First results of high performance ge gamma-ray spectrometer onboard lunar orbiter selene (kaguya)

N. Hasebe*, E. Shibamijra, T. Miyaohi, T. Takashima, M. N. Kobayashi, O. Okijdaira, N. Yamashita, S. Kobayashi, Y. Karojjji, M. Hareyama, S. Kodaira, S. Komatsu, K. Hayatsjj, K. Iwabuchi, S. Nemoto, K. Sakurai, M. Miyajima, M. Ebihara, T. Hihara, T. AraiT. Sugihara, H. Takeda, C. D'Uston, O. Gasnault, B. Diez, O. Forni, S. Maurice, R. C. Reedy, K. J. Kim

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


The high precision gamma-ray spectrometer (GRS) is carried on the first Japan's large- scaled lunar explorer, SELENE (KAGUYA), successfully launched by the H-IIA rocket on Sep. 14, 2007. The GRS consists of a large Ge crystal as a main detector and massive bismuth germanate crystals and a plastic scintillator as anticoincidence detectors. After a series of initial health check of the GRS, it started a regular observation on December 21, 2007. Energy spectra including many clear peaks of major elements and trace elements on the lunar surface have been measured by the GRS. Global measurement of thorium counting rate on the lunar surface is presented. The region showing the highest count rate of thorium extends from Kepler to Fra Mauro region in the Procellarum. And Apennine Bench and Aristillus region and the northwestern region of Mare Imbrium are high in thorium count rate. Second high count rate region is located in the South Pole-Aitken basin of the farside. Arago and Compton/Belkovich craters are also enriched in thorium. The initial results observed by GRS during the period from Dec. 21, 2007 to Feb. 17, 2008 is reviewed.

Original languageEnglish
Pages (from-to)18-25
Number of pages8
Journaljournal of the physical society of japan
Issue numberSUPPL. A
Publication statusPublished - 2009
Externally publishedYes


  • Chemical composition
  • Formation and evolution of the moon
  • Gamma-ray spectroscopy
  • Lunar polar orbiter

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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