PhD ceremony Mr. M.A. Najafi: Quasi-free proton and neutron knockout reactions in 20o

PhD ceremony: Mr. M.A. Najafi

Dissertation: Quasi-free proton and neutron knockout reactions in 20o

Promotor(s): prof. N. Kalantar-Nayestanaki

Faculty: Mathematics and Natural Sciences

The atomic nuclei are composed of nucleons, protons and neutrons, that are arranged in a shell structure similar to that of atoms. The nuclear shell model has been remarkably successful in describing many properties of nuclei; however, its predictions of the nucleon-knockout cross sections are systematically larger than the measured values.

This phenomenon, being yet an open question in the field, is interpreted to be partially due to the inter-nucleon correlations that influence the shell structure of the nucleus. By measuring the quenching of the spectroscopic factors, one can obtain a measure of the extent to which the shell model is influenced by these correlations. We have employed the quasi-free proton-knockout reaction at beam energies of around 415 MeV per nucleon using the LAND-R3B setup, to extract this quenching factor for the proton states of 20O, using the inclusive cross sections of the reaction, as a part of the physics programme of the LAND-R3B project. R3B is one in a multitude of envisaged physics experiments at the FAIR facility, under construction in Germany. EXL is another major project of FAIR, which will be complementary to R3B, and together they make it possible to investigate almost every query in the low and medium-energy nuclear reactions. The foreseen setup of the EXL project is a sophisticated combination of several thousand detection units, which requires development of new instruments, and careful study of their properties. We report on the results of one of these studies in a chapter of the thesis.