HZE particle and neutron dosages from cosmic rays on the lunar surface

Kanako Hayatsu*, Makoto Hareyama, Shingo Kobayashi, Naoyuki Yamashita, Kunitomo Sakurai, Nobuyuki Hasebe

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    19 Citations (Scopus)


    The lunar surface is directly exposed to galactic cosmic rays (GCRs) and solar energetic particles (SEPs) because of the lack of atmosphere and magnetic field on the Moon. These charged particles successively interact with the lunar material and then produce secondary radiations as neutrons and gamma rays. The annual ambient dose equivalent on the lunar surface is estimated about 840 mSv/yr during the quiet period at the solar activity minimum. Particularly, GCR heavy component largely contributes by about 80% to the annual dose equivalents. The ambient dose equivalents of SEPs are also calculated for two transient solar particles events on October 28th in 2003 and January 20th 2005. The SEP protons take the largest contribution of about 90% to the dose, while the heavy components of SEPs do not contribute so much unlike GCRs. The ambient dose equivalent due to the SEP event on 2003 exceeds 2 Sv on the lunar surface. It is clear, however, that an aluminum shield with a thickness of 10 g/cm2 effectively reduces the dose to 0.1% of total because the solar event has a soft energy spectrum.

    Original languageEnglish
    Pages (from-to)149-152
    Number of pages4
    JournalJournal of the Physical Society of Japan
    Issue numberSUPPL. A
    Publication statusPublished - 2009


    • Aluminum shield
    • Galactic cosmic ray
    • Moon
    • Radiation dose
    • Solar energetic particle

    ASJC Scopus subject areas

    • Physics and Astronomy(all)


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