternary absorption coefficients were determined. The theory of Van Kranendonk and the available molecular parameters of deuterium and the perturbing gases were used to calculate the binary absorption coefficients of the individual lines of the O and S branches and of the quadrupole part of the Q branch of the band in all three binary mixtures. Using these calculated values and the experimental values of the total binary absorption coefficients of these mixtures, the overlap parts of the binary absorption coefficients of the Q branch were estimated.
ACCURATE ANALYTICAL SELF-CONSISTENT-FIELD (SCF) HARTREE–FOCK (H–F) WAVE FUNCTIONS FOR SECOND-ROW ATOMS
Authors: Malli Gulzari L.
Published: April 2011

Analytical H–F SCF wave functions have been calculated for the second-row atoms in their ground and lowest excited states. Expectation values for the various one-electron operators evaluated by using these wave functions are also presented. Tables of the basis-function orbital exponents, expansion coefficients, and the orbital energies of all the occupied atomic orbitals are given. Nuclear magnetic shielding constants and the magnetic susceptibilities for these atomic systems are also calculated.
THE a1Δ–X3Σ− SYSTEM OF NF
Authors: Jones W. E.
Published: April 2011

The 0–0 band of the a1Δ–X3Σ− transition of NF has been observed in the afterglow which results when NF3 and Ar are passed through a microwave discharge. The spectrum found in the region of 8 742 Å has been photographed on a 6-m concave-grating spectrograph. Analysis of the spectrum gives the rotational constants B0 = 1.222 5 cm−1 and r0 = 1.308 2 A for the a1Δ state and an improved value of A = 1.215 cm−1 for the ground state.
DIFFRACTION BY A NARROW SLIT IN THE INTERFACE BETWEEN TWO DIFFERENT MEDIA
Authors: Houlberg Karen
Published: April 2011

The two-dimensional problem of diffraction of a plane electromagnetic wave by a narrow slit in an infinitely thin, perfectly conducting screen between two different media is studied. The cases of both E and H polarization are considered. In the case of E polarization, a differential-integral equation is obtained for the unknown function in the slit; in the H polarized case, a pure integral equation is obtained for the unknown. These integral equations are solved by a perturbation technique and formal solutions are given in the form of series in powers of the ratio of slit width to wavelength, the coefficients of which depend on the logarithm of this ratio. Expressions are found for the transmission and back-scatter coefficients and some numerical results are given for special values of the parameters. Errors in earlier work (Barakat 1963; Stöckel 1964) are noted.
CROSS RELAXATION BETWEEN CR3+ IONS IN DILUTE POTASSIUM CHROMICYANIDE
Authors: Weissfloch C. F.
Published: April 2011

Cross relaxation between the 1/2 ↔ −1/2 paramagnetic resonance lines of the two nonequivalent complexes in dilute potassium chromicyanide has been studied, using a technique of cross saturation. The observed dependence of the cross-relaxation rate on frequency and concentration is in good agreement with Grant's theory of cross relaxation. The cross-relaxation rate between spins occupying nonequivalent sites is strongly affected by exchange coupling between nearest neighbors and the large gap between the nearest-neighbor and next-nearest-neighbor sites.
WAVE FUNCTIONS FOR THE GROUND STATE OF THE He2 MOLECULE
Authors: Barnett Gene P.
Published: April 2011

One- and two-configuration wave functions have been calculated for the He2 molecule over a range of interatomic separation from 3/4 to 6 atomic units. The one-electron basis consists of σ-type elliptical orbitals with the nonlinear parameters varied to minimize the total energy. The functions are formed with completely open shells and the complete set of singlet spin functions. The results give a good description of the system and compare favorably with other calculations.
A PARTIAL ANALYSIS OF A NONLINEAR ELECTROMECHANICAL SYSTEM, THE EXPLODING LOOP
Authors: Dodson C. T. J.
Published: April 2011

This paper presents a partial analysis and some restricted solutions of the problem of the exploding loop. The loop envisaged here is of the form of a narrow hairpin, whose open end may be connected to an electrical generator which produces short pulses in excess of 103 A. The magnetic field of a current-carrying loop of wire interacts with the loop. Such devices find application as special fuse elements and in the production of shock waves.The theory exploits the plausibility of symmetrical mechanical deformations of the loop and serves to demonstrate the physical results of nonlinearity in the mathematical model. Predictions are in quantitative agreement with the limited experimental data that are available from nondestructive tests.
COLD NEUTRON SCATTERING BY MOLECULAR LIQUIDS: III. METHANE
Authors: Sears V. F.
Published: April 2011

It is shown that a relationship exists between cold neutron scattering by simple molecular liquids and the corresponding infrared and Raman spectra of these substances. In particular, for liquids in which statistical correlations between the rotational and translational motion are negligible, the contribution of the rotational motion to the cold neutron scattering cross sections can be obtained from the infrared and Raman rotation–vibrational line-shape functions, thereby enabling one to interpret the observed cross sections directly in terms of the translational motion of the molecules. Numerical calculations are carried out for liquid methane and compared with recent observed cross sections.
STAGE II WORK HARDENING IN CRYSTALS
Authors: Hirsch P. B. , Mitchell T. E.
Published: April 2011

