- 第3日 5月17日（木） 16:05～16:25 C会場（星雲2）
Femto-level trace isotope, naturally produced by cosmic ray interaction, and its record in natural archives are precious codes to elucidate the earth environment history. Accelerator Mass Spectrometry (AMS) is most powerful decoding tool.Recently new isobar separation techniques were proposed on the basis of the difference of electrons configuration between isotopes. One of such technique is using the difference of the electron affinity. As a negative ion source is typically used for the initial ionization, the difference of the electron affinity results in the selective ionization. Actually 14C-AMS uses this maximally for the elimination of 14N. In the case that the difference of the electron affinity between isobars is not so large, both of isobars are ionized. If the laser having energy precisely between two electron affinities is irradiated to the beam, one of the isobars (with lower electron affinity) is neutralized. This entirely new separation method is called “Laser Photo Detachment”. If the electron affinity of the interest nuclide is larger than the interference isobar, the LPD is quite effective. However in the opposite case, it isn’t. Even in the non-preferable case, in some molecular forms the relation could be inverted. This kind of selection is also conducted by the reactive gas, especially the electron providing gas.