Cross section measurements of the reactions induced by deuteron particles on ¹³C

Nuclear reactions induced by deuterons have been found to be an ideal analysis tool for depth profiling of light elements in the first microns of materials. In particular, the nonresonant nuclear reactions (d, p), (d, α) and (d, t) are well adapted to determine depth distributions of C and C in a single measurement. Nevertheless, only the cross section of the C(d, p)C nuclear reaction is well known for various experimental configurations. Thus, we measured the differential cross sections of the C(d, p)C, C(d, α)B, C(d, α)B and C(d, t)C nuclear reactions. A thin C foil (83 nm thick) was used and the measurements were performed at deuteron energies from 0.5 to 1.65 MeV for different laboratory angles of detection (135°, 150° and 165° with respect to the incident beam). Then, the results obtained in this work were compared to cross sections measured by Marion and Weber for a detection angle of 135°. © 2006 Elsevier B.V. All rights reserved

Formation of carbon nitride compounds during successive implantations in copper

Copper substrates are successively implanted with carbon and nitrogen (C and N) at high fluences (5 × 10 and 1 × 10 at. cm, respectively) in order to synthesize specific carbon nitride compounds. The concentration as well as the depth distribution of carbon C and nitrogen N are determined using non resonant nuclear reactions induced by a 1.05 MeV deuteron beam. The use of (d,p) and (d,α) reactions allows us to profile both C and N elements with a single and relatively rapid measurement and a quite good resolution. The bonded states of carbon and nitrogen are studied as a function of depth by X-ray photoelectron spectroscopy (XPS). The curve fitting of the C 1s and N 1s photopeaks shows that carbon and nitrogen atoms exist in different chemical states depending on the analysis depth, which correspond to specific kinds of chemical bonds. At least two characteristic C-N bonds are detected indicating that different carbon nitride compounds have been formed during the implantations. © 2005 Elsevier B.V. All rights reserved

Depth profiling of carbon and nitrogen in copper using nuclear reactions

Simultaneous implantations of C and N were performed into copper using the non-deviated beam line of a 2 MV Tandetron accelerator. The atomic composition of the implanted layer was measured using appropriate nuclear reactions with a 1.05 MeV deuteron beam. C(d, p)C and N(d, α)C nuclear reactions were used to depth profile simultaneously C and N and to determine the relative contribution of multi-ionised C and N ions to the carbon and nitrogen distribution. We also used the narrow resonance at 429 keV of the N(p, αγ)C nuclear reaction to check the validity of our results. The depth distributions obtained with this resonant nuclear reaction confirmed that (d, p) and (d, α) reactions are well suited to profile both carbon and nitrogen elements with a quite good resolution. Moreover, using these reactions makes possible to profile C and N atoms with a single and relatively rapid measurement. © 2006 Elsevier B.V. All rights reserved

Scent lure effect on camera-trap based leopard density estimates

Density estimates for large carnivores derived from camera surveys often have wide confidence intervals due to low detection rates. Such estimates are of limited value to authorities, which require precise population estimates to inform conservation strategies. Using lures can potentially increase detection, improving the precision of estimates. However, by altering the spatio-temporal patterning of individuals across the camera array, lures may violate closure, a fundamental assumption of capture-recapture. Here, we test the effect of scent lures on the precision and veracity of density estimates derived from camera-trap surveys of a protected African leopard population. We undertook two surveys (a 'control' and 'treatment' survey) on Phinda Game Reserve, South Africa. Survey design remained consistent except a scent lure was applied at camera-trap stations during the treatment survey. Lures did not affect the maximum movement distances (p = 0.96) or temporal activity of female (p = 0.12) or male leopards (p = 0.79), and the assumption of geographic closure was met for both surveys (p >0.05). The numbers of photographic captures were also similar for control and treatment surveys (p = 0.90). Accordingly, density estimates were comparable between surveys (although estimates derived using non-spatial methods (7.28-9.28 leopards/100km 2 ) were considerably higher than estimates from spatially-explicit methods (3.40-3.65 leopards/100km 2 ). The precision of estimates from the control and treatment surveys, were also comparable and this applied to both non-spatial and spatial methods of estimation. Our findings suggest that at least in the context of leopard research in productive habitats, the use of lures is not warranted