Nuclear Polarization by Means of Laser Optical Pumping and its Application to the Research for Nuclear Structure.

激光系统刚安装完毕，就对铒的同位素位移进行了研究。天然Er I的582.7 nm跃迁用于测量同位素位移，从而测量均方核电荷半径的变化。并对<^(197)Er>的超精细结构进行了研究。与邻近的同位素类似，在Er中也观察到均方核电荷半径的奇偶交错现象。用（< α >,n）反应测定了<^(211m)Po>异构体的产率。在激光光泵浦中，研究了Po中16831 <cm^(-1)>能级的跃迁强度。目前正在进行自旋交换反应应用于实现Po核极化的可行性研究。利用激光光泵浦激发二价Tm原子的宽吸收带，在<SrF_2>晶体中产生<^(170)Tm>（不稳定）的核极化。通过对不稳定Tm同位素衰变中发射的β和γ射线的探测，测量了核取向和极化。得到的核极化约为8 <+！-> 4%，表明该方法对核结构研究的潜在适用性。

Just after the laser system has been installed, the isotope shift of erbium I was investigated. The transition of 582.7 nm for the natural Er I was used for the measurement of the isotope shift and thus of the change of the mean-square nuclear charge-radii. Also the hyperfine structure of <^(197)Er> was investigated. Even-odd staggering in the mean square nuclear charge radii was also observed in the Er, similar to the neighboring isotopes.Production rate of the <^(211m)Po> isomer was measured with the ( <alpha> ,n) reaction. The transition strength for the 16831 <cm^(-1)> level in the Po was also investigated for the use in laser optical pumping. Feasibility study for the possible application of spin-exchange reaction to the achievement of nuclear polarization of Po is now in progress.Nuclear polarization of <^(170)Tm> (unstable) in <SrF_2> crystal was produced with the laser optical pumping via the excitation of broad absorption band in divalent Tm atom. Nuclear alignment and polarization were measured with the detection of beta and gamma rays emitted in the decay of unstable Tm isotope. Obtained nuclear polarization was about 8 <+!-> 4 %, indicating potential applicability of this method for the study of the nuclear structure.