Proton beam dose-mapping via color centers in LiF thin-film detectors by fluorescence microscopy

Author： Piccinini Massimo Nichelatti Enrico Ampollini Alessandro Picardi Luigi Ronsivalle Concetta Bonfigli Francesca Libera Stefano Vincenti Maria Aurora Montereali Rosa Maria

Publisher： Edp Sciences

E-ISSN： 1286-4854|117|3|37004-37004

ISSN： 0295-5075

Source： EPL (EUROPHYSICS LETTERS), Vol.117, Iss.3, 2017-03, pp. : 37004-37004

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Abstract

With the purpose of studying the behavior of novel solid-state lithium fluoride (LiF) films detectors based on the photoluminescence (PL) of radiation-induced defects for proton beam diagnostics and dosimetry, polycrystalline LiF thin films thermally evaporated on glass were irradiated at room temperature in a linear proton accelerator under development at ENEA. The irradiations were performed in air by proton beams of 3 and 7 MeV energy, in a fluence range from 10¹¹ to 10¹⁵ protons/cm². In the LiF films, proton irradiation induces the formation of F₂ and $\text{F}_{3}^{+}$ aggregate color centers, which simultaneously emit broad PL bands in the visible spectral range under excitation in the blue one. The integrated PL signal, acquired by a fluorescence microscope equipped with a s-CMOS camera, shows a linear dependence on the dose deposited in LiF films, extending from 10³ to 10⁶ Gy, independently of the proton energy. A simple theoretical model is put forward for the formation of color centers in LiF and is utilized to obtain a proton beam dose-map by processing the PL image stored in the LiF film detectors.