Nuclear spin orientation of 12,13B created in heavy ion collisions Original Research Article

The momentum dependences of the nuclear spin polarization P and alignment A of 12B (Iπ = 1+, T1/2 = 20.20 ms) [13B (Iπ = 3/2−, T1/2 = 17.36 ms)] produced in 100AMeV 13C [15N] + Be collisions have been measured by detecting the β-ray asymmetry. Because both the P and A were significantly smaller than the prediction from a simple kinematical model, some depolarization mechanisms must be taken into account related with the collision process itself. Comparing the signs of the observed alignment of 12B and 13B, the sign of the quadrupole moment Q(13B) was determined to be positive.