نشریه پژوهش های نوین فیزیک
سال دوم شماره 2 (پیاپی 3، پاییز و زمستان 1396)

In present paper, effect of electron scattering due to presence of rough interfaces is investigated on electrical conductance in tunneling structures. The tunneling structure is a fifth layer (double barriers) that all of them are semiconductor. Calculations are carried out in the frame work of nearly free electron approximation and transfer matrix method. Our results show that increasing of roughness results in increasing of incident electrons scattering and also cause to decreasing of transmission probability of electrons, and hence, decreasing of electrical transport through tunneling structures. Besides, with increasing of rough exponent, roughness of surface becomes smoother and into greater rough exponent, interfacial seems more plain. The influence of variation of more than one characteristic of roughness on tunneling current leads to interesting results that can regard in electronic devices fabrication.

In the present paper, we simulate fission process of the excited nuclei 217Fr produced in fusion reactions 19F with 198Pt nuclei in the framework of the Langevin equations. We calculate the pre-scission neutron multiplicity for the excited nuclei 217Fr with considering the effects of temperature and projection of spin about the symmetry axis, K. We show that temperature and projection of spin about the symmetry axis affect on the results of pre-scission neutron multiplicity and without considering the effects of temperature and projection of spin; the results of calculations are less than the experimental data. Furthermore, based on fission process simulation and considering the reduced dissipation coefficient as a free parameter we reproduce experimental data on the pre-scission neutron multiplicity for the excited nuclei 217Fr. We also show that the appropriate value of reduced dissipation coefficient for 217Fr is equal to.

In this paper the trajectory of electron in a free-electron laser (FEL) with modified planar wiggler is analyzed using single particle dynamics. It is shown that the new odd harmonics are generated due to the transverse oscillations of electron in the wiggler frequency and its harmonics. Spontaneous emission of modified FEL is calculated analytically and possibility of emission at up-shifted wiggler frequency and their odd harmonics has been found. After that by calculating the spontaneous emission numerically, we show that peaks of spontaneous emission spectrum are in good agreement with analytical calculations

In this paper, we present a detailed study to probe top-quark flavor changing neutral current (FCNC) interactions at , , and vertices with top-quark pair in association with a photon and three-top-quarks signal at the Large Hadron Collider (LHC). We investigate the top-quark FCNC couplings and carry out a full simulation for the triple-top production considering the main backgrounds. In addition, having at hand the cross section of a top-quark pair produced in association with a photon in collisions at a centre-of-mass energy of 8 TeV with 20.2 of data collected by the ATLAS detector, we also investigated the FCNC coupling. The obtained exclusion limits on coupling strengths and branching ratios are summarized and compared with the results in literature. The discovery potential for anomalous couplings , , and with an integrated luminosity of are also examined in detail. We show that, for higher luminosities within Run-II of LHC, a dedicated search for the top-quark FCNC couplings can achieve comparable or even better sensitivities to the triple-top signal than the other top-quark production scenarios. We have shown that the triple-top signal could potentially provide evidence for new physics at the LHC.

The aim of the present work is a synthesis and investigation of the structural properties of tungsten trioxide (WO3) nanoparticles. The prepared samples were calcined at 400 and 450˚C. The structural, compositional, morphology and molecular properties of the samples were investigated by using X-Ray Diffraction, Scanning Electron Microscopy, Energy-Dispersive X-Ray Spectroscopy and Fourier Transform Infrared Spectroscopy, respectively. The structural parameters of the samples were studied by the Size-Strain Plot (SSP) method. The results show that the particle size increases with increasing calcination temperature and the amount of impurities also decreases. The photocatalytic activity of the tungsten trioxide nanoparticles was evaluated by the photocatalytic discoloration of methylene blue in aqueous solution.

In this study, graphene oxide (GO) was prepared by Hummers-Offeman method and used as a promising precursor for the preparation of graphene sheets in the α-Fe2O3/RGO nanocomposite. Highly dispersed hematite nanoparticles on the graphene surface were sucessfully synthesized via solvothermal method. Structure properties and morphology of the samples were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrophotometer (FT-IR). In continue, photocatalytic activity of the samples for degradation of Congo red was studied using UV-visible spectroscopy (UV-vis). The results showed that αFe2O3/RGO nanocomposite has beter photocatalytic activity with comparison to pure αFe2O3.

In this note, Logamediate inflationary model on the brain by using canonical scalar fields is studied. The equation of motion is calculated in the slow-roll approximation for canonical model. Perturbation parameters of the model are presented and constrained by the Planck observational data. The results are compatible with the observations.