Table of contents

A multitemporal non-hereditary formulation of relativistic dynamics is given. According to it, a dynamical system of N particles involves some realization of the N-parameter abelian group. The usual concept of flow is replaced by more general tools coming from bitensor calculus. The basic axioms of the theory are expressed in terms of partial differential equations and a non-trivial solution is exhibited.

The motion of three free particles is studied in their center-of-mass frame. In the six-dimensional space of relative momenta the invariant mass is used as a radial variable. Curves perpendicular to surfaces of constant mass ("mass-shells") are labelled by their direction at threshold mass. The relativistic distortion from the nonrelativistic case when the mass shells are ellipsoids is studied. This means a mapping in the radial variable and two of the angular variables (Dalitz plot variables). Since an analytic treatment of the problem seems hardly feasible a numerical study has been made.

In relativistic mechanics the forces acting on a body have the following two properties: (i) their sum is equal to the rate of change of momentum of the body, and (ii) they have certain prescribed transformation properties under Lorentz transformations. It is pointed out that not both of these properties can be taken over to relativistic thermodynamics: they lead to different interpretations of the energy-momentum tensor and its divergence for a heat conducting continuum. Postulating the first of them gives the thermostatics of Planck and others, whereas postulating the second one gives that of Ott, Kibble, Møller, and others. The work differential of Kibble and Møller is generalized to include changes of velocity. The equilibrium of rotating systems is also discussed.

After a short analysis of current methods for preparation of spatial filters for restoration of defocussed images it is shown that such a filter can be made in a single step by holographic technique which uses a very weak reference beam. A high reconstruction efficiency is obtained since bleaching of the filter is necessary in order to realize the desired filter function. Measurements on a monobath developer show that the diffraction efficiency of a hologram can be made almost independent of the exposure over a range greater than 250:1, possibly of the order of 1 000:1. This effect has been utilized to increase significantly the range of linear response of the filter. It is also shown that the filter generated in this way is automatically optimum with respect to granularity noise in the input image. In order to reduce the number of optical elements in the image processing system the filter has been made self-focussing and acts as the imaging lens. A quantitative analysis of the effects of defocussing and restoration has been made possible by introducing a spoke target in the picture to be restored.

Multipole character of some transitions connecting the quadrupole and octupole vibrational bands to the ground-state rotational band in ¹⁵²Sm have been determined by measuring directional correlations using a Ge(Li)-NaI(Tl) spectrometer. A total of 14 correlations have been measured. From these measurements it can be concluded that the 2_β⁺ - 2⁺, 689 keV, 2_γ⁺ - 2⁺, 964 keV and 3_γ⁺ - 2⁺, 1 112 keV transitions are essentially pure E2, and 3^- - 2_γ⁺, 1 457 keV, 3^- - 4⁺, 1 213 keV and 2^- - 2⁺, 1 408 keV transitions contain less than 2% M2.

The ²³Na(p,α₀)²⁰Ne reaction has been investigated in the energy region E_p = 590-1 810 keV; 16 resonances have been observed. The angular distributions of α particles have been measured in 14 cases. Analysis of the distributions allowed of the following assignments for the resonance states: 592 keV 3^-; 744 keV 2^-; 919 keV 0⁺, 1^-, 2⁺; 1 091 keV 1^-, 2⁺; 1 136 keV 1^-, 2⁺; 1 163 keV 0⁺, 1^-, 2⁺; 1 010 keV 3^-; 1 284 keV 1^-; 1 417 keV 2⁺; 1 458 keV 3^-(1^-); 1 500 keV 2^-; 1 556 keV (2⁺); and 1 650 keV (1^-). The population probabilities of different magnetic substates and the formation parameters of the resonances are given.

The decay of ¹⁷⁶Tm has been studied by means of Ge(Li) detectors and some gamma-gamma as well as gamma-beta coincidence arrangements. For the half-life of ¹⁷⁶Tm a value of 1.9±0.1 min was measured. A total of 31 gamma rays were assigned to the decay of ¹⁷⁶Tm. According to the proposed level scheme these depopulate 19 levels in ¹⁷⁶Yb, of which those at 977, 1 360, 1 599, 1 673, 2 142, 2 372, 2 411, 2 954 and 3 188 keV are new. Spin and parity assignments are suggested for some of these levels and for the ground state of ¹⁷⁶Tm. In addition, four gamma transitions possibly belonging to an isomer in ¹⁷⁶Tm were found with energies 116.3, 122.3, 193.6 and 199.0 keV and with half-life 1.4±0.1 min. Also the decay of ^176mYb has been reinvestigated the results obtained being consistent with the previous data.

The energies and intensities of thermal-neutron capture γ-rays from natural neon have been measured with a Ge(Li) detector in pair and anti-coincidence spectrometer arrangements. Internal target of neon gas has been used. The reaction Q-value and excitation energies have been determined. Cross sections for thermal neutron capture in ²⁰Ne and ²²Ne have been deduced. The level schemes of ²¹Ne and ²³Ne are discussed on the basis of the Nilsson model. Calculations with and without inclusion of Coriolis interaction have been made for ²³Ne. These are compared with corresponding calculations on ²⁵Al and ²³Na.

