Xiaodong Li
National University of Defense Technology, China
Title: To understand atomic nucleus from a new nuclear structure model
Biography
Biography: Xiaodong Li
Abstract
To explain some very basic facts of atomic nucleus, such as the stability of isotopes, the even-odd variation in many properties and so on, a nuclear structure model of ring plus extra nucleon is proposed. For nuclei larger than 4He inclusive, protons (P’s) and neutrons (N’s) are basically bound alternatively to form 2ZZ E ring. The ring folds with a bond angle of 90Ëš for every 3 continuous nucleons to make the nucleons packed densely. The ring must be identical when all the P and N interchange (negative symmetry). Extra N(’s) can bind to ring-P with the same manner. When 2 or more ring-P’s are geometrically available, the nuclide with extra N tends to be stable. Extra P can bind with ring-N in a similar way when the ratio of N/P <1 although the binding is much weaker. Even-Z rings always have superimposed gravity centers of P and N; while for odd-Z rings, both centers of P and N must be eccentric. The eccentricity results in a depression of EB and therefore specific zigzag features of EB/A. This can be well explained by the shift of eccentricity by extra nucleons. Symmetrical center may present in even-Z rings and normal even-even nuclei. While for odd-Z ring, only antisymmetric center is possible. Based on this model, a pair of mirror nuclei, PX+nNX and PXNX+n, should be equivalent in packing structure just like black-white photo and the negative film. Therefore, an identical spin and parity was confirmed for hundreds of pairs. In addition, the EB/A difference of all the mirror nuclei pair is very nearly a constant of 0.184n MeV. Many other facts can also be easily understood from this model, such as the nuclear stabilities of isotopes in elements from He to Ne; the stability sequence of 9Be, 10Be, 7Be and 8Be; the neutron halo in neutron-rich nuclides, the general rule for most stable isotopes: Odd-Z elements are odd A, even-Z elements are even A; and the highest cohesive energy of Li, Be, B atoms in their own elementary group and so on.