Current theories of work hardening in stage II of stress–strain curves of f.c.c. crystals are reviewed critically. A detailed account is given of a theory described previously in outline by Hirsch (1964).
THEORY OF INFINITESIMAL DISLOCATIONS DISTRIBUTED ON A PLANE APPLIED TO DISCONTINUOUS YIELD PHENOMENA
Authors: Weertman J.
Published: April 2011

An analysis is made of the behavior of groups of dislocations in a slip band, when the frictional stress that hinders dislocation motion undergoes a static or a dynamic drop. A static stress drop is the lowering of a frictional stress that decreases with increasing displacement across the slipped zone; a dynamic stress drop is associated with a frictional stress that decreases with increasing velocity of displacement. It is shown that the presence of a static stress drop can lead to the upper and lower yield point phenomena, even if the stress drop is very gradual. The dynamic case leads to the Portevin–Le Chatelier effect (serrated stress–strain curves). According to this analysis, the Portevin–Le Chatelier effect has its origin in the inherent instability of a boundary separating dislocations that are acted upon by a high frictional stress from those acted upon by a low frictional stress.
SLIP PLANES IN Fe – 3% Si SINGLE CRYSTALS DEFORMED AT 77 °K
Authors: Šesták B. , Zárubová N. , Sládek V.
Published: April 2011

Macroscopic slip planes were determined on specimens of different orientations, cut from a single crystal of Fe – 3% Si alloy after slow deformation [Formula: see text] by four-point bending at 77 °K. On the compression side of the specimens with orientations [Formula: see text] the slip planes were found to be very close to those with maximum resolved shear stress. On the compression side of the specimens with [Formula: see text] and on the tension side of specimens with [Formula: see text] (except the specimens with χ = ±30°) either crystallographic slip along {110} planes or large deviations of slip planes from maximum resolved shear stress planes to {110} planes were observed. The ψ(χ) curves obtained at 77 °K are compared with those obtained similarly at room temperature. The ψ(χ) curves for 77 °K cannot be explained microscopically on the basis of the composite slip on {110} and {112} planes if only the effect of the slip sense is assumed.
THE EFFECT OF ORIENTATION AND IMPURITIES ON THE MECHANICAL PROPERTIES OF MOLYBDENUM SINGLE CRYSTALS
Authors: Stein D. F.
Published: April 2011

Molybdenum single crystals containing less than 10 p.p.m. of carbon, 5 p.p.m. of nitrogen, and 5 p.p.m. of oxygen have been prepared by zone melting and hydrogen gas purification. The mechanical properties of the crystals have been measured in tension and compression over a range of temperature from 20 to 298 °K. It was found that the critical resolved shear stress and the temperature dependence of the critical resolved shear stress decreased with increasing purity. It was found that at all test temperatures the CRSS law fails. The critical resolved shear stress is a minimum in the (100) tension axis orientation and reaches a maximum with the tensile axis along the (110)(111) line of the stereographic triangle. It was also found that the ductility of molybdenum single crystals was not improved by purification.
MEASUREMENTS OF THE VELOCITY OF SOUND IN LIQUID ARGON AND LIQUID KRYPTON
Authors: Lim C. C. , Aziz R. A.
Published: April 2011

The velocity of sound in liquid argon and liquid krypton has been measured in the temperature range between their normal boiling points and their triple points, using a tube acoustic interferometer. The results for argon agree with those of most other investigators to within 0.2%. There are no velocity data for liquid krypton. Compressibilities for these liquids have been calculated, using available density data.The results were analyzed, using a law of corresponding-states treatment in the temperature interval under consideration. To within the limits of uncertainty in the Lennard-Jones 6:12 potential parameter ε, the law is found to be obeyed.
NUCLEAR MATTER AND THE LONG-RANGE PART OF THE NUCLEON–NUCLEON POTENTIAL
Authors: Pearson J. M.
Published: April 2011

Elementary nuclear-matter calculations are performed with five different central nucleon–nucleon potentials. These are all static with a hard core of radius 0.4 fm and an OPEP tail, but are characterized by vastly different forms in the intermediate region. It is concluded that nuclear matter is insensitive to the precise form of the central part of the nucleon–nucleon potential everywhere beyond the short-range repulsive region, provided the nucleon–nucleon data are well fitted.
SOME DIELECTRIC AND ELECTRONIC PROPERTIES OF CdSe FILMS
Authors: Brodie D. E. , LaCombe J.
Published: April 2011

