Cross Sections For Fluorine Research Articles

Dynamics Research on Electron-Stimulated Desorption of Fluorine from Fluorinated Graphene Surface

The experiment of stimulating fluorine to desorb from fluorinated graphene was carried out in order to make clear the dynamical mechanism of the electron-stimulated desorption (ESD) of fluorine. X-ray photoelectron spectroscopy (XPS) with an electron beam gun accessory was used not only to stimulate fluorine to desorb, but also to characterize the concentration of fluorine after ESD. The concentration of fluorine dropped quickly following electron beam irritation. The desorption cross section of fluorine is about 1.5×10-17 cm2. It was also found that electron beam with low current density did not damage the structure of fluorinated graphene. These results confirm that it is feasible to fabricate all graphene electronics by ESD technology.

Measurement of Charged-Particle Emission Double-Differential Cross Section of Fluorine for 14.2MeV Neutrons

We carried out detailed measurement of the double-differential cross sections of fluorine for the emissions of protons, deuterons, tritons, and α-particles with 14.2MeV incident neutrons. An improved charged-particle spectrometer with a pencil DT-neutron beam furnished at the FNS facility of the Japan Atomic Energy Agency enabled us to obtain precise data with a fine energy resolution over a wide energy range and an angular range from 15 to 150°. The present experiment is the first simultaneous measurement of the four different kinds of charged particles and provides useful data to establish a nuclear reaction model of fluorine as well as to confirm previous experimental data. Angular-differential cross sections for several discrete peaks corresponding to excited states of residual nuclei were extracted to discuss the reaction mechanism of charged-particle emission. The obtained data suggest that the charged-particle emission reaction of fluorine has a complicated mechanism in which there are contributions from the direct reaction, pre-equilibrium, and equilibrium processes. The obtained data were compared with the nuclear data evaluated in JENDL-3.3 and ENDF/B-VII.0. The results show large differences in the energy and angular distributions of emitted particles and the charged-particle production cross sections between the measured and evaluated data.

High-energy neutron detection and spectrometry with superheated emulsions

The response of some superheated emulsions was investigated using quasi-monoenergetic neutron beams in the 46–134MeV energy range at the Université Catholique de Louvain, Louvain la Neuve, Belgium and at The Svedberg Laboratory, Uppsala, Sweden. In order to determine the detector response to the high-energy beams, the spectra of incident neutrons were folded over functions modeled after the cross-sections for the neutron-induced production of heavy ions from the detector elements. The cross-sections for fluorine and chlorine were produced in this work by means of the Monte Carlo high-energy transport code HADRON based on the cascade-exciton model of nuclear interactions.

High-energy neutron dosimetry with superheated drop detectors.

A systematic analysis of the response of dichlorodifluoromethane superheated drop detectors was performed in the 46-133 MeV energy range. Experiments with quasi-monoenergetic neutron beams were performed at the Université Catholique de Leuvain-la-Neuve, Belgium and the Svedberg Laboratory, Sweden, while tests in a broad field were performed at CERN. To determine the response of the detectors to the high-energy beams, the spectra of incident neutrons were folded over functions modelled after the cross sections for the production of heavy ions from the detector elements. The cross sections for fluorine and chlorine were produced in this work by means of the Monte Carlo high-energy transport code HADRON based on the cascade exciton model of nuclear interactions. The new response data permit the interpretation of measurements at high-energy accelerators and on high-altitude commercial flights, where a 30-50% under-response had been consistently recorded with respect to neutron dose equivalent. The introduction of a 1 cm lead shell around the detectors effectively compensates most of the response defect.

Charge-state dependence of fluorineKx rays in F-Ne collisions

The $K$ x-ray-production cross sections for fluorine are measured as a function of charge state for 15-MeV ${\mathrm{F}}^{q+}+\mathrm{Ne}$ collisions. The measurements are differential in energy of the $K$ x rays with sufficient resolution to identify the final-state configurations of the fluorine ions following the collision. The final states are identified with the processes of single $K$-shell to $L$-shell excitation, single $K$-shell - multiple $L$-shell ionization, and single $L$-shell electron capture.

Dynamics of water and amphiphile molecules in lamellar liquid crystalline phases

Thin layers of water of controlled thickness may be prepared between the fluorocarbon sheets in the ammonium perfluoro-octanoate/water system at 23°C. Neutron scattering in this system is almost exclusively from the inter lamellar water due to the low scattering cross-section of fluorine and carbon. In a first series of experiments, the modification of water diffusion as a function of layer thickness has been studied and the anisotropy of this effect determined by using oriented samples. The results are compared with nuclear magnetic resonance spin-echo measurements, which measure the same phenomenon but on a timescale approximately 106 times longer. The difference between these two types of measurements allows some tentative conclusions to be made about the presence of cracks and holes in the lamellae.In the second series of experiments the motion of probe molecules (for example octanol) has been studied in the fluorocarbon layer to determine diffusion kinetics in this region.

Slow Neutron Velocity Spectrometer Studies of H, D, F, Mg, S, Si, and Quartz

The neutron proton cross section has been measured using a paraffin sample. The observed free proton cross section is (20.6\ifmmode\pm\else\textpm\fi{}1). The cross section-curve below 0.05 ev is well matched by a theoretical curve and approaches 4 times the free proton cross section at very low energies. The thermal cross section of ${\mathrm{D}}_{2}$O is well matched by the curve ${\ensuremath{\sigma}}_{{\mathrm{D}}_{2}\mathrm{O}}=(10+0.72{E}^{\ensuremath{-}\frac{1}{2}})$. The free cross section of D is (3.3\ifmmode\pm\else\textpm\fi{}0.2). The thermal cross section of fluorine in a fluorocarbon oil is well matched by the curve ${\ensuremath{\sigma}}_{\mathrm{F}}=(3.3+0.11{E}^{\ensuremath{-}\frac{1}{2}})$. The cross section of the free fluorine is (3.3\ifmmode\pm\else\textpm\fi{}0.5). The cross section of Mg is essentially constant at (3.4\ifmmode\pm\else\textpm\fi{}0.1) ev. No resonances are observed in Mg. Microcrystalline interference effects are noticed in the low energy region. The thermal cross section of sulfur is well matched by the curve $\ensuremath{\sigma}=(1+0.098{E}^{\ensuremath{-}\frac{1}{2}})$. No resonances are observed in S. The cross section of Si is essentially constant at (2.25\ifmmode\pm\else\textpm\fi{}0.1). No resonances are observed in Si. Microcrystalline interference effects are noticed in the low energy region. The effective neutron cross section of an optical quartz crystal decreases from the additive cross section of (9.2\ifmmode\pm\else\textpm\fi{}0.2) at \ensuremath{\sim}10 ev to 1.25 at 0.025 ev which is taken to be the residual incoherent cross section.