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The effects of fine metal oxide particles, particularly those of high-density elements (7.7 to 9.7 x 10(3) kg/m3), on the acoustic properties of silicone rubber have been investigated in order to develop an acoustic lens with a low acoustic attenuation. Silicone rubber doped with Yb2O3 powder having nanoparticle size of 16 nm showed a lower acoustic attenuation than silicone rubber doped with powders of CeO2, Bi2O3, Lu2O3 and HfO2. The silicone rubber doped with Yb2O3 powder showed a sound speed of 0.88 km/s, an acoustic impedance of 1.35 x 10(6) kg/m2s, an acoustic attenuation of 0.93 dB/mmMHz, and a Shore A hardness of 55 at 37 degrees C. Although typical silicone rubber doped with SiO2 (2.6 x 10(3) kg/m3) shows a sound speed of about 1.00 km/s, heavy metal oxide particles decreased the sound velocities to lower than 0.93 km/s. Therefore, an acoustic lens of silicone rubber doped with Yb2O3 powder provides increased sensitivity because it realizes a thinner acoustic lens than is conventionally used due to its low sound speed. Moreover, it has an advantage in that a focus point is not changed when the acoustic lens is pressed to a human body due to its reasonable hardness.

We have investigated the relationship between solar wind speeds and the energetic proton intensity associated with corotating interaction regions (CIR) observed at 1 AU during 1973 – 1995 using NSSDC Data. The speed-difference between the high-speed solar wind and the slow-speed solar wind, which forms CIR at outer heliosphere, shows a good correlation with the peak intensity of 1 – 2 MeV protons during the solar quiet periods. The speed-difference is probably related to the shock strength of the reverse shock of the CIR formed beyond ∼ 1 AU. We have also found the solar activity dependence of the correlation between these quantities in CIR events during the period between 1973 and 1995. The intensity of CIR particles during the solar active periods is higher than that during the quiet periods, suggesting that the density of seed particles in CIR events during the solar active periods is larger than that during the solar quiet period.

The energy loss distributions of heavy ions (Z ≤ 8) with high energies (2 MeV/u–50 MeV/u) in thick silicon detectors with uniform thickness have been measured in a wide range of fractional energy loss, Δ E / E 0 , where Δ E is the energy loss and E 0 is the initial energy of incident ions. The measured distributions of energetic He, Li, Be, B and C ions are in good agreement with those predicted from Livingston-Bethe's theory when Δ E / E 0 0.2, which are much wider than those expected from the theory, are approximately expressed by Stoquert's method considering the effect of velocity decrease into Livingston-Bethe's theory. In the previous experiment of the energy loss of heavy ions from K to Fe in thick Si detectors, Hasebe et al. obtained consistent results for heavier elements. By conbining the results in the previous and this works, it is concluded that the straggling in energy loss of heavy ions from proton to Fe with e...

The energy spectra (40 to 300 MeV/n) of galactic cosmic ray particles (C, N, O, Ne, Mg, Si, and Fe) observed by the HEP-HI silicon detector telescope onboard the GEOTAIL satellite were investigated over the period from January 1993 to May 1996, from the viewpoint of solar modulation. From the GEOTAIL data and those of relativistic heavy particles observed by HEAO-3, the modulation potential φ was obtained by using a solution of the Fokker-Plank equation with the “force-field” approximation. In the equation the diffusion coefficient was used as adjustable parameter, under the assumptions of a fixed velocity of solar wind (400km/sec) and the radius of the heliosphere of 50AU. The time variation of the modulation potential thus obtained is compared with that obtained from the CLIMAX neutron monitor. A reasonable correlation between both time variations is found when five months delay is applied to the results obtained by the HEP-HI telescope.

Interplanetary ions in a few MeV/n energies were observed by the GEOTAIL spacecraft at 1 AU during the period from December 1993 to April 1994. The measurements were performed with the HEP-particle telescopes onboard the GEOTAIL. We have examinedthe correlation between the interplanetary ion events and cosmic ray modulation. It is found that the variation of counting rates of neutron monitor is well correlated with the flux variation of low energy ions. The corotating interaction regions formed in the interplanetary space significantly affect the intensities not only of low energy galactic cosmic rays (GCRs) but also of high energy GCRs. It implies that corotating streams cause the decrease of GCR flux because they act as barriers that impede the flows of GCRs toward the Sun.

The instruments for the HEP (High Energy Particle) experiments of the GEOTAIL mission, launched in July 1992, consist of 5 spectrometers (LD, BD, MI-1, MI-2 and HI). The LD (Low energy particle Detector) and the BD (Burst Detector) are mainly used to measure electrons, protons, helium and oxygen ions which reflect plasma dynamics in the magnetotail region. On the other hand, MI-1, MI-2 (Medium energy Isotope telescope-1, -2) and HI (High energy Isotope telescope) are used to measure the isotope abundance of solar flare particles and cosmic ray particles which reflect physical conditions of interplanetary space and origin of these particles

An optical near-field probe with extremely high throughput and resolution capability was fabricated with a metallized pyramidal silicon structure. Using a finite-difference time-domain method, we found the tip parameters that are required for localized surface plasmon resonance at the probe tip. The optical near-field energy distribution on the metallized pyramidal silicon probe was observed by scanning a fiber probe that had an aperture diameter of 50 nm. The spatial distribution profile observed was in good agreement with the numerical results. The throughput and spot size were determined to be 2.3% and 85 nm, respectively.

