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  • 11
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The bunch length was measured by using a highly sensitive streak camera with a time resolution of 2 ps. It was found that fine structures appeared in the electron bunch shape and that the shapes of electron bunches were described by a Gaussian distribution on the average. The dependence of bunch length on beam current was measured for an electron beam of 607 MeV. The bunch length was well represented by a power function of beam current with an exponent of 0.197 at currents lower than 35 mA or 0.30 at high currents. The experimental results suggest that the longitudinal coupled-bunch beam instability takes place at low beam currents and the turbulent instability dominates at high currents. It was also found from the three-dimensional bunch shape measurements that the bunch shape tended to blow up at high currents.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3126-3128 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hydrogenation effects on the structural relaxation and defect evolution in amorphous silicon (a-Si) prepared by ion implantation and evaporation have been investigated using Raman scattering spectroscopy and positron lifetime measurements. Bond angle deviation Δθ in nonhydrogenated a-Si was significantly reduced due to 300 °C annealing in atomic hydrogen atmosphere. This indicates that the reduction in Δθ of hydrogenated amorphous silicon (a-Si:H) is not only due to relaxation during the deposition process of a-Si:H films as proposed by Jackson et al. [Philos. Mag. B 64, 611 (1991)] but also due to posthydrogenation of nonhydrogenated a-Si. It was also found that agglomeration of vacancy-type defects in evaporated a-Si during 450 °C annealing is enhanced after posthydrogenation, while no remarkable enhancement can be seen in a-Si prepared by ion implantation. © 1996 American Institute of Physics.
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  • 13
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design of a 10-T superconducting wiggler as a synchrotron radiation source for angiography has been carried out to be installed in an 800-MeV electron storage ring, TERAS, at Electrotechnical Laboratory (ETL). Synchrotron radiation generated by the wiggler has a critical photon energy of 4.47 keV and the radiation spectrum identical to that from a 2.5-GeV storage ring with a bending radius of 8.3 m. The magnet of the wiggler consists of three pairs of iron-cored superconducting coils designed to provide a peak field of 10.5 T on the beam trajectory. The effect of the wiggler on the storage ring has been investigated and a pair of quadrupole doublets on both sides of the wiggler can compensate a large deviation of the betatron tune.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 216-222 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Variable-energy positron beams were utilized to study SiO2 films grown on Si substrates. Annihilation characteristics of positrons in the SiO2 films were found to be dominated by the formation probability of positronium (Ps). For the SiO2 film grown by wet oxidation, a high formation probability of Ps was found by measurements of Doppler broadening profiles of the annihilation radiation and those of lifetime spectra. For SiO2 films grown by an atmospheric-pressure chemical vapor deposition technique using tetraethylorthosilicate and ozone, however, the formation probability of Ps drastically decreased. The inhibition of the Ps formation was attributed to interactions between positrons and –OH bonds.
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  • 15
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 4064-4064 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is well known that the effective anisotropy field change Δ(Hk−4πMs) in as-He+/Ne+-implanted garnet films reaches a maximum value (2500 Oe) and then decreases with increasing the ion dose. It has been also reported that the Δ(Hk−4πMs) is recovered to the maximum value by annealing in the heavily implanted films. We have found an anomalous increase in Δ(Hk−4πMs) for the films which are heavily implanted with He+ or Ne+ and subsequently annealed at high temperature (350–600 °C). With annealing, Δ(Hk−4πMs) increases with annealing time and reaches a maximum value (5000 Oe for He+ implantation). It should be noticed that this maximum value is 2500 Oe larger than that in as-implanted films. This anomalous increase has been observed only for the films whose initial strain is more than about 1.5%. This effect has not been observed in heavily H+2 implanted films. This difference may be related to the type of damage induced by He+/Ne+ implantation and H+2 implantation. Using the above-mentioned effect, 4-μm-period ion-implanted propagation tracks have been fabricated and tested . The ion implantation condition was 50 keV/1×1014 Ne cm−2+200 keV/4.5×1014 Ne cm−2. Δ(Hk−4πMs) in the as-implanted film was 1900 Oe. After 560 °C annealing, it increased to 3700 Oe. For the 4-μm-period contiguous disk propagation tracks, 10% bias field margin has been obtained.
