Response of LaBr 3 (Ce) scintillators to 14 MeV fusion neutrons

Abstract

Measurements of the response function of LaBr 3 (Ce) to 2.5 MeV neutrons have been carried out at the Frascati Neutron Generator and at tokamak facilities with deuterium plasmas. The observed spectrum has been interpreted by means of a MCNP model. It is found that the main contributor to the measured response is neutron inelastic scattering on La. An extrapolation of the count rate response to 14 MeV neutrons from deuterium-tritium plasmas is also presented. The results are of relevance for the design of γ-ray diagnostics of fusion burning plasmas.carlo.cazzaniga@mib.infn.it 1

A Review of Inorganic Scintillation Crystals for Extreme Environments

“…LaBr 3 (Ce)-a suitable choice to meet these requirements-has a fast scintillation time, high light yield, and high resistance to neutron damage. Besides, in fusion devices, the detector measures in a harsh environment at high neutron fluxes [105]. LaBr 3 (Ce) has a ~70% light output at 175 • C, 16-ns short decay time [28], and strong radiation resistance [106].…”

A new tangential gamma-ray spectrometer for fast ion measurements in deuterium and deuterium–tritium plasmas of the Joint European Torus

“…The T-GRS is based on a 3"x6" (diameter x length) cylindrical LaBr 3 scintillator developed by St Gobain (see figure 1) and replaces a former 7.5 cm x 7.5 cm Bismuth Germanate (BGO) spectrometer 11 . The upgrade of the BGO was required predominantly to enable measurements at MHz counting rates, such as those expected from the 14 MeV neutron background in DT plasmas 13 or in runaway electron experiments in D plasmas. Another need was to distinguish lines separated by ≈100 keV in the MeV range, for example those arising from radio-frequency heating in hydrogen plasmas with 3 He 14 .…”

“…However, the online version of record will be different from this version once it has been copyedited and typeset. neutrons 13 , a carefully studied attenuator based on LiH has been designed and built for the T-GRS LOS. The design has been driven by MCNP simulations, with additional constraints provided by existing mechanical components along the LOS.…”

First spatially resolved measurements of the D–3He α-particle source with the upgraded JET gamma-ray camera

“…In particular the neutron induced back- ground due to fusion born 14 MeV neutrons has been characterized in Ref. 21 and extends up to approximately 10 MeV. An experimental estimate of such background for channels 1 and 15 is shown by the red triangles in figure 2.…”

“…Two spectral regions can be clearly distinguished, depending on whether E γ < 10 MeV or E γ > 10 MeV. The E γ < 10 MeV region has a similar shape between the two channels and is dominated by the response function of the LaBr 3 (Ce) scintillator to neutron background 20,21 . In particular the neutron induced back- ground due to fusion born 14 MeV neutrons has been characterized in Ref.…”