Measured response of bubble neutron detectors and prospects for alpha knock-on diagnostics
| Autor: | A. Belian, J. Liptac, E. Morse, R. K. Fisher, C. E. Brient, M. L. Loughlin, A. L. Roquemore, S. S. Medley, Paul Parks, D. C. Ingram |
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| Rok vydání: | 2001 |
| Předmět: |
inorganic chemicals
Physics Bonner sphere Neutron emission Nuclear Theory technology industry and agriculture Neutron temperature Nuclear physics Neutron generator Physics::Plasma Physics biological sciences Neutron cross section Neutron detection Neutron source lipids (amino acids peptides and proteins) Neutron Nuclear Experiment Instrumentation |
| Zdroj: | Review of Scientific Instruments. 72:796-800 |
| ISSN: | 1089-7623 0034-6748 |
| Popis: | Measurement of the neutron energy spectrum above ∼16 MeV will yield information on the spatial and energy distributions of confined fast alphas in deuterium–tritium (DT) tokamaks (Fisher, Nucl. Fusion; Gorini Rev. Sci. Instrum.). The energetic neutrons result from fusion reactions involving the energetic ions created by alpha-fuel ion knock-on collisions. Standard two-gas bubble neutron detectors, designed to only detect neutrons with energies above a selectable threshold determined by the gas mixture, were used in preliminary attempts to measure the knock-on neutrons from DT plasmas in the Tokamak Fusion Test Reactor and Joint European Torus (JET). Subsequent measurements at accelerator neutron sources showed an unexpected below-threshold detector response that prevented observations of the alpha-induced neutron tails. Spontaneous bubble nucleation measurements show that the majority of this below-threshold response is due to slight variations in the gas mixture, and is not present in single-gas detectors. Single-gas detectors will be tested at the University of California Berkeley to determine the neutron energy threshold as a function of detector operating temperature and to confirm their suitability for alpha knock-on tail measurements. An array of single-gas detectors operating at different temperatures should allow measurements of the alpha knock-on neutron tail during planned DT experiments on JET.Measurement of the neutron energy spectrum above ∼16 MeV will yield information on the spatial and energy distributions of confined fast alphas in deuterium–tritium (DT) tokamaks (Fisher, Nucl. Fusion; Gorini Rev. Sci. Instrum.). The energetic neutrons result from fusion reactions involving the energetic ions created by alpha-fuel ion knock-on collisions. Standard two-gas bubble neutron detectors, designed to only detect neutrons with energies above a selectable threshold determined by the gas mixture, were used in preliminary attempts to measure the knock-on neutrons from DT plasmas in the Tokamak Fusion Test Reactor and Joint European Torus (JET). Subsequent measurements at accelerator neutron sources showed an unexpected below-threshold detector response that prevented observations of the alpha-induced neutron tails. Spontaneous bubble nucleation measurements show that the majority of this below-threshold response is due to slight variations in the gas mixture, and is not present in single-gas detector... |
| Databáze: | OpenAIRE |
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