Measurements of the cosmic-ray hydrogen and helium spectra at energies from 20 to 800 TeV are presented. The experiments were performed on a series of twelve balloon Ñights, including several long duration Australia to South America and Antarctic circumpolar Ñights. No clear evidence is seen for a spectral break. Both the hydrogen and the helium spectra are consistent with power laws over the entire energy range, with integral spectral indices 1.80^0.04 and for the protons and helium, respec-1.68~0 .06 0.04 tively. The results are fully consistent with expectations based on supernova shock acceleration coupled with a "" leaky box ÏÏ model of propagation through the Galaxy.

No abstract

No abstract

Laser-induced fluorescence spectroscopy and batch experiments were combined to study the sorbed species of Eu(III) on amorphous silica and montmorillonite. In the silica system, more than six water molecules were removed from the first coordination sphere of Eu(III) above pH 7, suggesting that Eu(III) was incorporated into the silica. This fact was confirmed through the dependence on aging time and the desorption behavior after acidification. In the montmorillonite system, the Eu(III) aquo ion was sorbed as an outer-sphere complex on montmorillonite below pH 6. Two species with different fluorescence lifetimes were separately detected in higher pH regions in montmorillonite system. The faster component may be Eu(III)-hydroxide precipitates or Eu(III) surface precipitates, while for the slower component, the number of water molecules in the first coordination sphere of Eu(III) was 2-3. Similar studies on Eu(III) sorbed on kaolinite was also conducted for comparison with the results on montmorillonite.studies have employed LIF to study the aqueous and solid species of Eu(III).In this study, LIF was applied to Eu(III) sorbed on unporous silica (aerosil) and montmorillonite. Europium(III) is a member of the lanthanide(III) elements which include various fission products and is also regarded as an analogue of actinide(III) ions; unporous silica represents the surface of silicate minerals and montmorillonite is an important buffer material in repositories. In some parts of this study, kaolinite has also been employed, for comparison. The fluorescence lifetime (mainly 5 D 0 -• 7 F 2 ) and the emission spectrum of Eu(III) were employed to obtain structural information on the sorbed species. The lifetime often contains information on N U20 , the number of water molecules in the first coordination sphere of Eu(III). Based on the results of LIF and batch experiments using Eu-152 tracer, characterization of the sorbed species of Eu(III) was investigated.

The isotope ratio of terrestrial air helium is believed to be constant on a global scale since the mixing time for the atmosphere is significantly shorter than the residence time for helium. Recently, the ³He/4He ratio at Ueno Park, central Tokyo, Japan, was found to be significantly lower than previously measured values. We report here a change in the atmospheric helium isotope ratio from 1.362 × 10−6 in December 1977 to 1.339 × 10−6 in September 1988 or a decrease of ∼1 × 10−9/year. Although this change could be due to local/nonglobal effects, minor changes in the atmospheric flux balance for helium or experimental artifacts, the observations are also consistent with a significant influx of a low ³He/4He ratio source to the atmosphere. The magnitude of the flux, 0.48 ‐ 2.9 × 1016 cm³STP He/year, is compatible with estimates of the anthropogenic release of crustal helium from gas and oil production from the solid Earth. Because of the inert chemistry of helium, a quantification of this change may provide a marker against which to calibrate the absolute flux and retention of anthropogenic CO2 in the atmosphere.

The helium-31helium4 ratio in bubbling gases from ten hot springs located around Mount Ontake, an active volcano in central Japan, ranges from 1.71 Ratm (1.71 times the atmospheric ratio of 1.40 x 10-6) to 6.15 Rat,. The value of the

No abstract

No abstract