Cross sections and thermonuclear reaction rates for Ta-181(alpha, n)Re-184, Tm-169(alpha, n)Lu-172, Ir-191(alpha, n)Au-194 and Au-197(alpha, n)Tl-200

Cross sections for the Ta-181(alpha, n)Re-184 reaction, populating the 3(-) ground state, were measured for energies ranging from 13 to 28 MeV by meas uring the radioactive products. These and previous results, for mass number s ranging from 160 to 200, are compared with theoretical cross sections usi ng transmission coefficients obtained from new prescriptions of optical mod el parameters for this mass region. Calculations were performed with the 'S TAPRE' code using a statistical model including pre-equilibrium emission. T hermonuclear reaction rates for explosive stellar nucleosynthesis temperatu res were calculated from our experimental values as well as from other expe rimental data for Tm-169(alpha, n)Lu-172, Ir-191(alpha, n)Au-194 and Au-197 (alpha, n)Tl-200 reactions.