Measurements of the Rate Capability of Various Resistive Plate Chambers

Resistive Plate Chambers (RPCs) exhibit a significant loss of efficiency for the detection of particles, when subjected to high particle fluxes. This rate limitation is related to the usually high resistivity of the resistive plates used in their construction. This paper reports on measurements of the performance of three different glass RPC designs featuring a different total resistance of the resistive plates. The measurements were performed with 120 GeV protons at varying beam intensitie

Surface-decorated ZnO nanoparticles and ZnO nanocoating on electrospun polymeric nanofibers by atomic layer deposition for flexible photocatalytic nanofibrous membranes

Cataloged from PDF version of article.Electrospun polymeric nanofibers were either surface-decorated with zinc oxide (ZnO) nanoparticles or coated with a continuous ZnO thin film with a precise thickness (similar to 27 nm) via atomic layer deposition (ALD) for the fabrication of flexible photocatalytic nanofibrous membranes

Pulsed Beam Tests at the SANAEM RFQ Beamline

A proton beamline consisting of an inductively coupled plasma (ICP) source, two solenoid magnets, two steerer magnets and a radio frequency quadrupole (RFQ) is developed at the Turkish Atomic Energy Authority's (TAEA) Saraykoy Nuclear Research and Training Center (SNRTC-SANAEM) in Ankara. In Q4 of 2016, the RFQ was installed in the beamline. The high power tests of the RF power supply and the RF transmission line were done successfully. The high power RF conditioning of the RFQ was performed recently. The 13.56 MHz ICP source was tested in two different conditions, CW and pulsed. The characterization of the proton beam was done with ACCTs, Faraday cups and a pepper-pot emittance meter. Beam transverse emittance was measured in between the two solenoids of the LEBT. The measured beam is then reconstructed at the entrance of the RFQ by using computer simulations to determine the optimum solenoid currents for acceptance matching of the beam. This paper will introduce the pulsed beam test results at the SANAEM RFQ beamline. In addition, the high power RF conditioning of the RFQ will be discussed.Comment: 6 pages, 6 figures. Proceedings of the International Particle Accelerator Conference 2017 (IPAC'17), May 14-19, 2017, TUPAB015, p. 134

Template-based synthesis of aluminum nitride hollow Nanofibers via plasma-enhanced atomic layer deposition

Cataloged from PDF version of article.Aluminum nitride (AlN) hollow nanofibers were synthesized via plasma-enhanced atomic layer deposition using sacrificial electrospun polymeric nanofiber templates having different average fiber diameters (~70, ~330, and ~740 nm). Depositions were carried out at 200°C using trimethylaluminum and ammonia precursors. AlN-coated nanofibers were calcined subsequently at 500°C for 2 h to remove the sacrificial polymeric nanofiber template. SEM studies have shown that there is a critical wall thickness value depending on the template's average fiber diameter for AlN hollow nanofibers to preserve their shapes after the template has been removed by calcination. Best morphologies were observed for AlN hollow nanofibers prepared by depositing 800 cycles (corresponding to ~69 nm) on nanofiber templates having ~330 nm average fiber diameter. TEM images indicated uniform wall thicknesses of ~65 nm along the fiber axes for samples prepared using templates having ~70 and ~330 nm average fiber diameters. Synthesized AlN hollow nanofibers were polycrystalline with a hexagonal crystal structure as determined by high-resolution TEM and selected area electron diffraction. Chemical compositions of coated and calcined samples were studied using X-ray photoelectron spectroscopy (XPS). High-resolution XPS spectra confirmed the presence of AlN. © 2012 The American Ceramic Societ

Polymer-inorganic core-shell nanofibers by electrospinning and atomic layer deposition: flexible nylon-znO core-shell nanofiber mats and their photocatalytic activity

