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surface by vacuum evaporation at Kyoto University Research Reactor In- stitute. The pressure of the evaporation chamber is around 10 $_{−}$3 Pa and the evaporation rate is about 1 ˚ A / s for each material. The facility used is described in Ref. [6]. 

Converter layers of 46 µ g cm $_{−}$2 (220 nm) and 11 µ g cm $_{−}$2 (230 nm) for $^{10}$B and $^{6}$Li, respectively, are attached to the CCD surface. To form a firm layer, a 9 µ g cm $^{$_{−}$2}$(20 nm) Ti layer is directly deposited on the CCD surface and the converter layer is mounted on the Ti layer. To repel moisture from the air, the outer surface of the converter layer is covered with a 9 µ g cm $^{$_{−}$2}$(20 nm) Ti layer. (Note that we incorrectly reported the amount of Ti and Li layer in our previous report [4].) Ti has good characteristics for this use, because of its chemical stability, adhesion and negative potential for neutrons. The stability of these Ti– $^{10}$B–Ti and Ti–$^{6}$Li–Ti structures have allowed our 

