First application of the $n\text{−}{}^9\mathrm{Be}$ optical potential to the study of the ${}^{10}\mathrm{Be}$ continuum via the $\left({}^{18}\mathrm{O},{}^{17}\mathrm{O}\right)$ neutron-transfer reaction

The ${}^9\mathrm{Be}\left({}^{18}\mathrm{O},{}^{17}\mathrm{O}\right){}^{10}\mathrm{Be}$ reaction has been studied at an incident energy of 84 MeV, and the ejectiles have been detected at forward angles. The ${}^{10}\mathrm{Be}$ excitation energy spectrum has been obtained up to about 18 MeV, and several known bound and resonant states of ${}^{10}\mathrm{Be}$ have been identified. Calculations that describe the interaction of the neutron removed from the ${}^{18}\mathrm{O}$ projectile with the ${}^9\mathrm{Be}$ target by means of an optical potential with a semiclassical approximation for the relative motion account for a significant part of the ${}^{10}\mathrm{Be}$ continuum. Two parametrizations of the optical-model potential for the system $n\text{−}{}^9\mathrm{Be}$ have been used and compared.

Figure 1

Excitation energy spectrum of the ${}^9\mathrm{Be}\left({}^{18}\mathrm{O},{}^{17}\mathrm{O}\right){}^{10}\mathrm{Be}$ reaction at 84-MeV incident energy and ${\theta }_{\mathrm{lab}}=4.5^{\circ }$. The background that comes from ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$ impurities is shown as the blue-dotted and red-hatched areas, respectively.

Figure 2

Inclusive excitation energy spectrum of the ${}^9\mathrm{Be}\left({}^{18}\mathrm{O},{}^{17}\mathrm{O}\right){}^{10}\mathrm{Be}$ reaction at 84-MeV incident energy and $3^{\circ }<{\theta }_{\mathrm{lab}}<{10}^{\circ }$. The background that comes from ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$ impurities has been subtracted. Peaks marked with an asterisk refer to the ${}^{17}\mathrm{O}$ ejectile emitted in its first excited state at 0.87 MeV. Total $1-n$ breakup calculations that result from the use of the DOM and the $AB$ potentials (see text) [12] are shown as the green-continuous and the violet-dashed lines, respectively. The experimental data [22] of the ${}^9\mathrm{Be}\left(n,nn\right){}^8\mathrm{Be}$ [23] and ${}^9\mathrm{Be}\left(n,\alpha \right){}^6\mathrm{He}$ [24] reactions are reported as the red-dotted and blue-dotted-dashed lines, respectively. The $1n\text{−}(S_n)$, $2n\text{−}(S_{2n})$, and $\alpha \text{−}\left(S_{\alpha }\right)$ separation energies are also indicated.

Figure 3

Inclusive excitation energy spectrum of the reaction for $3^{\circ }<{\theta }_{\mathrm{lab}}<{10}^{\circ }$ and theoretical calculations of various breakup components (see text) that use: (a) the DOM potential and (b) the $AB$ potential. In both panels, the red-dotted-dashed $\left(\mathrm{el}{}^{17}{\mathrm{O}}_{\mathrm{g}.\mathrm{s}}\right)$ and blue-dotted $\left(\mathrm{abs}{}^{17}{\mathrm{O}}_{\mathrm{g}.\mathrm{s}.}\right)$ curves represent the elastic and the absorption breakups that correspond to the emission of a neutron which leaves the ${}^{17}\mathrm{O}$ in its ground state. The green dashed curve $\left(\mathrm{el}{}^{17}{\mathrm{O}}_{0.87}\right)$ and the pink double-dashed-dotted curve $\left(\mathrm{abs}{}^{17}{\mathrm{O}}_{0.87}\right)$ represent the elastic and the absorption breakups that correspond to the ${}^{17}\mathrm{O}$ core in its first excited state at 0.87 MeV. The orange curve (total) is the sum of all contributions. All calculations are folded with the experimental resolution.

Figure 4

Dominant contributions to the partial-wave decomposition of the theoretical energy spectrum shown in Fig. 3. The legend indicates the single-particle angular momentum of each individual strength distribution.

Figure 5

Excitation energy spectra of the ${}^9\mathrm{Be}\left({}^{18}\mathrm{O},{}^{17}\mathrm{O}\right){}^{10}\mathrm{Be}$ reaction at 84-MeV incident energy for (a) ${\theta }_{\mathrm{lab}}=5.5^{\circ }$; (b) ${\theta }_{\mathrm{lab}}=7.5^{\circ }$; (c) ${\theta }_{\mathrm{lab}}=9.5^{\circ }$. The background that comes from ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$ impurities has been subtracted.