Oxygen depth profiling in Kr-implanted polycrystalline alpha titanium by means of O(α,α)O resonance scattering

The ¹⁶O(α,α)¹⁶O resonance scattering was applied to study the effects of ion implantation on the oxygen distribution in the near surface region of polycrystalline titanium implanted with 180 keV krypton ions at fluences, ranging between 1 × 10¹⁴ and 5 × 10¹⁵ Kr⁺/cm². Two sample sets were chosen: as-received polycrystalline titanium discs rolled and annealed in half-hard condition which had a thick oxygen layer and similar samples in which this surface layer was removed by polishing. An increase of the mean oxygen concentration observed in both unpolished and polished samples at low fluence suggests a knock-on implantation of surface oxygen atoms. At high fluence, an overall decrease in the mean oxygen concentration and mean oxygen depth suggests an out-diffusion of near-surface oxygen atoms.     

Methodology and application of the nuclear resonance reaction 16O(α, α)16O for the profiling of titanium oxide

A method is presented for the application of the ¹⁶O(α,α)¹⁶O resonance at 3.045 MeV to the depth profiling of oxide films. The resonance yield is translated into oxygen to metal stoichiometry as a function of the depth probed. The method is applied to anodic titanium oxide films grown in the absence and presence of tungsten anions. The oxygen depth profile is then utilized to obtain the profile of the dopants (W) incorporated in the oxide. A depth resolution of 6 μg/cm is achieved. The incorporation of tungsten anions of the order of 2 at.%, evaluated from the RBS yields, precludes the establishment of a constant oxygen to metal stoichiometry in the doped film. The tungsten atomic fractions have an estimated error of 5%.     

Tritium depth profiling in surface regions of solids by use of the T(d, α)n reaction

Tritium depth profiling with an incident deuteron beam by use of the T(d, α)n reaction was studied for the case where the energy spectrum of the emitted α-particles is used to evaluate the depth profile. Appropriate probing energies were considered to be from 100 keV to 1 MeV. The characteristics of this method were evaluated for a variety of experimental measurement conditions. The method was demonstrated for thin titanium layers containing tritium at probing energies of about 600 keV. The distribution of tritium obtained were almost uniform with depth, as expected, and the measured tritium content agreed well with that nominally stated.     

Analyses of d ~(16)O and p ~(19)F Reaction

The nuclear data of d ~(16)O reaction at incident energies spanning 0.1 to 35.0 MeV were obtained by calculation with optical model, distorted wave Born approximation, preequilibrium nuclear reaction and Hauser-Feshbach theory. The cross sections of d ~(17)F and p ~(17)F reaction were predicted.     

~(19)F(p,αγ)~(16)O反应产生的6～7MeVγ射线产额及其特性研究

测量了在Ep=34 0～ 34 90keV能区质子束引起19F( p ,αγ) 16O反应发射的 6 12 9、6 917和7 117MeV 3组γ射线的产额 ,并对其特性进行了分析讨论     

~(19)F(p,αγ)~(16)O瞬发核反应测定茶叶中的含氟量

本文介绍了在400kV高压倍加器上,利用~(19)F(p,αγ)~(16)O瞬发核反应测量国内150余种茶叶样品含氟量的原理及实验装置,给出了一批典型的测量结果。结果表明:同一品种的茶叶,茶的品级数越大,含氟量越高;茶叶的品种越好,含氟量越低。     

Depth profiling of Mg by 2010 keV resonance of Mg(p,p′γ)Mg nuclear reaction

Studies on the characteristics of 2010 keV resonance in ²⁴Mg(p,p′γ)²⁴Mg nuclear reaction for depth profiling Mg in thin films are reported. The resonance reaction, based on the detection of characteristic 1368 keV γ-rays, enables interference free measurement of Mg down to 2 × 10²⁰ atoms/cm³ and has a probing depth of about 20 μm. The width of the resonance extracted from excitation curves for thick (>180 nm) thermally grown elemental Mg films, by SPACES is about 350 ± 50 eV. The reaction has been used to depth profile Mg in a Mg/Ti/Mg/Si film which provides interesting information on interfacial mixing involving Ti layer and the underlying Mg layer.     

Theoretical Analysis of Neutron Double-Differential Cross Section of n ~(19)F at 14.2 MeV

A new reaction model for light nuclei of 1p shell is expanded to 19F with 2s-1d shell nucleus. The double-differential cross sections of total outgoing neutron for n 19F reactions at En = 14.2 MeV are calculated and analyzed, and the calculated results ag…     

Depth profiling of lithium by use of the nuclear reaction 7Li(p, α)4He

The nuclear reaction ⁷Li(p, α)⁴He induced by a primary beam of 1.5 MeV protons was used for measuring depth profiles of Li in Al. From the experiments with a detection angle of 90° a detection sensitivity of about 400 ppm was obtainable for a proton incidence at 30° from the surface. The best depth resolution was about 0.1 μm at 85° incidence. The sampling depth was over 17 μm at 50° incidence. These results are in good agreement with theoretical predictions. After the measurement of the reaction cross section, the applicability of the method to analyzing Li behaviour in solids was experimentally demonstrated on an AlLi (3.53 at.%) alloy.     

