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A new laser installation for the resonance ionization spectroscopy in a laser ion source and for rare isotope production has been put into operation at the IRIS mass-separator, working on-line with the 1 GeV proton beam of the Petersburg Nuclear Physics Institute synchrocyclotron. Isotope shift and hyperfine splitting of 276.9 nm atomic transition in the long chain of Tl isotopes and isomers have been measured. New data on the magnetic moments and changes in mean squared charge radius for 183,184,185,185m,186m2,195m,197mTl have been obtained.

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.

A high temperature refractory target (HTRT) specially designed for the suppression of the background of thermoion current coming from the target volume to the laser ion source has been off line and on line tested.

An application of the totalγ-absorption (TGA) spectroscopy to measurements of theβ-decay energies (Q) for nuclei far from stability is described. This approach provides theQ-values with accuracies up to 60 keV. TheQ values determined by this method at the IRIS facility for 64 nuclides in the mass region fromA=76 toA=165 are presented.

International audience; Production of Rb, Cs and Fr isotopes from uranium carbide targets of a high density has been investigated. The UC target material with a density of 12 g/cm3 was prepared in a form of pellets of 2 mm thickness, 11 mm in diameter and grain dimensions of about 20 microns. Two targets were tested on-line at the same temperature conditions: a) a reference small target with a thickness of 4.5 g/cm2; b) a big massive target with a thickness of 91 g/cm2. The yields and release efficiencies of the nuclides with the half-lives from some minutes to some milliseconds produced from the investigated targets have been presented. A preliminary analysis of the obtained results has shown an increase of the produced nuclide yields proportionally to the target thickness even for very short-lived isotopes 214Fr (T1/2=5 ms) and 219Fr (T1/2=20 ms). One month off-line heating test of a big target at a temperature of 2000 °C has been conducted. The yields and release of Rb, Cs and Fr measured on-line before and after the heating test coincided in the limits of measurement errors that demonstrated the conservation of the developed target unit parameters. The construction of a big target with the mass about 0.7 kg prepared presently at IRIS has been discussed.

The production of neutron-rich Ag, In and Sn isotopes from a uranium carbide target of a high density has been investigated at the IRIS facility in the PLOG (PNPI-Legnaro-GANIL-Orsay) collaboration. The UC target material with a density of 12 g/cm3 was prepared by the method of powder metallurgy in a form of pellets of 2 mm thickness, 11 mm in diameter and grain dimensions of about 20 μm. The uranium target mass of 31 g was exposed at a 1 GeV proton beam of intensity 0.05–0.07 μA. For the ionization of the produced species the electron beam–plasma ionization inside the target container (ionizing target) has been used. It was the first experiment when the new high density UC target material was exploited with the electron–plasma ionization. Yields of Sn isotopes have been measured in the target temperature range of (1900–2100) °C. The yields of some Pd, In and Cd isotopes were measured as well to compare to previously measured ones from a high density uranium carbide target having a ceramic-like structure. For the first time a nickel isotope was obtained from a high density UC target.

International audience; Production of on-line mass separated neutron-rich isotopes using fission induced by 1 GeV protons on high-density uranium targets (typically 11 g/cm3) has been investigated for several years at the IRIS facility. Here we review some of the achievements during the years up to 2006 and the perspectives. In particular, we present a comparison of yields in p and n-induced fission, enhancements by secondary neutrons, a comparison with lower-density targets used at PARRNe and ISOLDE for Rb and Cs isotopes and preliminary results obtained with a new UC target material.

International audience; The capacity of uranium carbide target materials of different structure and density for production of neutron-rich and heavy neutron-deficient nuclides have been investigated. The yields of Cs and Fr produced by a 1 GeV proton beam of the PNPI synchrocyclotron and release properties of different targets have been measured. Yields and release efficiencies of Cs and Fr produced from a high density UC target material and from low density UCx prepared by the ISOLDE method at IRIS in the collaboration with PARRNe group from Orsay are compared. The yields from ISOLDE original target are presented for comparison as well.

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.

One of the unsolved problems of laser ion-source application is the reduction of the background from the thermoionic current arising in the laser ion source (LIS) at high temperature. This background decreases the selectivity of the laser ionisation and hinders strongly the possibility to investigate nuclei far from stability. In order to avoid or, at least, to reduce the background to lower level it is suggested to use sources with a modified inner surface. The modifications are carried out in a special device and consist in multi-stage treatment of the LIS tube, made of Ta, with various species. The detailed description of the technology is presented and the first results are discussed.