Abstract
Clustering, especially alpha clustering, is known for long as an important feature of nuclei which is referred as the tendency of nuclear to aggregate protons and neutrons into more compact substructure. For instance, 8Be nucleus is famous for its developed α-α structure. In 2004, Ashwood et al have investigated the cluster breakup of neutron-rich Be isotopes. The experiment results indicate that the degree of clustering in the ground-state remains high from 10Be up to the dripline 14Be, and 14Be might have a well-developed cluster structure (α+6n+α) in its ground state. In 2018, we will conduct a nuclear experiment in RIKEN, Japan, to study the cluster structure in Be isotopes. This experiment will use a well-established method —cluster quasi-free scattering(QFS) reactions which will provide a direct and quantitative measurement of the clustering in the ground state of these nuclei. The 10,12,14Be(p,pα) reaction at 150 MeV/u will be studied and cluster SF will be extracted using Distorted wave Impulse approximation (DWIA) calculation.
As my second topic, the study of multi-neutron systems can be conducted simultaneously with exactly the same experiment setup. Request for bound or resonant multi-neutron systems is a longstanding problem for theoretical and experimental investigations. In a breakup experiment of 14Be at GANIL, a few “anomalous” events were detected in the neutron detectors in coincidence with 10Be fragments in which the deposited energy in the neutron detectors exceeded the maximum energy deduced from their time-of-flight. In the present project, we propose to investigate the 6-neutron system (“hexaneutron”) through the alpha QFS reaction on 14Be. The detection of the alpha-particle coming from the decay of excited states of 10He populated in the 14Be(p,pα) reaction in coincidence with the proton and alpha particles from the QFS allows to reconstruct the center of mass energy spectrum of the 6-neutron system for the first time.
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