Formation of {alpha} clusters in dilute neutron-rich matter

The surface of neutron-rich heavy nuclei, with a neutron skin created by excess neutrons, provides an important terrestrial model system to study dilute neutron-rich matter. By using quasi-free α cluster–knockout reactions, we obtained direct experimental evidence for the formation of α clusters at the surface of neutron-rich tin isotopes. The observed monotonous decrease of the reaction cross sections with increasing mass number, in excellent agreement with the theoretical prediction, implies a tight interplay between α-cluster formation and the neutron skin. This result, in turn, calls for a revision of the correlation between the neutron-skin thickness and the density dependence of the symmetry energy, which is essential for understanding neutron stars. Our result also provides a natural explanation for the origin of α particles in α decay.

Source: ScienceNOW - January 14, 2021 Category: Science Authors: Tanaka, J., Yang, Z., Typel, S., Adachi, S., Bai, S., van Beek, P., Beaumel, D., Fujikawa, Y., Han, J., Heil, S., Huang, S., Inoue, A., Jiang, Y., Knösel, M., Kobayashi, N., Kubota, Y., Liu, W., Lou, J., Maeda, Y., Matsuda, Y., Miki, K., Nakamura, Tags: Astronomy, Physics reports Source Type: news