Large enhancement of the sub-barrier fusion probability for a halo nucleus

The fusion-fission cross sections of the He-4 + U-238 and He-6 + U-238 systems have been measured, at Louvain-la-Neuve, for energies around and below the Coulomb barrier, using an array of Si detectors surrounding a UF4 target. The data taken with 4He are in good agreement with previous data and with the coupled channel fusion calculation performed with ECIS. The He-6 data show a regular trend with a large enhancement below the barrier which is attributed to the halo structure of the He-6 nucleus

The quadrupole moments of the 11

The measured spectroscopic quadrupole moments and deduced deformations of the 194,196Pb(11-) intruder isomers are reevaluated, making use of the recently measured magnetic moments of these states. This adjustment is necessary since the quadrupole moments were obtained from Level Mixing Spectroscopy measurements, being sensitive to the ratio of the quadrupole interaction frequency and the magnetic moment. The results confirm the moderate deformation of the \ensuremath{\pi(3s_{1/2}^{-2}1h_{9/2}1i_{13/2})_{11^{-}}} states. A systematic comparison between the updated experimental and the available theoretical values is presented

Restoration of the Cirsio dissecti-Molinietum in The Netherlands: Can we rely on soil seed banks?

Vegetation and soil seed banks of a threatened Atlantic fen meadow community were studied using recent phytosociological records and seedling emergence from soil samples. Similarly managed but differently degraded stands that suffered different levels of species impoverishment were compared. The actual vegetation was related to a set of phytosociological references representing the subassociations of the community. DCA positions of reference relevés from the different subassociations were overlapping, suggesting that in all references many common species occur. Recent records were positioned in-between the seed bank samples and the references. The soil seed banks of all stands were dominated by ordinary species. Most character species had at most sparse seed banks and no seedlings of locally extinct character species, mentioned in historic floristic records, were detected. In contrast species of pioneer and small-sedge communities as well as those of heathlands were abundant in the seed banks. Based on the vertical distribution of seeds in the soil layers most fen meadow species were classified into transient or short-term persistent seed bank types. We concluded that complete restoration of the Cirsio dissecti-Molinietum without reintroduction is only likely in stands that were degraded only a few years ago. On the other hand, the presence of viable seeds of Nanocyperion and Parvocaricetea species is promising for the restoration of these communities even after decades. Recreation of pioneer habitats by sod cutting will preserve these species.

Stroboscopic detection of nuclear forward-scattered synchrotron radiation

Stroboscopic detection of nuclear forward-scattered synchrotron radiation is proposed and applied. Stroboscopic measurements provide energy-resolved spectra and relax the condition on the bunch mode. This concept is applied to study the magnetism in (formula presented) under high pressure. © 2002 The American Physical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

g factors of the 9 - and 11 - isomers in 194 Pb and 196 Pb: Confirguration mixing and deformation

The g factors of the 9- and 11- yrast states in 194Pb and 196Pb have been measured using the time-dependent perturbed angular distribution (TDPAD) technique. An analysis of the systematics of the properties of these states in the light Pb isotopes is presented. The results confirm the dominance of the ν(2f5/2-11i13/2-1) configuration in the 9- isomer. The values for the 11- isomers are consistent with the π(3s1/2-21h9/2li13/2) configuration, but they are smaller than those in the Po isotones. The effects of core excitation and particle-vibration coupling are considered, but these do not lead to a detailed agreement between theory and experiment. A Nilsson approach, however, gives good agreement, providing support for a proposed oblate deformation

g factors of the 9(-) and 11(-) isomers in Pb-194 and Pb-196: Configuration mixing and deformation

The g factors of the 9(-) and 11(-) yrast states in Pb-194 and Pb-196 have been measured using the time-dependent perturbed angular distribution (TDPAD) technique. An analysis of the systematics of the properties of these states in the light Pb isotopes is presented. The results confirm the dominance of the nu(2f(5/2)(-1)1i(13/2)(-1)) configuration in the 9(-) isomer. The values for the 11(-) isomers are consistent with the pi(3s(1/2)(-2)1h(9/2)1i(13/2)) configuration, but they are smaller than those in the Po isotones. The effects of core excitation and particle-vibration coupling are considered, but these do not lead to a detailed agreement between theory and experiment. A Nilsson approach, however, gives good agreement, providing support for a proposed oblate deformation

Slowing Down of Gamma Photons

SCOPUS: re.jinfo:eu-repo/semantics/publishe

Principles of stroboscopic detection of nuclear forward-scattered synchrotron radiation

The basic principles of stroboscopic detection of nuclear resonant forward-scattered synchrotron radiation are discussed. It is explained how the experiment can be configured in such a way that energy-resolved spectra with a straightforward interpretation are obtained. The theory is supported by a set of experimental spectra on the single-line compound potassium ferrocyanide trihydrate. Further, it is shown that a stroboscopic measurement is equivalent to an interferometer experiment. Finally, a comparison of stroboscopic detection and other Mössbauer techniques is given.SCOPUS: ar.jSCOPUS: ar.jinfo:eu-repo/semantics/publishe