[en] Evaluation of barometer coefficients of neutron monitors located at high latitudes has been performed by using spherical harmonic analysis, based on records from around twenty stations for twelve years from January 1966 to December 1977. The average of data at eight stations, where continuous records are available for twelve years, show that the absolute value of the barometer coefficient is in positive correlation with the cosmic ray neutron intensity. The variation rate of the barometer coefficient to the cosmic ray neutron intensity is influenced by the changes in the cutoff rigidity and in the primary spectrum

[en] Temperature dependence of Raman scattering spectra of Kondo insulator CeRhAs has been measured. With decreasing temperature, the phonon peaks split into doublet and triplet at about 370 K and below 165 K, respectively. The splitting is caused by a zone-folding due to the lattice modulations. The temperature dependence of the background intensity below 70 cm^-1 is well explained by the resonance level model with V-shaped gap

[en] The valence-dependent Raman scattering spectra has been found for the RB₆ crystals (R=Ca²⁺,Yb²⁺, Ce³⁺, Pr³⁺, Gd³⁺, and Dy³⁺). In the divalent crystals of CaB₆ and YbB₆, E_g phonon shows doublet, while the line shape is a broad single peak for the trivalent case. Since both doublet peaks satisfy the selection rule due to the cubic symmetry, the doublet spectra is not explained by the structural phase transition, but by the anisotropic charge distribution on B₆. In the trivalent crystals, the two kind of the extra peaks have been commonly observed at around 200 cm^-1 and at around 1400 cm^-1. The peak intensities of the former decrease with decreasing temperature, and their peak energies increase with increasing lattice constant. These anomalous features are well explained by the vibration of R ion in the oversized cage space formed octahedral B₆ molecule. Thus, this new excitation can be attributed to a local vibration of the R ion, which can be regarded as ''rattler.''

No abstract available

No abstract available

[en] We examined hydrogen absorption/desorption behaviors in graphite mechanically milled under hydrogen pressures ranging from 0.3 to 6.0 MPa. Experimental results indicated that the chemisorbed hydrogen concentration during 80 h milling decreased from 6.1 to 4.1 wt.% with increasing milling hydrogen pressure, while the physisorption-like hydrogen concentration increased with increasing milling hydrogen pressure and reached more than 0.5 wt.% at 6 MPa. Moreover, higher pressure hydrogen suppressed the fracture rate of the milled graphite more effectively, suggesting that the hydrogen atoms trapped at the edges of the graphene sheets and between the graphene layers near the surface are responsible for preserving the lamellar nanocrystalline structure, which may be the host for physisorption-like hydrogen absorption

[en] Raman spectra of hcp solid ⁴He have been measured at a temperature of 0.71 K with an instrumental resolution of 1.1 cm^-1. The spectra have been confirmed to be consistent with those reported by former works: a sharp one-phonon peak is observed at 7.39±0.06 cm^-1, the two-phonon spectrum appears in the energy region about 10--45 cm^-1, and a broad continuous tail extends to energy shifts higher than the two-phonon region. Four peaks have been resolved in two-phonon spectra at 17.1, 20.9, 25.2, and about 30 cm^-1. The two-phonon spectral structure has good qualitative similarity to that calculated theoretically by former workers. This verifies that the two-phonon spectral structure can be used for quantitative determination of parameters of lattice dynamics in quantum solids, and necessary experimental accuracy and resolution are discussed

[en] A spherical harmonic analysis performed on the basis of the neutron monitor records at high latitude stations so far covers for nine years, from January 1966 to December 1974. Using the reconstructed N-component intensities from the spherical harmonic coefficients, we examined the relation between the daily mean barometric pressure and the pressure corrected neutron monitor data reported from each station. The result shows that the used values of barometer coefficients at a few stations are not adequate, and the variations of the barometric coefficients which supposedly accompany with the solar cycle variations of neutron monitor counting rate are discussed

[en] The possibility of the structural change in YbPd has been investigated by Raman scattering in the temperature range from 4 K to 300 K. One peak was clearly observed around 91 cm^-1 below 132 K. This is a clear evidence of a structural change at the transition temperature 132 K from the CsCl structure. The polarization dependence of the 91 cm^-1 peak shows that the cubic and tetragonal symmetries are ruled out for the crystal structure at 4 K.

[en] Raman scattering spectra of single crystalline PrRu₄P₁₂ have been measured in the temperature region between 4.6 K and 300 K. Additional peaks appear below metal-insulator transition temperature. Among these peaks, CEF excitations for two different Pr ion sites can be assigned from the results of magnetic field (H≤8T) dependence and polarization dependence. From the energy of CEF excitations in Raman spectra, we have re-determined CEF energy levels for Pr1 and Pr2 ions. From the result of CEF level schemes and the different atomic displacement of Ru around Pr1 and Pr2, Pr1 ion is affected by a strong positive point charge potential of Ru, and Pr2 ion feels strong p-f hybridization.