Color centers in NaCl single crystals induced by pulsed intense relativistic electron beams

Surface of Europa, a satellite of Jupitar, is known to be covered mainly by ice and there are some a nonice component with brown color. Recently, a new hypothesis has been proposed that the non-ice component is NaCl irradiated by charged particles in magnetosphere of Jupitar, which shows brown colors by formation of anion vacancies (F-centers) and their clusters[1]. However, there are many other candidates with brown colors so that a novel method to identify the non-ice component is required.
It is thought that the magnitude of magnetosphere of Jupitar may be fluctuating similar to that of the Earth. Using probes with dosimeters in the future, identification of NaCl can be made by the color change with radiation dose fluctuation. Even though there have been numerous results of irradiation effects of NaCl by DC accelerators[1-3], there are no data on formation and recovery behavior of Fcenters in NaCl induced by pulsed electron beams. In this research, electron irradiation tests were carried out by pulsed intense relativistic electron beams (PIREBs).