Tea Time学术活动系列邀请报告(140)

题  目：N=Z nuclei - a laboratory to test neutron proton pair correlations

报告人：Ramon Wyss (Professor, KTH Royal Institute of Technology)

时  间：2019年11月4日（周一）9:00-10:00

地  点：1-401物理学科会议室

报告内容：

Pairing correlations in atomic nuclei haveshown to play a crucial role to many properties, in spite of the small effecton the total binding energy. The talk will start with introductory remarks onthe symmetry energy in atomic nuclei, giving a different interpretation fromwhat is found in standard textbooks.

It will then move on to the specificproperties of N=Z nuclei, where neutron and proton occupy near degenerateorbitals.

This specific situation enables twodifferent kind of Cooper pairs to be formed, that either have isospin T=0 andintrinsic spin S=1 or T=1 and S=0. It is shown that both condensates cancoexist and generate a wavefunction that is a coherent superposition of bothcoupling modes. The effect of isospin excitation is then studied and its effecton the pair correlations. A Meissner effect in isospin is the resulting fromthose excitations. The formalism of approximate projection and symmetryrestoration is discussed.

报告人简介：

国际著名的理论核物理学家，瑞典皇家工学院教授，北京大学名誉教授，上海交通大学、四川大学客座教授。2002-2016年曾担任瑞典皇家工学院副校长，现任西班牙教育部、中国教育部海外评审专家、芬兰科学院海外评审专家。在原子核物理研究领域的主要贡献是发展了位能面（TotalRouthians (energy) Surface calculations）计算方法，并将其应用于研究原子核高自旋态、原子核形状、对关联，α衰变、质子衰变等，取得了丰硕的研究成果，已发表超过300篇论文、H-factor超过60。