Auswahl der wissenschaftlichen Literatur zum Thema „27Al(d,p)“

The pre - equilibrium and equilibrium double differential crosssections are calculated at different energies using Kalbach Systematicapproach in terms of Exciton model with Feshbach, Kerman andKoonin (FKK) statistical theory. The angular distribution of nucleonsand light nuclei on 27Al target nuclei, at emission energy in the centerof mass system, are considered, using the Multistep Compound(MSC) and Multistep Direct (MSD) reactions. The two-componentexciton model with different corrections have been implemented incalculating the particle-hole state density towards calculating thetransition rates of the possible reactions and follow up the calculationthe differential cross-sections, that include MSC and MSD models.The finite well depth, isospin, shell effects, Pauli effect, chargeeffect, pairing, surface, angular and linear momentum distributionscorrections are considered in this work. The nucleons (n and p) andlight nuclei (2D and 3T) have been employed as projectiles at thetarget 27Al nuclei and at different incident energies (4MeV, 14 MeVand 14.8MeV). The results have been compared with the availableexperimental and theoretical published work. The comparisons showan acceptable agreement with the TALAYS code (Tendel 2014) forthe reactions: 27Al (n, n) 27Al, 27Al (p, n) 63Zn, 27Al (p, D) 62Cu, 27Al(p, p) 63Cu and 27Al (p, 4He)60Ni and at different emission energiesand angles.

The 13C, 27Al and 11B NMR spectra of tri(tert-butyl)alane, AlBut3, and of the corresponding borane, BBut3, respectively, were examined in order to determine the magnitude of the coupling constants 1J(27Al,13C) = 94±5 Hz and 1J(13C,11B) = 52±2 Hz by measurement of the line widths of the 13C NMR signals and of the relaxation rates of the quadrupolar 27Al and 11B nuclei. This is the first example of 1J(27Al,13C) determined for a monomeric trialkylalane. In addition, the coupling constants were calculated by DFT methods (B3LYP) using the 6-311+G(d,p) basis set. The 1H, 13C and 27Al NMR spectra of lithium tetra(tert-butyl)alanate, Li[AlBut4], were measured under various conditions. Ion-pair separation in THF revealed the expected patterns for 27Al-13C spin-spin coupling across one and two bonds as well as for the three-bond 27Al-1H spin-spin coupling.

AbstractIntegral cross sections of the reactions 24Mg(n,p)24Na, 27Al(n,p)27Mg, 27Al(n,α)24Na, 58Ni(n,d + np)57Co and 60Ni(n,p)60Co were measured for the first time using the fast neutron spectrum of a TRIGA reactor extending from 0.5 to 20 MeV. The values obtained in this work were comparable with the recommended values for a pure 235U prompt fission spectrum. The measured integral value was utilized for integral test of excitation function of each reaction given in some data libraries, namely ENDF/B-VIII.0, TENDL-2017, IRDFF-1.05 and ROSFOND-2010. The integral measurements are generally consistent with the integrated values within 5 %, except for a few cases, e. g. the reaction 60Ni(n,p)60Co, where the data libraries appear to need improvement.

Two nuclear reactions of astrophysical interest, 26Mg(3He,d)27Al and 26Mg(d,p)27Mg, were measured for extraction of the Asymptotic Normalization Coefficients. Investigation of the target composition is presented, as well as the effects that showed up during analysis of the in-beam data obtained on CANAM accelerators in the Nuclear Physics Institute of the Czech Academy of Sciences (NPI CAS).

The oxidation behavior of ion-implanted steel samples in air, using Nuclear Reaction Analysis (NRA) and Rutherford Backscattering Spectroscopy (RBS) techniques. Austenitic stainless steel AISI 321 (Fe/Crl8/Ni8/Mn2/Ti) samples implanted with magnesium-, aluminum- and zirconium-ions (implantation energy 40 keV, dose: 1-1017 to 2-1017 ions/cm2) were oxidized in air in the temperature region 450-650 °C for several periods of time. The above implants were selected on the basis of the affinity to oxygen, as well as their ability to form protective oxides as MgO, AI2O3, Zr02 in order to improve the oxidation resistance of steel. The determination of the oxygen concentration and depth-profiles was performed by means of the 160(d, p)170 nuclear reaction. Rutherford Backscattering Spectroscopy was applied to investigate the near-surface layers and to determine the depth profiles of the implanted ions. The determination of the aluminum concentration and the depth distribution of the Al-ions was performed using the resonance at 992 keV of the 27Al(p, 7)28Si nuclear reaction whereas the concentration and the depth distribution of the Mg-ions by the means of the 24Mg(o;, p)27Al reaction. The excitation function of the 24Mg(a:, p)27Al nuclear reaction was studied in the energy region 4600-5000 keV and absolute cross section data allowing the determination of the Mg-profile were determined for this purpose.

