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

Simultaneous depth profiling of the ¹²C and ¹³C elements in different samples using (d,p) reactions

Nuclear reactions (d,p) are often used to perform depth profiling of light elements in solids. In particular, protons coming from C-12(d,p(0)) C-13 and C-13(d,p(0)) C-14 reactions are emitted at very different energies. Consequently these two reactions can be used to depth profile C-12 and C-13 simultaneously. Nevertheless the cross-section of C-13(d,p(0)) C-14 reaction is 10 times smaller than the C-12(d,p(0)) C-13 one. So, the geometry of detection must be judiciously chosen in order to depth profile these two elements with a high sensitivity and good resolution. In the framework of this study we have performed 400 keV C-13 ions implantation into polished copper substrates at different temperatures and implanted doses with a 2 MV Tandem accelerator. Using the reactions described above, we have studied the evolution of C-13 depth profile as a function of implanted doses and temperature. We have also determined the origin of surface contamination that appears during the implantation process

XPS and NRA depth profiling of nitrogen and carbon simultaneously implanted into copper to synthesize C₃N₄ like compounds

Carbon nitride nano-compounds have been synthesized into copper by simultaneous high fluence (10 at. cm) implantation of C and N ions. The implantations were performed with a 2 MV Tandem accelerator. The terminal voltage was fixed at 400 kV and the target temperature was maintained at 250 °C during the process. Depth profiling of C and N has been performed using (d,p) and (d,α) nuclear reactions induced by a 1.05 MeV deuteron beam. The retained dose deduced from NRA measurement is relatively close to the implanted one, which indicates that carbon and nitrogen diffusion processes were likely limited during implantation. The chemical bonds between carbon and nitrogen were studied as a function of depth by X-ray photoelectron spectroscopy (XPS). The C 1s and N 1s core level photoelectron spectra revealed the presence of different types of C-N bonds, which correspond to specific kinds of chemical states. These results indicate that different carbon nitride compounds have been formed during the implantation. © 2009 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

Accurate experimental determination of gallium K- and L3-shell XRF fundamental parameters

The fluorescence yield of the K- and L3-shell of gallium was determined using the radiometrically calibrated (reference-free) X-ray fluorescence instrumentation at the BESSY II synchrotron radiation facility. Simultaneous transmission and fluorescence signals from GaSe foils were obtained, resulting in K- and L3-shell fluorescence yield values consistent with existing database values(omega_Ga_K=0.515 +- 0.019, omega_Ga_L3=0.013 +- 0.001). For the first time, these standard combined uncertainties are obtained from a properly constructed Uncertainty Budget. These K-shell fluorescence yield values support Bambynek's semi-empirical compilation from 1972: these and other measurements yield a combined recommended value of omega_Ga_K=0.514 +- 0.010. Using the measured fluorescence yields together with production yields from reference Ga-implanted samples where the quantity of implanted Ga was determined at 1.3% traceable accuracy by Rutherford backscattering spectrometry, the K-shell and L3-subshell photoionization cross sections at selected incident photon energies were also determined and compared critically with the standard databases.Comment: 17 pages, 6 figure

New polyvalent low background γ-ray setup at UNamur: Application to S-factor measurements for the 13C(p,γ)14N reaction

The Laboratory of Analysis by Nuclear Reaction (LARN) at the University of Namur (Belgium) is equipped with a low background γ-ray detection system. This setup is made of one ton of lead as passive shielding and plastic scintillators as an anti-cosmic active shielding which covers a large area around a 3.5 × 3.5 inches HPGe detector. This setup makes it possible to reduce the background level from two to three orders of magnitude, depending on the energy range of interest. In this work, this polyvalent detection system is described and used to refine the cross-section measurements of the 13C(p,g)14N nuclear reaction at middle and lowenergies. The reaction 13C(p,g)14N plays an important role in the CNO cycle and s-process in stellar evolution. In this work, we studied more precisely the 13C(p,g)14N ground transition (= 8.06 MeV) for incident energies ranging from 147 to 574.3 keV in the centre-of-mass system generated by the 2 MV Tandetron accelerator ALTAÏS installed at the LARN. Our measurements performed both in reverse (i.e. 1H(13C,g)14N) and direct kinematics are in good agreement with all the data available in the literature, validating our low background detection system.The Laboratory of Analysis by Nuclear Reaction (LARN) at the University of Namur (Belgium) is equipped with a low background γ-ray detection system. This setup is made of one ton of lead as passive shielding and plastic scintillators as anti-cosmic active shielding that covers a large area around a 3.5 × 3.5 in. 2 high purity germanium detector. This setup makes it possible to reduce the background level from two to three orders of magnitude, depending on the energy range of interest. In this work, this polyvalent detection system is described and used to refine the cross-section measurements of the 13C(p,γ) 14N nuclear reaction at middle and low energies. The reaction 13C(p,γ) 14N plays an important role in the carbon-nitrogen-oxygen cycle and s-process in stellar evolution. In this work, we studied more precisely the 13C(p,γ) 14N ground transition (E γ = 8.06 MeV) for incident energies ranging from 147 to 574.3 keV in the center-of-mass system generated by the 2 MV Tandetron accelerator ALTAÏS installed at the LARN. Our measurements performed both in reverse [i.e., 1H( 13C,γ) 14N] and direct kinematics are in good agreement with all the data available in the literature, validating our low background detection system.</p