Table of contents

It is shown that the apparent impossibility of deriving Einstein's field equations of gravitation in a way similar to that used by him in deriving the equations of particle motion and electromagnetism–being a direct generalization of his famous imaginary experiment of a box falling freely in a gravitational field–may be overcome by using the quantal vacuum with its fluctuations instead of the vacuum of ordinary physics with its absolute emptiness. Thus, the Dirac equation with gravitation, thereby used, appears, in contrast to the ordinary view, as the prototype of interaction theory based on general principles, one of them being a generalized principle of equivalence.

The polarization of 185 MeV protons scattered inelastically from ¹²C has been measured for the 9.6 MeV level and for the 15.1 MeV level. Calculations in the distorted-wave impulse approximation (DWIA) give results which show good agreement for the 9.6 MeV level but disagreement for the 15.1 MeV level. The Coulomb interaction between two protons is included in the nucleon-nucleon matrix, and the effect of this is investigated, also for the 7.7 MeV level.

The g-factor of the 1 291.5 keV state in ⁵⁹Co has been determined by the IPAC method. A multichannel goniometer was used in the study of the perturbed angular correlation of the 142.5-1 291.5 keV cascade. Four sources were used, ⁵⁹Fe:Fe, ⁵⁹Fe:Co, ⁵⁹Fe:Ni and ⁵⁹Fe:Cu. The g-factor was found to be 1.69 (8) based on an analysis of the iron, nickel and copper data. The corresponding magnetic moment, μ = 2.54 (12)μ_N, is compared with the prediction of a unified vibrational model. Neglecting the static electric quadrupole interaction between the ⁵⁹Co nucleus and its environment in cobalt metal, the magnetic hyperfine field experienced by ⁵⁹Co in cobalt was found to be -217 (22) kG at room temperature.

The structure of ⁶⁵Zn and ⁶⁷Zn has been investigated by studying the yield function, angular distribution, linear polarization, and coincidence relationships of the γ-rays emitted during bombardment of enriched ^62,64Ni foils by α-particles of energy 14 MeV and lower. Additional information on the yield of transitions in ⁶⁵Zn* was obtained in the Cu(α,pn) reaction at incident energies 24 MeV and 31 MeV. High-spin states up to 13/2^- and 15/2⁺ were assigned. The negative parity states are discussed in the framework of the seniority coupling scheme for the neutrons and in the framework of the particle-plus-core coupling scheme. Concerning the positive parity states strong indications are found that the simple 1g_9/2 core coupling scheme is valid.

The spectrum of four-times-ionized vanadium has been observed by using a 5-m grazing-incidence and a 3-m normal-incidence spectrograph. The light sources have been a vacuum sliding spark and an open vacuum spark. This paper presents some additions to the analysis by C. H. H. Van Deurzen. 42 lines have been classified as ground-term transitions and 6 lines as combinations between excited terms. These transitions have established the levels of the nf-series up to 9f as well as 10 levels of 3p⁵3d² and 4 levels of 3p⁵3d4s. By applying the polarization formula to the hydrogen-like terms 5g, 6g, 7g, 6h, 7h and 7i as given by Van Deurzen the ionization energy has been determined to 526 530±4 cm^-1 (65.280 eV).

Lifetimes of 32 bands in NO originating from the A²Σ⁺, B²Π, B'²Δ and D²Σ⁺ states and a system reported by Migeotte have been directly measured, using the high frequency deflection technique. The results are compared to earlier direct measurements and the lifetimes are discussed in relation to various types of states. For instance the Migeotte bands are found to have lifetimes similar to those of the D²Σ⁺ state, and consequently they are likely to originate from this (Rydberg) state. The lifetime of the C²Π state is also discussed with particular application to the NO concentration in the atmosphere.

Oscillator strengths for the first four s-p transitions in Li, Na and K have been obtained from single Hartree-Fock-Slater computations, employing half-integral occupation numbers for the transition orbitals. The suggested form of the transition moment leads to f-values in good agreement with experiment.

An experimental and theoretical analysis is performed of a fully ionized, magnetized, quasi-steady plasma being separated from a surrounding neutral gas blanket by partially ionized boundary regions: (i) For rotating as well as high-frequency heated plasmas there exists a sharply defined minimum heating power P_m and temperature T_0m below which a steady fully ionized state cannot be maintained. At laboratory dimensions and ion densities of about 10²¹ m^-3, these parameters become P_m ≃ 0.5 MW and T_0m ≃ 2 × 10⁴ K. This "minimum-P effect" is important both to the processes of creating and maintaining laboratory plasmas in fusion research and to the studies of certain cosmical plasmas. (ii) The theoretically predicted behaviour of the plasma is roughly in agreement with the experiments in the power range close to the minimum value.

Computer results based on a self-consistent nonlinear analysis are given for the (one-dimensional) problem of laser interaction with a plasma layer. Effects of ion-acoustic wave excitation are studied assuming that the plasma is exposed to incident radiation from two oppositely directed laser beams.

The radiation damage in single crystals of CaF₂ and BaF₂ due to room temperature bombardment with 2.0 MeV helium ions has been studied by the channeling technique. Backscattering spectra for the ⟨111⟩ and ⟨110⟩ axial directions were taken after different doses of random irradiation. A slight increase of the aligned yield with radiation dose has been found for both crystals at doses below 10¹⁷ ions/cm². For CaF₂ at a dose of about 1.4 × 10¹⁷ ions/cm² a steep increase is found, after which the aligned yield saturates at a high value. Analyses of spectra measured along different aligned directions indicate that the structures of defects in CaF₂ and BaF₂ differ.

In the paramagnetic temperature region for the electrical resistivity it can be shown that

where the last ratio refers to projections of the Fermi surface. Critically examining the assumptions involved in these equalities we have evaluated the ratio of the projected areas in the case of dysprosium to be 1.3. This is in good agreement with our careful measurements on dysprosium along both the axes cut from the same monocrystal. Previously reported anomalous values of the slope ratios are discussed. Thus for the heavy rare earths from terbium to lutetium we conclude that it is the anisotropy of the Fermi surface alone which is responsible for the electrical resistivity anisotropy in the paramagnetic temperature region.