luag mineral (Lutetium Aluminium Garnet) is a very promising host material for the creation of composite scintillators, because it is well known for its high r and Z values, and its high light absorption coefficient. In particular, the LuAG garnet host has a higher value compared to other materials, such as YAG, for example r = 6.7 g/cm3 and Zeff = 61, which are corresponding to its superior scintillation properties [20, 21].
Several types of epitaxial structures were successfully grown by using LPE on LuAG:Pr SCF substrates and on LuAG:Pr SCF/LuAG:Sc SC composite scintillators. These epitaxial structures were characterized for their structural, content and absorption properties as well as cathodoluminescence and scintillation properties.
The CL spectra of LuAG:Pr SCF and LuAG:Pr SCF/LuAG:ScSC epitaxial structures (Figure 4, curves 2 and 3) exhibit two intensive UV emission bands peaked at 309 and 379 nm, which are correlated with the 5d1- 4f(3H4-6, 3H5, 4F2; 1G4) transitions of Pr3+ ions. In LuAG:Pr SCF/LuAG:ScSC, these sharp Pr3+ emission bands overlap with a wide band of defect centers in LuAG:Sc substrate peaked at 595 nm, which may be related to the luminescence of dimer or more complex charged oxygen vacancies with one or two trapped electrons.
The variation of LYs on the epitaxial structure a1 and on the a2 LuAG:Pr SCF/LuAG:ScSC composite scintillators under a-particles excitation with 241Am source (Figure 5a) is consistent with their variation under g-rays excitation with 239Pu source (Table 1). Under a-particles excitation, the maximal LY maxima for both samples are reached already at the 0.5-10 ms shaping time, while, in the case of g-rays excitation, the LY maximum of 7819 ph/MeV is reached already at the 0.15-0.10 ms shaping time (Figure 6a and b).