Study On Barometric Coefficient Of Cosmic Ray Neutron Component

Cosmic ray is kind of a stream of charged particles which comes from universe space, it has a lot of information about events in the universe. It has been established a global location detection network of many international cosmic ray stations detected on the ground. Weather conditions will affect Ground-base detection. Moreover, some complex factors such as temperature, humidity, atmospheric pressure all influence the detected intensity of cosmic ray. In the same time period, the change rates of cosmic ray neutron component and change rates of pressure presences a negative linear relation, specifically, when neutron count rate becomes large, the count rate of pressure will decrease, on the contrary, when neutron count rate becomes small, the count rate of pressure will increase. So the pressure influences the neutron count rate. It is important to correct neutron count rate in the practical processing.The main work of this paper is to study variation of barometric coefficient and the law of barometric coefficient change with other factors, we use the recent 12 years data of 6 neutron monitor stations of global neutron monitor network stations to study changes of cosmic ray neutron component barometric coefficient. We conclude the following phenomenon:The variation of the barometric coefficient is much bigger when the sun is active in the period of 1999-2006 year than the one in the quiet state of 2008-2009 year.Barometric coefficient of high cut-off rigidity stations in the solar activity quiet state present somewhat one year cyclical phenomenon, and the phenomenon is different between northern and southern hemispheres.Finally, we used relative change of sunspot number recorded by World Data Center SILSO, Royal Observatory of Belgium, Brussels to represent solar activity to study the relationship between solar activity and the barometric coefficient. We did find at higher geomagnetic cutoff rigidity of some stations, barometric coefficient fluctuate with enhanced solar activity, such fluctuations can be roughly divided into three phases:In phase 1, relatively quiet period of solar activity, sunspot number in range from 0 to about 60, barometric coefficient has a linear relationship with gradually increased solar activity.In phase 2, moderate period of solar activity, sunspot number changes approximately from 60 to 160, mean value of barometric coefficient tends to a constant value, but the fluctuation is bigger than the one in phase 1.In phase 3, relatively high intensive solar activity, sunspot number in range about from 160 to the maximum number, the variation amplitude of the barometric coefficient is much bigger and irregular.Also, the relationship of pressure coefficient change with enhanced solar activity is different between northern and southern hemispheres. Specifically, in YBJ station, in quiet solar activity period, barometric coefficient increase with enhanced solar activity, but in the two southern stations Tsumeb station and Potchefstroom station, barometric coefficient decrease with enhanced solar activity.The above points summarize the variation of barometric coefficient under certain conditions, apply these phenomenon to eliminate the impact of atmospheric can we give a more accurate and more precise result when we study neutron component of cosmic ray phenomenon.