The Interaction of 6He with 197Au and 206Pb

Abstract

Excitation functions have been measured for evaporation residues from compound nuclei formed in the interaction of 6He with 197Au and 206Pb. The transfer reactions leading to 194Au, 196Au and 198Au were also studied for the case of 6He + 197Au. The experiments were performed at the JINR accelerator complex for radioactive beams DRIBs, capable of providing 6He beams of about 10 AMeV maximum energy and an intensity of up to 2×107 pps. 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 reactions with the evaporation of two neutrons were 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 when the sequential fusion of 6He was taken into account has shown good agreement between the experimental and the calculated values of the cross sections for the case of sub‐Coulomb‐barrier fusion in the 206Pb+6He reaction. At the Coulomb barrier unusually high cross section was measured for the production of 198Au, whereas only an upper limit was determined for the formation of 199Au. Possible mechanisms of formation and decay of transfer reaction products are discussed.