Bachelor's theses

Permanent URI for this collection

https://testres.nu.edu.kz/handle/123456789/2395

Browse

Browsing Bachelor's theses by Subject "Research Subject Categories::NATURAL SCIENCES::Physics"

Now showing 1 - 4 of 4
  • Thumbnail Image
    ItemOpen Access
    Interaction of Turbulence with Shock Wave
    (Nazarbayev University School of Science and Technology, 2017) Zhaksylykov, Azamat
    At the final stages of the lives of massive stars supernova explosion occurs. Before that process nuclear shell burning happens and strong turbulent convection arises in between iron core and silicon shell. Turbulence by amplifying flow in the post-shock region aid supernova explosion. In this work the physical mechanism behind this amplifi cation using a linear perturbation theory was investigated. Shock wave was modeled as one-dimensional planar discontinuity. Vorticity and entropy perturbations in the upstream flow considered as turbulence. Amplifi cation of turbulent kinetic energy of ow crossing shock wave by a factor of 2 was obtained.
  • Thumbnail Image
    ItemOpen Access
    NUMERICAL INVESTIGATION OF AN EXTERNALLY DRIVEN SPIN DYNAMICS IN SEARCH OF A CLASSICAL CONDENSATION OF WAVES
    (Nazarbayev University School of Science and Technology, 2017) Yegovtsev, Nikolay
    The following work is a numerical study of a recently discovered Bose-Einstein condensation of magnons at room temperature by purely classical means. The classical Hamiltonian of the system includes exchange and dipolar interaction as well as interaction with external magnetic field. The system under consideration is a 2-dimentional lattice of classical spins with fixed positions. Classical equations of motions are derived from this Hamiltonian by applying the Poisson-bracket formalism. Equations of motions were solved numerically by the 4th order Runge-Kutta algorithm and obtained spin dynamics is transformed to the frequency space by the means of Fourier transform. This spectral decomposition of the dynamics allows monitoring the occupation of the energy states and observing condensation into the lowest energy state. In this work, we were able to reproduce the dispersion curve with characteristic minimum at non-zero value of the wave-vector by varying parameters of the system. We discuss models for pumping and dissipation, and hope to implement them in the future work.
  • Thumbnail Image
    ItemOpen Access
    Optimization of Liquid Scintillator Composition
    (Nazarbayev University School of Science and Technology, 2017) Batyrkhanov, Ayan
    Nowadays, many particle detectors use liquid scintillator (LS) as a detection medium. In particular, Water-based Liquid Scintillator (WbLS) that is a new material currently under development. It is based on the idea of dissolving the organic scintillator in water using special surfactants. This material strives to achieve the novel detection techniques by combining the Cherenkov and scintillation light, as well as the total cost reduction compared to pure liquid scintillator.
  • Thumbnail Image
    ItemOpen Access
    Particle detector calibration and performance for Horizon-T cosmic rays experiment
    (Nazarbayev University School of Science and Technology, 2017) Yessenov, Murat
    Due to large variation of particle density in EAS, a response linearity of each detector needs to be assessed. The number of photon in a photo multiplier tube (PMT) pulse allows inferring the deviation from linearity in each case. In order to obtain an approximate photon count of a pulse, a single photo-electron response pulse calibration for the R7723 PMT was conducted using low-level light pulse. Non-linearity measurements of PMT were conducted using the same setup. PMT signals were chosen such that their widths are comparable with the real data. Results included in this work show that the PMT signal is mostly linear and nonlinearity starts only at the upper end of ADC range.