Atmospheric X-rays at 11°S geomagnetic latitude

Abstract

X-ray measurements at balloon altitudes were made at São José dos Campos, Brasil (23°12′S, 45°51′W geographic coordinates, ~11°S geomagnetic latitude) on 18 December 1981, using an omnidirectional NaI(T1) scintillation detector. Atmospheric X-rays, namely secondary X-radiation from cosmic rays, were measured for the energy interval 30–155 keV and up to an atmospheric depth of 5.5 g cm −2. A comparison of the flux measured at the Pfotzer maximum during these measurements with those obtained previously by several research groups at other latitudes and with a similar technique has also been made. Finally, a comparison of the atmospheric component with that attributed to the diffuse component is also presented and it is concluded that both components are of about the same magnitude at ~ 5 g cm −2 and at ~ 11°S geomagnetic latitude.