Z. Szeglowski

Production, chemical and isotopic separations of the long-lived isomer 178Hfm2 (T1/2=31 years)

The nucleus 178Hf, with its long-lived (T1/2=31 y) high-spin isomeric state Ipi =16+, is a challenge for new and exotic nuclear physics studies. The authors describe the first experiments they have performed in order to produce a reasonable microweight quantity of this hafnium isomer with an isomeric to ground-state ratio as high as possible (here 5%). The reaction 176Yb (4He, 2n) using an enriched target has been studied by measuring the excitation functions and the isomeric to ground-state ratio. About 3*1014 isomeric atoms have been produced up to now in irradiations with high-intensity beams ( approximately=100 mu A) at the U-200 cyclotron in Dubna. Chemical separation methods could be checked using about 1013 atoms of the isomer. Isotopic separation experiments have been performed in Orsay and preliminary results are given for the separation efficiency.

Study of the Solution Chemistry of Element 104 – Kurchatovium

By Z. Szeglowski, H. Bruchertseifen, V. P. Domanov, B. Gleisberg, L. J. Guseva, M. Hussonnois, G. S. Tikhomirova 3 ,1. Zvara and Yu. Ts. Oganessian 1 Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, 141980, Dubna, USSR 2 Zentralinstitut für Isotopenund Strahlenforschung, Leipzig, DDR 3 V. I. Vernadsky Institute of Geochemistry and Analytical Chemistry, 117979 Moscow, USSR 4 Institut de Physique Nucleaire, Orsay, France

On-line separation of short-lived tungsten isotopes from tantalum, hafnium and lutetium by adsorption on ion exchangers from aqueous ammonia solution

The title goal was achieved using a DOWEX 50Wx8 cation exchange column saturated with La(OH)3 and ammonia solution as eluent. Hf, Ta and Lu were adsorbed on this column, whereas W remained in the solution. This chemical system may be used for fast on-line separations of element 106.

Sorption behaviour of rutherfordium and thorium from HCl/Hf containing aqueous solution

Abstract The sorption was studied of element 104 (rutherfordium, Rf) and thorium on the strongly acidic cation exchanger DOWEX 50×8. The experiments were carried out on-line. Rf is strongly retained on cation exchange resins from diluted HCl/HF solutions in a concentration range of 0.05 to 0.1 M HCl and HF concentrations up to 0.01 M. This behaviour is similar to its pseudohomologue thorium and very different from its lighter homologue hafnium which is desorbed from DOWEX 50×8 at HF concentrations above 10 −3 M. The tested ion exchange system is suitable for fast on-line separation of element 106 (seaborgium, Sg) from all other contaminations and its decay product Rf. It, therefore, allows the indirect identification of Sg.

On line ion exchange separation of short-lived Zr, Hf, Mo, Ta and W isotopes as homologs of transactinide elements

The short-lived isotopes of W and their descendants have been separated from nuclear reaction products arising in the bombardment of samarium target with24Mg ions at the U-400 cyclotron of JINR-Dubna. Chemical separations were performed using previously elaborated fast and continuous ion exchange. In similar way products of235U fission, obtained at the microtron MT-25 during irradiation of235U target with photoneutrons were separated.

Investigation of the 168Hf Electron Capture Decay Using Fast Radiochemical Separation

The (EC+/? ) decay of Hf, produced by the Gd ( , 0,4n) reaction, has been studied, with high efficiency HPGe coaxial detectors, using on-line measurements carried out with the RACHEL setup, built to investigate the chemical properties of transactinide elements. Off-line measurements were also carried out using catcher collection technique. Energies and intensities of 119 y-lines are reported among which only two were known in the earlier study of Chu and Reednick. The Lu level scheme built on the basis of single and γ—γ coincidence measurements, allows the interpretation of more than 79 y-transitions, between 38 excited states reported for the first time.

Chemical isolation of element 106 from aqueous solutions according to model experiments with short-lived tungsten isotopes

The short-lived isotopes of W and their descendants have been isolated from the products of the bombardment of144Sm with24Mg by a fast continuous ion-exchange method, using HF solution media. The feasibility of this method for isolation of element 106 is discussed.

Production, chemical and isotopic separation of the178m2Hf high-spin isomer

The 178m2Hf with its long-lived (T1/2=31 y), high-spin Iπ = 16+, isomeric state, is a challenge for new and exotic nuclear physics studies. The 178m2Hf isomer has been produced in microweight quantities using the 176Yb(α,2n) nuclear reaction, by irradiation with a high-intensity beam using the U-200 cyclotron in Dubna. Radiochemistry and mass separation methods have been developed, with the aim to separate and purify the produced Hf material. Thin targets of isomeric hafnium-178 on carbon backings have been prepared and used in experiments with neutron, proton and deuteron beams.

Fast and continuous chemical isolation of short-lived isotopes of Hf, Ta and W as homologs of elements 104, 105 and 106

Some short-lived isotopes of Hf, Ta and W, synthesized at the U-400 cyclotron of JINR-Dubna, have been isolated using a previously elaborated fast continuous method of chemical isolation of element 104 from nuclear reaction products. The products were transported by a NaCl aerosol jet, from the irradiated targets to a separation device in which Hf, Ta and W were isolated by using three coupled ion-exchange columns.

Hafnium decontamination from microquantities of some elements of groups I, II and III

A method for deep decontamination of high spin178m2Hf isomer from microquantities of Sc, Fe, Co, Ni, Sb and Ag was elaborated using ion exchange separation on Dowex-1 in Hf and CH3COOH−HCl media.