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  • 1
    Electronic Resource
    Electronic Resource
    TFTR epithermal neutron detector system: Recalibration and effect of nonisotropic neutron emission (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1682-1684 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The primary TFTR neutron source strength measurement system consists of seven fission detectors previously calibrated with D–D and D–T neutron generators and a 252Cf neutron source inside the TFTR vacuum vessel. A recalibration became desirable because of the addition of major components to the tokamak. The new calibration with the D–D neutron generator in situ is consistent with the detection efficiencies measured in the previous calibrations, within the uncertainties. Effects of the anisotropic emission of the neutron generator, due both to the variation of the differential D–D yield with angle (similar to that from beam–target and beam–beam reactions in the beam-driven TFTR plasma) and to scattering and absorption by the generator heads have been observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140132
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Relative intensities of 2.5- and 14-MeV source neutrons from comparative responses of U-238 and U-235 detectors (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1688-1690 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The response of polyethylene-moderated U-235 fission counters is only weakly dependent on incident neutron energy, while the response of unmoderated U-238 or Th-232 fission counters increases strongly with energy. A given concentration of D–T neutrons in a mixed DT–DD source results in a unique relative detector response that depends on the parameters R14 and R2.5, where R14 is the ratio of the unmoderated U-238 and moderated U-235 detector efficiencies for a pure 14-MeV neutron source, and R2.5 is the corresponding ratio for a pure 2.5-MeV source. We have recently determined R14 and R2.5 using D–D and D–T neutron generators inside the TFTR vacuum vessel. The results indicate that, for our detector geometry, the ratio of U-238 to U-235 count rates should increase by a factor of about 3 when the fusion neutron source changes from pure D–D to pure D–T. This calibration is being applied to recent TFTR "supershot'' data, where the uncollided neutron flux in the postbeam phase contains a high proportion of D–T neutrons from the burnup of D–D tritons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140134
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Calibration of the TFTR neutron activation system (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1715-1717 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Neutron generators, both D–D and D–T, have been used to calibrate the TFTR neutron activation (NA) system for point sources located within the tokamak. The foils used were In for D–D neutrons and Cu, Al, and 238U for D–T neutrons. Delayed neutrons following fission were counted when using 238U foils, 336-keV γ rays from 115In(n,n')115m In reactions, annihilation radiation from 62Cu following the 63Cu(n,2n)62Cu reaction, and 1368- and 2754-keV γ rays from the 27Al(n,α)24Na reaction. Large effects caused by source anisotropy and local machine structure were observed. These effects and the attempts to accommodate them in the data analysis will be described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140143
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  • 4
    Electronic Resource
    Electronic Resource
    Calibration of a surface barrier detector for 14-MeV neutron flux measurements on TFTR (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1718-1720 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Nuclear reactions in silicon semiconductor detectors with an energy threshold above 2.5 MeV can be used to measure dt neutrons in a high background of low-energy dd neutrons. This allows the measurement of 14-MeV neutrons from the d(t, n)α reaction in deuterium plasmas, where the tritons from the d(d, t)p reaction create 14-MeV neutrons due to burnup. Measurements with a surface barrier detector are presented together with the calibration of such a detector to measure the absolute 14-MeV neutron source strength.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140144
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Application of a Si-diode detector for fusion product measurements in ASDEX Upgrade (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 4434-4438 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The efficient confinement of the energetic charged fusion products and the complete transfer of their kinetic energy to the plasma is of great importance for the realization of a fusion reactor which will depend on alpha-particle heating. In todays fusion experiments with deuterium plasmas, this aspect can be investigated using the 1 MeV tritons from the d(d,p)t reaction. The slowing down behavior of these tritons can be studied by measuring the 14 MeV neutrons from the t(d,α)n reaction (triton burnup). At ASDEX Upgrade a time-resolved diagnostic based on a silicon barrier detector has been installed to measure the time evolution of the 14 MeV neutron rate. Using the Si(n,p)Al and Si (n,α)Mg reactions the high energy neutrons, with an energy above the 6 MeV threshold, are converted to charged particles directly inside the semiconductor diode. The complete functionality of the detector system is demonstrated by the successful measurement of the complex spectrum of the charged reaction products in silicon triggered by fusion neutrons during plasma discharges. As an integral component of this diagnostic a time dependent burnup code based on classical slowing-down theory has been developed for the use at ASDEX Upgrade to analyze the complex time evolution of the 14 MeV neutron rate. First measurements are compared to the results of the code. A new application for such detectors is proposed, as in conjunction with the materials of the tokamak structure it can be operated simultaneously as an in situ activation system. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148410
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  • 6
    Electronic Resource
    Electronic Resource
    Neutron calibration techniques for comparison of tokamak results (abstract) : Eighth topical conference on high-temperature plasma diagnostics (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 3232-3232 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A workshop on 1–3 August 1989 reviewed the techniques, uncertainties, and experiences of neutron calibration on PLT, TFTR, JET, Tore Supra, JT-60, JIPPT-IIU, Alcator C-Mod, ATF, FT, ASDEX, Textor, and DIII-D. In the summary session, the workshop participants discussed possible consensus neutron calibration techniques appropriate to D-D plasmas in tokamaks. The application of such techniques would facilitate a more accurate comparison of neutron yields from different devices, and also allow new calibration techniques to relate their precision to a reference value. General agreement was reached on the suitability of two techniques: (1) a 252Cf source calibration of epithermal neutron detectors, and (2) threshold neutron activation of Ni foils placed vertically above or below the plasma. This paper will present details on detector positioning, neutron transport calculations, and interlab normalization needed to accomplish the standardized calibration using a Cf neutron source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141648
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    In situ calibration of neutron detectors on TEXTOR (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 1945-1952 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Neutron yield measurements are performed at the Jülich Tokamak experiment TEXTOR with different detectors located around the Tokamak and on center axis above the shielding roof. Due to the large structure of the machine and the extended diagnostic equipment, both virgin and scattered neutrons are detected. To prepare a Bonner sphere of appropriate response, the shape of the degraded neutron spectrum was determined with a spherical ionization chamber in situ. These investigations have been enlarged under quasi-real conditions at the accelerator facility of the Physikalisch-Technische Bundesanstalt in Braunschweig with a set of Bonner spheres used as a spectrometer. For the calibration the plasma neutron source is simulated by two point sources, 238Pu/B and 252Cf. The sources are moved around the TEXTOR vessel along the position of the magnetic axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143309
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  • 8
    Electronic Resource
    Electronic Resource
    Neutron calibration techniques for comparison of tokamak results (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 3501-3504 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A workshop on 1–3 August 1989 reviewed the techniques, uncertainties, and experiences of neutron calibration on PLT, TFTR, JET, Tore Supra, JT-60, JIPPT-IIU, Alcator C-Mod, ATF, FT, ASDEX, Textor, and DIII-D. In the summary session, the workshop participants discussed possible consensus neutron calibration techniques appropriate to D-D plasmas in tokamaks. The application of such techniques would facilitate a more accurate comparison of neutron yields from different devices, and also allow new calibration techniques to relate their precision to a reference value. General agreement was reached on the suitability of two techniques: (1) a 252Cf source calibration of epithermal neutron detectors, and (2) threshold neutron activation of Ni foils placed vertically above or below the plasma. This paper will present details on detector positioning, neutron transport calculations, and interlab normalization needed to accomplish the standardized calibration using a Cf neutron source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141558
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    Paper (German National Licenses)
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