Open Access. Powered by Scholars. Published by Universities.®

Physics Commons™

Open Access. Powered by Scholars. Published by Universities.®

PDF

Association of Arab Universities

Journal

2020

Articles 1 - 6 of 6

Full-Text Articles in Physics

Negative Magnetoresistivity In Tl4se3s Crystals, Atef Fayez Qasrawi Nov 2020

Negative Magnetoresistivity In Tl4se3s Crystals, Atef Fayez Qasrawi

Journal of the Arab American University مجلة الجامعة العربية الامريكية للبحوث

The temperature and magnetic field dependencies of the magnetoresistivity of Tl4Se3S crystals have been measured in the temperature region of 195-310 K at magnetic fields up to 1.4 T. The magnetoresistivity is observed to exhibit negative values at all measured temperatures. Increasing the magnetic field intensity leads to larger values of negative magnetoresistivity. The magnetoresistivity as a function of applied field was described by the Khosla-Fischer model for spin scattering of carriers in an impurity band. The temperature dependence of magnetoresistivity has revealed the existence of paramagnetic–ferromagnetic and ferromagnetic–paramagnetic phase transitions at 270 and 220 K, respectively. The existence of …

Go to article

Indoor Radon-222 Concentration Levels Measurements And Exhalation Rates Calculations In Some Offices And Rooms Of Aauj During The Winter And The Spring Of 2014, Mohammad Abu-Samreh Nov 2020

Indoor Radon-222 Concentration Levels Measurements And Exhalation Rates Calculations In Some Offices And Rooms Of Aauj During The Winter And The Spring Of 2014, Mohammad Abu-Samreh

Journal of the Arab American University مجلة الجامعة العربية الامريكية للبحوث

In this study, we report on the radon concentration levels, the radon exhalation rate, and the annual effective dose equivalent in 10 buildings of AAUJ during the winter and the spring of 2014 using the CR-39 track detectors. The inspected facilities include 46 offices, 24 labs, seven storage rooms, nine coffee rooms, a cleaning room, eight bathrooms, four Xeroxing rooms, and three meeting rooms. The indoor radon concentration levels were found to vary from 26 to 258 Bq/m3, with an arithmetic mean and standard deviation of 76.6 and 16.2. In general, the bathrooms and stores were found to have a …

Go to article

Effect Of Sodium Based Transparent Binders On The Optical Properties Of Gase Thin Films, Ahmad Omar Nov 2020

Effect Of Sodium Based Transparent Binders On The Optical Properties Of Gase Thin Films, Ahmad Omar

Journal of the Arab American University مجلة الجامعة العربية الامريكية للبحوث

The effect of sodium based transparent binders on the optical properties of vacuum evaporated GaSe thin films are explored by means of optical reflectivity and transmittance of the binder, GaSe and GaSe/binder interfaces in the incident light wavelength range of 300-1100 nm. The analysis of the absorption coefficient spectra for the three samples revealed a pronounced red shift in the direct allowed electron transition's energy band gap of the GaSe. In addition, the band tail states of GaSe, which was observed at ~ 0.25 eV, disappeared upon binder coating. The binder coated GaSe films screen the energy band gap of …

Go to article

The Effect Of Biologically Synthesized Silver Nanoparticles On The Germination And Growth Of Cucurbita Pepo Seedlings, Salim Bamsaoud Nov 2020

The Effect Of Biologically Synthesized Silver Nanoparticles On The Germination And Growth Of Cucurbita Pepo Seedlings, Salim Bamsaoud

Journal of the Arab American University مجلة الجامعة العربية الامريكية للبحوث

Silver nanoparties were synthesized from aqueous solution of silver nitrate, with different molar ratio of silver (0, 1, 2, and 3M), using leaf extraction of Neem as well as Saisban. The effect of silver nanoparticles of Neem and Saisban solution on seed germination, hypocotyls and semi root lengths of Cucurbita Pepo was investigated. The Cucurbita Pepo seeds were immersed for 20 minutes in silver nanoparticles solution of Neem and Saisban along with distilled water as control. The seeds allowed to grow in petri dishes. The results show no effect on growth percentage while a remarkable change in seeding speed and …

Go to article

Dynamical And Thermal Properties Of 850 Nm Vertical Cavity Surface Emitting Laser (Vcsel), Muayad Abusaa Nov 2020

Dynamical And Thermal Properties Of 850 Nm Vertical Cavity Surface Emitting Laser (Vcsel), Muayad Abusaa

Journal of the Arab American University مجلة الجامعة العربية الامريكية للبحوث

Vertical cavity surface emitting laser diodes (VCVSELs) are widely used in different areas especially in telecommunications because of their unique properties compared to other types of lasers. In the present work, we explain the dynamical and thermal properties of 850 nm VCSELs. Specifically, we determine the threshold current, output power for a continuous wave operation and pulsed operation for different pulse durations, the wavelength as a function of (injected current/ dissipated power/ temperature).

Go to article

Studying The Linear Complex Pt Symmetric Potential, Roland Lombard Nov 2020

Studying The Linear Complex Pt Symmetric Potential, Roland Lombard

Journal of the Arab American University مجلة الجامعة العربية الامريكية للبحوث

We investigate the spectrum of the linear complex PT symmetric potential V(x) = λ|x| + icx. Semi analytical solutions are given by using properties of the Airy functions. The numerical integration of the differential equation system is discussed. We show that the number of eigenstates with a real eigenvalue is limited, depending on the ratio c/λ and on the quantum number n, reflecting a spontaneous breaking of the PT symmetry. For the ground state ( n = 0), we conjecture the eigenvalue to be real whatever the value of c.

Go to article