Japan Aerospace Exploration Agency

About: Japan Aerospace Exploration Agency is a facility organization based out in Tokyo, Japan. It is known for research contribution in the topics: Galaxy & Telescope. The organization has 4327 authors who have published 12054 publications receiving 208330 citations.

Massive layer of pure anorthosite on the Moon

Abstract: [1] We present a new global survey of the purest anorthosite (PAN) rock using the Spectral Profiler onboard Kaguya We found that PAN rocks are widely distributed over the Moon, including the Feldspathic Highland Terrain and the south and north polar regions All PAN sites are associated with huge impact structures with diameters larger than 100 km Based on the global distributions of PAN and olivine-rich sites, we propose the existence of a massive PAN layer with a thickness of ∼50 km below an uppermost mafic-rich mixed layer with a thickness of ∼10 km Below the PAN layer, a lower crustal layer with olivine-rich materials may be present on the nearside, but not on the far side of the Moon The existence of a PAN layer with a thickness of ∼50 km suggests an Al2O3 abundance of 33 to 34 wt% in the lunar crust, which is higher than previous estimates of <32 wt% Our data indicate the massive production event of PAN during the early stage of the formation of the Moon, supporting the lunar magma ocean scenario

High resolution Schottky CdTe diode detector

Abstract: We describe recent progress on the use of Schottky CdTe diode detectors for spectrometry. The low leakage current of the CdTe diode allows us to apply a much higher bias voltage than was possible with previous CdTe detectors. For a relatively thin detector of 0.5-1 mm thickness, the high bias voltage results in a high electric field in the device. Both the improved charge-collection efficiency and the low-leakage current lead to an energy resolution of better than 600 eV full-width at half-maximum at 60 keV for a 2/spl times/2 mm/sup 2/ device without any charge-loss correction electronics. Large-area detectors with dimensions of 21/spl times/21 mm/sup 2/ are now available with an energy resolution of /spl sim/2.8 keV. Long-term stability can be easily attained for relatively thin (<1 mm) detectors if they are cooled or operated under a high bias voltage.

Helium gas permeability of montmorillonite/epoxy nanocomposites

Abstract: Helium gas permeability of silicate clay (montmorillonite) particles/epoxy nanocomposites was examined. The incorporation of increasing amounts of montmorillonite particles reduced the helium gas permeability. Based on Fick’s law, gas permeation behavior of the nanocomposite was evaluated. With the increase of montmorillonite loading, gas diffusivity decreased, while gas solubility increased. Helium diffusion behavior is in agreement to the numerical results based on the Hatta–Taya–Eshelby theory. It has been revealed that dispersion of nanoscale platelets in polymer is effective in improving gas barrier property.