AbstractThe 50Cr(n,2n)49Cr, 52Cr(n,2n)51Cr, 52Cr(n,p)52V, 55Mn(n,2n)54Mn, 55Mn(n,α)52V and 55Mn(n,γ)56Mn reaction cross sections at the neutron energy of 14.54 ± 0.24 MeV were measured by using activation method along with off-line γ-ray spectrometry. The 27Al(n,p)27Mg monitor reaction was used for the 52Cr(n,p)52V and 55Mn(n,α)52V reactions, whereas the 197Au(n,γ)198Au monitor reaction for the 55Mn(n,γ)56Mn reaction. The 27Al(n,α)24Na monitor reaction was used for other three reactions. The neutron beam was generated from the T(d,n)4He reaction using the Purnima neutron generator at BARC, Mumbai. The covariance analysis for the uncertainties of reaction cross sections was performed by considering the correlations between different attributes. The present results were compared with the literature data, evaluated data of ENDF, ROSFOND, CENDL, JENDL and JEFF libraries as well as with the theoretical values based on TALYS-1.9 calculation.

The extracted s-wave scattering amplitude from both the polarized and unpolarized d + d → 4He + η reaction at 2385.5 MeV/c allowed to determine the scattering length which fulfills the requirements for bound η. In the p + 27Al → 3He + p + π- + X reaction studied at recoil free kinematics the η meson is produced almost at rest and so it can be bound with enhanced probability. This state proceeds via N*(1535) resonance and the decay products proton and pion emitted into opposite direction are detected in concidence with 3He produced at zero degree. Under these conditions some hints for bound state can be observed with an upper limit of the cross section of ≈ 0.5 nb.

The use of deuteron bunches collectively accelerated in a Luce diode to an average energy of 1200±200 keV and a number of 1013 per shot is shown for the radioactive determination of the stoichiometry of AlN coatings with a known thickness. In each shot, the deuteron energy was determined by measuring the drift velocity of the virtual cathode collectively accelerating deuteron bunches, and the coating stoichiometry was determined with an accuracy of no worse than ±5% from the ratio of the activities of the 28Al/15O radionuclides induced in the nuclear reactions 27Al(d,p)28Al and 14N( d,n)15O, respectively.

Collective acceleration of protons and deuterons is compared in the same geometry of a Luce diode with a polyethylene anode at an accelerating diode voltage of 250 kV, current and pulse duration of relativistic electrons up to 30 kA and 90 ns, respectively. The accelerated ions were intercepted by B4C, BN, and AlN plates, in which analytical radionuclides were produced according to nuclear reactions 10B( p , α)7Be, 12C( p, γ)13N, 10B( d , n )11C, 12C( d , n )13N, 14N( d , n )15O and 27Al( d , p )28Al. The ion energy was determined according to the ratios of activity of the analytical radionuclides, while the number of accelerated ions was calculated from the number of induced nuclei of the radionuclides. It was found that the velocities of the main group of protons and deuterons were the same within the measurement error, and the average number of ions accelerated in one pulse was, on average, 3 times higher when protons were accelerated.

Τhe 70Ge(n,2n)69Ge, 72Ge(n,a)69mZn, 72Ge(n,p)72Ga and 73Ge(n,p)73Ga reactions have been measured by means of the activation technique at neutron energy 17.9 MeV. The quasimonoenergetic neutron beam was produced via the 2H(d,n)3He reaction at the 5.5 MV Tandem Van de Graaff accelerator of NCSR “Demokritos.” Isotopically highly enriched targets of 70Ge, 72Ge and 73Ge, provided by the nTOF collaboration at CERN, have been used, thus allowing accurate cross section measurements since no corrections are needed to compensate for the parasitic reactions from neighboring isotopes that exist in the case of using natural Ge target. The cross section has been deduced with respect to the 27Al(n,α)24Na reference reaction.

