Effect of Majorana Phases in Neutrino Oscillation

Quantum gravity (Planck scale effects) lead to an effective SU(2) _L ×U(1) invariant dimension-5 Lagrangian involving neutrino and Higgs fields. On symmetry breaking, this operator gives rise to correction to the above masses and mixing. The gravitational interaction M _X =M _pl , we find that for degenerate neutrino mass spectrum, it is shown that the Majorana phase of the neutrino mixing matrix can effects in neutrino oscillation probability.     

Three Flavor Neutrino Mixing and Dark Energy Above GUT Scale

Neutrino mixing lead to a non zero contribution to the dark energy of the universe. We assume that the neutrino masses and mixing arise through physics at a scale intermediate between Planck Scale and the electroweak scale. The mechanism of neutrino mixing is a possible candidate to contribute the cosmological dark energy. Quantum gravitational (Planck scale) effects lead to an effective SU(2) _L ×U(1) invariant dimension-5 Lagrangian involving neutrino and Higgs fields, which gives rise to additional terms in neutrino mass matrix. There additional term can be considered to be perturbation of the GUT scale bi-maximal neutrino mass matrix. We assume that the gravitational interaction is flavor. In this paper, we discuss the three flavor neutrino mixing and cosmological dark energy contributes due to Planck scale effects.     

Inverted equations of state for solids under high pressures

In the present communication we have reviewed some inverted type equations of state for solids under high pressures. An inverted equation of state (EOS) gives volume as a function of pressure for a solid under isothermal conditions. We have considered various equations of state proposed by earlier workers which express volume as a function of pressure. Expressions for bulk modulus and its pressure derivatives based on such EOSs are obtained and reported here. It is emphasized here that the high pressure derivative properties are very sensitive to the forms of equations of state representing volume-pressure relationships. We have also studied the thermoelastic properties of solids based on pressure derivatives of bulk modulus. Applications have been extended in the present review article to the solids which are metals as well as non-metals including geophysical minerals present in the lower mantle and core of the Earth.     

Study of Compton scattering of gamma rays from atomic electrons

In the present work, measurements are made on the intensity and angular distribution of Compton scattered gamma rays of energy 279 keV from K-shell electrons of tin at scattering angles ranging from 30° to 150° and also determined the K-shell to free electron differential collision, absorption and scattering cross section ratio. For this purpose, two NaI(Tl) scintillation detectors working in coincidence with 30 nsec resolving time are used to record the events. The experimental results are compared with the available experimental and theoretical data.     

Electron scattering with open-shell molecules: R-matrix method

Many molecules with an even number of electrons belong to open-shell systems due to π ² ground state electronic configuration. This configuration gives rise to three low-lying states X ³ Σ ⁻, a Δ ¹ and b ¹ Σ ⁺. The inclusion of these target states in a trial wave function of the entire scattering system have important implications in the resonances that may be detected in these open-shell molecules. Various molecules like O₂, PX (X = H and halogens), SO, Si₂, BF have π ² ground state configuration. The R-matrix method is a well established ab initio formalism to calculate differential, integral and momentum-transfer cross sections for the elastic scattering of electrons by molecules. We have calculated these cross sections for PH and SO molecules in the incident electron energy range 0–10 eV. The results are obtained by using the R-matrix method in which the closecoupling expansion of the wave function of the scattering system includes only the ground state. This target state is described by configuration interaction wave function that includes correlation effects. The cross section for electron impact on PH and SO are presented.     

Effect of finite chemical potential on QGP-Hadron phase transition in a statistical model of fireball formation

We study the effect of finite chemical potential for the QGP constituents in the Ramanathan et al. statistical model [Phys. Rev. C70, 027903, (2004)]. While the earlier computations using this model with vanishing chemical potentials indicated a weakly first order phase transition for the system in the vicinity of 170 MeV [Pramana 68 757 (2007)], the introduction of finite values for the chemical potentials of the constituents makes the transition a smooth roll over of the phases, while allowing fireball formation with radius of a few ‘fermi’ to take place. This seems to be in conformity with the latest consensus on the nature of the QGP-Hadron phase transition.     

CPT Violating Neutrino Oscillation Under Planck Scale Effects

We give a phenomenological model of CPT violating neutrino oscillation above the GUT scale. In this paper, we consider the effect of Planck scale operators on neutrino mixing. We assume that the main part of neutrino masses and mixing arise through GUT scale operators The dispersion relation for the CPT violating neutrino and anti-neutrino oscillation are discussed.     

NIR to visible upconversion in Er/Yb co-doped CaYAl3O7 phosphor obtained by solution combustion process

Using the combustion synthesis, CaYAl₃O₇:Er³⁺ phosphor powders co-doped with Yb³⁺ have been prepared at low temperatures (550 °C) in a few minutes. Formation of the compound was confirmed by X-ray powder diffraction. Near-infrared to visible upconversion fluorescence emission in the Er³⁺ doped CaYAl₃O₇ phosphor powder has been observed. The effect of co-doping with triply ionized ytterbium in the CaYAl₃O₇:Er³⁺ phosphor has been studied and the process involved is discussed.     

Synthesis and characterization of thermoluminescent Li2B4O7 nanophosphor

Lithium borate (Li₂B₄O₇) is a low Z_eff, tissue equivalent material that is commonly used for medical dosimetry using the thermoluminescence (TL) technique. Nanocrystals of lithium borate were synthesized by the combustion method for the first time in the laboratory. TL characteristics of the synthesized material were studied and compared with those of commercially available microcrystalline Li₂B₄O₇. The optimum pre-irradiation annealing condition was found to be 300 °C for 10 min and that of post-irradiation annealing was 300 °C for 30 min. The synthesized Li₂B₄O₇ nanophosphor has very poor sensitivity for low doses of gamma up to 10¹ Gy whereas from 10¹ to 4.5×10² Gy this phosphor exhibits a linear response and then from 4.5×10² to 10³ Gy it shows supralinearity. Thermoluminescence properties of Li₂B₄O₇ nanophosphor doped with Cu has also been investigated in this paper. It shows low fading and a linear response over a wide range of gamma radiation from 1×10² to 5×10³ Gy. Therefore the synthesized lithium borate nanophosphor doped with Cu may be used for high dose measurements of gamma radiations.     

Electronic and optical properties of defect chalcopyrite HgAl2Se4

The structural, electronic and optical properties of HgAl₂Se₄ are investigated using the full potential linear augmented plane wave method based on density functional theory. The calculated structural parameters using LDA are in excellent agreement with the available experimental result. The obtained energy band gap (2.24 eV) using EV-GGA approximation is in excellent agreement with experimental data (2.20 eV). Variation in the energy band gap as a function of the unit cell lattice parameter has been studied. The optical properties show a considerable anisotropy, which makes this compound very useful for various linear–nonlinear optical devices.