V.L. Mikheev

Transfer reactions in the interaction of 40Ar with 232Th

Abstract Transfer reactions in the bombardment of a 232 Th target with 297 MeV and 388 MeV 40 Ar ions have been studied. The energy spectra, angular distributions and the cross sections for the formation of products having atomic numbers 5 ≦ Z ≦ 20 have been measured. In the energy spectra of the reaction products broad peaks having energies in the vicinity of the output Coulomb barrier height have been observed along with the quasi-elastic ones. The dependence of the partial angular distribution of the light products on the reaction Q -value has been determined. The observed partial angular distributions have been analysed by applying the Strutinsky model. The total cross sections of light product formation have been found to be 1100 mb and 2400 mb for the 40 Ar energies E = 297 MeV and E = 388 MeV, which give the values of the critical angular momentum of 102 ħ and 94 ħ respectively for the two cases.

New isotopes29,30Mg, 31,32,33Al, 33,34,35,36Si, 35,36,37,38P, 39,40S and 41,42Cl produced in bombardment of a 232Th target with 290 MeV 40Ar ions

Abstract 17 new nucleides: 29,30Mg, 31,32,33Al, 33,34,35,36Si, 35,36,37,38P, 39,40S and 41,42C together with other, already known nucleides, have been detected and identified in bombardment of a 232Th target with 290 MeV 40Ar ions. The charged-particle identification system combining the magnetic analysis and the ΔE−E technique has been used. The resolving power of the system was good enough to resolve isotopes of argon.

On some regularities in multinucleon transfer reactions with heavy ions

Abstract Multinucleon transfer reactions have been investigated by bombarding 232 Th and 197 Au targets with 137 MeV 16 O ions. An exponential yield dependence on the Q -values was observed for nucleon exchange reactions.

Multinucleon transfer reactions in the 232Th+22Ne system

Abstract Energy spectra of 58 light particles (Z = 3–12) produced in the bombardment of 232Th with 174 MeV 22Ne ions were measured. The kinematics of the two-body reactions leading to the production of these particles is examined in the framework of the model of Siemens, Bondorf, Gross and Dickmann. The phenomenological systematics of the cross sections, covering the whole set of the experimental data, is presented.

Identification of charged particles by combination of the magnetic analysis and the ΔE, E method

Abstract A new method for detecting nuclear reaction products with Z ≲ 10 is described where the combination of the magnetic analysis and the ΔE , E method has been applied. The use of a telescope consisting of thin and thick detectors in the output focus of the magnetic analyzer eliminates the ambiguity of particle identification with magnetic analyzer due to various charge states and improves the mass resolution of the ΔE , E method.

Evidence for particle instability of 10He

Abstract The cross section for 10 He production in the reaction 232 Th ( 15 N −5 protons ) → 10 He at E lab ( 15 N ) = 145 MeV has been estimated from the systematics of the cross sections for multinucleon transfer reactions. In the experiment in which, assuming the particle stability of 10 He, about 80 10 He events should be expected not even a single one has been observed. This result is interpreted as evidence for the particle instability of 10 He.

New isotopes 22O, 20N and 18C produced in transfer reactions with heavy ions

Abstract The new isotopes 22 O, 20 N and 18 C have been produced in transfer reactions by bombarding 232 Th with the 18 O ions accelerated in the Dubna heavy ion cyclotron. The combination of the magnetic analysis and the ΔE × E method have been used to identify the isotopes.

On the nuclear properties of the isotopes 256103 and 257103

Abstract The isotopes 256 103 and 257 103 were synthesized by bombarding 243 Am with 18 O ions. The assignment was based on the excitation functions of the reactions 243 Am( 18 O, 5n) 256 103 and 243 Am( 18 O, 4n) 257 103. The isotope 256 103 has a complicated alpha spectrum in the range 8.35 ≦ E α ≦ 8.60 MeV. An intense group of alpha particles has E α = 8.42 MeV. The measured half-life for 256 103 is about 35 sec. The obtained experimental data permit as to conclude that 257 103 has T 1 2 ≈ 35 sec and 8.5 ≦ E α ≦ 8.6 MeV . The experiments were performed on the external beam of the 310 cm cyclotron of the Laboratory of Nuclear Reactions, JINR.

New isotopes 23F, 24F, 25Ne and 26Ne, produced in nuclear reactions with heavy ions

Abstract New isotopes: 23 F, 24 F, 25 Ne and 26 Ne have been obtained by bombardment of a 232 Th target with 174 MeV 22 Ne ions. The reaction products were identified with a magnetic spectrometer combined with the d E /d x , E technique.

Detection of radioactive 236Pu decay with emission of 28Mg nuclei

Abstract Using solid-state track registration detectors, two cases of 236 Pu decay with 28 Mg emission are detected. The estimate of the partial half-life yields the value of 1.5×10 14 yr; for the relative probability with respect to α-decay, 2×10 −14 .