| Objective To investigate the influence rule of the atmospheric Rainfall to theγradiation Kerma rate in surface air in order to revise the result of its measurement during rainfall.Methods The change tendency of earth's surfaceγKerma rate in atmosphere during single rainfall was monitored by mobile X-γdose rate instrument(BH3103A).The high tension ionization chamber(RSS-131) which was produced by America General Electricity Company was used asγradiation detector and so the change tendency of earth's surfaceγKerma rate in atmosphere was monitored continuely far away during complicated rainfall.The influence factors of rainfall to the measurement of theγKerma rate in atmosphere were analyzed and then the differential equation of the correlation factors was established theoretically,and by resolving the equation,the mathematical model was obtained.The model was discussed through several practical examples.Results The mathematical model was coincided with the tendency of curve about the measured data on the influence rule of rainfall to theγKerma rate in atmosphere.Conclusions1.By analysis the influence factors to rainfall,we can make sure that the main mechanism of the increase of earth's surfaceγKerma rate in atmosphere which was induced by rainfall is that the rainfall washes the radionuclides from upper air to earth surface and so elevates the radioactivity of the earth surface.These radionuclides were mainly Radon daughters(isotopes of Po,Pb and Bi).They exist in the air by the form of micro-dust or aerosol.The Radon daughters emitsγrays during radioactive decay.2.The study results showed that the main influence factors of rainfall to the change of earth's surfaceγKerma rate in atmosphere were the distribution of Radon daughters in the air,rainfall volume and washout factors.They are the independent variables of regular function.3.By applying the mathematics model in this article which was established to explain the influence regularity of rainfall to the earth's surfaceγKerma rate in atmosphere,we can describe the change of the earth's surfaceγKerma rate in atmosphere inducing by rainfall.By using this mathematics model,we can revise the influence of rainfall to the earth's surfaceγair kerma rate efficiently. |
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