Selectivity in Laser Isotope Separation based on Polarization Selection Rules

在原子激光同位素分离过程中，利用同位素吸收峰的光谱差即同位素位移，用精细调谐激光选择性地激发目标同位素。在元素的同位素位移很小或奇同位素的超精细结构扩散覆盖了其他不需要的同位素吸收峰的情况下，基于极化选择规则的同位素分离方法是比较可取的。在本研究中，我研究了这种分离方法在富钆和富锆同位素上的应用，这些同位素在核技术领域尤其有用。并对外加磁场对同位素选择性的影响进行了数值分析。以下是本研究的主要结果。原子激励动力学数值分析程序的开发开发了原子激励动力学数值分析程序。同位素的降解。更多的ic选择性发生，因为原子排列在磁场的影响下被破坏。磁亚能级在激光激励下的垂直跃迁用速率方程或密度矩阵运动方程来描述，在磁场作用下的横向跃迁用拉莫尔进动方程来描述。磁场对同位素选择性的影响利用上述程序分析了磁场对同位素选择性的影响。结果表明，影响选择性的主要因素不是激光强度，而是磁场强度和磁场与激光偏振角。结果表明，Gd的同位素选择性仅在3高斯场强下就完全丧失。Zr激光同位素分离实验^<91>Zr激光同位素分离实验的初步结果表明，Zr的富集因子约为8。为了确保数值分析的结果，还需要进行进一步的实验研究。少

In the atomic laser isotope separation process the target isotope is selectively excited by a finely tuned laser making use of a spectral difference of isotopic absorption peak so called isotope shift. In the case that element has a very small isotope shift or in the case that the hyperfine structure spread of the odd isotope covers other unwanted isotope absorption peak, however, the isotope separation method based on the polarization selection rules is rather preferable. In this research I studied the application of this separation method on Gadolinium and Zirconium enriched isotopes of which are very useful especially in the field of nuclear technology. And the influence of an external magnetic field on the isotopic selectivity was numerically analysed. The following are the main results obtained in this research.1. Development of the numerical analysis code of atomic excitation dynamicsThe numerical analysis code of atomic excitation dynamics is developed. Degradation of the isotop … More ic selectivity occurs because the atomic alignment is destroyed the influence of a magnetic field. Vertical transitions between magnetic sublevels by laser excitations are described by the rate equations or the density matrix equation of motion, and transverse transitions by an magnetic field are by the Larmor precession equation.2. Influence of a magnetic field on the isotopic selectivityBy using the code described above the influence of a magnetic field on the isotopic selectivity was analysed. It Was found that the laser intensities are not the significant factors for the selectivity but the magnetic field strength and the angle between the magnetic field and the laser polarization are. Results shows that for Gd case the isotopic selectivity may be completely lost by the field strength of only 3 gauss.3. Laser isotope separation experiment of ZrPrimitive results of the laser isotope separation experiment of ^<91>Zr showed the enrichment factor of about 8. Further experimental investigations are to be performed for making sure of the numerical analyses results. Less