X. Aslanoglou

Proton induced thick target γ-ray yields of light nuclei at the energy region Ep=1.0–4.1 MeV

Excitation function measurements of thick target c-ray yields were taken for the elements Li, B, F, Na, Mg, Al, Si and P after bombardment with protons at the energy interval Epa 1.0‐4.1 MeV. The yields of all c-rays emitted at Epa 1.77 and 4.0 MeV are tabulated and discussed. ” 1999 Elsevier Science B.V. All rights reserved.

An aluminum pillared montmorillonite with fast uptake of strontium and cesium from aqueous solutions

The uptake of Sr and Cs by 2 types of aluminum pillared layered clays (Al-PILC), a reference sample (AZA) and a specially tailored sample (FRAZA), were investigated. The AZA sample was prepared from air-dried precursors and the FRAZA sample from freeze-dried precursors. X-ray diffraction (XRD), pore and grain size measurements revealed that freeze-drying leads to a very fine-grained material with substantial mesoporosity. In contrast, air-drying results in coarse grains and an essentially micro-porous material. Four different methods were tested for restoring the cation exchange capacity (CEC) of the prepared PILCs. The most effective method proved to be exposing the material to ammonia fumes, then soaking it in a NaCl solution at pH =10. Strontium and Cs kinetic experiments were carried out with PILCs after restoring their CEC by this method. The results revealed 1 fast uptake component in both materials but with different relaxation times for each PILC.

Dielectric properties of CVD grown SiON thin films on Si for MOS microelectronic devices

The bulk properties of SiON films grown on n-Si substrates by CVD are examined by means of electrical measurements and Rutherford backscattering spectroscopy (RBS). The main aim of this project was to investigate the performance of the films in order to test their suitability for the construction of CMOS devices with SiON being the gate insulator. The CVD technique was used to produce the films and subsequent metallization leads to the creation of MOS devices. Rutherford backscattering spectroscopy (RBS) was used to verify the film bulk properties. Electrical measurements including current–voltage, capacitance–conductance–voltage (C–G–V) measurements and admittance spectroscopy were performed allowing determination of the bulk trapped charges and the dielectric constant of the films. These charges were calculated to have values between 0.76 nCb and 2.54 nCb, while the dielectric constant of the films was found to be quite high, with values greater than 5 and as high as 34. The RBS concluded that the films were uniform, and the nitrogen concentration was not higher than 10%.

Simulations of channeling spectra in the system p+28Si

The channeling process in the system p+ 28 Si was studied at the energy range Epa 1.7‐2.5 MeV in a back scattering geometry. Energy spectra were taken at several energies in both random orientation of the target and aligned at the directionh 100 i. The channeling spectra were simulated assuming an exponential behavior of the dechanneling process and the energy loss of protons in channeling direction was determined. ” 1998 Elsevier Science B.V.

Study of a multilayer wavelength-selective reflector prepared by the sol-gel process

Multilayer, wavelength-selective reflective coatings have been prepared by alternating deposition of TiO2 and SiO2 layers from solutions. Appropriate alkoxide solutions in ethanol were used as starting materials. The thickness of each layer, the profile of the coatings and the diffusion effects between multilayers were examined by the Rutherford back scattering method, using 12C ion scattering. The spectral reflectance of multilayer coatings was studied, as a function of both the number and thickness of layers, and the range of maximum reflectance determined.

Heavy ion RBS characterization of multilayer coatings deposited through the sol-gel technique

Abstract Multilayer reflecting thin films of the systems ZrO 2 SiO 2 and TiO 2 SiO 2 were deposited on glass surfaces using the sol-gel technique. A 12 C beam was utilized in RBS analysis to investigate the inner structure of these multilayer stacks. The layers showed uniform thickness and no evidence for significant diffusion between the layers was found. Optical Spectroscopy showed wavelength selectivity in the reflection of an 8-layer TiO 2 SiO 2 sample.

PIGE and XRF analysis of a nano-composite pillared layered clay material for nuclear waste applications

Abstract A special tailored aluminium pillared montmorillonite was prepared for radiostrontium removal in complex ionic environment. In a first series of experiments, the methods of PIGE and XRF were used to characterise the material as a cation exchanger. Furthermore, the charge carried by the pillars, a critical quantity of the pillaring process, was estimated. A qualitative model for the organisation and structural evolution of the clay lamellas from the nm to the mm scale was developed. The possible use of a microbeam for quantitative studies of pillared clays will be discussed.

Determination of the stopping power of channeled protons in SiO2 in the backscattering geometry

Energy spectra of protons channeling along the optical axis (c-axis) of a quartz crystal in the energy region Epa 1.7‐ 2.5 MeV in the backscattering geometry were taken and analyzed. Computer simulations based on the assumption that the dechanneling of protons follows an exponential law are in good agreement with the measured spectra, yielding electronic stopping powers for the specific crystal orientation that vary between 2.35 and 1.74 eV/ A, respectively, for the energy interval in consideration. The results are compared with the ones obtained in the past for simpler crystallographic structures, namely Sih 100 i and Sih 111 i, and an attempt is made to explain the occurring similarities as well as the diAerences. ” 2001 Elsevier Science B.V. All rights reserved.

A method of determining the stopping power of light ions in crystal channels in the backscattering geometry

Abstract A method for determining, in the Backscattering Geometry, the energy loss and mean dechanneling distance of light ions is presented. The results of applying this method to crystals of Si, MgO and Al 2 O 3 are discussed and possible improvements are indicated.

A study of the effects of 15N ion beam irradiation on organic compounds

Abstract The organic compounds EDTA, EDTA-Na, cellulose, and the biological samples bovine liver and DNA, were irradiated with 15 N ions at an energy of 8.5 MeV; the hydrogen yields during bombardment were monitored via the 1 H( 15 N, αγ) 12 C resonant reaction. In all cases, the hydrogen yield as a function of the total beam charge decreases in a multiple exponential way. This indicates that there are different mechanisms by which hydrogen is lost. By fitting the hydrogen yields with proper multiple exponential functions, the initial hydrogen concentration of the samples was determined.