http://dspace.nbuv.gov.ua:80/handle/123456789/132702 2026-04-19T08:12:19Z http://dspace.nbuv.gov.ua:80/handle/123456789/140211 The influence of BaF₂ on scintillation properties of PbWO₄ crystal Youbao Wan; Jianxing Zhang; Rurong Wu; Sanfa Xing; Hui Yang PbWO₄ crystals doped with BaF₂ was grown up by using modified temperature-grads technique. The crystal defects were investigated by chemical etching. The XRD of the sample has shown that the peaks were at normal sites, but the lattice parameters was slightly larger than that of pure PbWO₄ crystal. The transmittance spectrum along c axis of the PbWO₄:BaF₂ crystal has evidenced a higher transmittance than that of pure PbWO4 crystal. The luminescence intensity of the 400-450 nm peak in X-ray excited luminescence spectrum of the PbWO₄:BaF₂ crystal is increased significantly, about twice than that of pure PbWO₄ crystal. The light yield of BaF₂ doped PbWO₄ crystal was enhanced up to 2.5 times. These results show that BaF₂ doping of PbWO₄ can improve scintillation properties of the crystal for medium-energy particle detection. 2007-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/137215 Nanoscale Co/C multilayers for "carbon window" Schwarzchild objective Bugayev, Ye.A.; Devizenko, A.Yu.; Zubarev, E.N.; Kondratenko, V.V. The formation features of the Co/C multilayer with ≈2.3 nm period have been studied with aim to form a Schwarzschild objective on a "carbon window" for medical and biological investigations. A sequence of multilayer deposition on curved substrates has been proposed that provides the matched functioning of both objective mirrors. The interaction features of the Co and C layers during deposition, period and reflectivity changes under heating have been considered. 2007-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/136976 Optical properties of LiNbO₃:Zn and LiNbO₃:Zn:Nd fiber single crystals grown by micro-pulling down method H.J. Lee; J.W. Shur; O. Nakamura; D.H. Yoon The present interest in small compact diode pumped lasers has supported research on new solid state laser systems based on non-linear crystals. High quality LiNbO₃ fiber single crystals were grown by micro-pulling down method. It was found indirectly from the optical properties of the LiNbO₃ fiber single crystals that doping those with ZnO increases their photorefractive resistance. In addition, photoluminescence properties due to the addition of Nd₂O₃ dopant have been investigated. 2007-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/136974 Nonlinear spin waves in antiferromagnets with unixial magnetic anysotropy in a magnetic field Gorobets, O.Yu. It was shown in this paper that nonlinear spin waves can propagate in antiferromagnets with uniaxial magnetic anisotropy in an external magnetic field. The nonlinear waves are characterized by simultaneous oscillations of great amplitude of polar and azimuth angles of antiferromagnetism vector. It means that nonlinear wave can propagate being the exact dynamic 3D solution of Landau-Lifshitz equations in antiferromagnet. The dispersion of polar and azimuth angle oscillations are found for antiferromagnetism vector. In particular, the dispersion for oscillation of azimuth angle in a long wavelength approximation coinsides with known spin wave dispersion in antiferromagnet when the polar angle is constant. Besides, the new type of spin waves obtained in this work is characterized by possibility to form front structure at the wide class of 2D harmonic functions, possibility of two-frequency and amplitude modulation. 2007-01-01T00:00:00Z