Search results for "Quadrupole"
showing 10 items of 460 documents
Determination of accurate rest frequencies and hyperfine structure parameters of cyanobutadiyne, HC5N
2020
Very accurate transition frequencies of HC$_5$N were determined between 5.3 and 21.4 GHz with a Fourier transform microwave spectrometer. The molecules were generated by passing a mixture of HC$_3$N and C$_2$H$_2$ highly diluted in neon through a discharge valve followed by supersonic expansion into the Fabry-Perot cavity of the spectrometer. The accuracies of the data permitted us to improve the experimental $^{14}$N nuclear quadrupole coupling parameter considerably and the first experimental determination of the $^{14}$N nuclear spin-rotation parameter. The transition frequencies are also well suited to determine in astronomical observations the local speed of rest velocities in molecula…
Gas-filled recoil separator for studies of heavy elements
1995
Abstract A gas-filled recoil separator for the study of heavy elements has been constructed. The separator is of type QDQQ with the first, vertically focusing, quadrupole providing improved matching to the acceptance of the dipole magnet. The separator has been designed also for use in vacuum mode in which case a mass resolving power of ≈ 100 is estimated. The deflection angle is 25° and the radius of curvature is 1850 mm. Maximum beam rigidity is 2.2 T m. In the first experiments, new isotopes in the region Z = 85–90 have been synthesized.
Recent applications of the JYFL gas-filled recoil separator
1997
Abstract The gas-filled recoil separator RITU at the Department of Physics, University of Jyvaskyla (JYFL) was constructed in 1992–1993, and the first experiments were performed in late 1993. RITU differs from other gas-filled separators by having a vertically focusing quadrupole magnet in front of the separating dipole for better matching with the dipole acceptance. New results from RITU include the discovery of 13 previously unpublished isotopes of At, Rn, Fr, Ra, Ac and Th, while experiments in the transuranium region have also been made. Illustrative examples from these studies together with results on background properties, efficiency of separation, and other performance data will be p…
Mass and half-life measurements of neutron-deficient iodine isotopes
2020
The European physical journal / A 56(5), 143 (2020). doi:10.1140/epja/s10050-020-00153-5
A compact apparatus for mass selective resonance ionization spectroscopy in a buffer gas cell
1997
Abstract An ultra-sensitive laser spectroscopic method for the investigation of transuranium nuclides has been developed based on resonance ionization in an argon buffer gas cell. This method has been combined with ion-guide extraction and mass selective direct detection of the resonantly ionized atoms. Using argon as a buffer gas, recoils of fusion reactions can be thermalized even at low pressure. The differential pumping system consists of only one roots pump and two turbo molecular pumps. The set-up has been tested with 243 Am evaporated from a filament located inside the optical gas cell. Resonance ionization is performed using a two-step excitation with an excimer-dye-laser combinatio…
Quadrupole interaction of $^{8}$Li and $^{9}$Li in LiNbO$_{3}$ and the quadrupole moment of $^{9}$Li
1988
The quadrupole interaction of nuclear spin polarized8Li (I=2) and9Li (I=3/2) in LiNbO3 has been studied at room temperature. The polarization was achieved by optical pumping of a fast atomic beam with circularly polarized laser light. The atoms were implanted into a hexagonal LiNbO3 single crystal and the quadrupole splitting ofβ-NMR spectra was measured. A ratio of ¦Q(9Li)/Q(8Li)¦=0.88(4) for the nuclear quadrupole moments was deduced, yielding a new value of ¦Q(9Li)¦=25.3 (9) mb for the quadrupole moment of9Li.
Ramsey technique applied in a Penning trap mass spectrometer
1991
Abstract The Ramsey method has been applied in an experiment aiming for accurate mass determination of unstable isotopes. The ion motion in a Penning trap has been excited with time-separated oscillatory fields and Ramsey fringes were observed in the case of dipole and quadrupole excitation. The experimental resonances are in good agreement with theory. Further applications of the technique are discussed.
The squeezer ion guide
1992
Abstract The properties of an ordinary ion guide can be improved by inserting a grid between the nozzle and the skimmer. When positive ions are transported, an electric potential lower than +10 V is connected to the grid and one of the order of − 10 V to the skimmer. Efficient focusing is achieved between the nozzle and the grid by a combined action of the viscous helium flow field and the weak electric field. The focusing device is called a “squeezer”. It can be extended by adding more grids, a second skimmer, and differential pumping. Contrary to the first grid, the additional elements act more or less like electrostatic lenses in medium vacuum. With the squeezer ion guide, ions created i…
Nuclear moments and laser spectroscopy
1990
Laser spectroscopy measurements have yielded a wealth of new information about the moments and charge radii of unstable isotopes. The procedures of evaluating these moments from the magnetic dipole and electric quadrupole terms of the hyperfine structure arew discussed. Examples are presented, with emphasis on the isotopic chains of odd-proton nuclei, and their essential features are put into the context of current theoretical model descriptions for spherical and deformed nuclei. Finally, new developments of extremely sensitive experimental techniques are discussed with regard to an application to nuclei very far from stability.
The EFG in oxonium ferric orthophosphate hydrate and related compounds
1988
The point cherge model was used to interpret the small quadrupole spilting of Fe3H15(PO4)8·5H2O by comparing it with related phosphates of known structure. The approximation is sufficient as long as octahedrally coordinated compounds are compared for which Vzz and η do not change their signs.