Ajman Campus
+971 6 748 2222
Admission & Registration
+971 6 748 2222
Finance Department
+9716705 6874
Housing
+971 6 7056635
Transportation
+971 6 7056912
Medical Clinic
+971 6 7056294, +971 6 7056773
Associate professor of Physics with specialization in nanomaterials and nanotechnology. He received his MSc in Materials Physics and Nanotechnology from Linkoping Institute of Technology, Linkoping University in Sweden (2004), PhD in Physics from Debye Institute for Nanomaterials, Utrecht University in the Netherlands (2009). His PhD work investigates the shaping of nanomaterials for future applications in renewable energy, optical harvesting, biological sensors, and optical switches. E. A. Dawi carries out research in assembly of nanoscale particles and their modified optical properties, solar enhancement, and ion-beam implantation techniques. Has authored and co-authored a number of articles published in highly renowned journals. E.A. Dawi is involved in a number of international collaborations with scientists from Netherlands, Sweden, France, China, India, and Pakistan. He contributed to publication of a specialized book in ion-nanoscale matter interaction. Besides, he contributed to international conferences in different research disciplines of interest.
In this study, we investigate the behavior of two-dimensional wet foam when it is subjected to shear strain. As a result of their rheological properties, which may range from solid-like to liquid-like, foams are considered elastic when they are subjected to shear strain. In conformational experiments, we show that wet foam topologically reshapes into a parallelogram when confined within a square rubber band cell. We applied a shear strain by dislocating one side of the cell. These results suggest that the changes in the foam are consistent with the occurrence of avalanches of changes in wet foam. With increase in strain and wetness of the cells, disordered wet foams become more ordered.
We study the transverse momentum spectra of charged particles from 0.1 − 2 GeV/c in bins of pseudorapidity ???? of width 0.2 ranging from 0 to 2.4 produced in ???????? collisions, at three different center of mass energies, namely √ ???? = 0.9, 2.36, 7 TeV. We used PYTHIA8.307 and QGSJETII-04 and compared the simulation results with experimental data under the same conditions. The PYTHIA8 model has an excellent description of the experimental data, particularly at the high ???????? region of the distribution, and the prediction is independent of the ???? ranges. Furthermore, the predictions are more or less the same at lower values of ???????? , but a more prominent bump is observed for 0.4 ≤ ???????? ≤ 0.8 GeV/c with increasing the center-of-mass energy. The QGSJET model reproduces the data only in the intermediate region of the ???????? over all the ???? slices and underpredicts for low and high ???????? regions. With the increase in the center of mass energy, the model’s predictions got closer to the data, particularly at a high part of the ???????? distributions. Furthermore, the Blast wave model with Tsallis statistics is applied to the ???????? spectra of CMS data and PYTHIA8 and QGSJET models, and the kinetic freeze-out temperature, transverse flow velocity, and the entropy parameter ???? are extracted. The kinetic freezeout temperature increases from lower pseudorapidity regions to higher pseudo-rapidity regions. Transverse flow velocity and the entropy parameter ???? have the opposite trend to kinetic freeze-out temperature. All these parameters are also more significant at 7 TeV and have the lowest values at 0.9 TeV, which shows the dependence of these parameters on the collision energy.
Analysis of the spectra of unidentified charged particles obtained by the CMS experiment in proton–proton collisions is reported in comparison with the simulation results of PYTHIA8.24 and EPOS-LHC models. The spectra obtained by the experiment were normalized to all non-single-diffractive (NSD) events using corrections for trigger and selection efficiency, acceptance, and branching ratios. The transverse-momentum (???????? ) spectra of the charged particles are measured in twelve equal bins of pseudorapidity (????) from 0.0 to 2.4 for ???????? from 0.1 to 2 GeV/????. The PYTHIA model reproduces the experimental data well in all bins of ???? especially in the region of high ???????? while the EPOS model predicts well in the intermediate ???????? regions. The intermediate regions where the EPOS model predicts well, broadens with increasing ????. We used the Blast-wave model with Boltzmann–Gibbs statistics to study collective properties of the hadronic matter and for better comparison of the models’ prediction with the experimental data while determining the values of kinetic freeze-out temperature (????0) and transverse flow velocity (???????? ) for data and models. The values of ????0 decrease with increasing ???? for data as well as for both the models. The transverse flow velocity has no clear trend with increasing ???? but a run through shows an increasing trend in the case of the data and the PYTHIA model but a decreasing trend in the case of the EPOS model. The multiplicity parameter ????0 increases with increasing ???? and its values obtained by the fit function for the PYTHIA are closer to the ones obtained for data than the EPOS. It is concluded that none of the models completely describes the data in all bins of ???? over the entire ???????? range but the PYTHIA has better prediction than the EPOS model because the former has implied flow-like effects and formation of color string resulting from multiple hard sub-collisions between final and initial partons (color reconnection) from independent hard scatterings due to which the model predicts the data well.
