Table of contents

A recent proposal of two-component spin-½ wave equations is discussed and criticized.

Longitudinal phase space plots in arbitrary frames are considered. In any frame moving with constant velocity relative to the target or beam system, these plots, when scaled by the incident momentum, approach regular hypertetrahedrons when s increases. Plots in target and beam system longitudinal momenta are useful for investigating beam and target fragmentation, respectively.

The decay of ²³Ne to levels in ²³Na has been studied by measuring the gamma radiation following the β-decay of the ²³Ne nuclei produced in the ²²Ne(d,p)²³Ne reaction. New levels in ²³Na reported by Lancman et al. could not be confirmed. The ft-values have been calculated using the Nilsson model and mixed states from Rotation Particle Coupling calculations including pairing effects in the matrix element. Reasonable agreement with the experimental result is obtained.

The ²⁰Ne(³He,d)²¹Na reaction has been studied at 16 MeV bombarding energy. The emitted deuterons have been analysed in a double focusing magnet. Levels in ²¹Na were deduced. Furthermore the ²⁰Ne(p,γ)²¹Na reaction has been investigated using a 44 cm³ Ge(Li) detector. Gamma ray branching ratios and life times have been measured at the 1 169, 1 311 and 1 504 keV resonances. The experimental information is discussed in terms of the Nilsson strong-coupling model and recent shell model calculations.

A versatile facility for studying nuclear reaction has been built. The ²⁰Ne-(d,pγ)²¹Ne reaction has been studied using particle-gamma and gamma-gamma coincidence technique. Surface barrier solid state detectors and Ge(Li)-detectors were used together with a multi-dimensional storage of data in a PDP-15 on-line computer. Energies and gamma radiation branching ratios of levels in ²¹Ne up to 4.7 MeV have been measured. Levels in ²¹Ne are discussed in terms of modern shell model calculations and the Nilsson strong-coupling model.

The gamma-ray production cross sections of nitrogen have been measured at three different incident neutron energies, 4.2, 5.9 and 6.9 MeV. The gamma-ray spectrometer was a Ge(Li)-detector. Time-of-flight techniques were employed to suppress the background caused by neutron interactions in the Ge(Li)-detector. The efficiency of the gamma-ray spectrometer was measured with calibrated gamma-ray sources and (p,γ)-reactions. The primary neutron flux was measured with a proton-recoil telescope. Differential gamma-ray production cross sections at 55° are given. The angular distributions of the gamma-rays were measured at E_n = 6.9 MeV between 40° and 140°. The results were compared with calculated distributions obtained with a statistical compound-nucleus theory. The life-times of the six lowest excited states in ¹⁴N could be estimated from the observed Doppler shifts in the angular distribution measurement.

The following activation cross sections for the (n,p) and (n,α) reactions on Yb isotopes have been measured at 14.5±1.0 MeV using the mixed powder method with Ge(Li) γ-ray detection: ¹⁷²Yb(n,p)¹⁷²Tm (63.8 h), 6.3±0.8 mb; ¹⁷³Yb(n,p)¹⁷³Tm (8.24 h), 4.2±0.3 mb; ¹⁷⁴Yb(n,p)¹⁷⁴Tm (5.4 min), 2.1±0.3 mb; ¹⁷⁶Yb(n,p)¹⁷⁶Tm (1.9 min), 0.55±0.14 mn; ¹⁷⁴Yb(n,α)¹⁷¹Er (7.52 h), 0.82±0.05 mb; and ¹⁷⁶Yb(n,α)¹⁷³Er (1.4 min), 0.33±0.09 mb. The (n,p) cross sections agree well with Gardner's predictions. Both the (n,p) and (n,α) cross sections have also been compared with calculations based on evaporation approximation.

The spectrum of doubly ionized strontium emitted from a sliding spark discharge has been studied. About 590 Sr III lines have been identified in the 9 800-350 Å range, all but eight of them being previously unobserved. 71 even and 76 odd energy levels have been established, including all levels of the 4p⁵5g, 6g, and 6h configurations. Weak s↔d interaction causing s-f transitions and strong p↔f interaction causing p-g transitions have been observed. The ²P_3/2 series limit has been determined to be 345 879.0±1.5 cm^-1 above the ground state.

A new system belonging to RuC has been found between 4 100-4 800 Å. Eight bands were detected. They seem to belong to three sub-systems. The molecular constants for the lower states are of the same magnitude as those for the lower states of earlier reported bands between 6 000-8 700 Å. In spite of this, the arrangement of sub-states into electronic states is still not settled.

Our previous level crossing measurements in the 6, 7, and 8p²P_3/2 levels of Cs¹³³ have been extended to the 9 and 10p²P_3/2 levels. For the magnetic dipole and the electric quadrupole interaction constants a and b we obtain

The natural lifetime of 9p²P_3/2 was found to be 390 (30) ns. The previous analysis for the 6 and 7p²P_3/2 levels is revised, taking new experimental data from this and other laboratories into account. This leads to a better consistency for the quadrupole moments Q for Cs¹³⁵ and Cs¹³⁷ as evaluated from the 6 and 7p²P_3/2 levels. We obtain

Q(Cs¹³⁵) = +0.052 (4) barn

Q(Cs¹³⁷) = +0.053 (4) barn

Using an enriched sample in a high temperature scattering cell we have determined the hyperfine structure of Te¹²⁵ in the 5p³6s⁵S₂ level of the Te I spectrum by the optical double resonance and level crossing techniques. For the magnetic dipole interaction constant a we obtain

|a (5p³6s⁵S₂ Te¹²⁵)| = 1 010.4 (1.3) MHz

The spin density at the nucleus, calculated using this value, is compared with the value derived from optical data, and with the result of a self-consistent-field calculation.

The gyro-synchrotron radiation from the solar coronal plasma is investigated with special regard to temperature effects. The influence of non-zero temperature is to enhance the radiated synchrotron power from the solar coronal plasma. We also observe that fast test charges radiate more power than slow charges.

By use of the channeling technique an attempt to study precipitations of copper atoms in single crystals of aluminium 4 wt.% copper alloy have been made. It is found that the stable phase θ gives an aligned yield in Rutherford backscattering spectra quite different from the unstable phases preceding θ. The channeling measurements have been correlated with electron microscopy studies on the same ageing stages.

A high intensity, super radiant light source has been studied. A 2 000 A, 250 keV pulsed electron beam was used to pump a semiconductor target consisting of a large number of small CdS crystals. Peak powers in excess of 5 MW and a pulse length of 20 ns were obtained.

An Echelle spectrograph specially developed for image tubes is presented. A Czerny-Turner mount is used and the optimization of the optics in respect to aberrations, order sorters and the focal surface is discussed. The image tube used is an image dissector tube with a photocathode 20 mm in diameter. The wavelength range covered is 1 700-4 000 Å.