Table of contents

A theory is developed from two postulates: that the speed of light is invariant, and that any two synchronized clocks which are separated will again agree on reuniting. The existence of a preferred inertial frame is demonstrated and the coordinate transformations for non-uniform motion are obtained and used in an analysis of a return journey to elucidate further the clock paradox. With electrodynamics and mechanics as examples it is shown that physical laws are invariant in the special case of uniform motion and consequently that many of the arguments alleged to demonstrate special relativity do not in fact do so. However, in the case of non-uniform motion the theory appears to have an inherent restriction to events on the common path of observers with rectilinear motion, and until this restriction can be removed the physical validity of the theory is doubtful.

A band of the CaH molecule has been observed in the ultra-violet region of the spectrum with its P head at 2720 Å. The analysis showed that the band is the (0, 0) band of a new system belonging to F²Σ → X²Σ transition. The fact that the band has appeared only in absorption and not in emission at ordinary pressures shows that the upper state of the molecule is predissociated. This is also confirmed by the very diffuse nature of the rotational lines. It has been suggested that the predissociation is caused most probably by a ⁴Σ or ⁴II term originating from the first ³D atom term. In addition, a diagram showing correlation of the observed molecular states to the atomic states of some of the analogous molecules is given.

The rotational constants of the F²Σ → X²Σ band are given below:

B₀' = 4.70 cm^-1

B₀" = 4.24 cm^-1

v₀₀' = 36793.60 cm^-1

A new band system in ZnH, with its corresponding analogue in ZnD, at 2426.46 Å (0, 0 band) has been observed and analysed. The analysis showed that the transition is of the C²Σ → X²Σ type. The rotational lines observed (in absorption) are very diffuse and therefore it is concluded that the upper state is predissociated. It has been suggested that the predissociation is caused by a quartet state. The dissociation in this case will therefore lead to ³P + ²S atom states.

Rotational constants are calculated.

The spectrum of singly ionized argon was investigated using a 2450 Mc/s electrodeless discharge operated in a magnetic field of strength up to 24 000 gauss, and was found to be strongly enhanced by this field. Landé g-factors are given for energy levels based on the 3p⁴(³P)3d configuration in A II, for which close agreement with the theoretical values to be expected on the basis of LS coupling is found.

Recent theoretical and experimental values of the cross section for the photodetachment of the negative hydrogen ion are checked for consistency with a number of sum rules. Attention is drawn to the unusually large cross sections to be expected for the photodetachment process in which the final state of the hydrogen atom is in the 2s state.

The radial electric field in the positive column, which is needed to promote ambipolar diffusion, is shown to be given to a good approximation by a second-order linear differential equation as the next stage beyond the Schottky approximation.

Microwave resonant cavity techniques have been used to investigate the afterglows of low pressure pulsed discharges in argon, helium and neon. The values for the reduced mobilities of the various ions in their parent gases, derived from the ambipolar diffusion coefficients, disagree with previous microwave measurements but are in close agreement with the accepted drift tube values which cover a wide range of E/p.

The mobilities of the various ions in their own gases were found to be He⁺, 10.2; He₂⁺, 20.3; Ne⁺, 3.9; Ne₂⁺, 7.5; Ar⁺, 1.4; Ar₂⁺, 2.6 cm² v^-1 sec^-1. The average energy of electrons and ions, during measurement, was 0.04 ev. Finally, diffusion cooling was observed in argon and neon.

The motion of non-relativistic test charges is studied for a class of fields (arising, for example, in cavity resonators) which oscillate with a high frequency ω comparable with or greater than the local peak gyromagnetic frequency ω_g of the charges. Thus the recently developed methods based upon ω « ω_g are supplemented whenever the (variable) magnetic field so confines the charges that the total field may be regarded as locally homogeneous. Rapidly converging expansions involving integral order Bessel functions J_n(ω_g/ω) as coefficients are used to obtain asymptotic expressions for the kinetic energy limited by a simplified collision term in Lorentz's equations of motion. Kinetic energy resonances, reminiscent of the action of the betatron, arise for certain values of the critical ratio ω_g/ω, notably near the peaks of [(ω_g/ω)J₁(ω_g/ω)]².

