A method of the magnetic field formation in cyclotron DC-72

A method of the magnetic field formation in the cyclotron DC-72 model (scale 1:5) is described. The cyclotron is planned to be built in Slovakia. The stages in the shimming of the cyclotron sectors and an automatic system designed for magnetic measurements are described. The data on the magnetic field measurements in the median plane of the cyclotron are presented. A brief description of a computer simulation model and an algorithm of fitting the required sector profiles is presented, as well as the data on the computer simulation of magnetic field distributions. The data on the magnetic field measurements and those on the computer simulations are compared and analyzed. Possible reasons of differences between the measured and simulated data are discussed. The results of the above mentioned computer simulations will be used for building a large facility - the cyclotron DC-72

Excitation functions of fusion reactions and neutron transfer in the interaction of

Excitation functions for evaporation residues in the reactions 197Au(6He, xn)203-xnTl, x = 2-7, and 206Pb(6He, 2n)210Po, as well as for neutron transfer reactions for the production of 196Au and 198Au in the interaction of 6He with 197Au were measured. The 6He beam was obtained from the accelerator complex for radioactive beams DRIBs (JINR). The maximum energy of the beam was about 10AMeV and the intensity reached 2×107pps. The stacked-foil activation technique was used directly in the beam extracted from the cyclotron or in the focal plane of the magnetic spectrometer MSP-144. The identification of the reaction products was done by their radioactive γ- or α-decay. The fusion reaction with the evaporation of two neutrons was characterized by an increase in the cross-section compared to statistical model calculations. The analysis of the data in the framework of the statistical model for the decay of excited nuclei, which took into account the sequential fusion of 6He has shown good agreement between the experimental and the calculated values of the cross-sections in the case of sub-Coulomb-barrier fusion in the 206Pb + 6He reaction. An unusually large cross-section was observed below the Coulomb barrier for the production of 198Au in the interaction of 6He with 197Au. Possible mechanisms of formation and decay of transfer reaction products are discussed