Table of contents

New band systems in the red attributed to MnF and MnBr have been observed in a hollow cathode discharge. The MnBr bands degraded to shorter wavelengths consist of two sequences of double headed bands in the region λ 6285-6246 Å. The MnF bands degraded to longer wavelengths, each band with four heads, comprise five sequences between λ 7300 Å and λ 6230 Å. It is suggested that both systems are due to a transition of the type O^±-⁵Σ⁺.

High dispersion spectrograms have shown the existence of two new band systems of MnBr in the region λ 8850-9700 Å. The bands in both systems are degraded to longer wavelengths. The shorter wavelength system is double headed and is considered to be the analogue of the Π-Σ system observed in MnCl. The longer wavelength system is single headed and is attributed to a Σ-Σ transition. Both systems show an isotope effect which confirms the vibrational analysis.

The conductivity of a homopolar semiconductor with an arbitrary band shape is considered. The corresponding Boltzmann equation is solved after making a simplifying assumption about the form of the matrix element of the lattice-scattering potential.

The fraction of electron capture transitions in the decay of ²²Na has been found by comparing the rate of evolution of ²²Ne from a source of ²²Na with the rate of emission of positrons. The ratio of electron capture to positron transitions is found to be 0.122 ± 0.010; a possible systematic error in the ²²Ne determination would increase this figure.

The cellular method for obtaining electronic eigenvalues in crystals is formally extended to the close-packed hexagonal lattice, and the use of a double atomic cell is investigated, boundary conditions being obtained for a wave function with an arbitrary wave vector. The symmetry properties of wave functions at the zone centre are outlined. After calculating a potential function for the titanium ion-core, point boundary conditions are applied to determine eigenvalues for low-lying states at the centre of the zone in both modifications of the metal. The ground state is found to possess s-like symmetry in both cases.

A demountable discharge tube has been constructed for spectroscopic and probe exploration of low-voltage electron beam discharges through gas at low pressure. Using argon, the probe evidence for presence of electron with excess energy when plasma-electron oscillations are occurring has been confirmed spectroscopically. The spectroscopic results also confirm the probe evidence for the distribution of oscillations in the discharge, and for the variation with discharge parameters of the position of the main oscillating region.

The x- and γ-radiations excited during the decay of ⁵⁷Co have been investigated with scintillation and proportional counters. These measurements showed that the 14.4±0.1 keV γ-ray follows the 123 keV γ-ray with a half-life of 1.0±0.1 x 10^-7 sec and that its internal conversion coefficient (α_total) is 15 ± 1. No evidence for β⁺ emission with an intensity greater than 1/1300 per disintegration was found and upper limits of about 14% were set on the number of disintegrations proceeding directly to the ground and first excited states of ⁵⁷Fe. Spin and parity assignments are suggested.

An orange beam, obtained with the author's recent active nitrogen apparatus, is considered to constitute a nitrogen afterglow. Its spectrum is compared with the exciting arc spectrum over a range of pressure and current. The decay is exponential, with a mean life of the order of 10^-4 second. Other physical and chemical properties are briefly discussed.

The K-spectrum of neon has been examined with a photographically recording bent crystal x-ray spectrometer. The radiation source was an electrodeless discharge tube. The intensity contour of the spectrum was derived leading to a study of the shape of the diagram line Kα_1,2 and an analysis of some satellite structure. Wavelength values are given for the diagram line Kα_1,2 (14.5847 kx units), the semi-optical diagram line Kβ₁ (14.430 kx units) and twenty satellite lines (14.278-14.539 kx units).

An investigation of the equations of state of elements as given by the Thomas-Fermi theory has been carried out in a region corresponding to higher pressures than have hitherto been discussed in detail. Both analytical and numerical methods have been used. The results thus obtained suggest modifications to be made in the recent formulae given by Gilvarry, who fitted the available numerical data with functions having the correct limiting forms. The introduction of exchange is also considered and the modifications thus caused are exhibited explicitly for very high pressures.

The lifetime of the 46.5 keV excited state following β-decay of RaD has been shown, by delayed coincidence methods, to be less than 3 × 10^-9 sec; this specifies the 46.5 keV transition to be a dipole one. An investigation of the scintillations from an activated sodium iodide crystal containing RaD has determined the complete integrated spectrum of RaD, free from effects of source absorption. This spectrum consists in the main of a single peak, and indicates directly that at least 90% of the disintegrations involve soft β-decay to the 46.5 keV excited state followed by rapid de-excitation. Less than 5% of the disintegrations pass through metastable states. The β-decay is briefly discussed.

The effect of the electron mass on the differential cross section for the scattering of high energy electrons by atomic nuclei is investigated. It is shown that it is negligible for point nuclei above 5 MeV. The effect on the scattering by extended nuclei is more difficult to estimate, but is almost certainly negligible in the 100-200 MeV region.

The p-phases for the scattering of neutrons by alpha-particles have been calculated by the resonating group structure method assuming an interaction between nucleons of the form

V₀{mM_ij + hH_ij + bB_ij + w + S ℏ^-2(s_i + s_j). r_ij × (P_i-P_j)} exp (-βr_ij²) + (e²/r_ij)_ij, where _ij = 1 if the nucleons are protons and zero otherwise. M_ij, H_ij and B_ij are the normal Majorana, Heisenberg and Bartlett exchange operators, s_i, s_j and P_i, P_j are the spin and orbital angular momentum of the two nucleons. m, h, w, b are constants which satisfy the conditions m + h + w + b = 1, m + w - (h + b) = x = 0.6 V₀ and β are taken to be -45 MeV and 0.2657 × 10²⁶ cm^-2 respectively. The parameter S measures the relative strength of the spin-orbit interaction, and the aim of the work was to determine S to give the best fit with the observed scattering data. It is found that the mean p-phase shift is only given correctly when the exchange operator in the central interaction is close to the Serber form m = w = ¼(1 + x), h = b = ¼(1 - x).

A good fit is obtained with the following constants: m = 0.258 + 0.325x,h = 0.258 - 0.325x,w = 0.242 + 0.225x,b = 0.242 - 0.225x, S = 0.1.

The phase shifts were calculated from the integro-differential equation using the Pilot ACE electronic computer at the National Physical Laboratory Teddington. Values of the d-phases have also been obtained for neutron energies up to 16 MeV.

The energy spectrum and angular distributions of some neutron groups emitted from the bombardment of a thin phosphorus target by 8 MeV deuterons have been investigated. The Q value of this reaction is found to be 6.63 ± 0.08 MeV. New excited states in ³²S at 6.29, 7.28 and 8.23 MeV, with errors of ±0.10 MeV have been observed. Angular distributions of neutron group corresponding to the transition to the ground state and two excited states at 2.25 MeV and 3.81 MeV in ³²S are compared with theoretical curves calculated on the basis of Butler and Born approximation stripping theories. The angular momentum of the captured proton to these states is found to be 0, 2 and 0 respectively. In an appendix, R Huby and H C Newns discuss the interpretation of these results of the shell model.