19-09-2014, 01:42 PM
Abstracts: Gamma ray spectroscopy is an important technique used for remote sensing studies of chemical composition of planetary surfaces, and has been used to study surface composition of the Moon, Mars and Asteroids at various spatial resolutions. Elements on the surface of the moon, planets and satellites in the solar system are constantly bombarded by cosmic radiations and the excited nuclei in turn emit photons. By studying this radiation pattern, we can know the elemental composition of these bodies as each element has a characteristic emission pattern. The chemical composition gives us clues to the origin and evolution of these bodies. Accuracy of such a detector should be as high as possible. Gamma-ray spectral analyses with a 38 mm × 38 mm LaBr3(Ce) detector show that the LaBr3(Ce) has much better gamma-ray peak resolution and full-energy peak counting efficiency but worse detection sensitivity. The LaBr3(Ce) detector has relatively high intrinsic radiation background due to the naturally occurring La radioisotope in lanthanum. Although this La background is entirely below the energy of 1,500 keV, additional background is in the energy region between 1,500 keV and 2,750 keV. The manufacturer attributes this radiation to alpha particles emitted by the five short-lived progeny of an Ac impurity. Comparative values for peak resolution, full-energy peak counting efficiency, and detection sensitivity are reported for Ba, Na, Co, and Cs.