A. E. Barzakh

Nuclear electromagnetic moments and charge radii of deformed thulium isotopes with the mass numbers A = 157−172

Abstract Hyperfine structures and isotope shifts of thulium isotopes in the mass range 157–172 have been measured in the atomic transitions 4f 13 6s 2 −4f 12 5d6s 2 (589.565 nm) and 6s 2 −6s6p (597.13 nm), using resonance ionization Spectroscopy at the IRIS facility. Nuclear magnetic dipole and electric quadrupole moments, and the changes in mean square charge radii have been obtained. They are analysed within the framework of the microscopic-macroscopic approach and the Hartree-Fock method, revealing single-particle and collective properties. Some conclusions on effective nucleon-nucleon interactions are drawn.

Nuclear deformation of holmium isotopes

Abstract Hyperfine structures and isotope shifts of holmium isotopes and isomers in the mass range 152–165 have been measured for the atomic transition of 592.17 nm using resonance ionization Spectroscopy. Nuclear magnetic dipole and electric quadrupole moments, and changes in mean square charge radii have been derived from the results. Nuclear spins for some isotopes and isomers have been determined too. A sudden change of nuclear deformation between N = 89 and N = 90 has been found. The experimental data are discussed within the framework of the macroscopic-microscopic approach and the Hartree-Fock method. The intrinsic quadrupole moments, including their change at N = 89–90, are described fairly well. At the same time, some difficulties in the description of the mean square charge radii by the Hartree-Fock theory have been revealed.

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.

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.

Combined target-ion source unit for production of rare nuclides

A combined target-ion source unit (ionizing target) has been developed for the on-line production of radioactive single-charged ions. The target is able to withstand temperatures of up to 2500 °C and also acts as an ion source of surface, electron-beam, and laser ionizations. Using tantalum foil as a target material, the on-line combined target-ion source unit efficiency, which is the product of the ionization and release efficiencies, has been obtained for neutron-deficient isotopes of Eu, Gd, and Yb. These nuclides were ionized by the surface ionization inside a hot tungsten target container, holding tantalum foils as a target material. The results of the combined target-ion source unit use for on-line laser resonant ionization spectroscopy investigation of neutron-deficient Gd isotopes have been also presented. For neutron-rich isotopes produced from a high-density UC target, which were ionized by the surface ionization inside the target container, the ionization efficiency values have been obtained close to 100% for Rb and Cs and 10% for In. For Ag and Sn neutron-richisotopes, the values of the electron-beam ionization efficiency in the volume of the targetcontainer, correspondingly equal to 4% and 2%, have been obtained.

Development of high temperature targets at IRIS facility

Abstract High-temperature targets with different kind of target material, as tantalum foils, tungsten foils, NbC powder, TaC powder and UC powder have been developed and off-line and on-line tested. The yield and delay time measurements have been carried out for radioactive isotopes of Li, Rb and Cs.