The real part of the dielectric constant, K′, has been measured for high-resistivity films of CdSe at temperatures between 4.2 and 240 °K, at frequencies between 500 Hz and 50 kHz. Typically, its value is 9.0 at 4.2 °K, 9.5 at 77 °K, and it increases slowly with temperature to 10.0 at 240 °K. Within experimental error it is independent of frequency in the above range.The electrical resistivity of vacuum-deposited CdSe films has been investigated to determine the effect of substrate temperature, deposition rate, film thickness, sample aging, and heat treating. Measurements of film resistivity variations with temperature from 125 to 350 °K reveals the presence of two activation energies in the lower-resistivity films, but only one in the high-resistivity films in this temperature range.
THE TEMPERATURE DEPENDENCE OF THE ENERGY LEVELS OF SHALLOW DONOR IMPURITIES IN SILICON
Authors: Cheung C. Y. , Barrie Robert
Published: April 2011

A calculation is made of the temperature dependence of the energy levels of shallow donor impurities in silicon. This temperature dependence arises from the electron–phonon interaction and we consider mixing only of the {1s}, {2s), and {2p0} electronic states. A comparison is made with experiment for the case of phosphorus-doped silicon.
EFFECT OF FINITE ION LARMOR RADIUS ON THE STABILITY OF SUPERPOSED FLUIDS
Authors: Kalra G. L.
Published: April 2011

The effect of finite ion Larmor radius on the problem of stability of incompressible and infinitely conducting superposed fluids is investigated for a general direction of perturbation. It is found that whereas the interchange perturbations are stabilized in the presence of Larmor radius, the noninterchange perturbations (which affect the ambient magnetic field) lead to overstability due to Larmor radius effects in a configuration (unstable in the absence of magnetic field) stabilized by a strong enough magnetic field. The configuration which is monotonically unstable in the absence of Larmor radius now, in addition, exhibits overstable modes. Similar conclusions are obtained in the presence of vortex sheet as well.
LATTICE DYNAMICS OF NICKEL
Authors: Singh S. P.
Published: April 2011

The vibration spectrum of the nickel lattice has been calculated using the simple de Launay method with values for the effective force constants determined from published experimental data for the elastic constants. The density-of-states curve reproduces the same general features found by Birgeneau et al. (1964) using a fourth-neighbor model. The Debye temperature at 0 °K is found to be 474 °K in good agreement with the experimental value of 468 °K, and the calculated variation of the Debye temperature with temperature agrees quite well with that deduced from measurements of the specific heat.
ENERGY LEVELS IN THE STATISTICAL ATOM WITH EXCHANGE AND CORRELATION
Authors: Jain Ashok , Kumar Satish
Published: April 2011

In this paper, quantum numbers are introduced in a statistical model of atoms that includes the correlation and the exchange terms (TFDC model). Two different types of angular momentum assignments have been introduced into the model and, as an application of this, the single-particle energy levels of the argon atom in its ground state have been calculated. A simple relativistic generalization of the present formalism is discussed and is shown to give better agreement with experimental values. Finally, some suggestions for improvement of the present formalism are made.
A STUDY OF THE GAMMA RADIATION FOLLOWING THERMAL NEUTRON CAPTURE BY SILICON
Authors: Lycklama H. , Hughes L. B. , Kennett T. J.
Published: April 2011

A study of the gamma radiation following thermal neutron capture by natural silicon has been conducted. Precise energy measurements were obtained using a Ge(Li) counter and a decay scheme was constructed using the time correlation results obtained with a Ge(Li)–NaI(Tl) spectrometer. The neutron separation energy was found to be 8 474 ± 1 keV for 29Si. An examination of the reduced radiation widths revealed that, while E1 and E2 radiation agreed well with the single-particle estimate, the M1 strength was hindered by a factor of from 10 to 100.
THE DISTRIBUTION OF ABSORBED ENERGY FROM A POINT BETA SOURCE
Authors: Cross William G.
Published: April 2011

The distribution of absorbed energy/g (dose) around a point source in a homogeneous medium has been measured for a variety of beta emitters in air, argon, ethane, and expanded polystyrene. At short distances the dose falls off faster than 1/r2, contrary to the results of measurements in solids but in agreement with previous measurements in air for maximum beta energies below 1.6 MeV. Except at short distances, distributions in different media differ only by a constant scaling factor on distance (mg/cm2) that is the same within ± 1% for all beta energies considered, but that is not proportional to electron density. Except close to the end of the range, the absolute doses calculated from Spencer's numerical solutions of the transport equation agree with the measured values within about ± 4%, for maximum beta energies from 0.16 to 3.58 MeV and for a wide variety of spectral shapes. The calculations predict correctly the observed variation of attenuation with the atomic number of the medium.
SOME REACTIONS FORMING IN THE UPPER ATMOSPHERE
Authors: Arnold S. J. , Ogryzlo E. A.
Published: April 2011

