Optical Characteristics of Gamma-Radiated Polymeric Scintillators

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Optical Characteristics of Gamma-Radiated Polymeric Scintillators S. V. Afanaseva, A. Yu. Boyarintsevb, I. A. Golutvina, E. M. Ibragimovac, A. I. Malakhova, I. Nuritdinovc,*, V. A. Smirnova, M. Yu. Tashmetovc, B. S. Yuldashevc, and Z. U. Esanovc a The

Joint Institute for Nuclear Research, Dubna, Moscow oblast, 141980 Russia for Scintillation Materials, National Academy of Sciences of Ukraine, Kharkov, 61000 Ukraine c Institute of Nuclear Physics, Academy of Sciences of Uzbekistan, Tashkent, 100214 Uzbekistan *e-mail: [email protected]

b Institute

Received April 29, 2019; revised April 29, 2020; accepted May 4, 2020

The effect of the dose rate from 0.00022 to 0.0032 MGy/h and the radiation dose of 0.043 and 0.2 MGy of the 60Co gamma source, as well as of oxidative conditions on the optical transmission and absorption spectra of plastic scintillators of the BC-408 (Bicron, USA), UPS-923A (Amcrys-H, Ukraine), and LHE (JINR, Russia) brands has been investigated at 300 K. It has been shown that the optical transmission of scintillators in the range of 400–850 nm decreases when increasing radiation dose. There was no noticeable effect of adsorbed oxygen on the induced optical losses under these conditions. DOI: 10.1134/S0030400X20090271

INTRODUCTION Polymer scintillators are widely used in various experiments as particle detectors. These scintillators are easier to manufacture, have good sensitivity and performance, and are also relatively cheap (see, e.g., [1]). Nevertheless, the optical properties of scintillators gradually deteriorate under the influence of ionizing radiation and, thus, its light output decreases [1]. In the experiments that are conducted, e.g., on colliders, high luminosities are required, i.e., the detectors using scintillators should withstand high radiation doses (e.g., from 0.01 to 0.1 MGy per year for 10 years). Thus, there is a need to find such polymer scintillators that can withstand the effects of large particle fluxes and high radiation doses without significantly impairing their optical properties. Some studies of the effect of gamma radiation on various characteristics of scintillators were conducted earlier (see, e.g., [2–10]). Thus, it is assumed in [2, 3] that, the degradation of the light flux will be the same as that at lower doses as a result of exposure to gamma radiation at relatively high doses (0.005 MGy/h or higher). The authors of [4] question this assumption, considering that the degradation of the mechanical properties of polymer scintillators depends on the radiation dose. Some researchers indicate a strong dependence of the light output of scintillators on dose rate [1, 5–7], which explain by the occurrence of oxygen in the volume of scintillators under irradiation: they assume that more efficient formation of stable color centers occurs (not annealed over time) in the presence of dissolved oxygen in the polymer scintilla-

tors, while others argue that there is no significant dependence on the dose rate [8]. Thus, to date, there is no u