Speaker
Description
Heavy-ion fusion-evaporation reactions populating nuclei near Z ≈ 85–90 reveal an evaporation-channel puzzle: charged-particle channels pxn and axn are enhanced relative to pure neutron evaporation (xn). In several cases the axn channel exceeds xn by up to two orders of magnitude. A weaker but structurally analogous enhancement is predicted for selected superheavy-element reactions — including ⁵¹V + ²⁴⁸Cm forming Z = 119 — where axn channels can compete with xn even though the effect is less dramatic. At the vanishingly small cross sections typical of superheavy nuclei synthesis, this competition creates a genuine identification hazard: a decay chain assigned to xn evaporation may instead originate from a charged-particle channel populating an already-known nuclide. This talk examines the mechanism behind the pxn/axn enhancement — equivalently, xn suppression — and traces its consequences for interpreting current and future experiments. For some reactions employing projectiles heavier than ⁴⁸Ca, pxn emission has already been reported experimentally, underscoring that this is not a marginal correction but a channel demanding quantitative treatment in reaction-model predictions for the heaviest elements.