84
W. H. Dickhoff
current implementation and corresponding details can be found in [3]. The method
is known as the dispersive optical model (DOM) and has proceeded way beyond
its original form [4]. A more general review of the optical model is available
in [5]. We discuss some recent developments of the DOM with applications to
transfer reactions in Sect. 2, the analysis of the (e, e p) reaction solely with DOM
ingredients in Sect. 3, predictions of neutron distributions in Sect. 4, and finally offer
some conclusions in Sect. 5.
2 Transfer Reactions and the DOM
Transfer reactions are under intense study in order to develop a reliable method to
generate accurate results given certain ingredients like overlap functions and optical
potentials. A remaining source of uncertainty in the calculation of transfer reaction
observables is the optical potential for the relevant nucleons and the deuteron. Our
group has made several contributions to this effort documented in Refs. [6, 7] mostly
involving exploratory efforts.
Deuteron-induced reactions have played an important role in elucidating properties of neutrons that are either added to or removed from the target nucleus. This
role will be even more prominent when such transfer reactions are studied in inverse
kinematics at radioactive beam facilities like FRIB [8, 9]. While scientifically
compelling in its own right, the (d, p) reaction also yields indirect access [10] to
the study of neutron capture and therefore provides essential information for the
(n, γ ) reaction which is critical for the study of the understanding of the r-process.
The present state of the reaction description can be summarized by noting that the
distorted-wave Born approximation and coupled-channel approaches have mostly
studied discrete final states. The treatment of the continuum was proposed in the
late 1970s but efforts ended in the 1990s, with an unresolved controversy. Only
recently, three different groups [11–13] have revived this subject and during a recent
workshop at MSU/FRIB [14] have concluded that the relevant issues have now been
resolved.
The main ingredients of the present state of the (d, p) reaction description allows
a simultaneous treatment of transfer, elastic breakup, and the formation of the
compound nucleus. Critical ingredients for the relevant calculations are provided
by the deuteron optical potential, the description of the propagation of the added
neutron, and the final proton optical potential. Phenomenological optical potentials
suffer from being non-dispersive, local, and are not constrained by negative energy
data. A proper description of the reaction therefore requires dispersive, non-local
potentials that are also constrained by negative energy data. Such potentials are
provided by the latest implementation of the DOM [3] for the neutron and proton
propagation. An initial assessment of the DOM ingredients has been implemented
by employing the local version [15] for Ca isotopes including an extrapolation
to 60 Ca. These results together with an overview of the current theory relevant
for elastic and non-elastic breakup have been published in [16]. Already at this
W. H. Dickhoff
current implementation and corresponding details can be found in [3]. The method
is known as the dispersive optical model (DOM) and has proceeded way beyond
its original form [4]. A more general review of the optical model is available
in [5]. We discuss some recent developments of the DOM with applications to
transfer reactions in Sect. 2, the analysis of the (e, e p) reaction solely with DOM
ingredients in Sect. 3, predictions of neutron distributions in Sect. 4, and finally offer
some conclusions in Sect. 5.
2 Transfer Reactions and the DOM
Transfer reactions are under intense study in order to develop a reliable method to
generate accurate results given certain ingredients like overlap functions and optical
potentials. A remaining source of uncertainty in the calculation of transfer reaction
observables is the optical potential for the relevant nucleons and the deuteron. Our
group has made several contributions to this effort documented in Refs. [6, 7] mostly
involving exploratory efforts.
Deuteron-induced reactions have played an important role in elucidating properties of neutrons that are either added to or removed from the target nucleus. This
role will be even more prominent when such transfer reactions are studied in inverse
kinematics at radioactive beam facilities like FRIB [8, 9]. While scientifically
compelling in its own right, the (d, p) reaction also yields indirect access [10] to
the study of neutron capture and therefore provides essential information for the
(n, γ ) reaction which is critical for the study of the understanding of the r-process.
The present state of the reaction description can be summarized by noting that the
distorted-wave Born approximation and coupled-channel approaches have mostly
studied discrete final states. The treatment of the continuum was proposed in the
late 1970s but efforts ended in the 1990s, with an unresolved controversy. Only
recently, three different groups [11–13] have revived this subject and during a recent
workshop at MSU/FRIB [14] have concluded that the relevant issues have now been
resolved.
The main ingredients of the present state of the (d, p) reaction description allows
a simultaneous treatment of transfer, elastic breakup, and the formation of the
compound nucleus. Critical ingredients for the relevant calculations are provided
by the deuteron optical potential, the description of the propagation of the added
neutron, and the final proton optical potential. Phenomenological optical potentials
suffer from being non-dispersive, local, and are not constrained by negative energy
data. A proper description of the reaction therefore requires dispersive, non-local
potentials that are also constrained by negative energy data. Such potentials are
provided by the latest implementation of the DOM [3] for the neutron and proton
propagation. An initial assessment of the DOM ingredients has been implemented
by employing the local version [15] for Ca isotopes including an extrapolation
to 60 Ca. These results together with an overview of the current theory relevant
for elastic and non-elastic breakup have been published in [16]. Already at this