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  • 16
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 4080-4080 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hybrid bubble memory devices using ion-implanted and Permalloy bubble propagation tracks have been proposed and developed. In this paper, the reduction of the cell size from 4 to 3 μm will be discussed. In the hybrid devices, the minor loops are composed of ion-implanted tracks and the functions are composed of Permalloy tracks. To reduce the cell size, therefore, both of the tracks should be improved. For the 3-μm-period ion-implanted tracks, the bubble diameter is reduced from 1 to 0.8 μm. According to the reduction of a bubble diameter, magnetostrictive anisotropy Δλ=λ100−λ111 is increased from 5 to 8×10−6 because the Sm content is increased to increase the anisotropy field Hk. The large Δλ affects the characteristics of inside and outside turns in the ion-implanted tracks. To get a good margin for the turns, the anisotropy field change induced by ion implantation ΔHk should be larger than in 4-μm-period tracks. There is a new problem in 3-μm-period hybrid devices. In the hybrid devices, there is no deep ion implantation in the Permalloy track region, while there is a deep ion implantation in the ion-implanted track region. The effective bubble height is, therefore, different in the ion-implanted and Permalloy track region, and the bias field region where bubbles exist stable is different. In the typical 3-μm-period devices, the bias field region of the ion-implanted tracks is 20–30 Oe lower than that of the Permalloy tracks. The operating bias field adjustment (OBA) is needed. We have checked some OBA methods and found that the thinning of the garnet film in the Permalloy track region is a good method. Thinning the garnet film partially, the operating bias field can be adjusted easily and there is no harmful effect.
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  • 17
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 8546-8554 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Electron emission spectra obtained by thermal collisions of He*(2 3S) metastable atoms with CO on Ni(100) in the c(2×2) structure and on Ni(111) in the c(4×2) structure were measured to probe directly the spatial electron distribution. For a systematic comparison, the metastable spectra of free CO, condensed CO on Ni(111), and gaseous Cr(CO)6 were also measured under the same beam conditions. Our data showed that the relative ionization cross sections for the CO 4σ-, 1π-, and 5σ-derived states depend drastically on the molecular orientation of CO with respect to the metastable beam, reflecting the local electron density of CO in the impact region. Moreover, it was found that the 4σ- and 5σ- derived states of CO at hollow sites on Ni(111) are strongly modified in space by mixing with each other, where considerable charge transfer occurs from the C site to the O site in the 5σ-derived state and in the opposite way in the 4σ-derived state. In contrast, such a strong charge redistribution was not seen in the cases of terminal CO on Ni(100) and Cr(CO)6. These findings were in good accordance with the crystal orbital overlap population obtained by density functional theory through a generalized gradient approximation. © 2001 American Institute of Physics.
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  • 18
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 34 (2003), S. 0 
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Vertebral deformities were investigated in cultured red sea bream, Pagrus major. In the field, deformities in seedlings were categorized and their incidence was calculated. In the laboratory, the symptoms of major vertebral deformities were examined morphologically using radiographs and by making transparent skeletal specimens. The internal structure of deformed vertebrae was examined histologically. The shortened body condition had the highest incidence (0.9–8.3%) of all deformities in the seedlings. In individuals with the shortened body condition, the ratio of trunk and caudal part length to body height was smaller. These fish had skeletal anomalies in the vertebrae, mainly centrum defects (64.3%) or undersized centrums (25.2%). The specimens with centrum defects had a characteristic anomaly in the vertebrae, with plural pairs of neural and haemal spines on a single centrum. This anomaly was frequently observed in the posterior abdominal vertebrae. The internal skeletal structure of such abnormal centrums was basically the same as that of normal centrums. In all the specimens with undersized centrums, both the centrum length and diameter were shorter than normal except for the first and second centrum, and urostyle.
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  • 19
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 204 (1994), S. 898-904 
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Physics and Chemistry of Solids 48 (1987), S. 701-705 
    ISSN: 0022-3697
    Keywords: Brillouin zone ; Graphite ; electron momentum distribution ; positron annihilation ; π-electron
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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