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Nuclear Science, IEEE Transactions on

Issue 4 • Date Aug 2000

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Displaying Results 1 - 4 of 4
  • Effect of gamma ray irradiation on the conduction mechanisms of radio-frequency-sputtered Ta2O5 films

    Page(s): 1704 - 1709
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB)  

    The microstructural and electrical conduction properties of sputtered Ta2O5 films pre-irradiated and γ-ray-irradiated were systematically investigated. Analytical results revealed that the crystallinity and the leakage current of the pre-irradiated sample were effectively improved by raising the irradiation dose at low doses of irradiation [1 M~4 M rad(Ta2O5)]; however higher doses of γ-ray irradiation [>4 M rad(Ta2O5)] undesirably deteriorated the film crystallinity, yielding a larger leakage current. Such a result leads the Frenkel-Poole conduction (pre-irradiated sample) transformed to Schottky emission conduction process [low doses (1 M~4 M rad(Ta2O5)) of γ-ray-irradiated samples] and then gradually to the Frenkel-Poole conduction [high doses (>4 M rad(Ta2O5)) of γ-ray-irradiated samples] again View full abstract»

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  • Photoelectron backscattering from silicon anodes of hybrid photodetector tubes

    Page(s): 1685 - 1690
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    The impact of photoelectron backscattering on spectral distributions measured with hybrid photodetector tubes has been calculated. The calculations are based on the backscattering coefficient μ, the average number of photoelectrons N¯phel emitted from the photocathode, and on the distribution of the fractional photoelectron energy q absorbed in silicon during the backscattering process. We obtained the following results: the average number of absorbed (measured) photoelectrons N¯meas in the silicon anode amounts to ~88% of the incident N¯phel. Photoelectron- and gamma-absorption peaks are broadened by a factor 1.043 due to backscattering. As an example, for photomultiplier tubes, this broadening can amount to an average factor of 1.18 due to statistic and gain fluctuations on the dynode chain View full abstract»

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  • A solid-state intraoperative beta probe system

    Page(s): 1696 - 1703
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB)  

    Successful beta-sensitive intraoperative probes must be capable of detecting relatively small amounts of beta-emitting radionuclides in an environment where a significant photon background exists. The probe system described in this investigation utilized a new photon correction scheme consisting of a stark of two ion-implanted-silicon detectors (IISDs) mounted in a compact unit. The rear detector operated as a photon monitor, whose data was used to correct for photon contamination present in the front detector's readings. The completely battery-powered system incorporated a computer-controlled data acquisition and processing system. Positron and photon detection sensitivities were measured using fluorine-18. The probe was found to have a positron detection sensitivity of 7.21±0.11 cps/nCi and a 0.0001±0.0389 cps/nCi photon detection sensitivity. In a simulated search for tumor remnants following a tumor resection using a phantom presenting a realistic annihilation photon background, the intraoperative probe was capable of definitively identifying 12-mm- and 6-mm-diameter, 1-mm-thick disks of simulated tumor View full abstract»

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  • Single-side biasing of silicon drift detectors with homogeneous light-entrance window

    Page(s): 1691 - 1695
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB)  

    In this work, we present a biasing scheme for silicon drift detectors (SDD's) with a homogeneous light-entrance window. The aim of the proposed solution is to provide a biasing of the single electrode of the detector on the light-entering side (back electrode) without any external electrical connection. The control of this electrode is performed by suitably biasing only the electrodes plated on the opposite side of the detector. In this mechanism, the leakage holes collected by the back electrode are used to create a reach-through current through the depleted bulk to the front side of the detector. This biasing scheme is of particular interest when the SDD has to be coupled to scintillators for γ-ray spectroscopy and imaging applications. In this paper, the biasing scheme is presented and results obtained using the method with a cylindrical SDD are reported View full abstract»

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IEEE Transactions on Nuclear Science focuses on all aspects of the theory and applications of nuclear science and engineering, including instrumentation for the detection and measurement of ionizing radiation; particle accelerators and their controls; nuclear medicine and its application; effects of radiation on materials, components, and systems; reactor instrumentation and controls; and measurement of radiation in space.

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