Absolute calibration of neutron detectors on the C-2U advanced beam-driven FRC

• Published in: Review of scientific instruments Vol. 87; no. 11; p. 11D815
• Main Authors: Magee, R M, Clary, R, Korepanov, S, Jauregui, F, Allfrey, I, Garate, E, Valentine, T, Smirnov, A
• Format: Journal Article
• Language: English
• Published: United States 01.11.2016
• ISSN: 1089-7623
• DOI: 10.1063/1.4960416

In the C-2U fusion energy experiment, high power neutral beam injection creates a large fast ion population that sustains a field-reversed configuration (FRC) plasma. The diagnosis of the fast ion pressure in these high-performance plasmas is therefore critical, and the measurement of the flux of neutrons from the deuterium-deuterium (D-D) fusion reaction is well suited to the task. Here we describe the absolute, in situ calibration of scintillation neutron detectors via two independent methods: firing deuterium beams into a high density gas target and calibration with a 2 × 10 n/s AmBe source. The practical issues of each method are discussed and the resulting calibration factors are shown to be in good agreement. Finally, the calibration factor is applied to C-2U experimental data where the measured neutron rate is found to exceed the classical expectation.