The rate constant for the energy pooling reaction,[Formula: see text]has been determined. The value of 2 × 10−18 cc2 sec−1 obtained is several orders of magnitude too small to account for the formation of [Formula: see text] in the nocturnal upper atmosphere. An alternative mechanism for [Formula: see text] formation is proposed and its consistency with available data is discussed.
HARTREE–FOCK WAVE FUNCTIONS FOR EXCITED STATES: IV. OSCILLATOR STRENGTHS IN THE HELIUM ISOELECTRONIC SEQUENCE
Authors: Cohen Maurice , Kelly Paul S.
Published: April 2011

Orbital wave functions for a number of singlet and triplet S, P, and D states of the helium sequence through C+4 have been calculated using an approximation described earlier. The wave functions have been employed to calculate the oscillator strengths for all allowed dipole transitions between these states, using both the length and velocity forms of the transition matrix element. Our results are in good agreement with the most accurate values available.
PROPERTIES OF THE 7.02-MeV AND 10.65-MeV LEVELS OF 20Ne
Authors: Smulders P. J. M. , Broude C. , Litherland A. E.
Published: April 2011

The 7.02-MeV level of 20Ne has been studied by the I2C(12C, αγ)20Ne reaction, using angular correlation techniques, with a particle counter and six Nal crystals. The spin and parity of this level were determined to be 4−. The branching ratio of the decays to the 5.63, 4.97, and 4.25 MeV levels was found to be 22:65:13. The transition to the 5.63-MeV state (4− → 3−) is an almost pure E2 transition with an M1/E2 amplitude ratio of 0.03 ± 0.03. The branching ratio of the E2 transitions to the 5.63-MeV 3− level and the 4.97-MeV 2− level is in excellent agreement with predictions from the rotational model and also with SU3 calculations.Similar measurements on the 10.65-MeV level in 20Ne support the tentative 6− assignment to this level.
FIELD OF A LINE SOURCE SITUATED PARALLEL TO A SURFACE-WAVE STRUCTURE COMPRISING A PAIR OF UNIDIRECTIONALLY CONDUCTING SCREENS
Authors: Arora R. K.
Published: April 2011

The problem of radiation from an electric line source situated parallel to a surface-wave structure composed of a pair of parallel unidirectionally conducting screens is considered. The screens are conducting in directions making angles α and — α, respectively, with the x axis, while the line source is directed parallel to the γ axis and is located either above or between the two screens. The problem is resolved as the superposition of symmetrical and antisymmetrical sources, since either of the two surface-wave modes that can be supported on the structure is associated with an appropriate type of excitation. Both surface-wave modes are excited in the superposed case of a line source.The radiation field is evaluated and, under suitable conditions, is seen to exhibit sharp peaks. The correspondence of these peaks with complex poles in the integral representation of the field is demonstrated. It is further observed that, when the line source is situated above the structure, the amplitude of the field components in the lower half-space is independent of the location of the source, although the phase is affected. The surface-wave power is determined and it is shown that high values of launching efficiency are readily attainable.
POLARIZATION CAPACITANCE AND DISTORTION IN KBr AT LOW FREQUENCIES
Authors: Wintle H. J.
Published: April 2011

A bridge to measure high impedances in the frequency range 0.01 to 100 Hz is described. The conductance and capacitance of calcium doped KBr single crystals were measured between 50 and 330 °C. The polarization capacitance was not inversely proportional to the square of the thickness, a condition expected from the linearized theory. Severe harmonic distortion was observed at low frequencies, and was attributed to the onset of space-charge control following completion of a vacancy monolayer at the surface, forming a blocking boundary. At the higher frequencies this monolayer is not completed, the crystal boundaries are not blocking, and distortion is not observed. An expression is derived for the limiting frequency at which distortion sets in, and is shown to be in good agreement with experiment.
NONLEPTONIC DECAYS OF HYPERONS
Authors: Murtaza G. , O'Donnell P. J.
Published: April 2011

The s- and p-wave mesonic decays of hyperons are studied in the context of a general Hamiltonian of a current × current type. The form of the Hamiltonian chosen allows a distinction to be made between the ΔI = 1/2 and ΔI = 3/2 contributions and thus clarifies the role of octet enhancement vis à vis that of the ΔI = 1/2 rule. A simple assumption, less restrictive than octet dominance, about the Hamiltonian yields all the ΔI = 1/2 rules for both s- and p-wave decays and the result that Σ+ → nπ+ decay is purely p wave. A new sum rule is also obtained which determines, fairly accurately, the ratio F/(D + F) for Yukawa-type coupling, giving the result 0.356 ± 0.068.
EFFECTS OF QUASI-LINEARITY IN SOME SIMPLE BENT MOLECULES
Authors: Johns J. W. C.
Published: April 2011

