Browsing by Subject "crystals"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Nanocomposites for low dose gamma-ray sensor: Effect of matrix and oxidizer on the performance(SPIE, 2019-05-14) Dayal, Vishall; Singh, Narsingh Bahadur; Su, Ching Hua; Gill, Puneet; Lee, Brit; Choa, Fow-Sen; Arnold, Bradley; Kelly, Lisa; Cullum, BrianSynthesis and crystal growth of scintillators and semiconductor materials for radiation detectors have been proven to be time consuming and very costly. Several alternative crystals such as Tl3ASSe3, TlGaSe2, Tl4HgI6, PbSe(1-x)Ix have developed in our laboratory. These heavy metal and high Z based compounds have shown great promise. We have been working on some innovative approaches based on Cerenkov radiation and nanocomposites of ionizing organics for faster and efficient sensors. By combining some metallic oxides with an organic material, it should be possible to both extend the energy range of particles capable of being detected while also providing more discrimination for high energy gamma-rays, based on local secondary effects in the surrounding organic matrix. We have been working with a highly ionizing organic compound p-chloranil (2,3,5,6-Tetrachloro-1,4-benzoquinone) matrix. In addition, we have determined effect of oxidizing compounds MnO2 on urea-based composites. We use metal oxide as active ingredient in this matrix. We will present effect of morphology and processing on the performance of nanocomposite for sensing gamma-rays.Item Optical characteristics of novel bulk and nanoengineered laser host materials(SPIE, 2018-02-23) Prasad, Narasimha S.; Sova, Stacey; Kelly, Lisa; Bevan, Talon; Arnold, Bradley; Cooper, Christopher; Choa, Fow-Sen; Singh, N. B.The hexagonal apatite single crystals have been investigated for their applications as laser host materials. Czochralksi and flux growth methods have been utilized to obtain single crystals. For low temperature processing (<100 ⁰C), several techniques for crystal growth have been developed. The hexagonal apatite structure (space group P⁶3/m) is characteristic of several compounds, some of which have extremely interesting and useful properties as laser hosts and bone materials. Calcium lanthanum silicate (Nd-doped) and lanthanum aluminate material systems were studied in detail. Nanoengineered calcium and lanthanum based silicates were synthesized by a solution method and their optical and morphological characteristics were compared with Czochralski grown bulk hydroxyapatite single crystals. Materials were evaluated by absorbance, fluorescence and Raman characteristics. Neodymium, iron and chromium doped crystals grown by a solution method showed weak but similar optical properties to that of Czochralski grown single crystals.