Structure of the 8.65--8.69-MeV doublet in 11C

The 8.65- and 8.69-MeV states in ¹¹C have been studied with the ¹⁰B(³He,d)¹¹C reaction, with a resolution of 9 keV (full width at half maximum). Comparison of absolute spectroscopic strengths for this reaction and for the ¹⁰B(d,p)¹¹B reaction to the 9.19-MeV ($J^{\pi }={\frac{7}{2}}^{+}$) and 9.27-MeV ($J^{\pi }={\frac{5}{2}}^{+}$) states in ¹¹B shows unambiguously that the spin sequence in ¹¹C is the same as in ¹¹B. An additional outcome of the present experiment is a measurement of the width of the 8.69-MeV state: ${\Gamma }_{TOTAL}=15\pm 1$ keV. The natural width of the 8.65-MeV state is considerably less than the experimental resolution width of 9 keV.