Measurement of 42 MeV 7Li projectile breakup on 208Pb target near grazing incidence Original Research Article

Breakup of 42 MeV 7Li projectiles in the field of a 208Pb target are studied near the grazing angle. In inclusive breakup measurements, angular distribution of the α and t fragments are found to be rather flat in nature. The α–t coincidence measurements are carried out with wide angular separations between the detected fragments. The choice of detection angles enables measurement in the same range of fragment relative energies but very different 7Li∗ scattering angles. The direct breakup contribution is found to dominate over the sequential breakup for the View the MathML source set, while the reverse is true when View the MathML source. Calculations performed in a full quantum mechanical framework reproduce the overall shape of the direct breakup part of the present data and several existing data on 197Au and 208Pb targets at nearby energies. The sequential breakup is observed only from the decay of the 4.63 MeV (7/2−) resonant excited state of 7Li and its angular distribution does not fully agree with the existing theoretical predictions. Unlike the direct part, the sequential breakup cross section does not decrease with increasing scattering angles. Similar measurements with halo nuclei would be helpful to study their unknown resonant states.