PSI - Issue 79

George Papageorgiou et al. / Procedia Structural Integrity 79 (2026) 138–145

139

Keywords: Single crystals; (Lu,Y) 2 SiO 5 :Ce; LYSO:Ce; Lu 2 SiO 5 :Ce; LSO:Ce; Gd ₂ SiO ₅ :Ce; GSO:Ce; Thermal behavior; extreme environments; medical imaging

1. Introduction Cerium doped, single crystal scintillators, are widely used in imaging applications, including medical or high energy physics detectors, since they have high luminescence efficiency (LE) and most of them, very fast response [1]. These applications often involve extreme environmental conditions where temperature can significantly influence the performance of the scintillator [2]. Therefore, the effect of temperature on the light output signal of single crystal scintillators is crucial for ensuring their reliability and optimal functionality in practical scenarios. The Lutetium Yttrium Oxyorthosilicate ((Lu,Y) 2 SiO 5 :Ce or LYSO:Ce) has emerged as an alternative to the commercial Lutetium Oxyorthosilicate (Lu 2 SiO 5 :Ce or LSO:Ce). LYSO:Ce offers several distinct advantages, since the introduction of Yttrium in the host lattice reduces the cost of the material, while maintaining most of the internal properties of LSO:Ce, as can be depicted from Table 1 [3]. Another Cerium doped single crystal scintillator is the Gadolinium Orthosilicate (Gd ₂ SiO ₅ :Ce or GSO:Ce) which is commonly employed in imaging applications due to the significantly lower cost, compared to the Lutetium based crystals, however at the expense of the much lower luminescence efficiency. Furthermore, GSO:Ce has excellent radiation resistance, thus taking also into consideration its low cost, GSO:Ce is a practical choice for applications where budget constraints predominate over performance [2]. The study aims to examine the luminescence efficiency (LE) of three commercially available Cerium-doped single crystal scintillators (LSO:Ce, LYSO:Ce and GSO:Ce) under the influence of X-rays and external heating in order to simulate practical operational environmental conditions. Such comparative analysis aims to provide insights into the relative variation of the performance of these materials, under temperature variations and highlight the potential advantages for various applications. 2. Materials and Methods 2.1. Scintillator properties Table 1 shows the properties of the three examined 10X10X10mm LSO:Ce, LYSO:Ce and GSO:Ce single crystals.

Table 1. LSO:Ce, LYSO:Ce and GSO:Ce scintillator properties.

Properties

Units

(Lu,Y) 2 SiO 5 :Ce

Lu 2 SiO 5 :Ce

Gd ₂ SiO ₅ :Ce

Density

g/cm³

7.15 [4,5]

7.4 [6]

6.7 [7]

Atomic number (effective)

65 [8]

66 [9]

58 [7]

Decay time

ns

30-50 [4,6]

40 [5]

30-60 [5]

Light yield

photons/MeV

2.6-3.0 ∙ 10 4 [4,6,10]

2.6-3.3 ∙ 10 4 [5,11]

8-12 ∙ 10 3 [7,12]

Energy resolution

FWHM@662 keV

7-9 % [4,6]

7-8 % [5]

10-13 % [13]

Melting point

°C

2070 [14]

2150 [15]

1900 [12]

Coefficient of thermal expansion Mineral hardness

°C -1

7 ∙ 10 - ⁶ [14]

5-11 ∙ 10 - ⁶ [15]

4-12 ∙ 10 - ⁶ [12]

Mho

5.8 [14]

5.8 [16]

5.7 [12]

Maximum of emission

nm

420 [6,10]

420 [11]

430 [12]

Hygroscopic

No [10]

No [16]

No [12]