超重核的質量與穩定性

Nuclear Masses and Stability of Super Heavy Elements

吳成禮(Cheng-Li Wu)

《中原學報》 24卷1期 (1996/01) Pp. 1-6

https://doi.org/10.6358/JCYU.199601.0001

摘要

本文根據費米子動力對稱模型（FDSM）所預言的原子核質量指出，人們長期以來期盼找到的超重元素島應出現在Z=114和N=164附近。過去傳統模型所預言的超重元素島出現在中子的滿殼層附近，比FDSM的預言重了差不多20個中子。造成這種變化的原因有二：（1）是與等同粒子問的排斥性單極矩相互作用有關，它破壞了在滿殼層處殼修正的能量極小值；（2）是與SU（2）及SU（3）動力對稱性的競爭及與其相關的動力包里效應有關，它在半滿殼層附近開闢了一個球形核的小窗口，增加了超重核抗裂變的的穩定性。這兩個物理因素都是以往所沒有注意到的。我們的計算表明，正是這兩個物理因素使得超重元素島移向中子數較少的區域。最近實驗上新發現的Z=110（N=159）和Z=111（N=161）兩個元素正好處在費米子動力對稱模型所預言超重元素島的邊沿。FDSM並預測它們的原子核應是球形或近球形。傳統模型所預言的在N=184附近的超重元素島則可能不存在。

關鍵字

原子核質量 ； 超重元素 ； 原子核模型 ； 動力對稱性

並列摘要

The mass calculation by the Fermion Dynamical Symmetry Model (FDSM) predicts a super heavy island of elements located at around Z=l 14 and N=164. In contrast, it was predicted by other models previously to locate at around neutron closed shell, which was about 20 units heavier then the FDSM prediction. This change is a consequence of two physical reasons that were not recognized before: (1) the repulsive monopole-monopole interactions among like particles which destroy the shell correction energy minimum at closed shell; (2) the competition between SU(2) and SU(3) symmetries and the related dynamical Pauli effects which create a small window at around mid-shell favoring spherical nuclei thus increasing stability of super heavy nuclei against fission. Our calculations suggest that the recent discovery of isotopes with Z=110-111 are near spherical, and may represent a true island of super heavy nuclei, but shifted downward in neutron number by these new physical effects. The super heavy island around N=184 predicted by traditional models may not even exist.

並列關鍵字

Nuclear Masses ； Super Heavy Elements ； Nuclear Model ； Dynamical Symmetries