Development of a versatile method to produce spin-polarized radioactive nuclear beams

对放射性核束产生自旋极化的可行性进行了研究。这种通用方法的处方是：(I)通过激光光泵使Rb中最外层的电子自旋极化；(Ii)将电子转移到放射性核束离子；(Iii)通过超精细相互作用使核自旋极化。这种方法对于质子来说是相当成功的。虽然这种方法基本上适用于各种各样的核物种，但还没有尝试过对比氦更重的离子进行应用。我们在大阪大学核物理研究中心搭建了一个试验台，在TRIUMF的ISAC或JHF的E-Arena等高强度放射性束流设施建成之前，我们已经建造了一个试验台，并开始了这种新方法的可行性试验。用稳定的束流代替了放射性核束。用束箔谱的方法测量了核极化，试验台刚刚建成。在第一次实验中，我们成功地观察到了14N核2%的自旋极化。传输效率约为60%。这些结果具有很好的实际应用前景。我们已经开始了详细的调查，以增加核极化。

The feasibility of producing spin polarization for radioactive nuclear beams has been investigated. The prescription of this versatile method is (i) to spin-polarize the outermost electron in Rb via laser optical pumping and (ii) to transfer the electron to the radioactive nuclear beam ion and (iii) to polarize the nuclear spin through the hyperfine interaction. This method is quite successful for proton. Although the method is essentially applicable for a wide variety of nuclear species, no application has been tried for ions heavier than helium. The feasibility must be investigated on (i) how much we can reduce the depolarization effects after the electron transfer process and (ii) how high transmission efficiency we can achieve for the radioactive nuclear beams.We have constructed a test stand and started the feasibility test of this new method at Research Center for Nuclear Physics, Osaka University, prior to the completion of high intensity radioactive beam facilities such as ISAC at TRIUMF or E-arena at JHF. Instead of the radioactive nuclear beams, stable beams have been used. The nuclear polarization has been measured by the method of the beam-foil spectroscopy.The test stand has just completed. At the first trial we have successfully observed 2 % spin polarization for the 14N nucleus. The transmission efficiency was approximately 60%. These results are very promising for the practical application. We have started detailed investigation to increase the nuclear polarization.