Using 5-in.-diameter Si(Li) detectors with a detector thickness of 1, 2 and 3 mm combined with 62 mm × 62 mm position-sensitive Si detectors, an excellent isotope telescope has been constructed for the Geotail mission. The performance of the telescope and the individual detectors has been investigated using 56Fe beams with energies between 430 and 696 MeV/n. The nonuniformity of the detector thickness as measured by exposing the detectors to a monochromatic Fe beam is 0.44% for 1 mm thick detectors, 0.54% for 2 mm thick detectors and 0.15% for 3 mm thick detectors. The secondary isotopes of Al through Fe produced by 430 MeV/n 56Fe in a polyethylene target were clearly resolved by the telescope. The measured mass resolution for Si, Ca and Mn were 0.36 amu, 0.42 amu and 0.44 amu in FWHM, respectively. The telescope has the following two key features: an excellent resolution (better than 0.5 amu) and an exceptionally high sensitivity ( SΩ = 43 cm 2 sr ) for a broad range of species from He through Ni with energies between 2.4 and 210 MeV/n.

Effects of heavy density (rho = 9.2 x 10(3) kg/m(3)) Yb(2)O(3) fine dopant (16 nm in diameter) on the acoustic properties of a high-temperature-vulcanization (HTV) silicone rubber have been investigated, to develop a new acoustic lens material with a low acoustic attenuation (alpha) for the medical array probe application. The HTV silicone rubber has advantages in that it shows a lower alpha than that of a room-temperature-vulcanization (RTV) silicone rubber and it can be mixed by applying shear stress, using roll-milling equipment. Roll-milling time dependence of the HTV silicone rubber indicates that the alpha is closely affected by the dispersion of nanopowders in the rubber matrix. The 8 vol% Yb(2)O(3)-doped HTV silicone rubber mixed for 30 min showed the lowest alpha of 0.73 dB/mm MHz with an acoustic impedance [AI = sound speed (c) x density (rho)] of 1.43 x 10(6) kg/m(2)s at 37 degrees C. Moreover, simulation results reveal that a 5 MHz linear probe using the HTV silicone rubber doped with Yb(2)O(3) powder showed relative sensitivity around 2.6 to 3.0 dB higher than a probe using RTV silicone rubber doped with Yb(2)O(3) powder or SiO2-doped conventional silicone rubber for the ultrasonic medical application.

35 × 10 6 kg/m 2 sv s.Ztissue = 1.55 × 10 6 kg/m 2 s. In general, the ultrasound is reflected at the boundary with different Z. Moreover, a convex-shaped acoustic lens is attached on top of the acoustic matching layers to focus the ultrasound beam and to ensure good contact to the human body. Specifically, the acoustic lens is used for focusing of the short axis; the elevation dimension determines the effective slice thickness of the image plane. The ultrasound transmission is attenuated in acoustic matching layers, acoustic lens, and human tissue. The acoustic attenuation (α) of the acoustic lens is very important because it is usually thicker than the matching layers. Moreover, α becomes large with increasing frequency; the α of the acoustic lens has a great effect on the sensitivity of a medical ultrasonic probe as well. Silicone rubber has been the predominant acoustic lens material for external focusing since 1974 (Iinuma and Hashiguchi 1974, 1978) because it is safe to use

Effects of fine nano-powder ceramic powders on the acoustic properties of silicone rubber have been investigated, in order to develop an acoustic lens material with a low sound velocity (c) and a low acoustic attenuation (alpha). Silicone rubber doped with Yb2O3 powders having nanopowder size of 16 nm showed lower alpha than silicone rubber doped with other powders. The silicone rubber doped with Yb2O3 powder showed a density of 1.54 times 103 kg/m3, c=919 m/s, an acoustic impedance Z= 1.42 times 106 kg/m2s, alpha = 1.08 dB/mm/MHz at 25degC. The low c and alpha of the lens material contributes to realize a low loss acoustic lens for medical array probes for diagnostic application.

The frame-transfer CCD (FT-CCD) achieves a saturation signal voltage of 270mV and a sensitivity of 280mV/lx-s in full-resolution still mode. The sensor can also operate in a 30f/s VGA with a movie mode with saturation signal voltage of 1040mV and a sensitivity of 960mV/lx-s. A 9-phase vertical transfer technique reduces smear signals to -75dB.

The rate of deposition of tungsten on quartz was determined with the aim of clarifying the mechanism of losing the selectivity of tungsten deposition on Si/SiO/sub 2/ substrates. The gaseous species above a quartz substrate proceeding during the deposition reaction were identified by the use of a mass spectrometer.