DOE OSTI2015
In this contribution, we will describe neutron and proton removal from {sup 9}C and {sup 7}Be which are two particularly interesting nuclei entering the nucleo-synthesis pp-chain [1, 2]. Neutron and proton removal reactions have been used in the past twenty years to probe the single-particle structure of exotic nuclei. The core parallel-momentum distribution can give information on the angular momentum and spin of the nucleon initial state while the total removal cross section is sensitive to the asymptotic part of the initial wave function and also to the reaction mechanism. Because knockout is a peripheral reaction from which the Asymptotic Normalization Constant (ANC) of the single-particle wave function can be extracted, it has been used as an indirect method to obtain the rate of reactions like {sup 8}B(p,γ){sup 9}C or {sup 7}Be(p,γ){sup 8}B. Nucleon removal has recently been applied by the HiRA collaboration [3] to situations in which the remaining “core” is beyond the drip line, such as {sup 8}C and {sup 6}Be, unbound by one or more protons, and whose excitation-energy spectrum can be obtained by the invariant-mass method. By gating on the ground-state peak, “core” parallel-momentum distributions and total knockout cross sections have been obtained similar to previous studies with well-bound “cores”. In addition for each projectile, knock out to final bound states has also been obtained in several cases. We will report on the theoretical description and comparison to this experimental data for a few cases for which advances in the accuracy of the transfer-to-the continuum model [4, 5] have been made [6]. These include the use, when available, of “ab-initio” overlaps for the initial state [7] and in particular their ANC values [8]. Also, the construction of a nucleus-target folding potential for the treatment of the core-target S-matrix [9] using for the cores “ab-initio” densities [10] and state-of-the-art n−{sup 9}Be optical potentials [11]. Preliminary results and open problems will be discussed.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