Galactic Neutron Irradiation Distribution Function

In this paper, we mainly introduce the neutron exposure distribution function of the galaxyρgal (τ, t)to describe the nucleosynthesis elements of s-process ,obtain the evolution function of theρgal (τ,t)through the chemical evolution function of the galaxy . We establish the relation of the neutron exposure distribution function of the galaxyρgal (τ,t)and the neutron exposure distribution function of the AGB starρAGB (τ,Z). We study the neutron exposure distribution function of the galaxyρgal (τ,t)based on two instance ofρAGB (τ,Z) is exponential function or the new function ,and compare the result with the distribution function of neutron exposure of the solar system ( )ρsunτ.The result of our work are as follows:(1)The distribution function of neutron exposure of the solar system ( )ρsunτcan be explained withρAGB (τ,Z)and the chemical evolution function of the galaxy.(2)The main component of ( )ρsunτcan be looked as the weighted average of the distribution function of neutron exposure of the higher metal abundance AGB star. It,s distribution can be looked as exponential distribution approximately. The mean neutron exposuresτ0m≈0.3mb-1 .The proportional comparison factor f m is bigger﹙ f m≈5×10?4﹚.The reason is the higher metal abundance AGB star have more seed nucleus .Nucleosynthesis efficiency is higher.(3) The strong component of ( )ρsunτcan be looked as the weighted average of the distribution function of neutron exposure of the lower metal abundance AGB star. It,s distribution can be looked as exponential distribution approximately. The mean neutron exposuresτ0 m≈8mb?1.The proportional Comparison factor f m is smaller﹙ f m≈10?6﹚. The reason is the lower metal abundance AGB star have less seed nucleus. Nucleosynthesis efficiency is lower.(4) Lower metal abundance AGB star early have less seed nucleus, nucleosynthesis efficiency is lower. The proportional comparison factor f m is smaller. So the slope is small. When t = t, the distribution function of neutron exposure of the solar system ( )ρsunτwe getted has nearly the same fluctuant shape as the distribution of exponential model of Beer et al.(1997).