A. V. Isaev

Experimental Tests of the Modernized VASSILISSA Separator (SHELS) with the Use of Accelerated 50 Ti Ions

A high intensity ion beam of 50Ti ions was obtained using the ECR ion source on the U400 cyclotron. The experimental tests using accelerated 50Ti ions were performed with a modernized VASSILISSA separator (SHELS). Data has been obtained on the transmission coefficients of recoil nuclei synthesized in complete fusion reactions. Estimates from ion optical calculations performed in the design phase of the project of modernizing the separator are completely confirmed.

First Experimental Tests of the Modernized VASSILISSA Separator

The results of the first experimental tests of the modernized VASSILISSA separator with the use of accelerated 22Ne ions are presented. Data has been obtained on the transmission coefficients of recoil nuclei synthesized in asymmetric combinations of the incident ion and target nuclei. Estimates from ion optical calculations performed in the design phase of the project of modernizing the separator are completely confirmed.

A detector for studying the characteristics of spontaneous fission of short-lived heavy nuclei

The detector system of the VASSILISSA separator has been complemented with an array of 54 3He neutron counters to study the multiplicity of prompt spontaneous-fission neutrons. The detection efficiency of the new neutron detector is 39%. The description of the detector system and the characteristics of 252No spontaneous fission, obtained in the test experiment in July of 2010, are presented.

Spontaneous fission of 256 Rf, new data

Spontaneous fission properties of the short-lived neutron-deficient 256Rf nucleus produced in the complete fusion reaction with a beam of multiply charged heavy 50Ti ions from the U-400 cyclotron (FLNR, JINR) are experimentally investigated. Its half-life and decay branching ratio are measured. The average number of neutrons per spontaneous fission of 256Rf (\(\bar v = \;4.47 \pm \;0.09\)) is determined for the first time.

Application of a double-sided stripped Si detector in the focal plane of the VASILISSA separator

A new double-sided multistrip (48 × 48 strips) Si detector is described, and the first results of its application in experiments on spectroscopy of transfermium elements at the VASILISSA separator are given.

Characteristics of spontaneous fission of 250 No

This study describes an experiment on investigating the properties of spontaneous fission of shortlived neutron-deficient nuclei synthesized in the reaction of complete fusion 48Ca + 204Pb = 252No*. The experiment is performed using the SHELS separator and the beam of multicharged ions at U-400 accelerator (LNR, JINR). Two activities undergoing spontaneous fission, which can be related to the ground and isomeric states of 250No nucleus, are registered. The half-lives, total kinetic energies of fission fragments, and neutron multiplicities are measured for the short-lived nuclei. The average number of neutrons per fission for the activity with t 1/2 = 5.1 ± 0.3 μs is = 4.38 ± 0.13 μs, and for nuclei with the half-life t 1/2 = 36 ± 3 μs it is xxxxx.

Short-Lived Isotopes of Transfermium Elements: Studying Characteristics of Spontaneous Fissioning

Abstractseries of experiments performed in 2014–2015 using the SHELS separator and a beam of multicharged ions from the U-400 accelerator at the Flerov Laboratory of Nuclear Reactions (Joint Institute for Nuclear Research) in Dubna is described. In preparation for a large program of experiments with a beam of highly charged ions of 50Ti, an experiment is performed to study the spontaneous fissioning (SF) of short-lived neutron-deficient isotope 256Rf formed in complete fusion reaction50Ti + 208Pb = 256Rf + 2n. The half-life of 256Rf is measured along with the probability of its SF decay. The average number of neutrons per one event of 256Rf SF (

Investigating neutron multiplicity during the spontaneous fission of short-lived isotopes (Z ≥ 100) using the VASSILISSA recoil separator

\bar v