Low energy gamma radiation （0.2-10.0） MeV near the Earth＇s surface has several origins. Primary and secondary cosmic radiations with interactions of very high energy protons （〉 1 GeV） in terrestrial atmosphere a...Low energy gamma radiation （0.2-10.0） MeV near the Earth＇s surface has several origins. Primary and secondary cosmic radiations with interactions of very high energy protons （〉 1 GeV） in terrestrial atmosphere are the main sources. The second most important source near the surface of the Earth and in the tropical and equatorial regions is the radon gas （Rn-222） that decays in alpha particles and gamma rays in this energy range. Also the telluric radionuclides 238U, 235U, 40K and 232Th in decays produce gamma radiation with different intensities at different locations on the surface of the Earth. Other sources less present are electrical discharges （lightning strikes） and man-made radioactive sources for medical, dental and industrial applications. In this work, it is shown that measurements of these components during all year 2016 are carried out at the ITA （Technological Institute of Aeronautics） campus in Sao Jose dos Campos, SP, Brazil and their possible correlations with atmospheric phenomena.展开更多
The quasinormal mode frequencies can be understood from the massless particles trapped at the unstable circular null geodesics and slowly leaking out to infinity. Based on this viewpoint, in this paper, we semiclassic...The quasinormal mode frequencies can be understood from the massless particles trapped at the unstable circular null geodesics and slowly leaking out to infinity. Based on this viewpoint, in this paper, we semiclassically construct the entropy spectrum of the static and stationary black holes from the null geodesics. The result shows that the spacing of the entropy spectrum only depends on the property of the black hole in the eikonal limit. Moreover, for a black hole far from the extremal case, the spacing is found to be smaller than 2π for any dimension, which is very different from the result of the previous work by using the usual quasinormal mode frequencies.展开更多
文摘Low energy gamma radiation （0.2-10.0） MeV near the Earth＇s surface has several origins. Primary and secondary cosmic radiations with interactions of very high energy protons （〉 1 GeV） in terrestrial atmosphere are the main sources. The second most important source near the surface of the Earth and in the tropical and equatorial regions is the radon gas （Rn-222） that decays in alpha particles and gamma rays in this energy range. Also the telluric radionuclides 238U, 235U, 40K and 232Th in decays produce gamma radiation with different intensities at different locations on the surface of the Earth. Other sources less present are electrical discharges （lightning strikes） and man-made radioactive sources for medical, dental and industrial applications. In this work, it is shown that measurements of these components during all year 2016 are carried out at the ITA （Technological Institute of Aeronautics） campus in Sao Jose dos Campos, SP, Brazil and their possible correlations with atmospheric phenomena.
基金supported by the National Natural Science Foundation of China(Grant Nos.1120507411375075 and 11522541)the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2015-jl01)
文摘The quasinormal mode frequencies can be understood from the massless particles trapped at the unstable circular null geodesics and slowly leaking out to infinity. Based on this viewpoint, in this paper, we semiclassically construct the entropy spectrum of the static and stationary black holes from the null geodesics. The result shows that the spacing of the entropy spectrum only depends on the property of the black hole in the eikonal limit. Moreover, for a black hole far from the extremal case, the spacing is found to be smaller than 2π for any dimension, which is very different from the result of the previous work by using the usual quasinormal mode frequencies.
