The high precision gamma-ray spectrometer (GRS) onboard the Japanese lunar explorer, SELENE (KAGUYA) consists of a large Ge crystal as the main detector and massive BGO and plastic scintillators as anticoincidence detectors. After a series of initial health checks, it started regular observation officially on December 21, 2007. Energy spectra of lunar gamma rays were obtained by GRS with very good energy resolution being 0.6% at 1.46MeV over the lunar surface. Many peaks of gamma rays from major elements and natural radioactive elements in the lunar surface have been observed. Individual gamma-ray lines emitted from the lunar surface have been identified. Here, we report the initial results obtained practically during the period from December 14, 2007 to February 17, 2008. Global maps of K and Th gamma-ray intensities are reported using count rates in several energy bands.
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)