High performance detectors for upgraded gamma ray diagnostics for JET DT campaigns

Abstract

In forthcoming deuterium-tritium (DT) experiments on JET a significant population of alpha-particles will be produced. For operating alpha-particle diagnostics at high DT neutron fluxes, specific improvements have to be made. Proposed new detectors for gamma-ray measurements will be based on CeBr3 and LaBr3:Ce scintillators. They are characterized by a good energy resolution, a relatively high detection efficiency for a few MeV gamma-rays and a fast response time. An overview of scintillator parameters is presented. A description of the properties of photodetectors is given to indicate optimal setups. Results of measurements, using gamma-ray sources with energies up to a few MeV, are discussed with relation to the DT campaign requirements.

Characterization of some modern scintillators recommended for use on large fusion facilities in γ-ray spectroscopy and tomographic measurements of γ-emission profiles

“…So, it is important to make a detailed study with crystals of different sizes [11]. Measurements with sources emitting a few lines of -rays of energy in a MeV range are in progress [19].…”

Performance of the prototype LaBr3 spectrometer developed for the JET gamma-ray camera upgrade

“…Part of the contribution to this shift may also come from local heating of the MPPC induced by the larger signal current, as we did not perform our tests in a climatic chamber. This second contribution can however be reduced by adjusting the MPPC gain with a temperature feedback sensor 9 .…”

“…The use of fast, high light yield inorganic scintillators such as LaBr3 8 together with Silicon Photo-Multipliers (SiPMs) can represent a good alternative to the existing CsI and photodiodes, given their high photon detection efficiency, high internal gain, insensitivity to magnetic field and an extremely compact size. SiPMs, which have experienced great improvements in the last years, still show voltage-temperature dependence 9 and a limited linearity but both issues can be corrected for 9 . In this work we describe the solution developed to meet the requirements.…”

Control and data acquisition software upgrade for JET gamma-ray diagnostics

“…The Joint European Torus (JET) gamma-ray diagnostics are in the scope of the diagnostic package of the JET deuterium-tritium (DT) campaign in preparation for ITER [ [1], [2]]. This includes the Gamma-Ray Spectrometer (GRS), Gamma Camera Upgrade (GCU) and Gamma-Ray Spectrometer Upgrade (GSU) projects.…”