Prompt gamma emission excitation functions for PIGE analysis

A proton energy scan from 2.2 to 3.8 MeV (Δ E = 20 keV) was performed to measure differential cross sections of prompt gamma reactions on Li, B, F, Mg, Al, Si and P at θ_lab = 90°. The purpose of the present work is to provide the basic data necessary to set up the PIGE (proton induced gamma ray emission) technique for the analysis of thin and intermediate samples.     

Proton elastic scattering cross sections of carbon,nitrogen and silicon for backscattering analysis in the energy range 0.7—2.5 MeV

Differential elastic scattering cross sections of 0.7—2.5 MeV protons for carbon, nitrogen and silicon have been determined at a scattering angle θ = 170°. Results from previous measurements near θ = 170° show large variations, of the order of 10–30% in the nonresonant regions. The purpose of the present investigations is to tabulate cross section data for backscattering analysis at a single scattering angle for many elements. Proton backscattering in the non-Rutherford energy region is more sensitive in the detection of C, N and many other light elements than other ion beam methods when a high background from the matrix is absent. Proton backscattering by using the present scattering cross sections and computer data analysis are outlined. The possible interference from other nuclear reactions is considered.     

The 11B(p,α0)8Be nuclear reaction and 11B(p,p)11B backscattering cross sections for analytical purposes

The ¹¹B(p,α₀)⁸Be nuclear reaction and the ¹¹B(p,p)¹¹B backscattering cross sections were measured at a laboratory scattering angle of 165° in the energy range from 1700 to 2700 keV with an absolute accuracy of about 7%. The cross section values were derived by using the simultaneously measured RBS spectra of the protons backscattered from a thin gold layer. The measured cross section values are compared with X-ray photoelectron spectroscopy (XPS) and heavy ion elastic recoil detection analysis (HERDA) results of amorphous hydrogenated boron/carbon (a-B:C:H) layers. The cross section data are presented in graphical and tabular form.     

Differential cross section measurements of the S(d,p)S reaction for nuclear reaction analysis purposes

Differential cross sections of the ³²S(d,p_{0,1,2,3,4-6,7}) reactions were determined for deuteron energies E_lab = 1975-2600 keV (in steps of 25 keV) and for detector angles between 140-170° in steps of 10°. A comparison of the experimental data with the existing ones and possible applications to nuclear reaction analysis (NRA) studies are discussed.     

Proton elastic scattering and proton induced γ-ray emission cross-sections on Na from 2 to 5 MeV

Differential cross-sections for proton elastic scattering on sodium and for γ-ray emission from the reactions ²³Na(p,p′γ)²³Na (E_γ = 440 keV and E_γ = 1636 keV) and ²³Na(p,α′γ)²⁰Ne (E_γ = 1634 keV) were measured for proton energies from 2.2 to 5.2 MeV using a 63 μg/cm² NaBr target evaporated on a self-supporting thin C film.The γ-rays were detected by a 38% relative efficiency Ge detector placed at an angle of 135° with respect to the beam direction, while the backscattered protons were collected by a Si surface barrier detector placed at a scattering angle of 150°. Absolute differential cross-sections were obtained with an overall uncertainty estimated to be better than ±6.0% for elastic scattering and ±12% for γ-ray emission, at all the beam energies.To provide a convincing test of the overall validity of the measured elastic scattering cross-section, thick target benchmark experiments at several proton energies are presented.     

Elastic scattering of 7Li + 27Al at several angles in the 7–11 MeV energy range

Elastic cross sections for the ⁷Li + ²⁷Al system were measured at laboratory energies between 7 and 11 MeV in steps of 0.25 MeV, and angles between 135° and 170° in steps of 5°. Excitation functions for the elastic scattering were measured using an array of eight Si surface-barrier detectors whereas a solid-state telescope was used to estimate and subtract background from other reactions. Contamination from α particles arising from the ⁷Li breakup process at E_lab ? 10 MeV makes the use of these energies inadvisable for RBS applications. The present results are compared with previous data obtained at 165° (E_lab ? 6 MeV), 140° and 170° (E_lab ? 8 MeV). The experimental data were analyzed in terms of the Optical Model. Two different energy-independent potentials were found. These optical potentials allow an interpolation with physical meaning to other energies and scattering angles. The experimental cross sections will be uploaded to the IBANDL database.     

