Gamma rays from dark matter annihilation in the Draco and observability at ARGO

The CACTUS experiment recently observed a gamma ray excess above 50 GeV from the direction of the Draco dwarf spheroidal galaxy. Considering that Draco is dark matter dominated, the gamma rays may be generated through dark matter annihilation in the Draco halo. In the framework of the minimal supersymmetric extension of the standard model we explore the parameter space to account for the gamma ray signals at CACTUS. We find that the neutralino mass is constrained to be approximately in the range between 100 GeV∼400 GeV and a sharp central cuspy of the dark halo profile in Draco is necessary to explain the CACTUS results. We then discuss further constraints on the supersymmetric parameter space by observations at the ground-based ARGO detector. It is found that the parameter space can be strongly constrained by ARGO if no excess from Draco is observed above 100 GeV.     

Collective bands in 104,106,108Mo

We have used our analysis of γ-γ-γ data (5.7 × 10¹¹ triples and higher folds) taken with Gammasphere from prompt γ rays emitted in the spontaneous fission of ²⁵²Cf to study the collective bands in ^104,106,108Mo. The one-phonon and two-phonon γ-vibrational bands and known two-quasiparticle bands in neutron-rich ^104,106Mo were extended to higher spins. The one-and two-phonon γ-vibrational bands have remarkably close energies for transitions from the same spin states and identical moments of inertia. Several new bands are observed and are proposed as quasiparticle bands in ^104,106Mo, along with the first β-type vibrational band in ¹⁰⁶Mo. The quasiparticle bands have essentially constant moments of inertia near the rigid-body value that indicate blocking of the pairing interaction. Candidates for chiral doublet bands in ¹⁰⁶Mo are strong. These are the first reported chiral vibrational bands in an even-even nucleus. The text was submitted by the authors in English.     

On the Formation of Nanostructures from Stilbazolium-like Dyes

Nanostructures with well-defined shape and highly monodisperse size were fabricated from model stilbazolium-like dyes with specific molecular structural and conformational characteristics. With the help of absorption and fluorescence optical spectroscopy, the correlated spectroscopy (COSY) and two- dimensional nuclear Overhauser effect spectroscopy (2D NOESY) techniques, along with X-ray diffraction (XRD) measurement, distinctively different aggregation processes of the model molecules are demonstrated. For model dye molecule with linear donor–π system–acceptor (D–π–A) structure, strong D–A pair, and planar conformation, specific intermolecular interaction was identified and special crystal structures as well as spectral properties were observed. For model dye molecules bearing nonlinear D–π–A–π–D structure, weak D–A pair but actual amphiphilic characteristics, a special aggregation process was confirmed and a focused size distribution of the produced nanostructures was obtained.     

Separate Polarization Modes Synchronization and Synchronization Switches between Vertical-Cavity Surface-Emitting Lasers

For vertical-cavity surface-emitting lasers (VCSELs) with polarization-rotated feedback, there exist several synchronization types such as synchronizations between total powers and synchronizations between separate polarization modes. Based on the two-mode rate equations, we study and compare numerically the performances of different synchronization types. Our results show that three synchronization types exhibit good performances when their synchronization conditions are satisfied. They are the complete synchronization between total powers, complete synchronization between x-polarized modes, and generalized synchronization between x-polarized and y-polarized modes. The former two types are sensitive to the injection rate and spontaneous emission, while the third type is contrary. Synchronization type with the best performance may switch from one to another, with changing of injection rate and spontaneous emission factor.     

Crystal field analysis of the magnetization curves of R2Fe17 and R2Fe17H3 (R=Tb,Ho,Er)

In this paper the values of the crystalline-electric-field parameters A_nm for R₂Fe₁₇ and R₂Fe₁₇H₃ (R=Tb,Ho,Er) are evaluated by fitting calculations to the magnetization curves measured on the single crystal at several temperatures. The fitted A_nm for R₂Fe₁₇ are strikingly different from those for the corresponding R₂Fe₁₇H₃. The energy gaps between the lowest four energy levels for Ho ions in Ho₂Fe₁₇₂ can be reproduced by using the fitted A_nm and exchange field 2μ_BH_ex, which estimated from the fit of the temperature dependence of the spontaneous magnetization combined with inelastic neutron scattering experiment.     

