Boron Plus Deuteron Reactions

Gamma and alpha emission from the 15-Mev level of C12 is investigated in the reaction B11(d, n)C12*. An upper limit on the ratio of α- to γ-radiation from the state is Γα / Γγ<1.5. The excitation threshold for 15-Mev gamma radiation is 1.633±0.003 Mev, and the cross section is given as a function of bombarding energy up to 3.25 Mev. Resonances are found at 2.180±0.010 and 3.080±0.015 Mev. Momentum analyses of α particles from deuteron bombardment of B10 and natural boron reveal no excited states in Be8 in the range of excitation 9.8 to 14.8 Mev, and no new states in Be9 below 4.7-Mev excitation. The nature of the 1.75-Mev level of Be9 is discussed. The branching of the β-decay of B12 to the 4.43-Mev state of C12 is found to be 1.4±0.4%, allowing the unique assignment J=1+ to the B12 ground state, which is presumed to be the analog of the 15-Mev state of C12. Upper limits of (0.00±0.01) and (0.1±0.1)%, respectively, are found for γ rays with Eγ>6 Mev and Eγ=3.2 Mev following B12 decay. The cross section for the production of B12 is given as a function of bombarding energy for 0.5<~Ed<~3.25 Mev.