Cataloged from PDF version of article.Polymer-inorganic core-shell nanofibers were produced by two-step approach; electrospinning and atomic layer deposition (ALD). First, nylon 6,6 (polymeric core) nanofibers were obtained by electrospinning, and then zinc oxide (ZnO) (inorganic shell) with precise thickness control was deposited onto electrospun nylon 6,6 nanofibers using ALD technique. The bead-free and uniform nylon 6,6 nanofibers having different average fiber diameters (∼80, ∼240 and ∼650 nm) were achieved by using two different solvent systems and polymer concentrations. ZnO layer about 90 nm, having uniform thickness around the fiber structure, was successfully deposited onto the nylon 6,6 nanofibers. Because of the low deposition temperature utilized (200 °C), ALD process did not deform the polymeric fiber structure, and highly conformal ZnO layer with precise thickness and composition over a large scale were accomplished regardless of the differences in fiber diameters. ZnO shell layer was found to have a polycrystalline nature with hexagonal wurtzite structure. The core-shell nylon 6,6-ZnO nanofiber mats were flexible because of the polymeric core component. Photocatalytic activity of the core-shell nylon 6,6-ZnO nanofiber mats were tested by following the photocatalytic decomposition of rhodamine-B dye. The nylon 6,6-ZnO nanofiber mat, having thinner fiber diameter, has shown better photocatalytic efficiency due to higher surface area of this sample. These nylon 6,6-ZnO nanofiber mats have also shown structural stability and kept their photocatalytic activity for the second cycle test. Our findings suggest that core-shell nylon 6,6-ZnO nanofiber mat can be a very good candidate as a filter material for water purification and organic waste treatment because of their photocatalytic properties along with structural flexibility and stability. © 2012 American Chemical Society

Fabrication of AlN/BN bishell hollow nanofibers by electrospinning and atomic layer deposition

Cataloged from PDF version of article.Aluminum nitride (AlN)/boron nitride (BN) bishell hollow nanofibers (HNFs) have been fabricated by successive atomic layer deposition (ALD) of AlN and sequential chemical vapor deposition (CVD) of BN on electrospun polymeric nanofibrous template. A four-step fabrication process was utilized: (i) fabrication of polymeric (nylon 6,6) nanofibers via electrospinning, (ii) hollow cathode plasma-assisted ALD of AlN at 100 degrees C onto electrospun polymeric nanofibers, (iii) calcination at 500 degrees C for 2 h in order to remove the polymeric template, and (iv) sequential CVD growth of BN at 450 degrees C. AlN/BN HNFs have been characterized for their chemical composition, surface morphology, crystal structure, and internal nanostructure using X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction. Measurements confirmed the presence of crystalline hexagonal BN and AlN within the three dimensional (3D) network of bishell HNFs with relatively low impurity content. In contrast to the smooth surface of the inner AlN layer, outer BN coating showed a highly rough 3D morphology in the form of BN nano-needle crystallites. It is shown that the combination of electrospinning and plasma-assisted low-temperature ALD/CVD can produce highly controlled multi-layered bishell nitride ceramic hollow nanostructures. While electrospinning enables easy fabrication of nanofibrous template, self-limiting reactions of plasma-assisted ALD and sequential CVD provide control over the wall thicknesses of AlN and BN layers with sub-nanometer accuracy. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License

Fabrication of flexible polymer-GaN core-shell nanofibers by the combination of electrospinning and hollow cathode plasma-assisted atomic layer deposition

Here we demonstrate the combination of electrospinning and hollow cathode plasma-assisted atomic layer deposition (HCPA-ALD) processes by fabricating flexible polymer-GaN organic-inorganic core-shell nanofibers at a processing temperature much lower than that needed for the preparation of conventional GaN ceramic nanofibers. Polymer-GaN organic-inorganic core-shell nanofibers fabricated by the HCPA-ALD of GaN on electrospun polymeric (nylon 6,6) nanofibers at 200 °C were characterized in detail using electron microscopy, energy dispersive X-ray analysis, selected area electron diffraction, X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence measurements, and dynamic mechanical analysis. Although transmission electron microscopy studies indicated that the process parameters should be further optimized for obtaining ultimate uniformity and conformality on these high surface area 3D substrates, the HCPA-ALD process resulted in a ∼28 nm thick polycrystalline wurtzite GaN layer on polymeric nanofibers of an average fiber diameter of ∼70 nm. Having a flexible polymeric core and low processing temperature, these core-shell semiconducting nanofibers might have the potential to substitute brittle ceramic GaN nanofibers, which have already been shown to be high performance materials for various electronic and optoelectronic applications. This journal is © The Royal Society of Chemistry