Green and red scintillator crystals with plastic fiber optics were used to investigate their application as optical fiber dosimeters. In Part 1, the radiation beam is perpendicular to the system with 20x20cm2 half field. We have a linear response for both systems with doubling the MU starting from 1MU up to 1024MU. Here we define the SOBR (Signal to Optical Background Ratio) to be the response of total signal (crystal and fiber) divided by the background (fiber) signal. The SOBR of red and green with no filter were 16.58 and 17.74 respectively. When we added the filter, the SOBR for red and green became 11.03 and 66.72 respectively. In Part 2, we changed the field to X=1cm, Y1=5cm and Y2=1cm. The SOBR for red and green with no filter are 44.43 and 45.47. After we added the filter, the SOBR for red and green became 15.62 and 1684. This change in field shape gave us a higher SOBR, especially when the filter was added. In Part 3, we tested the angular response of our detector. Both systems increased their response when gantry angle reach 45° and -45° (315°). When the filter was added, a change of a factor of 2 in response remained. When the crystal was then rotated and pointed in the direction of the gantry, good response was obtained from range 90° to -90° (270°). The response of green system was within 2.5%. For the red system, a large step about 10% was observed. Conversion of the fiber fluorescence and Cerenkov radiation in the scintillator crystal and transmission to the detector is a problem in all optical fiber systems, including the dual fiber system, that remains to be addressed.

Green and red scintillator crystals with plastic fiber optics were used to investigate their application as optical fiber dosimeters. In Part 1, the radiation beam is perpendicular to the system with 20x20cm2 half field. We have a linear response for both systems with doubling the MU starting from 1MU up to 1024MU. Here we define the SOBR (Signal to Optical Background Ratio) to be the response of total signal (crystal and fiber) divided by the background (fiber) signal. The SOBR of red and green with no filter were 16.58 and 17.74 respectively. When we added the filter, the SOBR for red and green became 11.03 and 66.72 respectively. In Part 2, we changed the field to X=1cm, Y1=5cm and Y2=1cm. The SOBR for red and green with no filter are 44.43 and 45.47. After we added the filter, the SOBR for red and green became 15.62 and 1684. This change in field shape gave us a higher SOBR, especially when the filter was added. In Part 3, we tested the angular response of our detector. Both systems increased their response when gantry angle reach 45° and -45° (315°). When the filter was added, a change of a factor of 2 in response remained. When the crystal was then rotated and pointed in the direction of the gantry, good response was obtained from range 90° to -90° (270°). The response of green system was within 2.5%. For the red system, a large step about 10% was observed. Conversion of the fiber fluorescence and Cerenkov radiation in the scintillator crystal and transmission to the detector is a problem in all optical fiber systems, including the dual fiber system, that remains to be addressed.

The growing interest towards polysiloxane-based radiation detection systems is related with the several advantages that polysiloxanes offer in comparison with other state-of-the-art plastic materials used in scintillation, like polyvinyltoluene and polystyrene. In this respect, polysiloxane elastomers offer higher thermal stability, flexibility and radiation hardness than the traditional plastic counterpart. For this reason, the study of polysiloxane-based systems for the detection of several types of radiation such as neutrons, high-energy photons and charged particles has recently received increasing attention by the scientific community. In this thesis, we report the current advances on both organic and hybrid polysiloxane-based radiation detection systems for scintillation and passive dosimetry applications. In this framework, we will start from the recent advances on organic polysiloxane-based scintillators for the detection of fast neutrons, with particular emphasis on their pulse-shape discrimination capabilities, allowing for the distinction of neutrons from the γ-ray background. The other and main part of the thesis will be then dedicated to hybrid nanostructured polysiloxane-based radiation detection systems. In this context, latest progress on polysiloxane scintillators embedding 6LiF nanocrystals for thermal neutron detection will be presented, with particular focus on the role of the nanocrystal size and dispersion in the detection performances. Subsequently, polysiloxane/quantum dots nanocomposites will be investigated for their possible use in both scintillation and passive dosimetry. In this latter application, the optical properties of the samples are analyzed after irradiation, with the aim to correlate the radiation-induced effects with the radiation dose. Lastly, the role of the polymer matrix in the post-irradiation optical response of the nanocrystals will be investigated.