Compact NE213 neutron spectrometer with high energy resolution for fusion applications

Abstract

Neutron spectrometry is a tool for obtaining important information on the fuel ion composition, velocity distribution and temperature of fusion plasmas. A compact NE213 liquid scintillator, fully characterized at Physikalisch-Technische Bundesanstalt, was installed and operated at the Joint European Torus (JET) during two experimental campaigns (C8-2002 and trace tritium experiment-TTE 2003). The results show that this system can operate in a real fusion experiment as a neutron (1.5 MeV<En<20 MeV) spectrometer with good energy resolution (ΔE/E<4% at En=2.5 MeV and ΔE/E<2% at En=14 MeV). First measurements performed under different plasma scenarios, including trace tritium experiments, are presented. The analysis of the pulse height data was carried out using a newly developed method based on maximum entropy unfolding. The results indicate that this efficient, inexpensive, and compact scintillator is suitable for use as a broadband spectrometer in large fusion devices (JET and the International Thermonuclear Experimental Reactor).

Velocity-space sensitivities of neutron emission spectrometers at the tokamaks JET and ASDEX Upgrade in deuterium plasmas

“…The other two JET neutron energy spectrometers considered here are compact detectors. One of them uses the liquid organic scintillator material NE213 to detect neutrons 16,20 .…”

Overview of spectral unfolding techniques and uncertainty estimation

“…This differs from other parameter estimation methods in which the data is used to search for particular values of the parameters that satisfy some "best fit" criteria (e.g., minimum of the chi-squared or some other condition) in that the end result is not a particular point in parameter space but a probabilistic evaluation of the parameters that includes a full description of their uncertainties. This approach has been used successfully to estimate ambient dose equivalent values with uncertainties from measurements made with a Bonner sphere spectrometer (Reginatto, 2006;Reginatto, 2009) and in applications of neutron spectrometry to fusion diagnostics (Zimbal et al, 2004;Bertalot et al, 2005). Here, I will illustrate the method with an example that is somewhat simpler than these and which is of relevance for fusion diagnostics: the analysis NE213 scintillator measurements of a neutron reference field with mean energy of w2.5 MeV, where the quantity of interest is the full width at half maximum (FWHM) of the peak (Reginatto and Zimbal, 2008).…”

ITER relevant developments in neutron diagnostics during the JET Trace Tritium campaign

“…Measurements with NE213 liquid scintillators were successfully carried out at JET during the 2002 DD campaigns and during TTE, aiming to determine the energy resolution at 2.5 MeV and 14 MeV neutron energy of such a compact spectrometer in a real fusion experiment [13]. One NE213 spectrometer had been fully characterized for neutron (1.5 MeV < E n < 20 MeV) detection at the Physikalisch-Technische Bundesanstalt accelerator facility [14].…”