A formalism suitable for the quasi-linear molecule, originally proposed by Thorson and Nakagawa, has been applied to an excited state of HCN and also to the lowest bent states of H2O, NH2, CH2, and BH2. The effects of "quasi-linearity" in these molecules gives rise to large anharmonicities in the bending vibrations. The calculations described in this paper lead to values of DK and αA which are in good agreement with experiment.
THE ELECTRON SPIN RESONANCE OF VO2+ IONS IN TWO TYPES OF ALUMINIUM ALUMS
Authors: Manoogian A. , MacKinnon J. A.
Published: April 2011

The electron spin resonance spectrum of the vanadyl ion VO2+ is studied in single crystals of RbAl(SO4)2.12 H2O and CsAl(SO4)2.12 H2O, at room temperature and in the 9.2 kMc/s microwave frequency range. In RbAl(SO4)2.12 H2O the V–O axes are found to have three orientations directed along the cubic crystallographic axes, giving rise to three magnetic complexes. The spin Hamiltonian parameters are S = 1/2, [Formula: see text], [Formula: see text], [Formula: see text] cm−1, and [Formula: see text] cm−1. In CsAl(SO4)2.12 H2O the V–O axes are displaced from the crystallographic axes, giving rise to 12 magnetic complexes. The spin Hamiltonian parameters are S = 1/2, [Formula: see text], [Formula: see text], [Formula: see text] cm−1, and [Formula: see text] cm−1. The observed spectra are attributed to a vanadyl pentahydrate complex (VO2+.5 H2O) associated with a water-molecule vacancy.
PHOTOLUMINESCENCE EFFICIENCY AND PHOTOCONDUCTIVITY IN CADMIUM SULFIDE
Authors: Nyberg D. W. , Colbow K.
Published: April 2011

The photoluminescence efficiency and photoconductivity response of high-purity cadmium sulfide crystals were measured and interpreted in terms of a simple model involving only the donor and acceptor levels previously established, an effective surface recombination velocity, and a bulk nonradiative recombination rate. The measurements at 64 and 78 °K included the effects on the photoluminescence efficiency of varying the excitation intensity and the wavelength of the excitation light, applying electric fields, removing chemically adsorbed oxygen ions from the surface, and of different acceptor concentrations. It was established that the surface does play an important role in reducing the photoluminescence efficiency and photoconductive response, and that the photogenerated carriers do not diffuse significantly into the interior of the crystal.
ON THE TRANSMISSION CROSS SECTION OF A SLIT IN AN ANISOTROPIC MEDIUM
Authors: Jull E. V.
Published: April 2011

Expressions for the transmission cross section of an infinite slit excited by an H-polarized plane wave in a gyrotropic medium such as a plasma with a magnetostatic field parallel to the slit edges are obtained. For normal incidence these are similar to the isotropic form of the cross-section theorem and some numerical results are presented for a wide slit. They suggest that greatly enhanced power transmission through the slit occurs in a particular frequency range in the plasma.
PATTERN OF A LINEAR ANTENNA ERECTED OVER A TAPERED GROUND SCREEN
Authors: Wait James R.
Published: April 2011

A theory is presented for the radiation from a thin vertical antenna located above and at the center of a sector ground system. The formulation is carried out for a general variation of the surface impedance of the system. To facilitate discussion, certain limiting cases are considered in some detail. Of special interest is the possibility that the low-angle radiation pattern of an h.f. antenna over a dielectric-type ground will be vastly improved by using a ground screen whose surface impedance varies exponentially, in the radial direction, from the base of the antenna.
PHOTOPROTON YIELDS FROM THE TITANIUM ISOTOPES
Authors: Pai H. L. , McNeill K. G.
Published: April 2011

Measurements have been made of the yields of protons ejected as the first particle after excitation of nuclei of the titanium isotopes by bremsstrahlung of 22 and 30 MeV energy. It is found that for 47Ti, 48Ti, and 49Ti, a constant-temperature compound-nucleus model fits the experimental data, the nuclear temperature being the same as that found to give a good fit to (n, p) data. 50Ti, however, has a relatively high yield, and it is suggested that this is due to direct emission.
GERMANIUM TOTAL ABSORPTION SPECTROMETER FOR 100-MeV PROTON SCATTERING
Authors: Horowitz Y. S. , Sherman N. K.
Published: April 2011

A lithium-drifted germanium total absorption spectrometer has been constructed and used to achieve an energy resolution of 0.49 ± 0.05 MeV in proton-scattering experiments at 100 MeV.
ABUNDANCE ANOMALIES PRODUCED BY NUCLEAR REACTIONS IN STELLAR SURFACE LAYERS: II. RESULTS AND COMPARISON WITH ANOMALIES IN PECULIAR A STARS
Authors: Brancazio P. J. , Cameron A. G. W.
Published: April 2011

