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11.
Wataru Ootani Makoto Minowa Takayuki Watanabe Yutaka Ito Yasuhiro Kishimoto Kentaro Miuchi Yoshizumi Inoue Youiti Ootuka 《Astroparticle Physics》1998,9(4):325-329
The performance of a 21-g lithium fluoride bolometer is presented. The background spectrum was measured in the surface laboratory. We derive an exclusion plot for the spin-dependent coupled Weakly Interacting Massive Particles (WIMPs) cross section. 相似文献
12.
The10Be method of dating of marine sediment cores is applied to five North Pacific cores. Assuming a constant10Be precipitation rate and varying sedimentation rates with time during the past 2.5 m.y. dating confirms to that obtained from paleomagnetic stratigraphy. The10Be concentration variations with depth in the cores are primarily due to changes in sediment dilution and do not reflect cosmic ray intensity or global climate variations. The limits of10Be deposition rate variation in the investigated cores are less than ± 10% for periods of (2–7) × 105 years and less than ±30% for periods of 1 × 105 years. The data set gives a half-life of10Be is 1.50 × 106 years. The latitudinal effect of10Be concentrations and10Be/9Be ratios relates to a frequency of particulate matter occurrence (detrital and biological particles) in the oceans and to oceanic circulation. 相似文献
13.
The depth profile of the long-lived radionuclide10Be in a marine sediment recovered in the vicinity of the Samoan Islands has been precisely assayed with a highly sensitive needle-type gas counter. The obtained irregular pattern of10Be concentrations with depths ranging from 4.7 to 0.3 dpm/kg dry sediment is interpreted as being due to dilution of10Be by volcanic eruptions in the past. 相似文献
14.
Eiichi Inoue 《Boundary-Layer Meteorology》1974,7(3):257-266
A brief review of the research activities of Japanese scientists in aerobiology, which is one of the interdisciplinary sciences closely related to atmospheric turbulence and diffusion as well as to biology, is presented in order to make contacts with interested scientists in other countries. 相似文献
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Application of Chlorite Geothermometry to Hydrothermal Alteration in Toyoha Geothermal System, Southwestern Hokkaido, Japan 总被引:1,自引:0,他引:1
In this study, we applied chemical geothermometers to the estimation of formation temperatures of chlorites from various types of hydrothermally altered rocks in the Toyoha geothermal field, using core samples from six drill holes (TH-2 to TH-7) together with wasted ore samples from Toyoha vein-type ore deposit. Based on the preliminary examination of mineral assemblages by X-ray powder diffraction and optical microscopy, hydrothermal alteration observed through the drill holes was classified into four types of alteration zones: propylitic, mixed-layer minerals, kaolin minerals, and ore mineralized zones. The mineral assemblage of the ore mineralized zone observed through TH-2, TH-4, and TH-6 is similar to those of Toyoha ore veins reported previously. The Fe3+/ΣFe ratios of chlorites were determined by X-ray photoelectron spectroscopy (XPS), in addition to the usual microprobe analyses. The ratios ranged from 0.20–0.26 for chlorites from the propylitic alteration zone and from 0.13 to 0.17 for those from the ore mineralized zone associated with sulfide minerals. After correcting the Fe3+ contents in the octahedral sites of chlorite structures, we obtained acceptable temperatures of the chlorite formation by application of geothermometers, for instance, a similar range of 150–300°C for chlorites from either the propylitic zone or the ore mineralized zone developed through TH-2, TH-4, and TH-6. Chlorites from the ore mineralized zone proximal to the Toyoha deposit are characterized by high Fe and Mn contents compared to the propylitic chlorites, which is similar to the Toyoha vein-filling chlorites; the formation temperatures were close to both the homogenization temperatures of fluid inclusions and the present subsurface temperatures measured through drill holes. Chlorites from the Toyoha ore veins, however, gave slightly higher formation temperatures (180–350°C) than those of chlorites from the ore mineralized zone in the drill cores. This suggests that several types of hydrothermal alteration occurred at different stages in the Toyoha geothermal field and the composition of product chlorite was controlled not only by the temperature but also the composition of fluid related to the formation. Reliable estimation of temperature for the chlorite formation provides basic information on evaluating correctly other physicochemical conditions prevalent at the formation. 相似文献
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N. Hayashida M. Nagano D. Nishikawa H. Ohoka N. Sakaki M. Sasaki M. Takeda M. Teshima R. Torii T. Yamamoto S. Yoshida K. Honda N. Kawasumi I. Tsushima N. Inoue E. Kusano K. Shinozaki N. Souma K. Kadota F. Kakimoto K. Kamata S. Kawaguchi Y. Kawasaki H. Kitamura Y. Matsubara K. Murakami Y. Uchihori H. Yoshii 《Astroparticle Physics》1999,10(4):125-311
Anisotropy in the arrival directions of cosmic rays with energies above 1017 eV is studied using data from the Akeno 20 km2 array and the Akeno Giant Air Shower Array (AGASA), using a total of about 114 000 showers observed over 11 years. In the first harmonic analysis, we have found a strong anisotropy of 4% around 1018 eV, corresponding to a chance probability of 0.2% after taking the number of independent trials into account. with two-dimensional analysis in right ascension and declination, this anisotropy is interpreted as an excess of showers near the directions of the Galactic Center and the Cygnus region. 相似文献
20.
The crystal structures of the two hydrous wadsleyite crystals with formulae, Mg1.75SiH0.50O4 (0.5H–β) and Mg1.86SiH0.28O4 (0.3H–β) have been analyzed in this study. The single-crystal X-ray diffraction data showed that the unit cells of the 0.3H–β
and the 0.5H–β are metrically monoclinic with a slight distortion from the orthorhombic cell but their intensity distributions
conform to the orthorhombic symmetry within the limit of experimental errors. The Fourier and the difference Fourier syntheses
were calculated. Small but significant Fourier peaks were found at the site, Si2, in a normally vacant tetrahedral void adjacent
to Mg3 site as reported for the monoclinic hydrous wadsleyite by Smyth et al.. From the comparison of the hydrous and anhydrous
wadsleyite structures, the Mg-vacant structural modules were found to be the building units for the structure of hydrous wadsleyite.
The dilution of symmetry from orthorhombic to monoclinic in the hydrous wadsleyite structure is interpreted qualitatively
due to lack of mirror perpendicular to the a axis in the module. The mode of arrangement of the Mg-vacant structural modules
interprets the symmetry and hydrogen content of the hydrous wadsleyite and gives the structural relationship between hydrous
wadsleyite and hydrous ringwoodite.
Received: 8 May 1998 / Revised, accepted: 3 October 1998 相似文献