Y.H. Ohtsuki

Atmospheric anomalies observed during earthquake occurrences

[1] Appearance of anomalies in the atmosphere before earthquakes (EQs) has been verified, through observation of anomalous transmission of VHF electromagnetic (EM) waves beyond line-of-sight. Anomalous increase of the received intensity for a few minutes - several hours on a day was identified by the previous 15-day running median and its inter-quartile range. The cross-correlation between the EQ occurrences and the anomalies shows that the appearance of anomalies was significantly enhanced within 5 days before M � 4.8 EQs. The one-day average number of the anomaly appearance within 5 days was found 2.4 times larger than that of other days. Through the polarization measurement of the received EM waves, the anomalies were found to occur in the atmosphere. INDEX TERMS: 6904 Radio Science: Atmospheric propagation; 6964 Radio Science: Radio wave propagation; 7223 Seismology: Seismic hazard assessment and prediction.Citation: Fujiwara, H., M. Kamogawa, M. Ikeda, J. Y. Liu, H. Sakata, Y. I. Chen, H. Ofuruton, S. Muramatsu, Y. J. Chuo, and Y. H. Ohtsuki (2004), Atmospheric anomalies observed during earthquake occurrences, Geophys. Res. Lett., 31, L17110,

PARAMETRIC X-RAY RADIATION BY RELATIVISTIC CHANNELED PARTICLES

Abstract In this paper, the radiation intensity around the Bragg angle (with respect to a target crystal plane) by relativistic channeled particles is calculated based on the kinematical theory of parametric X-ray radiation (PXR). It is predicted that, in consequence, not only PXR but also Bragg diffraction of channeling radiation will be observed. The latter process is divided into two types by the incident energy. Ordinary photon diffraction occurs in the high energy region and virtual photon diffraction in the low energy region.

NUMERICAL CALCULATION OF PARAMETRIC X-RAY RADIATION BY RELATIVISTIC ELECTRONS CHANNELED IN A SI CRYSTAL

Abstract Recently, a new type of radiation called “parametric X-ray radiation”, is of special interest and several experimental studies have been reported. By using the kinematical theory, we calculate differential scattering cross section of parametric X-ray radiation (PXR) and diffracted channeling radiation (CR) by (111) planes in silicon for 15–50 MeV electron beams channeled along (110) planes.

The skipping motion of ions and their energy loss spectrum

Abstract The skipping motion of protons for grazing incidence is examined by taking account of the neutralization effect near the metal surface. Furthermore we show the energy loss spectrum corresponding to the skipping motion. At an incident energy of 30 keV, the survival probability of grazing incident He + is about 40% in each skipping. The predicted energy spectrum is shown to be discrete, even if energy straggling is taken into account.

Skipping motion of ions at the surface

Abstract The skipping motion of ions for grazing incidence, especially specular reflection conditions, are examined by computer simulation. We show that the specular reflection is destroyed completely by taking into account the skipping motion for a few ten KeV protons. Furthermore, we have found discrete energy-loss spectrum corresponding to the skipping motion.

Study of the planar surface potential in grazing proton-surface scattering

Abstract The energy loss of 28.5–72.2 keV H+ specularly reflected off a graphite surface has been measured as a function of the surface temperature. The experimental data enable one to derive the interatomic potential between projectile and graphite surface atom for the intermediate range of interatomic distances. The interatomic potential thus found is in fair agreement with a first order perturbation theory calculation where the Hartree-Fock electron densities have been approximated by a continuous piecewise exponentially decreasing function. The potential is much weaker than the potential derived from the Thomas-Fermi statistical model of the atom.

Z2-dependence of energy spectra of electrons excited by fast heavy ions incident at grazing angle

Abstract The dependence of the energy distributions of electrons induced by grazing-angle-incident Ar 12+ ions (0.98 MeV/amu) on the atomic number of the target is examined for Al, Si, Cu, Ag, and Au targets. For each target, a prominent peak of accelerated convoy electrons is observed. The most probable energy, E m , of these electrons is higher than that of electrons with the same velocity as incident projectiles by 70–140 eV; E m is 625 eV for Al, 634 eV for Si, 624 eV for Cu, 652 eV for Ag, and 665 eV for Au, at an emission angle of about 10° with respect to the surface. The results are discussed in relation to collective response of the valence electrons.

Theory of charged fractions for low energy protons

Abstract We study theoretically the negative charged fractions for hydrogen in the energy range of a few keV. Our purpose is to derive the qualitative feature of the negative charged fractions in the dependence on the target materials parameter, e.g. the work function, the Fermi energy, the local density of states, etc. We show that the most important parameter is the energy difference between the affinity level and the Fermi level.

Experimental conditions for ball lightning creation by using air gap discharge embedded in a microwave field

An experiment was carried out to reproduce ball lightning by using microwave radiation and electric discharge without a metal cavity. When the energy of the discharge was high, a plasma fireball was produced. When high-power microwave existed, a plasma fireball was produced even if the power of the discharge was low. We must pay more attention to places where high-power electromagnetic waves exist to see ball lightning.

Computer simulation of skipping motion on the graphite (0001) surface

Abstract Recently the observation of skipping motion was reported by Stolzle and Pfandzelter. We compare the calculated results with the experimental ones to make sure that skipping motion has been observed. We also succees in explaining their additional peaks observed at more than 1.4°.