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The PRIMA project aims at the construction of two ITER-NBI facilities in Padova (Italy). The first one is called SPIDER which is negative H/D 100 keV RF source, while the second one (MITICA) will be a full scale 1 MeV deuterium beam injector as the one that will be used in ITER. In order to resolve the horizontal beam intensity profile in MITICA and one of the eight beamlets groups in SPIDER, the Close-contact Neutron Emission Surface Mapping (CNESM) system is being developed. The goal of this device is to reconstruct the D− beam evaluating the map of the neutron emission due to interaction of the deuterium beam with the deuterons implanted in the beam dump surface. For this reason, the CNESM diagnostic, which is based on nGEM detectors for fast neutrons, will be placed right behind the SPIDER and MITICA beam dump, i.e. in an UHV (Ultra High Vacuum) environment. Since the nGEM detectors need to operate at atmospheric pressure a vacuum sealed detector box has been designed to be installed inside the vacuum vessel and able to sustain atmospheric pressure inside. This paper describes the status of the CNESM diagnostic and underlines the different phases followed during the realization and installation of the diagnostic on the SPIDER beam dump as well as its imaging performances.

The crystal Cs2LiYCI6:Ce (CLYC) is a very interesting scintillator material because of its good energy resolution and its capability to identify gamma-rays and fast/thermal neutrons. The crystal Cs2LiYCI6:Ce contains Li-6 and Cl-35 isotopes, therefore, it is possible to detect thermal neutrons through the reaction Li-6 (n, alpha)t while Cl-35 ions allow to measure fast neutrons through the reactions Cl-35(n, p)S-35 and Cl-35(n, alpha)P-32. In this work two CLYC 1" x 1" crystals were used: the first crystal, enriched with Li-6 at 95% (CLYC-6) is ideal for thermal neutron measurements while the second one, enriched with Li-7 at > 99% (CLYC-7) is suitable for fast neutron measurements. The response of CLYC scintillators was measured with different PMT models: timing or spectroscopic, with borosilicate glass or quartz window. The energy resolution, the neutron-gamma discrimination and the internal activity are discussed. The capability of CLYC scintillators to discriminate gamma rays from neutrons was tested with both thermal and fast neutrons. The thermal neutrons were measured with both detectors, using an AmBe source. The measurements of fast neutrons were performed at the Frascati Neutron Generator facility (Italy) where a deuterium beam was accelerated on a deuterium or on a tritium target, providing neutrons of 2.5 MeV or 14.1 MeV, respectively. The different sensitivity to thermal and fast neutrons of a CLYC-6 and of a CLYC-7 was additionally studied. (C) 2015 Elsevier B.V. All rights reserved.

The response of a 3 '' x 3 '' LaBr3(Ce) scintillator to 14 MeV neutron irradiation has been measured at the Frascati Neutron Generator and simulated by means of a dedicated MCNP model. Several reactions are found to contribute to the measured response, with a key role played by neutron inelastic scattering and (n,2n) reactions on Br-79, Br-81 and La-139 isotopes. An overall 43% efficiency to 14 MeV neutron detection above an experimental threshold of 0.35 MeV is calculated and confirmed by measurements. Post irradiation activation of the crystal has been also observed and is explained in terms of nuclear decays from the short lived Br-78 and Br-80 isotopes produced in (n,2n) reactions. The results presented in this paper are of relevance for the design of gamma-ray detectors in burning plasma fusion experiments of the next generation, such as ITER, where capability to perform measurements in an intense 14 MeV neutron flux is required. (C) 2015 Elsevier B.V. All rights reserved.