http://nopr.niscair.res.in/handle/123456789/2464 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/2529 Title: Effect of ϒ-irradiation on polyvinyl alcohol films doped with some dyes and their use in dosimetric studies <br/> <br/>Authors: Bhat, N V; Nate, M M; Bhat, R M; Bhatt, B C <br/> <br/>Abstract: Using polyvinyl alcohol (PVA), water-soluble polymer, thin films were prepared by incorporating some dyes. On subjecting these films to ϒ-radiation, it was found that there is a gradual change in the colour. In case of PVA film containing methyl red sudden discolouration occurs at a dose of 30 kGy, however, optical density change was not very contrasting. In case of acid red-4, there is a gradual fading of the red colour in the dose range 10-55 kGy. The PVA film (control) without dye shows development of brownish shade. These changes can be explained in terms of scission of main chain, liberation of the H and OH radicals and their interactions with the dye molecules. It is shown that these films can be used as cheap, portable and reliable plastic detectors for dosimetry. <br/> <br/>Page(s): 545-548 Tue, 29 May 2007 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2528 Title: Sensitivity analysis of reflector types and impurities in 10 MW MTR type nuclear research reactor <br/> <br/>Authors: Khattab, K; Khamis, I <br/> <br/>Abstract: The 2-D and 3-D neutronics models for 10 MW nuclear research reactor of MTR type have been developed and presented in this paper. Our results agree very well with the results of seven countries mentioned in the IAEA-TECDOC-233. To study the effect of reflector types on the reactor effective multiplication factor, five types of reflectors such as pure beryllium, beryllium, heavy water, carbon and water are selected for this study. The pure beryllium is found to be the most efficient reflector in this group. The effect of the most important impurities, which exist on the beryllium reflector such as iron, silicon and aluminium on the reactor multiplication factor, have been analyzed as well. It is found that the iron impurity affects the reactor multiplication factor the most compared to silicon and aluminium impurities. <br/> <br/>Page(s): 491-495 Tue, 29 May 2007 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2525 Title: Growth, optical and thermal studies of L-arginine perchlorate—A promising non-linear optical single crystal <br/> <br/>Authors: Aruna, S; Anuradha, A; Thomas, Preema C; Mohamed, M Gulam; Rajasekar, S A; Vimalan, M; Mani, G; Sagayaraj, P <br/> <br/>Abstract: Optically good quality single crystal of L-arginine perchlorate (abbreviated as LARPCL), a promising analog of LAP was successfully grown by slow solvent evaporation technique at room temperature. The grown crystals were characterized by single crystal XRD, FTIR, FT-Raman, optical absorption and SEM studies. The thermal stability of the crystal was studied by TG, DTA and DSC analysis. The scanning electron microscopy (SEM) provides information about the surface morphology of the sample. The SHG efficiency is estimated using Kurtz powder method. <br/> <br/>Page(s): 524-528 Tue, 29 May 2007 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2521 Title: Effect of doping on stimulated Brillouin scattering in piezoelectric magnetized III-V semiconductors <br/> <br/>Authors: Singh, Manjeet; Aghamkar, Praveen; Sen, P K <br/> <br/>Abstract: Using the hydrodynamic model of a semiconductor-plasma and following the coupled mode approach, an analytical investigation has been made for stimulated Brillouin scattering (SBS) resulting from the nonlinear interaction of an intense pump beam with acoustic perturbations internally generated due to piezoelectric and electrostrictive property of the crystal. The analysis deals with the qualitative behaviour of threshold pump electric field for the onset of SBS and resulting gain coefficient with respect to doping concentration (through plasma frequency) in piezoelectric III-V semiconductors subjected to transverse magnetostatic field. The numerical estimates are made for n-type InSb crystal at 77 K duly shined by pulsed 10.6 μm CO₂ laser. The threshold value of pump field required for the onset of SBS is found to lower in the presence of magnetostatic field. At resonance, the Brillouin gain is two hundred and 10⁴ times in the presence of piezoelectricity and magnetostatic field, respectively, than in their absence. Moreover, the SBS gain coefficient increases with increasing in scattering angle and results in maximum value for the backscattered mode. The backward Brillouin gain is found to be 10⁴ times larger than the forward gain. The analysis also suggests the possibility of observing phase conjugation reflectivity as high as ~10⁶ in weakly piezoelectric doped III-V semiconductors subjected to a magnetic field. <br/> <br/>Page(s): 517-523 Tue, 29 May 2007 22:58:59 GMT