Three-body break-up in deuteron-deuteron scattering at 65 MeV/nucleon

We successfully identified several multibody final states in deuteron-deuteron scattering at 65 MeV/nucleon at KVI using a unique and advanced detection system called BINA. This facility enabled us to perform cross sections and polarization measurements with an improved statistical and systematic precision. The analysis procedure and a part of the results of the three-body break-up channel in the deuteron-deuteron scattering at 65 MeV/nucleon are presented. The physics phenomena of nuclei are for a large part understood by considering the interaction between their building blocks, the nucleons. In 1935 Yukawa described the nucleon-nucleon (NN) force by the exchange of mas- sive mesons (1) in analogy to the electromagnetic inter- action which can be represented by the exchange of of a massless photon. Several phenomenological nucleon- nucleon potentials have been derived based on Yukawa's theory and are able to reproduce the whole bulk of data points in neutron-proton and proton-proton scattering with extremely high precision. These so-called high-quality NN potentials are used in Faddeev equations (2, 3) to give an exact solution of the scattering problem of the three- nucleon system. Already, for the simplest three-nucleon system, the triton, an exact solution of the three-nucleon Faddeev equations employing two-nucleon forces (2NFs) underestimates the experimental binding energy (4), show- ing that 2NFs are not suffi cient to describe the three- nucleon system accurately. The existence of an additional force, the three-nucleon (3N) interaction, was predicted by Primakov (5) and confirmed by a comparison between precision data and state-of-the-art calculations. In general, adding 3NF effects to the NN potentials gives a better agreement between the cross section data of the proton- deuteron scattering and corresponding calculations (6-17), whereas a similar comparison for the spin observables yields various discrepancies (7-9, 18-22). This demon-