Fusion reactions around the barrier for Be+238U

Fusion-evaporation cross sections of U-238(Be-9, 5n)Cm-242 are measured over a wide energy range around the Coulomb barrier. These measured cross sections are compared with model calculations using two codes, namely HIVAP2 and KEWPIE2. HIVAP2 calculations overestimate the measured fusion-evaporation cross sections by a factor of approximately 3. In KEWPIE2 calculations, two approaches, namely the Wentzel-Kramers-Brillouin (WKB) approximation and the empirical barrier-distribution (EBD) method, are used for the capture probability; both of them properly describe the measured cross sections. Additionally, fusion cross sections of Be-7,Be-9+U-238 measured in two experiments are applied to constrain model calculations further through three codes, i.e., HIVAP2, KEWPIE2, and CCFULL. Parameters in these codes are also examined by comparison with measured fusion cross sections. All the comparisons indicate that the KEWPIE2 calculations using the WKB approximation agree well with the measured cross sections of both fusion reactions Be-7,Be-9+U-238 and the fusion-evaporation reaction U-238(9Be, 5n)Cm-242. Calculations using the fusion code CCFULL are also in good agreement with the measured fusion cross 7sections of Be-7,Be-9+U-238.

Automated summary

The fusion-evaporation cross sections of U-238(Be-9, 5n)Cm-242 were studied and compared with model calculations using two codes. HIVAP2 overestimated the results, while KEWPIE2 using WKB approximation properly described the measured cross sections. Parameters in the codes were examined and it was found that the WKB approximation was in good agreement with the experimental data.