Experimental and Monte Carlo characterization of radionuclidic impurities originated from proton irradiation of [O]HO in a modern medical cyclotron.

In this work we present a characterization of the radionuclidic impurities originated by proton irradiation of enriched water [O]HO in a medical cyclotron through Monte Carlo simulations and experimental measurements. A set of standard samples of enriched water loaded in the cyclotron target cell have been irradiated at 30 μA proton current for 1 h each and, after an appropriate cooling time, measured by HPGe gamma spectrometry. In this way it was possible to study the direct release of radionuclidic impurities from target components as well as the release as a function of target ageing.

Radiation resistance of elastomeric O-rings in mixed neutron and gamma fields: Testing methodology and experimental results.

Materials and components employed in the presence of intense neutron and gamma fields are expected to absorb high dose levels that may induce deep modifications of their physical and mechanical properties, possibly causing loss of their function. A protocol for irradiating elastomeric materials in reactor mixed neutron and gamma fields and for testing the evolution of their main mechanical and physical properties with absorbed dose has been developed. Four elastomeric compounds used for vacuum O-rings, one fluoroelastomer polymer (FPM) based and three ethylene propylene diene monomer rubber (EPDM) based, presently available on the market have been selected for the test.

Characterisation of the secondary neutron field generated by a compact PET cyclotron with MCNP6 and experimental measurements.

The production of the most common used PET radioisotope Fluorine-18 with commercial cyclotrons is obtained from the O(p,n)F nuclear reaction when O-enriched water is bombarded with a proton beam. We present the characterization of the secondary neutron field spectra produced by this reaction in different locations around the cyclotron, through a comparison between MCNP6 Monte Carlo simulation results and experimental data obtained with Neutron Activation Analysis (NAA) of thin target foils of different materials.

The origin of neutron biological effectiveness as a function of energy.

The understanding of the impact of radiation quality in early and late responses of biological targets to ionizing radiation exposure necessarily grounds on the results of mechanistic studies starting from physical interactions. This is particularly true when, already at the physical stage, the radiation field is mixed, as it is the case for neutron exposure. Neutron Relative Biological Effectiveness (RBE) is energy dependent, maximal for energies ~1 MeV, varying significantly among different experiments.

Neutron flux characterisation of the Pavia TRIGA Mark II research reactor for radiobiological and microdosimetric applications.

Nowadays the Pavia TRIGA reactor is available for national and international collaboration in various research fields. The TRIGA Mark II nuclear research reactor of the Pavia University offers different in- and out-core neutron irradiation channels, each characterised by different neutron spectra. In the last two years a campaign of measurements and simulations has been performed in order to guarantee a better characterisation of these different fluxes and to meet the demands of irradiations that require precise information on these spectra in particular for radiobiological and microdosimetric studies.