The Kaguya Gamma‐Ray Spectrometer uniquely identified uranium gamma‐ray lines from the Moon with a superior energy resolution of ∼1%. A global lunar map of uranium distribution is derived for the ...first time. It was found that uranium abundances vary up to 2 ppm with an average of ∼0.3 ppm, while the average thorium abundance was ∼1.2 ppm. From these analyses, significant variation in U/Th ratio was found in the farside of the Moon that had not been reported by previous observations or in lunar materials. Our observations suggest that the lunar highland is not as uniform as has been long considered.
The Kaguya gamma-ray spectrometer (KGRS) has great potential to precisely determine the absolute abundances of natural radioactive elements K, Th and U on the lunar surface because of its excellent ...spectroscopic performance. In order to achieve the best performance of the KGRS, it is important to know the spatial response function (SRF) that describes the directional sensitivity of the KGRS. The SRF is derived by a series of Monte Carlo simulations of gamma-ray transport in the sensor of the KGRS using the full-fledged simulation model of the KGRS, and is studied in detail. In this paper, the method for deriving absolute abundance of natural radioactive elements based on the SRF is described for the analysis of KGRS data, which is also applicable to any gamma-ray remote sensings. In the preliminary analysis of KGRS data, we determined the absolute abundances of K and Th on the lunar surface without using any previous knowledge of chemical information gained from Apollo samples, lunar meteorites and/or previous lunar remote sensings. The results are compared with the previous measurements and the difference and the correspondence are discussed. Future detailed analysis of KGRS data will provide new and more precise maps of K, Th and U on the lunar surface.
An M6.5-class flare was observed at N12E56 on the solar surface at 16:06 UT on July 8, 2014. In association with the flare, two neutron detectors located at high mountains, Mt. Sierra Negra in Mexico ...and Mt. Chacaltaya in Bolivia, recorded two neutron pulses, separated approximately by 30 min. Moreover, enhancements were also observed by the solar neutron detector onboard the International Space Station. We analyzed these data combined with solar images from
Atmospheric Imaging Assembly
(AIA) onboard the
Solar Dynamics Observatory
. From these we noticed that the production mechanism of neutrons cannot be explained by a single model; at least one of the enhancements may be explained by an electric field generated by the collision of magnetic loops and the other by the shock acceleration mechanism at the front side of the CME.
A new type of solar neutron detector (FIB) was launched on board the Space Shuttle Endeavour on July 16, 2009, and began collecting data at the International Space Station (ISS) on August 25, 2009. ...This paper summarizes the three years of observations obtained by the solar neutron detector FIB until the end of July 2012. The solar neutron detector FIB can determine both the energy and arrival direction of neutrons. We measured the energy spectra of background neutrons over the South Atlantic Anomaly (SAA) region and elsewhere and found the typical trigger rates to be 20 and 0.22 counts/sec, respectively. It is possible to identify solar neutrons to within a level of 0.028 counts/sec, provided that directional information is applied. Solar neutrons were possibly observed in association with the M-class solar flares that occurred on March 7 (M3.7) and June 7 (M2.5) of 2011. This marked the first time that neutrons had been observed in M-class solar flares. A possible interpretation of the production process is provided.
The high precision gamma-ray spectrometer (GRS) is scheduled to be launched on the lunar polar orbiter of the SELENE mission in 2007. The GRS consists of a large Ge crystal as a main detector and ...massive bismuth germanate crystals as an anticoincidence detector. A Stirling cryocooler was adopted in cooling the Ge detector. The flight model of SELENE GRS has been completed and an energy resolution of 3.0
keV (FWHM) at 1.332
MeV has been achieved. The spectrometer aims to observe nuclear line gamma rays emitted from the lunar surface in a wide energy range from 100
keV to 12
MeV for one year and more to obtain chemical composition on the entire lunar surface. The gamma-ray data enable us to study lunar geoscience problems including crust and mantle composition, and volatile reservoirs at polar regions.
Response of acoustic signals generated in water by energetic xenon ions Miyachi, T.; Nakamura, Y.; Kuraza, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2006, Letnik:
560, Številka:
2
Journal Article
Recenzirano
The acoustic signals generated by bombarding 400
MeV/n xenon ions in water were studied using an array of piezoelectric lead–zirconate–titanate elements. The observed signal was reduced to a bipolar ...form through Fourier analysis. The output voltage corresponded to the amount of energy deposit in water, and it tailed off beyond the range of 400
MeV/n xenon in water. This magnitude was explained qualitatively as cumulative processes. Its behavior was consistent with the calculations based on the Bethe–Bloch formula. Possible applications of this detector to radiology and heavily doped radiation detectors are described.
Scintillation luminescence for high-pressure xenon gas Kobayashi, S.; Hasebe, N.; Igarashi, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2004, Letnik:
531, Številka:
1-2
Journal Article
Recenzirano
Scintillation and ionization yields in xenon gas for 5.49MeV alpha-particles were measured in the range of pressure from 0.35 to 3.7MPa and the electric field strength (E) over the number density of ...xenon atoms (N), E/N from 0 to 5×10−18Vcm2. When our data are normalized at the data point measured by Saito et al., the number of scintillation photons is 2.3×105 while the number of ionization electrons is 2.0×105 at 2.6MPa and at 3.7×10−18Vcm2. The scintillation and ionization yields of xenon doped with 0.2% hydrogen, High-Pressure Xenon gasH2-0.2%, at 2.6MPa was also measured. Scintillation yield of the Xe–H2 mixture gas is 80% as high as that of pure xenon. It is found that the scintillation yield is luminous enough to generate a trigger pulse of the high-pressure xenon time projection chamber, which is expected as a promising MeV Compton gamma-ray camera.
We analyze preliminary Lunar Prospector gamma-ray spectrometer data. Al–Mg and Fe–Mg petrologic maps of the Moon show that Mg-rich rocks are located in Mare Frigoris, the South Pole Aitken basin, and ...in some cryptomaria. Analysis of distances of Lunar Prospector pixels from three end-member plane in Mg–Al–Fe space reveals existence of Ca-rich, Al-low small-area anomalies in the farside highlands. An Mg–Th–Fe petrologic technique can be used for estimation of abundances of ferroan anorthosites, mare basalts, KREEP basalts, and Mg-rich rocks.
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