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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 58 (1994), S. 59-62 
    ISSN: 1432-0630
    Keywords: 78.70.Bj ; 72.80.Ey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Measurements of the positron lifetime and Doppler-broadened annihilation-radiation have been performed in electron-irradiated GaAs. The positron lifetime at the irradiation induced defects was ∼0.250 ns at 300 K. The defect clustering stage was found to occur at around 520–620 K, and the coarsening and annealing stage is believed to be above 620 K. Similar annealing stages were also observed in GaAs lightly doped with Si (0.2×1018 cm−3). Both the lifetime and the S-parameter in the irradiated GaAs were found to decrease with temperature from 300 K to 100 K, suggesting the coexistence of shallow traps in electron irradiated GaAs.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0630
    Keywords: 78.70.Bj ; 72.80.Ey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The positron lifetime of undoped Liquid-Encapsulated Czochralski (LEC)-GaAs and Si-doped (1.3×1018 cm−3) LEC-GaAs was measured before and after irradiation with protons (dose 1×1015/cm2, 15 MeV). In Si-doped GaAs, the decrease of positron lifetime at temperatures between 10 and 300 K are due to the decrease of the positron-diffusion length and the increase of the effective shallow traps such as antisite GaAs. The annealing stage of the proton-irradiation-induced defects which show the different behavior from that of electron-irradiation-induced defects suggests that proton irradiation creates more complicated defect complexes, containing vacancies rather than isolated vacancy-type defects or simple complexes which have been observed during electron-irradiation processes. Above 700 K, proton-irradiation-induced defects such as vacancy-type defects and simple vacancy complexes are almost annealed out, while Si-induced defects such as SiGa-VGa complexes cannot be annealed out above 973 K.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1920
    Keywords: Spinal cord ependymoma ; Positron emission tomography ; (11C-methyl)-L-methionine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An intramedullary spinal cord ependymoma was studied by positron emission tomography (PET) using (11C-methyl)-L-methionine (11C-Met). MRI showed a homogeneously enhancing tumour at C6-T2 with cysts at its rostral and caudal ends. Sagittal PET images demonstrated high11C-Met uptake in the solid portion of the tumour, particularly ventrally at C7-T2, where viable tumour cells proliferated in association with abundant perforating vessels. Met-PET would appear useful for delineating the viable protion of intramedullary ependymomas.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1920
    Keywords: Key words Spinal cord ependymoma ; Positron emission tomography ; (11C-methyl)-L-methionine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An intramedullary spinal cord ependymoma was studied by positron emission tomography (PET) using (11C-methyl)-L-methionine (11C-Met). MRI showed a homogeneously enhancing tumour at C6–T2 with cysts at its rostral and caudal ends. Sagittal PET images demonstrated high 11C-Met uptake in the solid portion of the tumour, particularly ventrally at C7-T2, where viable tumour cells proliferated in association with abundant perforating vessels. Met-PET would appear useful for delineating the viable portion of intramedullary ependymomas.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 28 (1986), S. 374-374 
    ISSN: 1432-1920
    Keywords: Choroid plexus carcinoma ; Computerized tomography ; Positron emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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