Ponente
Descripción
In the last years there is an increasing demand for advanced medical treatments, a field where particle accelerators play a crucial role. However, their availability is significantly limited due to high maintenance and operational costs, on the one hand, and the need for advanced technology and highly skilled personnel for their design and construction, on the other. The main goal of the project LINAC7 is to face these limitations with the design, fabrication and testing of a low energy proton accelerator. For this, all the components of the accelerator are being developed by the personnel involved in the project and, once constructed, the accelerator will serve for training students as well as for research studies.
In the current design, two experimental stations are to be constructed, one for protons with 3 MeV and other for protons with 7 MeV. In the first case, a 7Li target is aimed to be used for neutron production for different research purposes. In the second case, irradiation of different materials, such as cell cultures, and studies related with radioisotope generation are expected. Apart from that, a beam stop for beam characterization will be placed at the end of a third line.
The accelerator will be installed in the university of the Basque Country and its shielding design must guarantee adequate dose rate values in the surrounding areas in beam-on and beam-off conditions. The present work considers the above-mentioned applications to calculate the radiation that will be generated and the shielding needs. Moreover, a portable neutron source that will also be located in the room has been taken into account.
The tools used for the calculations are the MCNP6.2 for radiation transport and the ACAB-2008 software to determine the radioisotope inventory resultant from the activation of the materials. The starting shielding configuration has been defined based on the literature, and its optimization consists of an iterative process in which the geometry and type of the attenuating materials is modified basing on the dose rate values calculated in detectors positioned out from the accelerator room, for beam-on conditions, and in detectors located inside, for beam-off conditions. The plans of the building have been considered to obtain realistic results.
The final solution consists of three different shieldings, one of them moveable to be used for the portable neutron source and for the target station aimed for neutron generation. Highly efficient attenuating materials, such as lead for gammas and polyethylene for neutrons, allowed for a more compact design. Moreover, reduction of the iron quantity in the external layer reduces dose values in beam-off conditions.
In conclusion, different shielding designs that guarantee dose rates below the limit have been calculated and the next step is to discuss aspects related to fabrication and present the proposal to the CSN to advance with the construction of the setup.
