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.     

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.     

Muon induced fission of 237Np, 239Pu and 242Pu

The absolute yields for prompt and delayed fission induced by negative muons in ²³⁷Np, ²³⁹Pu and ²⁴²Pu have been measured and compared with photofission data.     

Second experiment at VASSILISSA separator on the synthesis of the element 112

The upgraded separator VASSILISSA was used to confirm results of previous experiments on the synthesis of the heavy isotopes of the element 112 obtained in complete-fusion reactions of ⁴⁸Ca and ²³⁸U. An additional reason was the non-observation of any events in the same reaction studied with the BGS separator at Berkeley. Limits of for the atomic mass number of the observed spontaneously fissioning isotope were measured. The obtained results on the decay mode, half-life and production cross-section are in agreement with those obtained in our first experiment.Received: 10 June 2003, Revised: 29 July 2003, Published online: 2 December 2003PACS: 23.60. + e decay - 25.70.-z Low and intermediate energy heavy-ion reactions - 25.85.Ca Spontaneous fission - 27.90. + b      

Synthesis of superheavy nuclei in the reactions of 244Pu and 248Cm with 48Ca

This paper presents results of the experiments aimed at producing long-lived superheavy elements located near the spherical-shell closures with Z ⩾ 114 and N ⩾ 172 in the ²⁴⁴Pu + ⁴⁸Ca and ²⁴⁸Cm + ⁴⁸Ca reactions. The large measured α-particle energies of the newly observed nuclei, together with the long decay times and spontaneous fission terminating the chains, offer evidence of the decay of nuclei with high atomic numbers. The decay properties of the synthesized nuclei are consistent with the consecutive α-decays originating from the parent nuclides ^{288, 289}114 and ²⁹²116, produced in the 3n and 4n evaporation channels with cross-sections of about a picobarn. The present observations can be considered as experimental evidence of the existence of the “island of stability” of superheavy elements. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: utyonkov@sungns.jinr.ru     

Electromigration Studies of Carrier-Free 239Np(V) in Aqueos Solutions

Ion mobilities of carrier-free ²³⁹Np(V) have been measured in aqueous solutions, T = 298.1 (1) K. Ion mobilities of ²³⁹NpO₂ ⁺ and its dependencies on pH of acidic inert electrolytes have been measured. In alkaline solutions the stoichimetric hydrolysis constants of NpO₂(OH) as well as NpO₂(OH)₂ ^? have been obtained. Complex formations of ²³⁹Np(V) with oxalate, tartrate, sulphate, acetate and citrate ligands have been studied in neutral solutions.     

Isolation and ion exchanging behaviour of mendelevium/II/

Mendelevium-256 was obtained by irradiating of Bk-249 with Ne-22 ions in the external beam of U-300 cyclotron. An efficient ionexchanging method of medelevium isolation and separation from nuclear reaction products have been developed in which a column with cation exchanger and zinc amalgam and 1M HCl solutions as eluents were used. Under these conditions mendelevium has been shown to be reduced and washed out as an alkaline earth element. The ionic radius of Md²⁺ has been estimated from a correlation of the elution peak positions with ionic radius of several divalent elements. This value was used to calculate the heat of hydration of Md²⁺ ion.     

Structural characteristics of different types of nanoparticles synthesised in mesomorphic metal alkanoates

The class of thermotropic ionic liquid crystals (LCs) of the metal alkanoates possesses a number of unique properties, such as intrinsic ionic conductivity, high dissolving ability and ability to form time-stable mesomorphic glasses. These ionic LCs can be used as nanoreactors for the synthesis and stabilisation of different types of nanoparticles (NPs). Thus, some semiconductors, metals and core/shell NPs were chemically synthesised in the thermotropic ionic liquid crystalline phase (smectic A) of the cadmium octanoate (CdC₈) and of the cobalt octanoate (CoC₈). By applying the scanning electron microscopy, the cadmium and cobalt octanoate composites containing CdS, Au, Ag and core/shell Au/CdS NPs have been studied. NPs’ sizes and dispersion distribution of the NPs’ size in the nanocomposites have been obtained.