A. Ayyad
Western Michigan University
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Publication
Featured researches published by A. Ayyad.
21st International Conference on Application of Accelerators in Research and Industry, CAARI 2010 | 2011
A. Ayyad; B S Dassanayake; A. Kayani; J A Tanis
The transmission of 3 MeV protons and 16 MeV O5+ ions through a single cylindrically‐shaped insulating macrocapillary glass has been investigated in a preliminary study. The capillary had a diameter d = 0.18 mm and length l = 14.4 mm, giving an aspect ratio l/d = 80. The sample was mounted on a goniometer to permit precise positioning with respect to the incident beam direction. Results show that 3 MeV protons transmit through the capillary without energy loss at small tilt angles (near zero), and the 16 MeV O5+ ions show transmission through the sample also with little energy loss at the same small tilt angles and little change in their charge state (∼1%). For a larger tilt angle (= 1.5°), appreciable losses in energy occurred for incident O5+ and the ions changed their charge state up to 7+.
22nd International Conference on the Application of Accelerators in Research and Industry, CAARI 2012 | 2013
D. Keerthisinghe; B.S. Dassanayake; S.J. Wickramarachchi; A. Ayyad; N. Stolterfoht; J. A. Tanis
Transmission and guiding of electrons traveling through insulating PET nanocapillaries were measured for different sample tilt angles at the energies of 500 and 800 eV. Direct transmission and guiding and the transition between the two regions were observed for angles near zero degrees. Elastic and inelastic spectra and a combination of the two were seen in the different regions.
Journal of Physics: Conference Series | 2012
R J Bereczky; B S Dassanayake; S Das; A. Ayyad; K Tökési; J. A. Tanis
The time dependence of electron transmission through a single, straight glass macrocapillary was investigated for 500-800 eV electrons. We show the time evolution of the transmitted electrons reveals characteristics different from the observation in the case of electron and ion guiding through insulating nanocapillary foils.
20th International Conference on the Application of Accelerators in Research and Industry, CAARI 2008 | 2009
B.S. Dassanayake; S Das; A. Ayyad; A. Kayani; N. Stolterfoht; J A Tanis
We report new measurements of the transmission and guiding of 350, 500, and 800 eV electrons through insulating polyethylene terephthalate (PET) polymer nanocapillaries. For 800 eV the onset of guiding is found to occur at a foil tilt angle of 3°, while the results for 350 and 800 eV, combined with previous results, show the direct transmission properties for incident electron energies ranging from 250–1000 eV. Also, transmission of 16 MeV O5+ ions through the same PET foil was studied. Transmitted O5+ ions were found to lose energy and change charge upon traversing the nanocapillaries.
Journal of Physics: Conference Series | 2012
D. Keerthisinghe; B S Dassanayake; G G De Silva; A. Ayyad; J A Tanis
Transmission of electrons through a polycarbonate nanocapillary foil with diameter 200 nm and aspect ratio ~ 40 has been studied at energies 500 and 1000 eV. The direct transmission of electrons was observed for both energies while onset of guiding was observed for 500 eV. Time (charge) evolution measurements were also carried out at different sample tilt angles.
Journal of Physics: Conference Series | 2012
B S Dassanayake; A. Ayyad; J A Tanis
Transmission of 300-1000 eV electrons through a single cylindrically-shaped glass capillary was studied. Transmitted electron intensities revealed three distinct regions with different characteristics depending on the mechanism of electron transmission.
Journal of Physics: Conference Series | 2012
A. Ayyad; B S Dassanayake; D. Keerthisinghe; G G DeSilva; T Elkafrawy; N Kayani; J A Tanis
Transmission of 3 MeV protons and 16 MeV O5+ ions through a single glass macrocapillary and a polycarbonate nanocapillary foil has been investigated. Results show that 3 MeV protons transmit through the capillary and the foils with little or no energy loss, while 16 MeV O5+ ions show transmission through the capillary and the foil with energy losses that vary with the tilt angle, and there are also changes in the charge state.
Journal of Physics: Conference Series | 2012
G G De Silva; B S Dassanayake; D. Keerthisinghe; A. Ayyad; J A Tanis
The transmission of electrons through a tapered glass capillary was observed for 500, 800 and 1000 eV incident electrons up to about ~1?. No significant energy loss was found for the sample tilt angles investigated. The guiding ability of electrons was found to decrease with increasing energy. Time evolution measurements reveal unstable transmission through the capillary consistent with sudden bursts of elastic transmissions.
Journal of Physics: Conference Series | 2012
B S Dassanayake; A. Ayyad; S Das; R J Bereczky; K Tökési; J A Tanis
Broadening of transmitted electron angular profiles through a single cylindrically-shaped glass capillary was studied. The broadening effects were almost two times smaller than under similar conditions for HCIs, and transmitted electrons were found to lose energy due to poor charge deposition at the capillary exit.
Journal of Physics: Conference Series | 2009
A. Ayyad; B S Dassanayake; S Das; A. Kayani; J. A. Tanis
Transmission of 16 MeV O5+ ions through Al2O3 and PET nanocapillary foils has been investigated. We find that O5+ is transmitted without energy loss for both foils, with little evidence of transmission for other charge states. However, for the PET foil at a detector position slightly displaced from the transmitted O5+ peak, we find large intensities of transmitted ions that have lost considerable energy. It is speculated that these peaks are due to nearly head-on collisions of the incident O5+ ions with carbon and hydrogen atoms in the PET sample.