Magnetic field quantization in pulsars

Magnetic field quantization is an important issue for degenerate environments such as neutron stars, radio pulsars and magnetars etc., due to the fact that these stars have a magnetic field higher than the quantum critical field strength of the order of $4.4\times 10^{13}~\text{G}$ , accordingly, the cyclotron energy may be equal to or even much more than the Fermi energy of degenerate particles. We shall formulate here the exotic physics of strongly magnetized neutron stars, known as pulsars, specifically focusing on the outcomes of the quantized magnetic pressure. In this scenario, while following the modified quantum hydrodynamic model, we shall investigate both linear and nonlinear fast magnetosonic waves in a strongly magnetized, weakly ionized degenerate plasma consisting of neutrons and an electron–ion plasma in the atmosphere of a pulsar. Here, linear analysis depicts that sufficiently long, fast magnetosonic waves may exist in a weakly dispersive pulsar having finite phase speed at cutoff. To investigate one-dimensional nonlinear fast magnetosonic waves, a neutron density expression as a function of both the electron magnetic and neutron degenerate pressures, is derived with the aid of Riemann’s wave solution. Consequently, a modified Korteweg–de Vries equation is derived, having a rarefractive solitary wave solution. It is found that the basic properties such as amplitude, width and phase speed of the fast magnetoacoustic waves are significantly altered by the electron magnetic and the neutron degenerate pressures. The results of this theoretical investigation may be useful for understanding the formation and features of the solitary structures in astrophysical compact objects such as pulsars, magnetars and white dwarfs etc.

The magnetic field quantization in pulsar

<p>Magnetic field quantization is an important issue for degenerate environments such as neutron star, radio pulsars and magnetars etc., due to the fact that these stars have magnetic field even more than the quantum critical field strength of the order of 4.4×10¹³G, accordingly the cyclotron energy may be equal or even much more than the Fermi energy of degenerate particles. We shall formulate here the exotic physics of strongly magnetized neutron star. The effect of quantized anisotropic magnetic pressure, arising due to a strong magnetic field is studied on the growth rate of Jeans instability of quantum electron–ion and classical dusty plasma.  Here we shall formulate the dispersion equations to govern the propagation of the gravitational waves both in perpendicular and parallel directions to the magnetic field, respectively.  We will depict here that the quantized magnetic field will result in Jeans anisotropic instability such that for perpendicular propagation, the quantized magnetic pressure will stabilize Jeans instability, whereas for the parallel propagation the plasma become more unstable.  We also intend to calculate the corresponding Jeans wave number in the absence of tunneling. The Madelung term leads to the inhomogeneity of the plasma medium. Numerical results are presented to show the effect of the anisotropic magnetic pressure on the Jeans instability.</p>

Evaluating Cross Sections of Gallium Isotopes Production Using proton and deuteron Irradiation

In the present work, the production of the cross sections of three Gallium isotopes: 35 66 31Ga (t1 ⁄2 = 9.4h, β+ = 4.2MeV), 36 67 31Ga (t1 ⁄2=3.2617d, EC=100%) and 37 68 31Ga (t1 ⁄2 = 68min, Iβ+ = 89%) have been discussed. The Gallium isotopes have important applications in nuclear medicine, particularly in Positron Emission Tomography (PET), Single Photon Emission Tomography (SPET) imaging technique and used in tumors diagnosing. The production of irradiant Ga 66 , Ga 67 and Ga 68 is made by irradiation of an enriched Zinc target using proton and deuteron charged particles. Utilizing high cyclotron yield and low radionuclide impurities, the optimum cyclotron energy range has been chosen for the production of Gallium isotopes. The cross sections of (p,xn), (p,γ) and (d,xn) reactions for the production of Gallium isotopes have been evaluated depending upon the empirical data taken from EXFOR library, which is belonging to the International Atomic Energy Agency (IAEA). Also the yield for each reaction has been evaluated

CONTROLLABLE SPIN POLARIZATION IN A DMS QUANTUM DOT

The effects of electro-magnetic confining potentials and the s–d exchange interaction between substituted Mn ions and carriers on the spin polarization of carriers in an diluted magnetic semiconductor quantum dot are investigated within the framework of the effective-mass theory. The energy eigenvalues and wavefunctions of a single electron in the presence of an external magnetic field are studied by solving the one particle Schrödinger equation including the conventional Zeeman effect, the s–d exchange interaction and the electric confining potential which describes the dot. The eigenenergy structure for low lying states is strongly dependant on the relative sizes of the s–d exchange interactions and the conventional Zeeman energy splitting. When the spin splitting exceeds the cyclotron energy splitting, the Landau level overlappings occur so that the spin polarization of carriers is induced in low lying energy states. This spin polarization of carriers in the diluted magnetic semiconductor quantum dot can be controlled by changing the electro-magnetic confining potentials.

Numerical Studies of Miniband Conduction in Quasi-One-Dimensional Superlattices

Monte Carlo simulations of electron motion in GaAs/A1As superlattices with narrow mini-band width are performed to investigate the effect of a strong magnetic field on miniband conduction. In the quantum limit at low temperatures when the cyclotron energy exceeds the miniband width, the miniband conduction is found to exhibit a strong suppression. This results from the quasi-one-dimensional states formed in the quantum limit and the restricted range of the scattering processes available to the conduction electrons. A small shoulder on the lower electric field side of the main peak is also found in marked contrast with Esaki-Tsu and Ignatov models.

ON THE INTERACTION ENERGY OF TWO-DIMENSIONAL ELECTRON FQHE SYSTEMS WITHIN THE CHERN–SIMONS APPROACH

The interaction energy of the two-dimensional electron system in the region of fractional quantum Hall effect is considered within the Chern–Simons composite fermion approach. In the limit when Coulomb interaction is very small comparing to the cyclotron energy the RPA results are obtained for the fillings ν=1/3, 1/5, 2/3, 2/5, 3/7 and compared with the exact diagonalization results for small systems (extrapolated for infinite systems). They show very poor agreement suggesting the need for looking for alternative approaches.