BigRIPS separator and ZeroDegree spectrometer at RIKEN RI Beam Factory. Evolution of shell structure in neutron-rich calcium isotopes. Three-body forces and shell structure in calcium isotopes. Shell-model study for neutron-rich sd-shell nuclei. Spectroscopic study of neutron-rich calcium isotopes with a realistic shell-model interaction. Shell evolution and the N = 34 “magic number”. New beyond-mean-field theories: examination of the potential shell closures at N = 32 or 34. β decay and isomeric properties of neutron-rich Ca and Sc isotopes. New evidence for a subshell gap at N = 32. Lowest excitations in 56Ti and the predicted N = 34 shell closure.
Shell-model description of neutron-rich Ca isotopes. Magic numbers in exotic nuclei and spin-isospin properties of the NN interaction. Masses of exotic calcium isotopes pin down nuclear forces. Relativistic Coulomb excitation of neutron-rich 54,56,58Cr: on the pathway of magicity from N = 40 to N = 32. A study of 52Cr, 54Cr and 56Cr by the (t,p) reaction. Reduced transition probabilities to the first 2 + state in 52,54,56Ti and development of shell closures at N = 32, 34. Structure of 52,54Ti and shell closures in neutron-rich nuclei above 48Ca.
Cross-shell excitation in two-proton knockout: structure of 52Ca. Beta decay of the new isotopes 52K, 52Ca, and 52Sc a test of the shell model far from stability. Evolution of nuclear shells due to the tensor force. Otsuka, T., Suzuki, T., Fujimoto, R., Grawe, H. Collapse of the N = 28 shell closure in 42Si. The results highlight the doubly magic nature of 54Ca and provide direct experimental evidence for the onset of a sizable subshell closure at neutron number 34 in isotopes far from stability. Here we report a spectroscopic study of the neutron-rich nucleus 54Ca (a bound system composed of 20 protons and 34 neutrons) using proton knockout reactions involving fast radioactive projectiles. Studies aiming to identify and understand such behaviour are of major importance in the field of experimental and theoretical nuclear physics. Although some of the standard shell closures can disappear, new ones are known to appear 2, 3. Away from stability, however, these so-called ‘magic numbers’ are known to evolve in systems with a large imbalance of protons and neutrons.
In the case of stable, naturally occurring nuclei, large energy gaps exist between shells that fill completely when the proton or neutron number is equal to 2, 8, 20, 28, 50, 82 or 126 (ref. In a manner similar to that of electrons orbiting in an atom, protons and neutrons in a nucleus form shell structures. Atomic nuclei are finite quantum systems composed of two distinct types of fermion-protons and neutrons.
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