SGER: Determination of Atmospheric Neutron Attenuation Length at Geomagnetic Cutoff Rigidity of 17-18 Gigavolt (GV) in Southeast Asia

University Of Arizona, Tucson AZ

Investigators

Abstract

The proposed study aims to improve surface exposure dating using in-situ accumulation of cosmogenic isotopes by improving knowledge of the spatial variability of the cosmic-ray intensity with geomagnetic cutoff rigidity (a measure of geomagnetic intensity) and with elevation. The proposal is to conduct a survey of the neutron intensity at the rigidity greater than 17 GV and at altitudes up to 6 km. The work will be conducted in southeast Asia (probably in Thailand), the only location with rigidities above 17 GV. The proponents will measure the neutron intensity using a small aircraft flying at a constant altitude. The results will be used to determine the neutron attenuation length (the function that relates neutron intensity to elevation) for this rigidity. The value will then be used with their other survey results and with other published data to determine how the attenuation length varies with the cutoff rigidity (or with geomagnetic latitude). The final goal of the project will be the construction of improved formulations for scaling production rates of cosmogenic isotopes from one location to any other arbitrary location.