The E_LIBANS project (INFN) aims at producing neutron facilities for interdisciplinary irradiation purposes among which pre-clinical research for BNCT. After the successful setting-up of the thermal ...neutron source based on a medical LINAC, a similar apparatus for epithermal neutrons has been developed. Both structures are based on an Elekta 18 MV coupled with a photoconverter-moderator system which deploys the (γ,n) reaction to convert the X-rays into neutrons. This communication describes the two neutron sources and the results obtained in their characterization.
•Development of photonuclear thermal and epithermal neutron sources for samples irradiation.•Sources based on an 18 MV medical-type electron LINAC and a photoconverter assembly.•Homogeneous thermal or epithermal neutron fields obtained in closed experimental cavities.•Active Bonner Sphere System used for the neutron spectrum measurement in the cavities.•Field characterization and feasibility demonstration of reduced-cost photonuclear neutron sources.
The paper is focused on the study of a novel photo-neutron source for BNCT preclinical research based on medical electron Linacs. Previous studies by the authors already demonstrated the possibility ...to obtain a mixed thermal and epithermal neutron flux of the order of 107cm−2s−1. This paper investigates possible Linac’s modifications and a new photo-converter design to rise the neutron flux above 5 107cm−2s−1, also reducing the gamma contamination.
•Proposal of a mixed thermal and epithermal (named hyperthermal) neutron source based on medical high energy electron Linac.•Photo-neutron production via Giant Dipole Resonance on high Z materials.•MCNP4B-GN simulations to design the photo-converter geometry maximizing the hyperthermal neutron flux and minimizing the fast neutron and gamma contaminations.Hyperthermal neutron field suitable for BNCT preclinical research.
Radiation-resistant, gamma-insensitive, active thermal neutron detectors were developed to monitor the thermal neutron cavity of the E_LIBANS project. Silicon and silicon carbide semiconductors, plus ...vented air ion chambers, were chosen for this purpose. This communication describes the performance of these detectors, owing on the results of dedicated measurement campaigns.
The e_LiBANS project aims at producing intense thermal neutron fields for diverse interdisciplinary irradiation purposes. It makes use of a reconditioned medical electron LINAC, recently installed at ...the Physics Department and INFN in Torino, coupled to a dedicated photo-converter, developed within this collaboration, that uses (γ,n) reaction within high Z targets. Produced neutrons are then moderated to thermal energies and concentrated in an irradiation volume. To measure and to characterize in real time the intense field inside the cavity new thermal neutron detectors were designed with high radiation resistance, low noise and very high neutron-to-photon discrimination capability. This article offers an overview of the e_LiBANS project and describes the results of the benchmark experiment.
Characterization of a neutron imaging setup at the INES facility Durisi, E.A.; Visca, L.; Albertin, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2013, Letnik:
726
Journal Article
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The Italian Neutron Experimental Station (INES) located at the ISIS pulsed neutron source (Didcot, United Kingdom) provides a thermal neutron beam mainly used for diffraction analysis. A neutron ...transmission imaging system was also developed for beam monitoring and for aligning the sample under investigation. Although the time-of-flight neutron diffraction is a consolidated technique, the neutron imaging setup is not yet completely characterized and optimized. In this paper the performance for neutron radiography and tomography at INES of two scintillator screens read out by two different commercial CCD cameras is compared in terms of linearity, signal-to-noise ratio, effective dynamic range and spatial resolution. In addition, the results of neutron radiographies and a tomography of metal alloy test structures are presented to better characterize the INES imaging capabilities of metal artifacts in the cultural heritage field.
A full characterization of the present INES imaging set-up was carried out.Two CCD cameras and two scintillators (ZnS/6LiF) of different thicknesses were tested.Linearity, effective dynamic range and spatial resolution were determined.Radiographies of steep wedges were performed using the highest dynamic range setup.Tomography of a bronze cube was performed using the best spatial resolution setup.
Bremsstrahlung photon beams produced by linac accelerators are currently the most commonly used method of radiotherapy for tumour treatments. When the photon energy exceeds 10 MeV the patient ...receives an undesired dose due to photoneutron production in the accelerator head. In the last few decades, new sophisticated techniques such as multileaf collimators have been used for a better definition of the target volume. In this case it is crucial to evaluate the photoneutron dose produced after giant dipole resonance (GDR) excitation of the high Z materials (mainly tungsten and lead) constituting the collimator leaves in view of the optimization of the radiotherapy treatment. A Monte Carlo approach has been used to calculate the photoneutron dose arising from the GDR reaction during radiotherapy with energetic photon beams. The simulation has been performed using the code MCNP4B-GN which is based on MCNP4B, but includes a new routine GAMMAN to model photoneutron production. Results for the facility at IRCC (Istituto per la Ricerca e la Cura del Cancro) Candiolo (Turin), which is based on 18 MV x-rays from a Varian Clinac 2300 C/D, are presented for a variety of different collimator configurations.
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