Figure 1

Schematic view of the transitions (full arrows denote particle transitions, dashed arrows are $\gamma$ transitions) in a compound reaction involving the nuclei A and F and proceeding via a compound state (horizontal dashed line) with spin $J_C^k$ and parity ${\pi }_C^k$ in the compound nucleus C. The reaction $Q$ values for the capture reaction ($Q_{\mathrm{cap}}$) and the reaction A → F ($Q_F$) are given by the mass differences of the involved nuclei. The effective cross section ${\sigma }^{\mathrm{eff}}$ [Eqs. (4) and (7)] for a reaction type is a sum over all energetically possible transitions to bound states (capture: in nuclei A and C; otherwise: in nuclei A and F) from the compound level as shown here (see text for details). In each nucleus, a number of low-lying states with given spin $J$ and parity π is explicitely specified. Above the last state, transitions can be computed by integrating over nuclear level densities (shaded areas). In stellar cross sections ${\sigma }^{*}$ all transitions are additionally weighted by a Boltzmann distribution factor depending on the stellar temperature, spin, and the excitation energy of the involved state [see Eq. (3)].Reuse & Permissions

Figure 2

Reaction $Q$ values for $(p,n)$ and ($\alpha ,n)$ reactions with $f_{\mathrm{rev}}<f_{\mathrm{forw}}$.Reuse & Permissions

Figure 3

Targets for endothermic reactions with $f_{\mathrm{rev}}<f_{\mathrm{forw}}$ in the nuclear chart, where charge is denoted by $Z$ and neutron number by $N$. The reaction type is given by the label. Only capture or photodisintegration reactions are shown. Also printed for orientation are stable and long-lived nuclides.Reuse & Permissions

Figure 4

Targets for endothermic reactions with $f_{\mathrm{rev}}<f_{\mathrm{forw}}$ in the nuclear chart, where charge is denoted by $Z$ and neutron number by $N$. The reaction type is given by the label. Only reactions without $\gamma$ channels are shown. Also printed for orientation are stable and long-lived nuclides.Reuse & Permissions

Figure 5

Simplified decay scheme of the products of the ${}^{85}\mathrm{Rb}(p,n){}^{85}\mathrm{Sr}$ reaction. The half-lives of the reaction products, the branching ratios, the spin and parity of the levels, and the transitions used to determine the reaction cross section are indicated [23].Reuse & Permissions

Figure 6

Typical $\gamma$ spectra taken after the irradiation of RbCl targets with 2.4 (left panel) and 3.8 MeV (right panel) proton beams. The 514.01-keV peak from the ${}^{85}\mathrm{Rb}(p,n){}^{85}\mathrm{Sr}{}^g$ reaction can be well separated from the annihilation peak as can be seen in the insets. The length of the waiting time ($t_w$) between the end of the irradiation and the start of the $\gamma$ countings were 540 ($E_p=2.4$ MeV) and 30 min ($E_p=3.8$ MeV). The lower panels show typical spectra taken in the repeated activity measurement approximately 1 month after the irradiations (for details see text).Reuse & Permissions

Figure 7

Experimental (full triangles) and theoretical (lines) astrophysical $S$ factors of ${}^{85}\mathrm{Rb}(p,n){}^{85}\mathrm{Sr}$. The solid line is the $S$ factor calculated with the modified proton optical potential introduced in Ref. [1] and the dashed line shows the result using the standard proton optical potential from Ref. [31] with low-energy modifications by Ref. [32] (see text).Reuse & Permissions

Figure 8

The newly derived stellar reactivity of ${}^{85}\mathrm{Sr}(n,p){}^{85}\mathrm{Rb}$ is compared to the one given in Ref. [33] (area labeled “new/std”). The temperatures $T_9$ are stellar plasma temperatures in GK. The shaded area accounts for an error of $\pm 10$%. As seen in Table , the experimental data contribute significantly in the range $2⩽T_9⩽4$. Also shown is the reactivity from a fit of our new result compared to the actual value (curve labeled “newfit/new”). This shows that the fit accuracy is high.Reuse & Permissions