The cross sections and analyzing powers of the ${}_{}{}^{19}{}_{}{}^{}$F(p→,${\gamma }_0$${\gamma }_1$${)}^{20}$Ne reactions have been measured with high precision at nine angles for 24 incident proton bombarding energies in the range 3.5–13.3 MeV, corresponding to excitation energies in ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ of 16.0 to 25.5 MeV. At each energy, the E1 and E2 transition matrix elements were determined from a partial wave analysis of the angular distributions of ${\gamma }_0$. For excitation energies above 23.5 MeV, the calculated direct capture E2 strength can account for most of the measured strength. However, a sizable E2 strength in excess of direct capture was measured for $E_{\gamma }$≤23.5 MeV. Our results indicate that ≊9% of the isoscalar E2 sum rule is exhausted in the (${\gamma }_0$,${\mathrm{p}}_0$) reaction for excitation energies from 16.0 to 25.5 MeV. A comparison with (α,α’) results shows for the first time essential agreement between E2 strengths observed with the two modes of excitation. The analysis of the (p,${\gamma }_0$) data reveals strong evidence for an M1 resonance near an excitation energy of 17.7 MeV. The analysis of angular distribution measurements for the ${\gamma }_1$ decay channel is also reported.

• Received 25 June 1987

DOI:https://doi.org/10.1103/PhysRevC.37.2301