Bonn 2020 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 54: Invited Talks IV

HK 54.2: Invited Talk

Friday, April 3, 2020, 09:30–10:00, H-HS X

Short-Ramge-Correlations in neutron-rich nuclei — •Meytal Duer for the CLAS collaboration — Technische Universität Darmstadt

Analysis of high-energy scattering experiments shows that some nucleons (protons and neutrons) in the nuclear ground state form temporarily close-proximity neutron-proton pairs with large relative momentum and small center-of-mass momentum, relative to the Fermi momentum of the nucleus. These pairs are referred to as Short-Range Correlated (SRC) pairs. However, how excess neutrons in neutron-rich nuclei form such pairs remains unclear.

Using data from CLAS detector at Jefferson Laboratory, we measure protons and, for the first time, neutrons knocked out by high-energy electrons. We show that the fraction of high-energy protons increases markedly with the neutron excess in the nucleus, whereas that of neutrons decreases slightly. This effect is surprising because in the classical nuclear shell model, protons and neutrons obey the Fermi statistics, have little correlation and mostly fill independent energy shells. These nucleons are important for understanding of neutron-rich systems such as neutron stars, the internal structure of bound nucleons, and more.

So far SRC measurements were done in direct kinematics off stable nuclei (N/Z<1.5). We will also present the next generation of proposed studies at GSI and the future FAIR facilities, using radioactive beams. This will allow a fully exclusive measurement of SRC pairs in very asymmetric nuclei (N/Z>1.5).