1,721,063 research outputs found
Elastic moduli and optical properties of LYSO crystals: theory and experiments.
Full text linkAbstract—In order to obtain a complete characterization and
understanding of the structural, optical andmechanical properties of LYSO scintillanting crystals, we studied a mechanical, optical and photoelastic model for a cylindrical prism of square cross-section bent by applied loads. This is the starting point which is necessary in order to design a set ofmechanical, electrical and optical experiments aimed to obtain the characterization of the macroscopical behavior of LYSO and similar crystals
Bertin surfaces and residual stress analysis in scintillating crystals
No full textScintillating crystals are employed in high-energy physics, in medical imaging, diagnostic and security because they are capable to convert gamma-rays and in general high-energy particles into light. The effectiveness of the crystal and the light production can be severely affected by the presence of defects or residual stresses generated by the crystal growth process. Photoelastic analysis is one of the most used investigation techniques for crystal properties characterization: here we present a detailed analysis of the residual stress in PWO which is based on the results obtained elsewhere by the Authors
PHOTOELASTICIMETRY FOR THE INSPECTION OF MECHANICAL STRESSES IN BIREFRINGENT MONOAXIAL CRYSTALS. APPLICATION TO PbWO4
No full textMechanical and optical properties of anisotropic single-crystal prisms.
No full textThe great interest in scintillating crystals, is related to their applications in the high energy physics, biomedicine and security. For this reason a complete characterization and understanding of their structural, optical and mechanical properties at the macroscopic level is necessary. We must give a complete theoretical characterization of the mechanics and optics of bulk prismatic single-crystal bodies in order to design experiments. This work shall deal solely with the theoretical description within the framework of linear theories
Isochromate fringes simulation by Cassini-like curves for photoelastic analysis of birefringent crystals
No full textIn optically birefringent uniaxial and biaxial crystals, analyzed by plane polariscope, isochromate
interference fringes can be observed. By means of the classical electromagnetic theory a Cassini-like
analytical equation of the isochromate fringes, depending on the refraction indexes, has been obtained.
The proposed analytical equation is a useful tool to evaluate the internal stress state, as it is related to
the isochromate shapes owing to the induced variation of the refraction indexes. Uniaxial crystals can
assume complex biaxial behaviour due to particular stress configurations. PbWO4 (PWO) uniaxial
scintillating crystals have been studied. The Cassini-like curves fit well experimental measurements in
the case of uniaxial stress. In this research work, a simple model has been proved in the case of strong
isochromate fringes distortion due to a stress gradient induced by the bending load. The model fits well
the interference pattern, acquired experimentally. This study can pave the way for the quality control on
scintillating crystals, used in the fields of high-energy detectors, security and biomedical applications,
with complex internal stress state
Theoretical Basis for the Photoelastic Residual Stress Evaluation in Misaligned Cubic Crystals
Full text linkPhotoelasticity is a fast and powerful technique for internal stress detection and quality control in crystals; to fully exploit its possibilities, an appropriate theoretical analysis must be devel- oped for different crystallographic structure and observation planes. For a cubic crystal specimen whose geometry is non-coherent with its crystallographic directions (i.e., observation planes and crystallographic directions are not parallel), we write a set of equations that allow an estimate of the refraction indices as a function of the residual stress. This is obtained upon the assumption that the residual stress may be represented by a plane stress parallel to the observation face. For cubic crystals, we obtain an explicit estimate of the residual stress intensity; this can be achieved provided we know the piezo-optic tensor component, the orientation of two non-parallel specimen faces with respect to the crystallographic axes, and that we can measure the principal directions of the refractive indices on the observation face
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