Fig. 1. Schematic diagram of PGAI measurement based on multi-coded collimators

Fig. 2. MCNP model of element imaging measuring device

Fig. 3. Composition distribution of sample

Fig. 4. Several typical pattern of coded-aperture collimators

Fig. 5. γ ray spectrogram (a) and Cl element 1.164 MeV characteristic peak under different coded collimators (b)

Fig. 6. Gray scale image of partial detection efficiency

Fig. 7. Cl element reconstruction without considering neutron self shielding effect

Fig. 8. Reconstructed image of Cl element after neutron self screen correction (a), deviation between simulation results of 11 pixels with Cl and true value (b)