Gamma-continuum at the Air-land Interface

Abstract

Abstract

Compton recoil gamma-ray spectroscopy has been used to measure the energy distribution of environmental gamma radiation at the air-land interface. Observations reveal a continuum which varies slowly with energy in the region 0.22–2.1 MeV. A number of distinct peaks are superimposed on this slowly varying continuum and correspond to gamma-ray transitions in naturally occurring radioisotopes. The integral gamma flux in the 0.22–2.1 MeV energy region is 1.9 ± 0.4 photons cm−2 sec−1 corresponding to a mean continuum intensity of 1.0 ± 0.2 photons cm−2 sec−1 MeV−1 at the Argonne National Laboratory site (53°N geomagnetic latitude). The physical dose rate due to gamma radiation in the energy interval 0.22–2.1 MeV is 4.3 ± 0.9 μR/hr.