L’IBA (Ion Beam Analysis) a été largement utilisée pour analyser quantitativement et avec une grande sensibilité la composition et les profils de profondeur des éléments dans les régions superficielles des solides. Pour l’analyse des éléments légers, on peut trouver des réactions nucléaires appropriées et, en particulier, les réactions induites par les deutérons, (d,p) ou (d,α), ont souvent des chaleurs de réaction Q élevées et des sections efficaces appréciables. Dans de nombreux cas de NRA (Nuclear Reaction Analysis) de films minces, des pics isolés de particules de réaction peuvent être obtenus avec un choix judicieux de l’angle de diffusion, de l’énergie du faisceau incident et des feuilles de filtrage devant le détecteur de particules chargées. Cependant, en général, la NRA génère des spectres complexes avec des pics qui se chevauchent, en particulier pour les échantillons épais. La connaissance des sections efficaces pour les cas de pics isolés est déjà utile pour concevoir des expériences visant à déterminer les contenus élémentaires des films minces. De nombreuses sections efficaces de ce type, par exemple 16O(d,p0)17O, 16O(d,p1)17O, 12C(d,p0), 14N(d,α0), ont été soigneusement mesurées dans des gammes d’énergie et d’angle d’intérêt analytique [87–90]. Il est parfois possible d’analyser plusieurs éléments légers simultanément par NRA. La connaissance des sections efficaces des réactions qui ne sont pas nécessairement d’un intérêt primordial pour l’analyse des couches minces, est alors souvent nécessaire pour les cas où les cibles contiennent des éléments donnant lieu à des réactions produisant des groupes de particules qui interfèrent avec le pic analytique primaire, et encore plus dans le cas de la NRA sur cible épaisse où l’élargissement des spectres de particules dû à l’épaisseur non nulle de la cible entraîne une probabilité beaucoup plus grande d’interférences élémentaires [26, 38, 91]. La nécessité de disposer de sections efficaces précises, même lorsqu’elles ne présentent pas un intérêt primordial pour un problème analytique spécifique, ou dans des gammes d’énergie qui ne sont pas directement utiles sur le plan analytique, s’est également accentuée récemment, avec l’introduction du concept d’IBA totale [92–94], dans lequel toutes les informations des spectres IBA [95] sont exploitées, et l’utilisation croissante de l’intelligence artificielle et des approches d’apprentissage automatique pour optimiser l’extraction d’informations de toutes les parties des spectres IBA. Jusqu’à présent, les réseaux neuronaux artificiels (ANN) ont été appliqués au cas de la spectrométrie de rétrodiffusion de Rutherford, où les sections efficaces sont connues analytiquement, mais l’extension fiable de ces techniques avancées de traitement des données à la NRA nécessite les meilleures sections efficaces de réaction nucléaire possibles. En outre, des sections efficaces de réaction nucléaire expérimentale précises sont nécessaires pour fournir des paramètres appropriées pour les approximations et les expressions appropriées des modèles théoriques de mécanismes de réaction nucléaire. L’oxygène étant l’élément le plus abondant de la croûte terrestre et en raison de l’importance universelle des oxydes dans les sciences de la terre et des matériaux, des sections efficaces précises pour les réactions nucléaires sur 16O et 18O ont déjà été déterminées [87, 96]. Le deuxième élément le plus abondant est le silicium, et bien qu’il s’agisse d’un élément de masse intermédiaire du point de vue de l’IBA, il y a également des réactions nucléaires d’intérêt analytique qui ont été déterminées [88, 97]. L’aluminium, troisième élément le plus abondant, est largement utilisé dans l’industrie pour ses propriétés mécaniques et électriques, ses applications décoratives et sa résistance aux agressions environnementales, notamment après une passivation électrochimique appropriée. L’aluminium est également largement présent dans les roches [...]
The overall objective of this thesis is to contribute experimentally determined and evaluated cross sections to a differential cross-section database for Ion Beam Analysis (IBA) that contains accurate and reliable data freely available to the user community, such as the Ion Beam Analysis Nuclear Data Library (IBANDL) database (https://www-nds. iaea.org/exfor/ibandl.htm) [1]. In the first part of the present thesis, we determined differential cross-sections of the reactions 27Al(d, p&α) and benchmarked them with thick target spectra derived from pure aluminum in two independent laboratories. The differential cross section of 27Al(d, p&α) reactions was determined between 1.4 MeV and 2 MeV at scattering angles of 165◦, 150◦, and 135◦ in the VDGT laboratory in Tehran (Iran), as well as measuring them again, including target preparation, at a scattering angle of 150° with independent equipment at INSP in Paris (France). We found close agreement between these two experimental measurements in two different laboratories at 150°. There is no nuclear reaction model that can be adjusted to represent these cross sections since the compound nucleus has a level structure that cannot be treated with current models. We proposed a fitted Fourier series function to represent the evaluated data to define the Al-cross sections. The evaluated differential cross sections have been benchmarked and validated using thick target charged particle spectra obtained using incident deuteron beams of energies between 1.6 MeV and 2 MeV at both laboratories. The validation was performed by fitting deuteroninduced particle spectra obtained from a high purity bulk Al target with SIMNRA, and the thick target spectra are reproduced, allowing the recommendation of the use of these cross sections for NRA. In the second part of the present thesis, the elastic proton scattering cross sections on 17O were measured for the first time at the SAFIR platform at INSP in Paris. Thin films of 17O were prepared by thermal oxidation of Si at 1100 ◦C under 17O2. The physical thickness of the silica was determined by ellipsometry and the atomic thickness by RBS with an uncertainty of 3%. The small quantities of 18O and 16O, present as impurities in the highly enriched 17O2 gas used to grow these films, were determined by the established NRA techniques using the 18O(p, α)15N and 16O(d, p1)17O nuclear reactions. We determined the yield of elastically scattered protons using the corresponding peak in the Elastic Backscattering (EBS) spectra; however, this peak sits on the large continuiiious signal from the silicon substrate. The Si signal was significantly suppressed by aligning the incident beam with the < 100 > axis of the single crystal silicon by ion channeling. The solid angle of the detector, placed at a scattering angle of 165◦, was determined by elastic scattering measurements of 2 MeV alpha particles on a reference sample of Bi implanted in Si. The measured 17O(p, p) cross section, with a systematic uncertainty of about 14%, consists of several resonant structures superimposed on a smoothly varying component increasing ranging from about 1.2 times the Rutherford cross section at 600 keV to about 3 times Rutherford at 2 MeV. A resonance at 1230 keV shows promise for EBS depth profiling, especially at large backscattering angles