Table of contents

The thermal conductivity of degenerate matter is calculated taking account of the effect of relativistic mechanics. The result is put in a form suitable for astrophysical calculations. The two limiting cases of non-relativistic degeneracy and extreme relativistic degeneracy are discussed.

It is suggested that the magneto-resistance coefficient of a ferromagnetic alloy is composed of two terms, one associated with the temperature-dependent, the other with the temperature-independent contribution to the electrical resistivity. An equation based on this hypothesis is in good agreement with the experimental results for silicon-iron alloys. The validity of the equation for other alloys is discussed.

A differential ionization chamber with electron collection has been designed for the study of α-particle spectra. Two chambers of this type have been used to investigate α-α coincidences in the reaction ⁷Li(d, α n)⁴He. The results confirm that this process takes place, and the observed angular correlation of successive α-particles lends some support to the view that the virtual ground state of ⁵He is P_3/2.

The lifetimes of certain atomic resonance states have been measured using a magnetic rotation method devised by Weingeroff in 1931. This method possesses the advantage of not requiring an accurate knowledge of the vapour pressure data. The experimental results are compared with theoretical values obtained using the recent Bates-Damgaard Coulomb approximation, and with results based on Hartree and Slater type wave functions. Good agreement is found with the Bates-Damgaard results

Previous workers have reported that lattice constants determined by electron diffraction differ from the accepted X-ray values. It has been suggested that these differences may be due to a change in lattice constant with crystal size. To examine this question further, the lattice constants of several alkali halides have been determined, by electron diffraction, to a higher accuracy than had previously been attained. The X-ray value of the lattice constant of TlCl was used as a standard reference. The lattice constants of six alkali halides, with crystal sizes greater than 150 A, were found to agree with the X-ray values to within the experimental error of 0.05% It has been shown that for crystal sizes less than 100 A the lattice constants of the alkali halides were found to be less than the X-ray values by an amount dependent on crystal size For a crystal size of about 30 A the decrease was approximately 0.5%

Similar determinations on evaporated gold films showed that, for a crystal size of about 20 A., the decrease in the lattice constant was almost 2% For a crystal size of 40 A., the largest obtained, the lattice constant was 0.2% less than the X-ray value. Evaporated films of silver and bismuth also were found to have lattice constants less than the X-ray values.

It can therefore be concluded that previous reports of an increase of the lattice constants of alkali halides with decreasing crystal sizes are in error Some of the discrepancies noted by previous workers may have resulted from assigning the X-ray value to the lattice spacing of gold films or gold foil used as a standard reference.

Graphical information is given which facilitates the evaluation of the parameters entering into the theory of simple excess semiconductors.

Measurements of two band-systems attributed to CF are reported. A rotational analysis of four bands, 1,0, 0,0, 0,1 and 1,1, of a transition A ²Σ⁺ - X ²II is given, and the vibrational analysis of a system B (near case b) - X ²II. The rotational constants of the B state have been estimated from band-head separations. X ²II is probably the ground-state of CF. The initial convergence of the vibrational levels in B is rather rapid, and suggests that D₀" is about 4.9₆ eV Constants derived are as follows:

State	νe	ωe	xeωe	Be	αe	re (A.)
B	49451·8	1191·0	19·4*	1.320	0.025	1.318
A 2Σ+	42705	1764	22	1.7277	0.0260	1.1516
	77
X 2II	0	1308·4	10.86	1.4190	0.0190	1.2708
			* -0·4(v+½)3

A method of standardizing polonium sources by measurement of the number of γ-rays is described. The hard γ-radiation of 0.773 MeV. energy emitted in the decay of ²¹⁰Po has been found to have an intensity of 1.8±0.14 × 10^-5 quanta per α-particle The internal conversion of this line to the extent of 6.7±1.7% gives rise to K X-radiation of lead. No other soft radiation was detected. The decay scheme of polonium is discussed.