Past and future pd breakup measurements at the intermediate energy region for the study of three-nucleon force and knock-out reactions

The effects of three-nucleon force (3NF) have been actively studied by using the nucleon-deuteron (Nd) scattering states. The differential cross sections of the elastic Nd scattering at the energy below 150 MeV can be well reproduced by the Faddeev calculation based on modern nucleon-nucleon (NN) interactions and 3NF. On the other hand, the data at 250 MeV was underestimated by the calculations with 3NF by 50%. And this large discrepancy between the data and the theory was also shown in the ²H(p, p)pn inclusive breakup reaction at 250 MeV.

For the systematic study to understand the missing picture of 3NF, we performed the measurements of the pd exclusive breakup reactions at 250 MeV at RCNP, Osaka University. The differential cross section data was well reproduced by the Faddeev calculations averaged by spectrometer acceptances.

Now, we are working on the ONOKORO project, which aims to understand the formation of various clusters within nuclei. In this project, a detailed understanding of knockout reactions is important, and the measurement of the pd breakup reaction as an elementary process plays an important part. We will present new inclusive pd breakup reaction measurements performed as part of this project.