B11(d,p)B12Angular Distributions atEd=5.5MeV for theB122.62- and 2.72-MeV Levels

Abstract

The angular distributions of the ${\mathrm{B}}^{11}\mathrm{}(d,p)\mathrm{}{\mathrm{B}}^{12}$ reaction leading to the 0.95-, 1.67-, 2.62-, 2.72-MeV levels of ${\mathrm{B}}^{12}$ were measured at an incident deuteron energy of 5.5 MeV. The angular distribution of the elastically scattered deuterons from ${\mathrm{B}}^{11}$ was also measured. The results were analyzed both by Butler theory and by zero-range distorted-wave Born-approximation calculations. The orbital angular momentum transferred in the reaction was determined to be $l_n=1,0,0,\mathrm{and} \mathrm{}\left(1\right)\mathrm{}$ for these states of ${\mathrm{B}}^{12}$. Some ${\mathrm{B}}^{11}(d,p\gamma ){\mathrm{B}}^{12}$ measurements were made. The results for the decay of the 1.67-, 2.62-, and 2.72-MeV states were consistent with previous work. The 3.39-MeV level of ${\mathrm{B}}^{12}$ was found to have a partial width for gamma decay which is less than 10% of the total width. The level structure of ${\mathrm{B}}^{12}$ is compared with the spectrum of ${\mathrm{C}}^{12}$ above 15-MeV excitation. Recent ${\mathrm{B}}^{11}\mathrm{}(d,p)\mathrm{}{\mathrm{B}}^{12}$ angular-distribution measurements of Mingay are used to analyze Doppler-shift measurements of Warburton and Chase for the ${\mathrm{B}}^{12}$ 1.67- and 2.62-MeV levels. The result is limits of less than ${10}^{-13\mathrm{}}$ sec on the mean lifetimes of both states.