Radiation damage tests on diamond and scintillation detector components for the ITER Radial Neutron Camera

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Abstract

During the ITER reactor operation time, the plasma will give rise to high energy neutron and gamma flux and this intense radiation field will result in serious radiation damage and activation effects on various detectors components. In this work, neutron detector candidates for the ITER Radial Neutron Camera (RNC), i.e. scintillator components (crystal and plastic scintillators, optical windows and PMTs) and single-crystal diamond detectors, were investigated to establish their radiation hardness and stability under gamma irradiation. Radiation test were carried out at the ENEA Calliope plant (Casaccia R.C., Rome). The facility is a pool-type irradiation plant equipped with a 60Co source (energy = 1.25 MeV). Gamma radiation test were performed in the dark and at room temperature for different total absorbed doses, as required for the application in ITER RNC. Scintillators, PMTs and optical windows were irradiated up to around 100 kGy absorbed dose, while single-crystal diamond detectors up to around 5 MGy. Scintillators and optical windows transmittance measurements were performed in the UV-VIS range (300-700 nm), paying particular attention to the behavior at 390 and 420 nm (scintillating emission wavelengths). Samples were measured in the dark before and after irradiation and their performances were monitored at room temperature for some weeks in order to study the damage recovery in different conditions. For plastic scintillators photo- and optical bleaching followed by thermal annealing processes in air were made to reduce the radiation damage. Quantum efficiency measurements were performed on the PMTs and the pulse height spectra and pulse shape capability of the scintillators were investigated by using gamma and neutron sources. The most relevant results of this work concern the radiation damage observed in scintillators and diamond detectors. The crystalline scintillator sample showed much less radiation resistance than plastic scintillators. A strong damage to the silver deposition of the diamond contacts was observed already at 1.0 MGy, almost leading to contact destruction at 4.7 MGy.
Original languageEnglish
Pages (from-to)-
JournalIEEE Transactions on Nuclear Science
DOIs
Publication statusAccepted/In press - 17 Feb 2018

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All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Electrical and Electronic Engineering

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