A≈250区原子核转动谱的系统研究

Systematic study of the rotational spectra in nuclei with A≈250

利用几个原子核转动谱公式系统研究了A≈250质量区偶偶核与奇A核的转动谱,这些公式包括Bohr-Mottelson提出的按I(I+1)展开的AB(ABC和ABCD)公式,按ω2展开的Harris公式以及吴崇试、曾谨言提出的ab公式.结果显示,在二参数公式中,相较于AB公式和Harris公式,ab公式能够更好地描述A≈250质量区的偶偶核基态转动带.对于这个质量区的奇A核,除了K=1/2的转动带之外,ab公式也能给出较好的描述.对于实验观测到的253No的一条转动带,组态指定存在争议.利用ab公式研究表明,该转动带的组态为7/2+[624].

The experimental rotational spectra in even-even and odd-A nuclei in the A≈250 region are systematically analyzed by using several empirical formulas,including the AB formula proposed by Bohr and Mottelson,the Harris formula,and the ab formula proposed by Wu and Zeng.It is shown that,compared with the AB formula and the Harris formula,the ab formula can give a better description for rotational spectra of ground-state bands in even-even nuclei in this mass region.For the odd-A nuclei,the ab formula gives a good description except for the rotational bands with quantum number K=1/2.There is a dispute about the configuration assignment of an observed rotational band in 253No.By using the ab formula we examine this rotational band with different bandhead spin assignments.It is found that the root mean square deviation of the fitting results from the experiment is the smallest if the bandhead spin is 7/2,which supports the configuration assignment of 7/2＋[624]for this rotational band.