Resolve the remaining discrepancies in the evaporation-residue excitation functions

Resolve the three explicitly identified discrepancies between the calculated and measured evaporation-residue cross sections for the $^{48}$Ca+$^{244}$Pu reaction: the uncertain $\sigma_{4n}/\sigma_{3n}$ ratio at $E^{*}=39$ MeV, the underestimated high-energy tail at $E^{*}=53$ MeV, and the overestimated cross sections on the rising flank near $E^{*}=34.8$–$35.2$ MeV, including the $4n$ non-observation limit that cannot be reconciled with the description at the maximum by varying the damping temperature.

Background

The paper models evaporation-residue production in the $^{48}$Ca+$^{244}$Pu reaction by combining a dinuclear-system description of capture and fusion with a coupled neutron-evaporation and fission cascade for the compound nucleus $^{292}$Fl. The coupled treatment improves the description of the correlation between neutron multiplicity and fission competition, but comparison with fourteen measured cross sections still reveals substantial channel- and energy-dependent discrepancies.

The authors identify three unresolved points: the calculated $\sigma_{4n}/\sigma_{3n}$ ratio at $E^{*}=39$ MeV lies at the lower end of the range allowed by mutually inconsistent $3n$ measurements; the calculated high-energy tail is too small, by a factor of seven at $E^{*}=53$ MeV; and the calculated cross sections are too large on the rising flank, notably exceeding the $4n$ non-observation limit at $E^{*}=35.2$ MeV by a factor of nineteen. They further state that no damping-temperature value was found that removes the last discrepancy while preserving the agreement near the excitation-function maximum.