A normal solar abundance distribution of the elements was subjected to a calculated bombardment by protons and alpha particles having energy spectra of the form E−n, where n was usually taken to be equal to 2.5, and having low-energy cutoffs on the spectra at 1 MeV. Bombardment with protons resulted in breakdown of nuclei to lower mass numbers. Bombardment with alpha particles resulted in buildup of nuclei to higher mass numbers. It is concluded that preferential acceleration of alpha particles to varying total fluxes can produce the abundance anomalies of peculiar A stars in concentrated patches on the surface. Local surface magnetic fields in the range 106–107 G are required to provide the necessary energy sources for the accelerated particles.
EFFECTS OF STRONG INTERACTIONS AND FINITE NUCLEAR CHARGE RADIUS IN PIONIC ATOMS
Authors: Fulcher L. P. , Eisenberg J. M. , LeTourneux J.
Published: April 2011

For studies involving the interaction of bound pions with the atomic nucleus, it is essential to investigate details of the pionic wave function at the nucleus. These are especially important for the1S orbitals, where both the repulsive strong interaction and the effects of finite nuclear charge radius are important. We present calculations based on the use of a square-well potential to simulate the strong interactions. The nuclear charge distribution is taken to be that of a uniformly charged sphere. The corresponding Schrödinger equation is solved exactly. The square-well radius is taken to be the same as the nuclear radius, and its strength is chosen so as to obtain agreement with the observed 2P−1S energy differences. For light nuclei, the probability of finding the meson in the nucleus is found to be approximately one-fourth to one-half that calculated with conventional hydrogenic wave functions.
THE PROTON MAGNETIC RESONANCE OF HgSO4∙1H2O
Authors: Lobo Jr. P. W. , Messa J. P.
Published: April 2011

The proton magnetic resonance spectrum of single crystals of HgSO∙1H2O has been investigated. This crystal is of interest since, according to the X-ray structure analysis, it appears likely that one of the protons of the water molecule is hydrogen-bonded in the structure, while the other is free. Two non-equivalent sets of parallel H–H vectors have been observed in agreement with the crystal symmetry. The angles of one of the intramolecular H–H vectors with the crystallographic axes are α = 58°, β = 95°, and γ = 36°. The results are consistent with the suggestion that one of the protons does not form a hydrogen bond in the crystal.
INTERACTION OF ACOUSTIC WAVES WITH POLARIZATION WAVES IN FERROELECTRICS
Authors: Dvořák V.
Published: April 2011

An expression for effective elastic constants which control the behavior of acoustic waves interacting with polarization waves in ferroelectrics is derived using the linear response theory. If interactions due to the piezoelectric effect only are taken into account, then the frequency and space dispersion of effective elastic constants are essentially determined by those of the linear dielectric susceptibility. Some consequences of this direct relation between the elastic and dielectric properties of ferroelectrics are discussed for the ultrasonic attenuation and the Brillouin or neutron scattering by acoustic waves.
Projected ranges of light ions in heavy substances
Authors: Schiøtt Hans E.
Published: April 2011

Computer programs have been worked out for the calculation of projected ranges of low-energy ions by means of the theory of Lindhard, Scharff, and Schiøtt. The stopping substance is assumed to be a random system, and may consist of several elements. In the case of a monatomic stopping substance, the program includes a calculation of the straggling in projected range. Comparisons are made with measurements of projected ranges, from which semiempirical estimates of electronic stopping may be made.
Scattering of keV protons from copper surfaces
Authors: Behrisch R.
Published: April 2011

For protons of 40 to 120 keV energy impinging on the surface of a copper single crystal, the energy and angular distributions of the backscattered hydrogen atoms were measured, especially in and around the [Formula: see text] direction.
Thermal release of inert gases from tungsten: Dependence on the crystal face bombarded
Authors: Kornelsen E. V. , Sinha M. K.
Published: April 2011

Flat (100), (110), and (211) faces of tungsten were bombarded in ultrahigh vacuum with inert-gas ions having energies up to 5 keV. The rate of release of the entrapped gas was then measured as the crystals were heated at 40 °K/s by electron bombardment. The spectra of release rate vs. temperature consist of a series of maxima which show distinctive variations with the type, energy, and number of the incident ions, and with the crystal face on which they impinge. Evidence is presented that the peaks at T < 1600 °K are associated with gas atoms trapped within a few lattice constants of the crystal surfaces, the binding energies being determined by characteristic arrangements of the lattice atoms about the trapping site. The gas release at T > 1600 °K is consistent with the diffusive motion of more deeply penetrating particles as impurities in the bulk of the crystal, the expected variations of penetration depth with energy and crystallographic direction being clearly evident. Evidence is also presented that for sufficiently high trapped neon atom concentrations, gas release can occur by the diffusive motion of two or three atom clusters.
Irradiation damage in aluminium single crystals produced by 50-keV aluminium and copper ions
Authors: Henriksen L. , Johansen A. , Koch J. , Andersen H. H. , Leffers T. , Cotterill R. M. J.
Published: April 2011

