Study on tensor force in ¹⁶O nuclei due to (p,d) reaction

Tensor force acting between proton and neutron in nucleus plays an important role in the atomic nucleus, such as a large contribution to the binding energy of deuterium and alpha particles. However, the effect of this tensor force has not yet been reported with direct evidence through experiments, except for the light nuclei up to alpha particles. The authors took up the contribution of tensor force to the nucleus structure of light nuclei, and examined it on the basis of a ¹⁶O (p,d) reaction experiment using the proton beams of 198, 295, and 392 MeV. In this experiment, the authors measured the momentum of deuterons using a high-resolution magnetic spectrometer Grand Raiden, and determined the ground state of ¹⁵O residual nuclei and the differential cross section of transition to lower excited state. The results of the experiment revealed the existence beyond our expectations of the high momentum neutrons believed to have occupied sd-orbital in the ground state of ¹⁶O. The calculation using Gaussian basis function, such as including a high-momentum component, led to the conclusion that the results of this experiment may be due to the tensor effect. (A.O.)