11B (7Li,t) reaction and 4p-5h negative parity states in 15N

The four particle transfer 11B(7Li, t) reaction has been studied at 12 MeV incident energy. Triton angular distributions corresponding to 18 energy levels in 15N below 10.8 MeV excitation are presented. Those exhibiting pronounced structures and indicative of direct reaction mechanisms have been compared with Coulomb distorted plane wave model. The angular momenta of the transferred alpha clusters together with their relative reduced widths have been derived. Significant alpha clustering has been observed for six states in 15N above 9 MeV excitation energy. Negative parity states at 9.152(3/2-), 9.827(7/2-), 9.925(1/2-) and 10.458(7/2-) MeV are found to possess appreciable 4p-5h character with the predominant configuration (p32/)-1(sd)4 mod j=0.2.