D. V. Fedorov

Measurement of the first ionization potential of astatine by laser ionization spectroscopy

The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of the minute quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential. Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states enabled the first determination of the ionization potential of the astatine atom, 9.31751(8) eV. New ab initio calculations are performed to support the experimental result. The measured value serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of superheavy element 117, the heaviest homologue of astatine.

On-line yields obtained with the ISOLDE RILIS

The ISOLDE resonance ionization laser ion source (RILIS) allows to ionize efficiently and selectively many metallic elements. In recent yield surveys and on-line experiments with the ISOLDE RILIS we observed 23–34 Mg, 26–34 Al, 98–132 Cd, 149 Tb, 155–177 Yb, 179–200 Tl, 183–215 Pb and 188–218 Bi. The obtained yields are presented together with measured release parameters which allow to extrapolate the release efficiency towards more exotic (short-lived) nuclides of the same elements. 2002 Elsevier Science B.V. All rights reserved.

High temperature ion sources with ion confinement

Different types of high temperature ion sources such as surface, laser, and electron beam ionization ion sources have been developed and tested in off-line and on-line experiments. All types of developed ion sources have an essential common feature: an existence of the ion confinement inside the ion source cavity.

Investigation of the release properties of MeCx targets at IRIS

Abstract The technology of preparation of the MeC x targets (Me = U, Th, Zr and Gd) is described. The results of the investigations on the release properties for this kind of target material are discussed. The production yields of some isotopes far from stability obtained at the IRIS facility from these targets are presented.

A mass-separator laser ion source

Abstract The results of an investigation and application of laser ion source intended for high-efficiency chemical selective ion production at the mass-separator IRIS are presented. The ion source is based on a stepwise resonance ionization of atoms in a hot capillary by laser radiation passing through it. A high degree of efficiency of ionization (up to 30%) is achieved. The laser ion source has been employed for on-line experiments with nuclides far from stability, as well as measurements of optical isotope shifts and hyperfine structure as well as a study of the beta strength functions. A new design of the ion source, the dependence of the surface ionization background on the capillary material and time properties of photoion bunches at the mass-separator are discussed.

Structure of 191Pb from α- and β-decay spectroscopy

Complementary studies of Pb-191 have been made in the beta decay of Bi-191 at LISOL (CRC) and in the alpha decay of Po-195 at ISOLDE (CERN). Fine structures in the alpha decay of the low-spin and h ...

Production of neutron rich nuclides from uranium carbide targets of different density

Abstract Online tests of uranium carbide targets of different density 11 and 1.25 g/cm3 coupled with a new type of high temperature electron beam ion source at a temperature of (2050–2300 °C) have been carried out. The yields of neutron rich isotopes of Mn, Fe, Co, Cu, Rh, Pd, Ag, Cd, In, Sn and isotopes of heavy elements such as Pb, Bi, Po and some others have been measured. Comparisons of the yields of Ag, In and Sn isotopes from tested targets are presented. In the temperature interval of (2100–2130 °C) the delay times for Ag and In were measured. The integral online production efficiency from the target – ion source unit estimated in the range (0.2–10%) for different nuclides.

Production of neutron-rich isotopes by one- and two-step processes in ISOL targets

The results are presented for an experiment that compares the difference between a one- and two-step reaction setup using 1 GeV protons. The rates of production from an on-line isotope separator target containing UCx are measured for isotopes in the neutron mass region of Rb and Cs. Some details about the measured results and predictions by the Monte Carlo models are discussed. The effects of the delayed release on the extracted efficiency are generalized using analytical models for application to a wide range of nuclear decay lifetimes.

New laser setup for the selective isotope production and investigation in a laser ion source at the IRIS (Investigation of Radioactive Isotopes on Synchrocyclotron) facilitya)

New laser installation for the resonance ionization spectroscopy in a laser ion source and for rare isotope production has been recently put into operation at the IRIS (Investigation of Radioactive Isotopes on Synchrocyclotron) facility (Petersburg Nuclear Physics Institute, Gatchina). This is a significant improvement of a previous target-laser ion source device of the IRIS mass-separator, working on-line with 1 GeV proton beam of PNPI (Petersburg Nuclear Physics Institute) synchrocyclotron. It makes possible for us to get the isobarically clean radioactive isotope beams of a great number of chemical elements. New laser setup provides the two- or three-resonance step ionization in the range of wavelength of 265-850 nm. The first results obtained at the laser setup for Tl isotopes are presented.

arXiv : Dipole and quadrupole moments of

Nuclear spins and precise values of the magnetic dipole and electric quadrupole moments of the ground-states of neutron-rich