Showing papers by "Nathal Severijns published in 1986"
TL;DR: A systematic on-line nuclear-orientation study of heavy isotopes using anisotropic ..capalpha.. emission is reported for the first time and may be interpreted in terms of the high sensitivity of the ..cap alpha..-emission probability to changes in the nuclear shape.
Abstract: A systematic on-line nuclear-orientation study of heavy isotopes using anisotropic cap alpha emission is reported for the first time The anisotrophies recorded for /sup 199/At, /sup 201/At, and /sup 203/At are remarkably pronounced and strongly varying At lower neutron number the cap alpha particles are more preferentially emitted perpendicularly to the nuclear-spin direction This may be interpreted in terms of the high sensitivity of the cap alpha-emission probability to changes in the nuclear shape
49 citations
14 citations
TL;DR: In this paper, the authors used both nuclear orientation and magnetic resonance on Au and Fe to show that the hypothesis of a conical field distribution is false for well-prepared samples with small Au concentration.
Abstract: Nonsaturation of hyperfine fields on Au and Fe has been studied primarily with regard to the existence of the Aharoni angle. With the use of both nuclear orientation and magnetic resonance on $^{189m}\mathrm{Au}$ in Fe, the hypothesis of a conical field distribution is shown to be unfounded---even at very moderate external magnetic field values---for well-prepared samples with small Au concentration. [$^{181}\mathrm{Ta}(^{12}\mathrm{C},xn)^{189m}\mathrm{Au}$, mass separation, $^{3}\mathrm{He}$-$^{4}\mathrm{He}$ dilution refrigeration, $\ensuremath{\gamma}$ anisotropies, Ge detection].
14 citations
01 Jan 1986
TL;DR: In this article, the authors proposed a new approach for weak interaction studies of nuclei in extreme conditions by coupling heavy ion accelerators to electromagnetic isotope separators, which correspond with theoretically predictable A1 parameters within a few percent, even without any scattering correction.
Abstract: Recent progress in different experimental areas has led to a new situation with regard to prospects of weak interaction studies of nuclei in extreme conditions. An immense variety of new nuclei has become available for β-decay investigations through the coupling of heavy ion accelerators to electromagnetic isotope separators. At the same time the progress in (and understanding of) implantation phenomena allows to prepare near ideal β-sources. Also we demonstrated since 1980 that almost all of these nuclei can be polarised to a very high degree by introducing new cryogenic “on line” orientation techniques [1]. Last but not least we developed detectors for particles emitted from a sample at m K temperatures without any window inbetween. The technique of measuring A1 parameters using this equipment was tested off-line: the results correspond with theoretically predictable A1 parameters within a few percent, even without any scattering correction.
01 Jan 1986
TL;DR: In this article, a systematic determination of the beta-decay asymmetries of the mirror nuclei was carried out and the results showed that the vector weak coupling constant (VLC) was in good agreement with the ones derived from the superallowed 0+→0+ beta-transitions between T=1 states and from hyperon betadecays.
Abstract: We started a systematic determination of the beta-decay asymmetries of the mirror nuclei. Up to now only three such measurements exist, viz. the neutron, 19Ne and 35Ar [1–3]. For the neutron and for 19Ne, the values for the vector weak coupling constant Gy which can be extracted from the measured asymmetries yield values for the Cabibbo angle that are in good agreement with the ones derived from the Ft-values for superallowed 0+→0+ beta-transitions between T=1 states and from hyperon beta-decays. 35Ar on the other hand is anomalous for many years already, and suggests that the Cabibbo angle would be zero in nuclear beta-decay.