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A simple and inexpensive method to perform passive thermal neutron imaging on large areas was developed on the basis of XRQA2 GAFCHROMIC films, commonly employed for quality assurance in radiology. To enhance their thermal neutron response, the sensitive face of film was coupled with a 1 mm thick cadmium radiator, forming a sandwich. By exchanging the order of Cd filter and sensitive film with respect to the incident neutron beam direction, two different configurations (beam-Cd-film and beam-film-Cd) were identified. These configurations were tested at thermal neutrons fluence values in the range 10 9 –10 10 cm −2 , using the ex-core radial thermal neutron column of the ENEA Casaccia – TRIGA reactor. The results are presented in this work. [ABSTRACT FROM AUTHOR]

A new directional neutron spectrometer called CYSP (CYlindrical SPectrometer) was developed within the NESCOFI@BTF (2011–2013) collaboration. The device, composed by seven active thermal neutron detectors located along the axis of a cylindrical moderator, was designed to simultaneously respond from the thermal domain up to hundreds of MeV neutrons. The new spectrometer condenses the performance of the Bonner Sphere Spectrometer in a single moderator; thus requiring only one exposure to determine the whole spectrum. The CYSP response matrix, determined with MCNP, has been experimentally evaluated with monochromatic reference neutron fields from 144 keV to 16.5 MeV, plus a 252 Cf source, available at NPL (Teddington, UK). The results of the experiment confirmed the correctness of the response matrix within an overall uncertainty of ±2.5%. The new active spectrometer CYSP offers an innovative option for real-time monitoring of directional neutron fields as those produced in neutron beam-lines. [ABSTRACT FROM AUTHOR]

In the framework of NESCOFI@BTF and NEURAPID projects, active thermal neutron detectors were manufactured by depositing appropriate thickness of 6 LiF on commercially available windowless p–i–n diodes. Detectors with different radiator thickness, ranging from 5 to 62 μm, were manufactured by evaporation-based deposition technique and exposed to known values of thermal neutron fluence in two thermal neutron facilities exhibiting different irradiation geometries. The following properties of the detector response were investigated and presented in this work: thickness dependence, impact of parasitic effects (photons and epithermal neutrons), linearity, isotropy, and radiation damage following exposure to large fluence (in the order of 10 12 cm −2 ). [ABSTRACT FROM AUTHOR]

The NESCOFI@BTF (2011–2013) international collaboration was established to develop realtime neutron spectrometers to simultaneously cover all energy components of neutron fields, from thermal up to hundreds MeV. This communication concerns a new spherical spectrometer, called SP^2, which condenses the functionality of an Extended Range Bonner Sphere Spectrometer (ERBSS) into a single moderator embedding multiple active thermal neutron detectors. The possibility of achieving the complete spectrometric information in a single exposure constitutes a great advantage compared to the ERBSS. The first experimental test of the instrument, performed with a reference 241Am–Be source in different irradiation geometries, is described. The agreement between observed and simulated response is satisfactory for all tested geometries. [ABSTRACT FROM AUTHOR]

Abstract: The performance of the new prototype of high quantum efficiency PMT (43% at 380nm), Hamamatsu R7600U-200, was studied coupled to a LaBr3:Ce crystal with the size of ∅12.5mm×12.5mm. The energy resolution results were compared with ones from two PMTs, Hamamatsu R7600U and R6231MOD, with 22% and 30% quantum efficiency (QE), respectively. Moreover, the photodetectors were equipped with tapered and un-tapered voltage dividers to study the non-linearity effects on pulse height distribution, due to very high peak currents induced in the PMT by the fast and intense light pulse of LaBr3:Ce. The results show an energy resolution improvement with UBA PMT of about 20%, in the energy range of 80–662keV, with respect to the BA one. [Copyright &y& Elsevier]

Abstract: In this work preliminary results of single-photon measurements made with a LaBr3:Ce continuous scintillation crystal (BrilLanCe 380™, by Saint-Gobain Crystals, FR) coupled to an array of Multi-Pixel Photon Counters (MPPC™, by Hamamatsu Photonics, JP) are presented. The array of 7 MPPCs was realized as the innermost element of the hexagonal Anger-like structure suitable for growing to larger areas by adding peripheral elements. The design of MPPC electronic readout for position determination was based on Anger logic. Wide-band amplifiers (by MITEQ®, US) were used for signals conditioning. Digitized traces of background, 57Co and 133Ba collimated irradiation were captured, characterized and stored by using the data-logging capabilities of a WaveMaster Oscilloscope (by LeCroy, US). Results are presented in terms of energy response, position sensing and signals fall and rise times. [Copyright &y& Elsevier]