1. Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba 305-8567, Ibaraki, Japan
2. SA Research and Development Department, JEOL Ltd., 3-1-2 Musashino, Akishima 196-8558, Japan
3. National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba 305-8563, Ibaraki, Japan