Role of breakup and direct processes in deuteron-induced reactions at low energies

Abstract

Background: Recent studies of deuteron-induced reactions around the Coulomb barrier $B$ pointed out that numerical calculations for deuteron-induced reactions are beyond current capabilities. The statistical model of nuclear reactions was used in this respect since the compound-nucleus (CN) mechanism was considered to be responsible for most of the total-reaction cross section ${\ensuremath{\sigma}}_{R}$ in this energy range. However, specific noncompound processes such as the breakup (BU) and direct reactions (DR) should be also considered for the deuteron-induced reactions, making them different from reactions with other incident particles.Purpose: The unitary and consistent BU and DR consideration in deuteron-induced reactions is proved to yield results at variance with the assumption of negligible noncompound components.Method: The CN fractions of ${\ensuremath{\sigma}}_{R}$ obtained by analysis of measured neutron angular distributions in deuteron-induced reactions on $^{27}\mathrm{Al}$, $^{56}\mathrm{Fe}$, $^{63,65}\mathrm{Cu}$, and $^{89}\mathrm{Y}$ target nuclei, around $B$, are compared with the results of an unitary analysis of every reaction mechanism. The latter values have been supported by the previously established agreement with all available deuteron data for $^{27}\mathrm{Al}$, $^{54,56\ensuremath{-}58,\mathrm{nat}}\mathrm{Fe}$, $^{63,65,\mathrm{nat}}\mathrm{Cu}$, and $^{93}\mathrm{Nb}$.Results: There is a significant difference between the larger CN contributions obtained from measured neutron angular distributions and calculated results of an unitary analysis of every deuteron-interaction mechanism. The decrease of the latter values is mainly due to the BU component.Conclusions: The above-mentioned differences underline the key role of the breakup and direct reactions that should be considered explicitly in the case of deuteron-induced reactions.