Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

You searched for subject:(Samarium doped glass). One record found.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters

1. Vahedi, Shahrzad. Optical and thermal properties of samarium-doped fluorophosphate and fluoroaluminate glasses for high-dose, high-resolution dosimetry applications.

Degree: 2014, University of Saskatchewan

Microbeam radiation therapy (MRT) is an experimental form of radiation treatment which causes less damage to normal tissue in comparison with customary broad-beam radiation treatment. In this method the synchrotron generated X-ray beam is passed through a multislit collimator and applied to the tumor in the form of an array of planar microbeams. MRT dosimetry is an extremely challenging task and no current detector can provide the required wide dynamic rang and high spatial resolution. In this thesis, fluorophosphate (FP) and fluoroaluminate (FA) glass plates doped with trivalent samarium (Sm3+) are characterized towards developing a potential X-ray detector suitable for MRT dosimetry. The detection is based on the difference in the photoluminescence signatures of Sm3+ ions and Sm2+ ions; the latter are formed under X-ray irradiation. This valency conversion is accompanied by the formation of defects including hole centers (HCs) and electron centers (ECs) in the glass structure which absorb light in the UV and visible regions (induced absorbance). Both FP and FA glasses show promising dynamic range for MRT and may be used as a linear sensor up to ~150 Gy and as a nonlinear sensor up to ∼2400 Gy, where saturation is reached. X-ray induced defects saturate at the same dose. The optimum doping concentration is in the 0.001˗ 0.2 at.% range. Doping with higher concentrations will decrease the conversion efficiency. The glass plates also show a very promising spatial resolution (as high as a few microns) for recording the dose profile of microbeams which is readout using a confocal fluorescence microscopy technique. These plates are restorable as well and the response is reproducible. The effects of previous X-ray exposure including samarium valency conversion as well as induced absorbance may be erased by annealing at temperatures exceeding the glass transition temperature Tg while annealing at TA < Tg enhances the response. This enhancement is explained by a thermally stimulated relaxation of host glass ionic matrix surrounding X-ray induced Sm2+ ions. Optical erasure is another practical means to erase the recorded data. Nearly complete Sm2+ to Sm3+ reconversion (erasure) is achieved by intense optical illumination at 405 nm. While, existing X-ray induced bands would be only partially erased. Electron spin resonance (ESR) and optical absorbance spectroscopy are used to investigate the nature of X-ray induced defects and their correlation with Sm valency conversion. A model based on competition between defect center formation and the Sm3+ ⇆ Sm2+ conversion successfully explains the different processes occurring in the glass matrix under X-ray irradiation. Advisors/Committee Members: Kasap, Safa, Chapman, Dean, Chen, Li, Zhang, Chris, Bui, Francis, Yang, Qiaoqin.

Subjects/Keywords: Samarium-doped glass; Fluorophosphate glass; Fluoroaluminate glass; Valency conversion; Dosimetry; Microbeam radiation therapy (MRT); X-ray induced defects

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Vahedi, S. (2014). Optical and thermal properties of samarium-doped fluorophosphate and fluoroaluminate glasses for high-dose, high-resolution dosimetry applications. (Thesis). University of Saskatchewan. Retrieved from http://hdl.handle.net/10388/ETD-2014-10-1780

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Vahedi, Shahrzad. “Optical and thermal properties of samarium-doped fluorophosphate and fluoroaluminate glasses for high-dose, high-resolution dosimetry applications.” 2014. Thesis, University of Saskatchewan. Accessed October 18, 2019. http://hdl.handle.net/10388/ETD-2014-10-1780.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Vahedi, Shahrzad. “Optical and thermal properties of samarium-doped fluorophosphate and fluoroaluminate glasses for high-dose, high-resolution dosimetry applications.” 2014. Web. 18 Oct 2019.

Vancouver:

Vahedi S. Optical and thermal properties of samarium-doped fluorophosphate and fluoroaluminate glasses for high-dose, high-resolution dosimetry applications. [Internet] [Thesis]. University of Saskatchewan; 2014. [cited 2019 Oct 18]. Available from: http://hdl.handle.net/10388/ETD-2014-10-1780.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Vahedi S. Optical and thermal properties of samarium-doped fluorophosphate and fluoroaluminate glasses for high-dose, high-resolution dosimetry applications. [Thesis]. University of Saskatchewan; 2014. Available from: http://hdl.handle.net/10388/ETD-2014-10-1780

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.