Effects of Nb2O5 on thermal stability and optical properties of Er3+-doped tellurite glasses

Er³⁺-doped tellurite glasses with molar compositions of xNb₂O₅-(14.7-x)Na₂O--10ZnO--5K₂O--10GeO₂-- 60TeO₂--0.3Er₂O₃ (x=0, 3, 5, 7 and 9) have been investigated for developing 1.5~μm fibre and planar amplifiers. The effects of Nb₂O₅ on the thermal stability and optical properties of Er³⁺-doped tellurite glasses have been discussed. It is noted that the incorporation of Nb₂O₅ (x=5) increases the thermal stability of tellurite glasses significantly. Er³⁺-doped niobium tellurite glasses exhibit a large stimulated emission cross-section (7.2\times 10^-21- 10.7×10^-21~cm² and the gain bandwidth, FWHM×\sigma_e^{\rm peak} (274\times 10^-28 - 480×10^-28~cm³), which are significantly higher than that of silicate and phosphate glasses. In addition, the intensity of upconversion luminescence of the Er³⁺-doped niobium tellurite glasses decreases rapidly with increasing Nb₂O₅ content. As a result, Er³⁺-doped niobium tellurite glasses might be a potential candidate for developing laser or optical amplifier devices.     

Defect-induced failure of optical coating filters

Optical filters composed of Ag, Al₂O₃, and ZnSe films were prepared on BK7 substrates by evaporation. By employing spectrophotometer, microscope, scanning electron microscope (SEM), and energy dispersive spectrum (EDS) analysis, the moisture-dependent stability of the samples was tested. The experimental results revealed that filter failure often occurs initially at defect sites. Small sputtering particles and pinhole are found to be two types of defects that induced the optical coating filter failure. The mechanisms of the defect-induced failure of the filters also are discussed in the article.     

Quantum noise property in coherent atomic system

The coherent superposition of atomic states leads to the characteristic change of interacting lights because of the coupling between the lights and atoms. In this paper, the noise spectrum of the quantified light interacting with the atoms is studied under the condition of electromagnetically induced transparency (EIT). It is shown that the noise spectrum displays a double M-shape noise profile resulted from the conversion of phase noise of probe beam. A squeezing of 0.3 dB can be observed at the detuning of probe light at the proper parameters of atoms and coupling beam.     

Spiral tip meandering induced by excitability modulation

In this work, we introduce a spatiotemporal modulation for excitability into an excitable medium, the Barkley model. The modulation can make the spiral wave tip meandering. Various types of periodic spiral and quasiperiodic meandering spiral motions can be observed numerically by varying the modulation. And the theoretical analysis for the conditions of Hopf bifurcation, based on an ordinary-differential-equation (ODE) model, is applied to well explain the rich behaviors of numerical simulations.     

Theoretical models for the extracavity Raman laser with crystalline Raman medium

The rate equation model of an extracavity Raman laser is deduced for the first time to the best knowledge of the authors. The normalized radiation transfer equations of the extracavity Raman laser are given. The normalized radiation transfer equations and rate equations were solved numerically to find the optimum reflectivity of the output coupler to realize the maximum conversion efficiency at the first Stokes for both the single and double-pass pumping configurations. Also, the pulse duration of the first Stokes was investigated numerically. The rate equations are verified to be a good approximation to the radiation transfer equations for the regime of low Raman gain and long pump pulse duration. Furthermore, it is found that the optimum reflectivity of the first Stokes and the second Stokes threshold are influenced significantly by the minor feedback of the resonator mirror at the second Stokes. PACS 42.55 42.55.Ye; 42.65 42.65.Dr; 02.60 02.60.Lj; 63.20 63.20.-e