Abstract: Monte Carlo program was used to simulate the shielding effectiveness of different adulterants and mass fraction of adulterant for a X-ray spectrum at low energy. The simulation results show that the alloy shielding effectiveness has a positive correlation with atomic number of adulterant, and a positive correlation （ΔZ>0） or a negative correlation （ΔZ<0） with mass fraction of adulterant. With the increases of the absolute value ΔZ, the variation of shielding effectiveness is getting lager, and the variation range has a positive correlation with mass fraction of adulterant. The shielding effectiveness of TaW alloy is the best and is nearly not affected by the variation of mass fraction of adulterant. The transmission rate of different low energy X-ray obtained by MCNP simulation shows good agreement with the experimental value.

Key words: Monte Carlo simulation, low energy Xray spectrum, shielding effectiveness, mass fraction of adulterant, atomic number of adulterant