Randomization of the energy and direction of an electron beam by interaction with a plasma often commences abruptly, with onset of electron oscillations, at a distance (D) of a few mm from where the beam enters the plasma. Measurements of D have been made in He, Ne, A and Hg, as a function of pressure P, current I, beam voltage V, and oscillation frequency, from the positions of appearance of certain lines of He II, Ne II, A II, Hg II and Hg III along the beam. Evidence has been found for limitation of the voltage amplitude of the electron oscillations by inelastic collisions with neutral gas atoms. D has been found to decrease with increase of PIV^1/2, and with increase in oscillation frequency. The experiments show that this form of oscillating discharge can probably exist in any gas at low pressure.

In experiments on diamond octahedra at temperatures of 1700 °C and above in high vacua, graphite has been observed to develop both internally and on the surfaces. The surface graphite that has been observed is different from that associated with etching, and is independent of the gaseous environment. Its development increases with time and rapidly increases with temperature. The internal graphite always has associated with it an intense strain in the surrounding diamond. It has varied in appearance from isolated particles to orientated distributions of crystallographic microscopic inclusions. Some diamonds have remained completely free from internal changes. For the diamonds which have developed inclusions the changes have occurred suddenly and discontinuously, the internal graphite generally not extending with time or increasing temperature. It is thought that both phenomena are due to a physical phase transformation, and that defects, of some particular kind which are present inside many but not all diamonds, initiate the transformation which has given rise to the internal changes that have been observed.

The nuclear magnetic resonance spectrum for a system of rotating nuclear pairs is calculated by a perturbation procedure. As was found by a semi-classical approach outlined by Andrew and Newing in 1958, the spectrum consists of a narrowed central spectrum together with side spectra, the intensities of which are weak when the rate of reorientation is rapid. The second moment of the entire spectrum is independent of the rate of rotation. The conditions under which the second moment can be expected to be invariant in practice are discussed.

The spectra have been calculated in detail for several special cases, including that of a polycrystalline solid containing pairs of nuclei reorienting about axes normal to their internuclear vectors. The dependence which the linewidth is found to have on the correlation time of the random motion is compared with the results of other theoretical approaches.

An account is given in this paper of the general features of a cosmic ray spectrograph with a maximum detectable momentum of 26.5 GeV/c. Particular attention is given to the determination of the correction factors needed for accurate measurements of particle momenta. The instrument has an acceptance rate of 5000 particles per day.

The design characteristics and performance of the electronic circuits used in the cosmic ray spectrograph described by Brooke et al. are described. These circuits select single particles which have traversed the instrument and automatically record their deflections in the magnetic field.

The momentum spectrum of muons in the vertical cosmic ray flux at Durham has been measured for the momentum range 0.4-10 GeV/c. The measurements are based on some 191 000 trajectories. The bias introduced by the condition that the particles should be unaccompanied has been studied and found to be small.

The measurements on the momentum spectrum are compared with those of other workers and possible causes of the discrepancies are examined. It is concluded that the relative intensities are known with an accuracy to about 3% over the range 0.4-10 GeV/c.

The production spectrum of cosmic ray pions has been determined under the assumption that the sea-level muons all come from pions. Representing the spectrum as N(p_π) = Ap_π^-γ, γ is found to be constant and equal to 2.65, for p_π > 5 GeV/c. Below this momentum γ falls continuously and reaches the value 1.93 at a pion momentum of 1 GeV/c. The production spectrum agrees well with those given by Olbert in 1954 and by Puppi in 1956 above 3 GeV/c but has significantly lower intensity at lower momenta.

The momentum spectrum of cosmic ray muons in the vertical direction at Durham has been measured for the momentum range 5-1000 GeV/c. The high maximum detectable momentum has been made possible by the modification of the original spectrograph by the addition of neon flash-tube arrays at the measuring levels. The work described in this paper is based on 14 556 particles, 4520 of which had momenta above 20 GeV/c, and together with the momentum spectrum determined by the Geiger counter spectrograph alone, Gardener et al. (1962) form a continuous spectrum from 0.4 GeV/c to 1000 GeV/c.

Comparison with other workers shows that the spectrum is in good agreement up to 100 GeV/c but that there is significant disagreement with the only other measurement at higher momenta (Holmes et al. 1961b).