Levels within three rotational bands in the odd A nuclide ¹⁶⁹Yb have been excited in the ¹⁶⁷Er(α,2n)¹⁶⁹Yb reaction. The positive parity ground-state band is strongly perturbed. The observed energy levels and relative transition rates within this band are compared with the results of a Coriolis coupling calculation. Good agreement is obtained if the theoretical Coriolis coupling strength is reduced for the orbitals close to the Fermi surface. With g_s = g_sfree and non-adiabatic wavefunctions the experimental E2/M1 mixing ratios are reproduced for the 7/2⁺ [633] ground-state band. The magnetic moment for the ground-state has been calculated and is compared with the measured one for the isotone ¹⁶⁷Er. This comparison indicates that the mechanism which reduces the Coriolis matrix elements may also be effective in preventing interband M1 transitions with |ΔK| = 1. The results of a Coriolis coupling calculation for N = 5 bands are also discussed. The rotational levels in the doubly-even nuclides ¹⁶⁸Yb and ¹⁷⁰Yb are observed up to the 10⁺ member.

The polarization of 185 MeV protons inelastically scattered from the 3^- level at 3.74 MeV in ⁴⁰Ca has been measured in the angular region 10° to 42.5° (lab. system). The total energy resolution was 0.28 and 0.50 MeV (FWHM) for the two different targets used. The angular distribution obtained is in qualitative agreement with calculations performed in the distorted wave impulse approximation.

In an experiment on inelastic scattering of 185 MeV protons from ⁴⁰Ca differential cross sections have been determined for scattering from individual excited states of the target nucleus. The measurements have been extended over the angular range 4° to 40° (lab. system), and the results are presented in the form of angular distributions of the most prominent peaks in the energy spectra. The identification with known states of ⁴⁰Ca is made by the determination of the excitation energy, and, in the cases where the energy resolution (approximately 250 keV, FWHM) is not sufficient, by the shape of the angular distributions. The results are compared with previously published measurements on other nuclei at the same incoming proton energy as well as with inelastic scattering data at lower energies. In particular, it is shown that the results on the two closed-shell nuclei ¹⁶O and ⁴⁰Ca are very similar and that these nuclei behave differently from other 1p- and 2s-1d shell nuclei studied.

Two new electronic states of ¹Π character have been found for the Th0 molecule. Rotational analysis shows that there are homogeneous perturbations between the two states, and these perturbations have been analysed by computer methods. Some derived molecular constants are given below.

Beam-foil studies of the prominent transitions of N I and N II below 1 200 Å have yielded accurate lifetimes and oscillator strengths. The lifetime of the N II transition at 916 Å (2s²2p²³P-2s2p³³P) was found to have a lifetime of 0.82 ns. These studies are discussed in relation with the results of other laboratories.

The resonance lines of He II were studied with the beam-foil technique. Helium beams from a Van de Graaff accelerator were sent through a thin exciter foil, and the emitted radiation was analyzed with a 3-meter grazing incidence spectrometer. Mean lives were measured for the 2p, 3p, 4p, 5p, and 6p²P levels in He II. The results are in good agreement with theory.

The contributions of cascades to multi-exponential decay curves are analysed. We define the quantitative cascade contribution to an exponential decay as the replenishment ratio, which is the ratio of the cascade repopulation rate to the decay depopulation rate. We recommend that this ratio be quoted in future papers on beam-foil or other cascade-affected decay measurements. We also present specific relationships between the fitting parameters and the level populations for decay curves which arise from electric dipole transition schemes of up to second order in cascading. Velocity dispersion effects in beam-foil decays are, in general, shown to be negligible, except for decays from ejected foil-particles.

From the compressibility conditions for a relativistic fluid, it is possible to deduce (1) the timelike character of the magnetohydrodynamical shock waves, (2) the main inequalities between the different speeds and the thermodynamics of shocks, and (3) the existence and the uniqueness of a non-trivial solution of the shock equations.

Dark field electron microscopy of single crystal epitaxially deposited gold films has shown that some of the anomalous spots in the diffraction pattern from such films arise through a double diffraction mechanism involving two different twin orientations. The same sort of mechanism is shown to be a possible explanation of the so-called "forbidden 110 ring" previously observed in ring patterns from polycrystalline epitaxial gold films.

Mössbauer data for temperatures between 16 and 342 K are given for the three structures of FeGe. The hyperfine field at the iron nuclei vary, at 0 K, between 95.5 and 201 kG for the different iron positions possible. The hexagonal phase shows a spin rotation at low temperatures and the monoclinic phase shows a complex behavior which is partly described by a change in the crystal lattice at about 110 K.