Aluminium single crystals, thin enough to be examined by electron microscopy, have been irradiated with 50-keV aluminium and copper ions. The irradiation fluxes were in the range 1011–1014 cm−2 s−1 and the doses were from 6 × 1012 to 6 × 1014 cm−2. Irradiation along either a [Formula: see text] or a [Formula: see text] direction produces rows of dislocation loops all lying parallel to one particular [Formula: see text] direction. If the aluminium target is quenched from 600 °C and annealed at room temperature prior to irradiation with aluminium ions, the rows of loops are suppressed. The amount of damage observed is considerably less than would be expected from isotropic damage theory.
The penetration of lattice defects in copper and gold foils bombarded with 1–5 keV argon ions
Authors: Diehl J. , Diepers H. , Hertel B.
Published: April 2011

Single crystalline copper and gold foils are bombarded with 1–5 keV argon ions. Transmission electron micrographs of the bombarded foils show black spots, which are caused by small interstitial agglomerates. Measurements of the spatial distribution of these agglomerates, carried out by means of a special stereo technique, indicate that the average distance of the agglomerates from the bombarded surface is much higher than the calculated range of the Ar ions. From the variation of the depth distribution of the agglomerates with the orientation of the foil and with the ion energy, it is concluded that the interstitial atoms, which form the agglomerates, penetrate into the lattice by means of focusing collisions. Tentative conclusions on the ranges of the focusing collision chains which transport matter (dynamic crowdions) are discussed.
Influence of temperature on phosphorus ion behavior during silicon bombardment
Authors: Glotin Philippe M.
Published: April 2011

Silicon samples have been bombarded with 20-keV phosphorus ions along the easy channeling direction. Annealing temperatures and activation energies of the defects created during irradiation have been determined using a Corbino structure. The nature of the defects varies as a function of depth. Large clusters exist in the superficial layers when mainly E and A centers have been identified in the channeled part of the profile. The influence of these defects on ion ranges is shown. The most important consequence of this study is to indicate a useful temperature range, between 550 and 650 °C, for phosphorus implantation into silicon.
Some regularities of ion-beam interactions with semiconductors
Authors: Mashkova E. S. , Molchanov V. A.
Published: April 2011

During the last few years, various regularities of ion interaction with crystals have been studied, and a number of effects, caused by the regular arrangement of the target atoms, have become apparent. It is interesting that a suitable interpretation of the observed crystal lattice effects can be produced on the basis of the perfect crystal. At first glance this is surprising, since it is known that ion bombardment causes radiation damage, thereby disturbing the regular arrangement of the lattice atoms. The success of the concept of the ideal crystal is determined by the fact that the conditions of many experiments permit rapid annealing of the defects caused by the ion bombardment. In order to prove this assumption, it was necessary to make measurements over a wide temperature range, including the annealing temperature. Semiconductor crystals are the most suitable materials, because their annealing temperatures are high enough. These temperatures are easily obtained and controlled under usual ion-bombardment conditions. Germanium and silicon monocrystalline targets were chosen. The targets were bombarded by 30-keV ions of the noble gases. The temperature range studied was from about 100 to 700 °C. The influence of temperature on the angular regularities of the secondary electron-emission coefficient and on the energy distributions of the scattered ions was investigated. Two strongly different types of ion–electron emission and of scattering regularities were established. At comparatively high temperatures, there are typical anisotropies of the secondary electron-emission coefficient and the "double"-scattering peaks in energy distributions, caused by regular arrangement of the target atoms. At lower temperatures, the normal polycrystalline dependences are observed, i.e., the secondary electron coefficient increases monotonically with increasing incident angle, and the "double"-scattering peak is smoothed out. It has been established that the dependences usually observed with polycrystals change sharply to those observed with single crystals within a small temperature range around the defect annealing temperature. Thus, the concept of the ideal crystal may be used for interpreting the results of ion interactions with crystals, provided the measurements are made at temperatures higher than the annealing temperature of the defects.
Sputtering efficiency of amorphous substances
Authors: Sigmund Peter
Published: April 2011

Sputtering efficiency is denned as the fraction of bombarding ion energy leaving a crystal via sputtering and backscattering. This quantity is calculated for the case of perpendicular incidence on a random medium with plane surface. Use is made of the spatial distribution of deposited energy as calculated by Sanders and the author. In the elastic collision region but above about 1 keV, the sputtering efficiency is predicted to be essentially independent of ion energy and to depend only on the mass ratio. For self-sputtering it should be 2.4% and increase with decreasing ion mass. The predictions appear to be consistent with existing experimental results, but a few direct checks are desirable. Qualitative arguments suggest that, in the case of single crystals, lattice effects with respect to the incoming beam are more pronounced in the sputtering efficiency than in the yield. Reversely, ejection patterns of sputtered energy should reveal less influence of lattice structure than those of sputtered intensity. The latter result is consistent with experiment.
Mass and energy analysis of positive ions emitted from metallic targets bombarded by heavy ions in the keV energy region
Authors: Jurela Z. , Perović B.
Published: April 2011

