No abstract available

[en] This report gives a survey on the research work and scientific/technical developments in the Institut fuer Kernphysik of Cologne University in the years 1972/73. Most of these projects were investigations of the mechanism of nuclear reactions and nuclear spectroscopy with the aid of the FN tandem accelerator of the institute. Other projects comprising work on nuclear physics, semiconductor detectors, and the expansion of the computer systems of the institute were continued. (orig./AK)

[en] This report gives a survey on the research work and scientific/technical developments in the Institut fue Kernphysik of Cologne University in the years 1972/73. Most of these projects were investigations of the mechanism of nuclear reactions and nuclear spectroscopy with the aid of the FN tandem accelerator of the institute. Other projects comprisingen work on nuclear physics, semiconductor detectors, and the expansion of the computer systems of the institute were continued. (orig./AK)

[en] We have investigated the thermally induced epitaxial recrystallisation of ion-implanted α-quartz. The samples were irradiated with different ions (Cs⁺, Si⁺, O⁺, Xe⁺) and subsequently annealed between 775 and 1275 K in air or in vacuum. Before and after annealing, the thickness of the disordered layer was monitored by means of Rutherford Backscattering Spectroscopy in channeling geometry. After Cs-implantation and subsequent annealing in air, complete recovery of the crystallinity was achieved at 1150 K. Only partial regrowth took place when heating the Cs-irradiated samples under vacuum. After the implantation of stoichiometric amounts of Si- and O-ions or of Xe-ions epitaxial recrystallisation did not occur up to 1175 K. The dependence of the recrystallisation rate on the Cs fluence was determined. The epitaxial recrystallisability after annealing in air can be explained by the topological alterations of the [SiO₄]-tetrahedral network due to the dissolution of alkali-oxide

[en] Identification of the very light Nb, Mo, and Tc isotopes has been achieved using HI reactions and the detection of prompt γ-rays in coincidence with recoils and/or evaporated particles. Level schemes were constructed using γγ coincidences, angular distributions, and DCO ratios. Lifetimes and g factors were also measured in some cases. These nuclei lie in the shape transition region between the N=50 shell closure and the region of large deformation centered about N=Z=38. Shell model calculations using g(9/2) and p_1/2 valence orbitals adequately describe the nuclei with N≥46. Geometric models and sytematics indicate moderately large deformations for nuclei with N≤44

[en] In this article, I shall present results on level energies and lifetimes in evaporation residues excited in ³⁶Ar and ⁴⁰Ca induced fusion reactions on ⁴⁰Ca targets. The experiments were performed with the 105-130 MeV ³⁶Ar beam of VICKSI/Berlin and the 120-170 MeV ⁴⁰Ca beams provided by the Brookhaven and Daresbury tandem accelerators. In choosing N=Z projectiles on ⁴⁰Ca targets, the neutron deficient isotopes with N≅Z are being populated by proton and α-particle evaporation (e.g. ^72,73Br, ^70,72Se, ^74,76Kr, ⁷⁷Rb), while neutron emission is strongly suppressed and the spectroscopy of the N=Z isotopes ⁷²Kr and ⁷⁶Sr is still very scarse, in spite of the use of sophisticated recoil spectrometers and filtering techniques. (orig./BBOE)

[en] Improvements in the techniques of lifetime measurements in medium-weight nuclei are discussed. Experimental results on transition and level energies or electromagnetic transition probabilities in neutron deficient Br, Kr, Rb and Sr isotopes are summarized and compared with several nuclear model calculations. The very large deformations found for the very light Kr, Rb and Sr isotopes,the role of (2qp) excitation on the B(E2) values, the possible effect of boson cut-off at high spin and the polarization effect of an unpaired g_9/2 proton on the respective core are also discussed. New results on quasi-bands in ⁷⁵Br, ⁷⁷Kr and ⁷⁷Rb are presented. 50 refs., 17 figs. (author)

[en] The authors of this paper gives a survey of the various depth profiling techniques which we presently use to determine the components of thin nitride and oxide films and to investigate diffusion processes in these films and of implantation profiles which are thermally activated or induced by heavy ion bombardment (sputtering/erosion, ion beam mixing, precipitations, etc.). Rather than trying to cover all systems which have been studied so far. The author first describe the lay-out of our implanter IONAS, then characterize the depth profiling techniques and illustrate their potential and limitations for a number of examples. Mostly those examples have been selected where several methods were necessary to arrive at detailed physical conclusions

No abstract available

[en] Recent lifetime measurements in the light Se, Br, Kr and Rb isotopes with N ≅ Z using ³⁶Ar and ⁴⁰Ca induced reactions point to rapid variations of the nuclear shape as function of the rotational frequency and particle number. This behaviour is intimately connected with the subshell closures at large prolate or oblate deformation. (orig.)