We investigated the strange hadrons transverse momentum (pT) spectra in Au-Au collision at ffiffiffiffiffiffiffiffi sNN p ¼ 54.4 GeV in the framework of modified Hagedorn function with embedded flow. It is found that the model can describe the particle spectra well. We extracted the kinetic freeze-out temperature T0, transverse flow velocity βT, kinetic freeze-out volume V, mean transverse momentum hpT i, the entropy parameter n, and the multiplicity parameter N0.We reported that all these parameters increase towards the central collisions. The larger kinetic freeze-out temperature, transverse flow velocity, kinetic freeze-out volume, and the entropy parameter (n) in central collisions compared to peripheral collisions show the early decoupling of the particles in central collisions. In addition, all the above parameters are mass dependent. The kinetic freeze-out temperature (T0), the entropy parameter n, and mean transverse momentum (hpTi) are larger for massive particles, while the transverse flow velocity (βT), kinetic freeze-out volume (V), and the multiplicity parameter (N0) show the opposite behavior. Larger T0, n, and smaller βT as well as V of the heavier particles indicate the early freeze-out of the heavier particles, while larger hpTi for the heavier particles evince that the effect of radial flow is stronger in heavier particles. The separate set of parameters for each particle shows the multiple kinetic freeze-out scenario, where the mass-dependent kinetic freezeout volume shows the volume differential freeze-out scenario. We also checked the correlation among different parameters, which include the correlation of T0 and βT, T0 and V, βT and V, hpT i and T0, hpTi and βT, hpTi, and V, n and T0, n and βT, and n and V, and they all are observed to have positive correlations with each other which validates our results.
Na0.90-yAlSiO4:0.1Er3+,yYb3+ (0 ≤ y ≤ 0.007) phosphors were prepared by the solid state reaction method and their dual mode multicolor luminescence properties were systematically investigated. The phosphors were crystallized into the carnegieite polymorph of NaAlSiO4 at 1300 °C. The synthesized phosphors were characterized by using powder XRD technique, FT-IR and UV-VIS-NIR diffuse reflectance spectra. Upon 380 nm excitation, the phosphors emitted visible and NIR downconversion emission, which follows the quantum cutting process. The upconversion emission spectra, irrespective of the laser excitation wavelength (980 nm, 808 nm, or 1550 nm), show characteristics sharp green, and red emissions, from 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2 transitions of Er3+, respectively. Intense green (552 nm), red (664 nm) and NIR (809 nm) emissions were observed at 980, 808 and 1550 nm laser excitation, respectively. The dual mode emission of the Na0.90-yAlSiO4:0.1Er3+,yYb3+ (0 ≤ y ≤ 0.007) phosphors is enhanced upon Yb3+ co-doping. By analyzing the dependence of upconversion emission intensities on the laser excitation power, a possible upconversion emission mechanism is proposed.
We used the modified Hagedorn function and analyzed the experimental data measured by the BRAHMS, STAR, PHENIX, and ALICE Collaborations in Copper–Copper, Gold–Gold, deuteron–Gold, Lead–Lead, proton–Lead and proton–proton collisions, and extracted the related parameters (kinetic freezeout temperature, transverse flow velocity, kinetic freezeout volume, mean transverse momentum, and initial temperature) from the transverse momentum spectra of the particles (non-strange and strange particles). We observed that all the above parameters increase from peripheral to central collisions, except transverse flow velocity, which remains unchanged. The kinetic freezeout temperature depends on the particle’s interaction cross-section such that a larger cross-section corresponds to a smaller and reveals the two kinetic freezeout scenarios. Similarly, the initial temperature follows the mass dependency of the particle, and it increases with the particle mass. The transverse flow velocity and mean transverse momentum depend on the particle’s specie. The former decreases while the latter increases for the massive particles. Furthermore, different freezeout surfaces for different particles are observed as the kinetic freezeout volume decreases for the heavier particles. We also extracted the entropy index-parameter “” and the parameter , the former remains almost unchanged while the latter decreases from central collisions to the periphery. Furthermore, the kinetic freezeout temperature, transverse flow velocity, kinetic freezeout volume, initial temperature, mean transverse momentum and the parameter at LHC are larger than that of RHIC, showing their dependence on the collision cross-section and collision energy.
Anisotropic deformation of colloidal particles was investigated under ion irradiation with 4MeVCu ions. In this study, 0.5 μm-diameter colloidal silica particles, 0.5 μm-diameter Au-silica core–shell particles, and 15 nm-diameter Au colloids embedding in a planar Si/SiO2 matrix were irradiated with 4MeV Cu ions at room temperature and normal incidence. In colloidal silica particles, ion beam irradiation causes dramatic anisotropic deformation; silica expands perpendicular to the beam and contracts parallel, whereas Au cores elongate. Au colloids in a planar SiO2 matrix were anisotropically transformed from spherical colloids to elongated nanorods by irradiating them with 4MeVCu ions. The degree of anisotropy varied with ion flux. Upon irradiating the embedded Au colloids, dark-field light scattering experiments revealed a distinct color shift to yellow, which indicates a shift in surface plasmon resonance. Asurface plasmon resonance measurement reveals the plasmon resonance bands are split along the arrays of Au colloids. Our measurements have revealed resonance shifts that extend into the near-infrared spectrum by as much as 50 nm.
This website uses cookies to enhance the user's experience. By using this website, you indicate consent to our privacy policy.