Fig. 1. Schematic diagram of the designed PGNAA system
(a): Top view; (b): Side view

Fig. 2. The background spectrum of system
(a): 450~1 000 keV; (b): 1 000~2 000 keV; (c): 2 000~4 500 keV

Fig. 3. Prompt gamma-ray spectra and peaks fitting of the meatal samples
(a): Spectra of Fe; (b): Peaks fitting of Fe; (c): Spectra of Ti; (d): Peaks fitting of Ti; (e): Spectra of Cr; (f): Peaks fitting of Cr; (g): Spectra of Ni; (h): Peaks fitting of Ni; (i): Spectra of Cu; (j): Peaks fitting of Cu

Fig. 4. The calibration curve of metal samples
(a): Fe; (b): Ti; (c): Cr; (d): Ni; (e): Cu