In order to obtain 3D mapping of the hydrogen distribution in solids in-situ, the nuclear reaction analysis (NRA) measurement has been carried out by using a tapered glass capillary to focus and introduce the incidence beam to the sample under atmosphere. A Y thin film covered with Pd was used for this measurement. In the N2 gas, hydrogen absorbed by the Y film was observed at a pressure up to 8×103 Pa. In the H2 gas and air, on the other hand, substantial γ-ray signals were observed at 15N energies of 6400~7200 keV, which obscured the signal originating from the Y sample. The origin of this signal is discussed.