Relative yields of negative and positive pions produced from deuterium by a bremsstrahlung beam of maximum energy of 320 MeV have been measured for six pion energies at an angle of 133° (laboratory system). The measured negative to positive pion ratios decreased from 1.42 to 1.19 for mean pion energies of 15.3 and 65.5 MeV respectively. These results are compared with dispersion relation theory and other current theoretical predictions. It is found that experimental photoproduction results show evidence for the existence of a T = 1, J = 1 pion-pion resonance.

The (p, n) reaction cross sections for proton bombardment of natural copper at a proton energy of 9.3 ± 0.3 MeV have been measured by an activation method. The results, 480 ± 20 mbn and 895 ± 35 mbn respectively for the isotopes ⁶³Cu and ⁶⁵Cu, when combined with accepted values of the (p, q) cross sections near this energy give a total reaction cross section of 910 ± 25 mbn, in good agreement with results obtained in this laboratory and elsewhere by direct methods.

First-order perturbation theory has been applied to calculate the annihilation rate of positrons in a metal, represented by a Fermi gas of free electrons. In view of the possibility that a bound positronium atom may be formed, some justification is needed before perturbation theory may be used. Calculations on a simple model show that, owing to the presence of the many electrons in the Fermi gas and the operation of the Pauli exclusion principle, a perturbation expansion may indeed be employed in finding the electron density at the position of the positron. Another simple model is used to investigate the validity of calculating only up to the first order in the perturbation series. Higher orders are found to contribute a relatively small amount to the electron density provided the Fermi momentum is large. The condition is satisfied by aluminium, for which a lifetime of 2.8 × 10^-10 sec is estimated.

The modification of the scattering of conduction electrons due to the thermal motion of impurities is considered. It is shown that, contrary to the calculations made by Koshino in 1960, inclusion of this effect does not sensibly alter the theoretical value of the resistivity.

Measurements have been made on the Kapitza boundary resistance between metals, principally lead, and liquid helium II. The results show that for the lead specimens investigated the resistance is larger in the superconducting state than in the normal state, decreases with magnetic field in the normal state and appears to increase with time. The results are discussed in terms of mechanisms suggested by Little in 1961. The increase with time is thought to be due to the formation of an oxide layer. Experiments to investigate changes in resistance with the state of anneal and the chemical impurity of specimens are somewhat inconclusive.

Slow domain wall motion in uniaxial cobalt films has been studied by the longitudinal Kerr effect with switching field and temperature. On applying a given reverse field, about H_c, domains grow with decreasing velocity until saturation. The films were made by evaporation from a filament of tungsten which has a profound effect.

Electron diffraction shows the structure of face-centred cubic metal surfaces (polycrystalline nickel, copper, silver, gold, platinum, aluminium; and single-crystal nickel {110} and copper and nickel {001} faces) abraded unidirectionally on 4/0 or 3/0 emery paper at similar 1 kg load. Four main regions are distinguished: (i) down to similar 50 Å mean depth the metal is heavily disoriented; (ii) from similar 50 to several hundred Å there is a backwardly inclined <110> orientation with additional {111} twinning; (iii) from several hundred Å to several thousand Å - as in (ii) but the tilt δ increases progressively to similar 30-35°, and one twin predominates, so that a normal <100> orientation is simulated; (iv) a deeper region of transition to the underlying undisturbed initial structure, which is several micrometres below the surface.

In the upper regions (ii) and (iii) the orientation, of mainly <110> one-degree type, closely approximates to the `rolling texture' (except that it is inclined) in its type and azimuthal preference, rather than to a pure compression texture. This orientation is also found at scraped or filed surfaces. The relation of δ to the friction coefficient is indicated. The transition region (iv) on the single crystals consists mainly of a large range of rotations of the initial lattice about an axis parallel to the surface and normal to the abrasion direction, but prominent preferential {111} twinning occurs here also. Such rotations appear to correspond to flexural rotational slip, but in some cases the slip plane appears to be {100}.

Lattice constants have been determined for a specimen of alpha titanium of greater purity than hitherto examined. Values of a₀ = 2.95111 Å ± 6 × 10^-5 and c₀ = 4.684 33 Å ± 10 × 10^-5 differ significantly from previous, accepted figures obtained by Clark in 1949. Comparative impurity contents for two grades of pure titanium are given.