Ithnin Abdul Jalil

The Quantum Hall Effect: Spin‐Charge Locking

In two‐dimensional electron gas when a large magnetic field is applied in one direction and an electric field perpendicular to it, there is a current in a direction perpendicular to both. This current is called the Hall effect. It remained without quantization until 1980 when it was found that the quantization leads to the correct value of h/e2. Therefore, the quantized Hall effect was further studied at high magnetic fields where fractional quantization was found. The fractional charge can arise from the “incompressibility” in the flux quantization. Laughlin wrote a wave function, the excitations of which are fractionally charged quasiparticles. This wave function comes in competition with charge density waves but for a few fractions it gives the ground state. If “incompressibility” is not considered and it is allowed to be compressible, the fractional charge can arise from the angular momentum which appears in the Bohr magneton in the form of g values. Usually the positive spin is considered but we cons...

The Mass of the Electron in GaAs/AlGaAs by the Shubnikov‐de Haas Effect and Spin‐Charge Locking

The energy of the free electron gas is calculated in three dimensions. In this calculation an integral over the wave vector space occurs which was solved by Dingle. In the low‐temperature approximation the integral over the Fermi distribution leads to an expression of the type x/sinh x, called Dingles formula. The spin symmetry is found to modify this formula, which determines the oscillation amplitude of the resistivity as a function of the magnetic field, called the Shubnikov‐de Haas effect. The theory introduces an effective charge, so that the cyclotron frequency becomes fractionalized, resulting in m/v±, which for v± = 1 becomes m, the electron mass. Thus, we have taken into account the spin‐charge fractions, to obtain the correct mass. For example, at a certain magnetic field, 1.5m is found instead of m. The Shubnikov‐de Haas effect uses quantization of Landau levels but not flux quantization. Hence we find that there is a “quantized Shubnikov‐de Haas effect” which measures m/h2. We determine that ...

The Exponential S-Factor in the PP Chain

The astrophysical S‐factor widely used in the literature is a linear or a second order polynomial fit in terms of energy. In this work, we assume an exponential form of the S‐factor. The S‐factor can then be written in the form lnS0 + f(E) where S0 = 5.523 MeV and f(E) = ax + bx2 + cx3. By fitting the experimental cross section for He3 − He3, we obtain a = −0.88, b = 0.59 and c = −0.11. We evolve a solar model and compare with those of the standard cross section compilation. Most of the physical and chemical profiles differ at most by a few percent but the He3 abundance is higher by 20 %. This might affect the Be7 and B8 neutrino productions.

Solar Neutrino Fluxes Using The Exponential S-Factor

Recently we propose an exponential form for the astrophysical S‐factor. This form produces about 20% more solar 3He production through the 3He‐3He reaction. In this note, we investigate the effects on the 7Be and 8B neutrino productions since the neutrino fluxes depend on the 3He abundance.

New measurements concerning a non-resonant photo-activation cross-section for 111Cd

In recent years, several groups have reported measurement of a finite non-resonant photoactivation cross section for 115In. Present evaluations of this same parameter have made use of an irradiation arrangement and detector which differ from those of other groups. Our values for the resonant and non-resonant contribution to the photoactivation cross-section are (1.6±0.3)·10−28 cm2 keV and (4.0±0.9)·10−32 cm2, respectively, comparing favourably with counterpart results by TUSTONIC et al.5 of (1.3±0.1)·10−28 cm2 keV and (5.5±0.8)·10−32 cm2.

New Measurements Concerning a Non-Resonant Photoactivation Cross Section for 115In

In recent years, several groups have reported measurement of a finite non-resonant photoactivation cross section for 115In. Present evaluations of this same parameter have made use of an irradiation arrangement and detector which differ from those of other groups. Our values for the resonant and non-resonant contribution to the photoactivation cross-section are (1.6±0.3)·10−28 cm2 keV and (4.0±0.9)·10−32 cm2, respectively, comparing favourably with counterpart results by TUSTONIC et al.5 of (1.3±0.1)·10−28 cm2 keV and (5.5±0.8)·10−32 cm2.