Mass spectra of positive ions emitted from polycrystalline metallic targets (Al, Mn, Co, Ta) were analyzed by the mass spectrometric method when the targets were bombarded by the analyzed Ar+ ion beam of 40-keV energy. Single- and multiple-charged atomic components, as well as single-charged molecular components, were detected. The energy distribution curves for some mass-spectra components, measured by the retarding potential method, are presented.
Note on the primary energy spectrum
Authors: Pointe M. La , Kamata K. , Gaebler J. , Escobar I. , Domingo V. , Suga K. , Murakami K. , Toyoda Y. , Shibata S.
Published: April 2011

The Mt. Chacaltaya air shower array in Bolivia has been used to collect data suitable for deriving the primary energy spectrum above 1014 eV. The spectrum was reported at the London Conference (Bradt et al. 1966). Since that time the array has been used to record showers above 107 particles in size. This note reports the results of the increased statistics on the upper end of the spectrum and also describes the results of some calculations designed to verify the validity of the method used. The spectrum reported previously is not changed appreciably by these considerations.
Atmospheric effects and sidereal variations of EAS
Authors: Efimov N. N. , Krasilnikov D. D. , Nikolsky S. I. , Shamsutdinova F. K.
Published: April 2011

The results of observations, made during 1959–64, on intensity variations of EAS of mean sizes 1.4 × 104 to 1.4 × 105 particles at sea level are reported. Variations of shower size caused by fluctuations in pion decay have been observed and these correlate with density variations in the atmosphere. The corrected sidereal rate shows no evidence for anisotropy of the arrival directions of showers.
The muon component of large extensive air showers
Authors: Earnshaw J. C. , Orford K. J. , Rochester G. D. , Turver K. E. , Walton A. B.
Published: April 2011

Further measurements are reported on the momenta and densities of muons in EAS using the Haverah Park solid iron magnet spectrograph. The observational data are based on measurements of 5 000 muons in the momentum range 1–100 GeV/c at distances 10–700 m from the cores of showers of size 105–108 particles. The results are compared with the predictions of recent models for the nuclear cascade. A possible explanation for the excess of high-momentum particles observed is the occurrence of secondaries with large transverse momenta.
Experimental work on radio pulses at Haverah Park
Authors: Allan H. R. , Neat K. P. , Jones J. K.
Published: April 2011

Radio pulses from extensive air showers have been observed at two receiver frequencies, 60 MHz and 32 MHz. The observations on pulse amplitude suggest that coherence at the higher frequency depends on favorable fluctuations in shower development, and that the coherent amplitude is proportional to the shower energy. The observed polarization at 32 MHz from a single large shower strongly favors a geomagnetic origin of the radiation.
Radio signals from air showers at 22 MHz
Authors: Prescott J. R. , Palumbo G. G. C. , Galt J. A. , Costain C. H.
Published: April 2011

Radio pulses from extensive air showers (EAS) have been observed with a 4 × 4 array of dipoles polarized E–W at a center frequency of 22.25 MHz and an effective bandwidth of 4 MHz. Observations were made simultaneously with antenna beams centered 30 °N and 30 °S of the zenith. The magnetic dip angle being 72°, the north beam faced across the geomagnetic field lines whereas the south beam faced along the field lines. In 600 hours of observation, 1 100 showers were recorded. Two 1-m2 plastic scintillators placed 30 m apart, in coincidence, triggered the cathode-ray-oscillograph recording system.Traces were scanned for 1 μs on either side of the expected location of the radio signals. Background levels were determined by scanning an interval of 0.75 μs, 3.5 μs after the beginning of the trace. Pulses were recorded on both antenna beams. Those on the north-pointing antenna were, on the average, twice as large as those on the south-pointing one. The results suggest that while charge separation in the earth's field is more important than charge excess in generating showers, it is not dominant.
The further study of MPP by means of a large spark calorimeter
Authors: Bibilashvili M. F. , Barnaveli T. T. , Grubelashvili G. A. , Muradova N. A. , Khaldeeva I. V.
Published: April 2011

New data are given on the energy of penetrating particles in MPP and their angular distribution at a depth of 200 m.w.e. The data were obtained by means of a large spark calorimeter with high angular resolution.
Search for quarks in cosmic rays at sea level
Authors: Hanayama Y. , Hara T. , Higashi S. , Kitamura T. , Miono S. , Miyamoto S. , Nakagawa M. , Ozaki S. , Takahashi T. , Tsuji K. , Watase Y.
Published: April 2011

A search has been made for fractionally charged particles in cosmic rays by using a telescope composed of 5 scintillation counters and 16 wire spark chambers. The geometric factor for acceptance of particles is 5 200 cm2 sr. Wire chambers are used to ensure that one and only one charged particle has passed through the counters. During about 800 hours of observation no event has been found which could be accepted as due to the passage of quarks. The upper limit of their intensity in cosmic rays is placed at 3.1 × 10−10 cm−2 sr−1 s−1.