Observation of the bond-dependent Doppler broadening of the p(15N, αγ)12C nuclear reaction

Excitation curves for the p(¹⁵N, αγ)¹²C nuclear reaction have been measured on a number of hydrogen-bearing gases to investigate the bond-dependent Doppler broadening resulting from the motion of the target hydrogen atoms. Contributions to the resonance width due to the intrinsic width of the resonance, gas-induced beam energy loss and energy straggle, accelerator beam energy spread, and Doppler broadening are considered. Calculations of Doppler broadening based on molecular spectroscopy data are presented.     

用~(19)F(p,αγ)~(16)O瞬发核反应测量环境污染土壤样品的含氟量

氟及其化合物在工农业生产中的广泛应用,造成大量的含氟废气、废水和废渣,污染了周围的空气、水源和植物,并富集在土壤中,这是一个较为突出的问题,日益为人们所重视。目前,我国环境保护规划已把氟列为重点防治的六种大气污染之一。因此,我们选用~(19)F(ρ,αγ)~(16)O瞬发核反应来测量污染土壤的含氟量。     

Expressions for the ~(18)F(p,α) ~(15)O and ~(18)F(p,γ) ~(19)Ne Astrophysical Reaction Rates

Hydrogen is burned explosively in stellar explosions such as novae, X-ray bursts, X-ray pulsars, and supemovae, as well as possibly in other exotic astrophysical environments such as accretion disks around black holes, Thorne-Zytkow objects, and supermassive stars. Temperatures in these environments range from 107 to 109 K and above, and densities from 102 to 106g/cm3. In such sites,     

A new measurement of the 429 keV 15N(p, αλ) 12C resonance. Applications of the very narrow width found to 15N and 1H depth location: II. Applications

The unexpectedly narrow width Γ_p = 120 eV or Γ_N¹⁵ = 1.8 keV of this resonance opens quite new possibilities for its use in ¹⁵N or ¹H depth location and for hydrogen adsorption studies using ¹⁵N beams. Resonance depth profiling of ¹⁵N is possible with much better near-surface depth resolution than thought until recently. In ¹H resonance depth profiling the indeep background originating from the surface contamination peak is also much smaller than previously assumed. These features are illustrated by ¹⁵N self-diffusion experiments in NbN films and by ¹⁵N adsorption experiments on copper single crystals in ultrahigh vacuum. The strong effect of Doppler broadening on the actual ultimate near-surface depth resolution of hydrogen depth profiling with ¹⁵N beams is discussed as well as the use of this resonance for the direct measurement, based on the Doppler effect, of the vibration speed distribution of hydrogen atoms adsorbed on clean surfaces.     

Determination of thermal neutron cross-section and resonance integral for the As (n, γ)As reaction by activation method using Mn (n, γ)Mn as a monitor

Nuclear constants for use in reactor activation analysis especially (n, γ) cross-sections and absolute gamma intensities, are known to show a rather large scatter in literature. Thermal and resonance cross-sections for the ⁷⁵As (n, γ)⁷⁶As reaction is determined by the method of foil activation using ⁵⁵Mn (n, γ)⁵⁶Mn as a reference reaction. The experimental sample with and without a cadmium cover of 1-mm wall thickness was irradiated in the isotropic neutron field of the outer irradiation sites 7 of Ghana Research Reactor-1 facility which is a miniature neutron source reactor designed by the Chinese. The irradiation channel used has a neutron spectral parameter (α) found to be (0.037 ± 0.001). The induced activity in the sample was measured by gamma ray spectrometry with a high purity germanium detector. A standard solution of Arsenic was used for the analysis. The necessary correction for gamma attenuation, thermal neutrons and resonance neutron self-shielding effects were not taken into account during the experimental analysis because they were negligible. By defining cadmium cut-off energy of 0.55 eV, the result for ⁷⁵As (n, γ)⁷⁶As reaction was found to be: thermal neutron cross-section σ₀ = (4.28 ± 0.19) b and resonance integral I₀ = (61.88 ± 1.07) b.     

Further Analysis of Neutron Double-Differential Cross Section of n ~(16)O at 14.1 and 18 MeV

By using a new reaction model for light nuclei, the double-differential cross section of total outgoing neutron with LUNF code for n 16O reactions at En=14.1 MeV and 18 MeV have been calculated and analyzed. The opened reaction channels, which have contri…