Photoluminescence nonlinearity and picosecond transient absorption in an LYSO:Ce scintillator excited by a 266 nm ultraviolet laser.

Kun Wei,Quan Guo,Dongwei Hei,Qing Xu,Xinjian Tan,Xiufeng Weng,Jun Liu,Liang Sheng

doi:10.1039/d1ra00347j

Kun Wei, Quan Guo + Show 6 more

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https://doi.org/10.1039/d1ra00347j

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Abstract

Lutetium–yttrium oxyorthosilicate doped with cerium (LYSO:Ce) is a widely used scintillator, and the study of its nonlinear behavior under high excitation density is very significant owing to its direct influence on radiation measurements. Using a 266 nm ultraviolet laser to excite an LYSO:Ce crystal, the relationship between the photoluminescence (PL) light yield and excitation density was studied by Z scan experiments. The excitation threshold of the LYSO:Ce was obtained, which is about 2.3 J cm−3. Picosecond transient absorption of LYSO:Ce at 800 nm was obtained and used to analyze the dynamic process of carriers. The physical mechanism behind the nonlinearity was discussed and analyzed using the Förster dipole–dipole interaction model, and the interaction characteristic radius was obtained by fitting. This work can help us understand the nonlinearity phenomenon in scintillators and provide references for related radiation detection applications.

Highlights

Scintillators are widely used to detect g/X-rays and charged particles
We studied the relationship between photoluminescence yield of Lutetium–yttrium oxyorthosilicate doped with cerium (LYSO):Ce and excitation uence with 266 nm ultraviolet laser excitation by Z scan experiments
The experiment results show that the nonlinear response of LYSO:Ce crystal increases with laser excitation uence

Summary

Introduction

Scintillators are widely used to detect g/X-rays and charged particles. It is known that the light yield of scintillators is not always completely proportional to the absorbed energy, and the deviation between light yield and absorbed energy is called nonlinearity or nonproportionality.[1,2,3] Recently, high peak brightness sources such as free electron lasers (FELs) and laser Compton scattering sources (LCSs) have been developed and applied in different elds. The nonlinearity of scintillators under high excitation density brings new challenges to accurate radiation measurements. Studying this effect is helpful for the accurate diagnosis of source parameters and relevant applications.[4,5,6] As an ideal means, ultraviolet laser photoexcitation can be used to quantitatively study the nonlinearity of scintillator crystals.[7,8,9] In this paper, the nonlinearity of an LYSO:Ce scintillator excited by an ultraviolet laser at high excitation uence was studied. Picosecond transient absorption of LYSO:Ce at 800 nm was obtained by pump–probe experiments and used to analyze the dynamic process of carriers

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