Proton elastic scattering differential cross-sections for C

Carbon depth profiling presents a strong analytical challenge for all the major ion beam analysis (IBA) techniques, with elastic backscattering spectroscopy (EBS) being widely implemented. In the past, the ¹²C(p,p)¹²C reaction has been successfully evaluated for proton beam energies up to 4.5 MeV. Currently, an attempt is being made to extend this evaluation to higher energies, namely up to E_p,lab = 7 MeV. There is a certain lack of available and/or coherent datasets in literature for these relatively high proton beam energies at backward angles, suitable for IBA. Moreover, the few existing datasets are in certain cases discrepant. Thus, in the present work, the differential cross-section of proton elastic scattering on carbon were measured between 140°and 170°, in steps of 10°, for the proton beam energy range between 2.7 and 7 MeV. The experimental results obtained, along with data from literature, were evaluated applying nuclear physics models. The evaluated results were benchmarked using a thick, mirror polished glassy carbon target at different beam energies and detector angles.     

Stopping cross sections of He+ ions in bismuth

The stopping cross sections, ?(E), of He⁺ ions in bismuth have been measured by Rutherford backscattering spectrometry (RBS) at incident energies ranging from E = 1.6–3.4 MeV. The energy loss of He⁺ ions and thicknesses of the bismuth films deposited on aluminium substrates were determined from the RBS spectra at each energy for scattering angles of 130° and 165°. The film thicknesses of some of the samples were also measured by weighing and the results compared with those from RBS. Parameters for energy dependence of stopping cross section in the Varelas-Biersack interpolation formula have been obtained for bismuth from a fit to all the available experimental data. Accuracy of our method based on RBS is demonstrated by measurements on copper, for which ?(E) is already well studied. It is also shown that reliable ?(E) values may be obtained even on samples with non-uniform film thickness.     

Evaluation of Neutron Cross Sections of Plutonium-241

The neutron cross sections of ²⁴¹Pu were evaluated in the energy range between 10^?5 eV and 15MeV, and are stored in the Japanese Evaluated Nuclear Data Library Version-1 (JENDL-1). In the energy range below 100eV, the evaluated data contained in ENDE/B-IV and the resonance parameters recommended in BNL-325 were tentatively adopted. The unresolved resonance parameters were determined between 100 eV and 21.5 keV so as to reproduce the experimental data of the fission and capture cross sections. Above 21.5 keV, the fission cross section was evaluated on the basis of the experimental data, most of which were reported as the ratio to the fission cross section of ²³⁵U and then were normalized by the fission cross section of ²³⁵U adopted in JENDL-1. The capture cross section was obtained from the experimental data of a in the energy range up to 250 keV. The capture cross section above 250 keV and the elastic and inelastic scattering, (n, 2n) and (n, 3n) reaction cross sections above 21.5 keV were obtained on the basis of the theoretical calculations. The calculated cross sections are connected smoothly with those obtained from the unresolved resonance parameters at 21.5 keV. This suggests the self-consistency of the present evaluation.     

Experimental cross sections for two-electron capture into nitrogen autoionising states in Nq+ (q = 6, 7) on He and H2 collisions at 10.5q keV

Singly differential cross sections for two-electron capture into autoionising states (nl, n'l') with n = 2, 3, 4 and n′≥ in N^q+ (q = 6, 7) on He and H₂ collisions have been measured at 10.5q keV collision energy and an observation angle θ_lab =11.6°Total cross sections are estimated assuming isotropic angular distributions.     

Calculation and analysis of proton-induced reactions on Ni at incident energies from threshold to 200 MeV

Proton-induced reactions on ⁵⁸Ni have been studied in the energy range from threshold to 200 MeV. Based on experimental data of elastic scattering angular distributions and nonelastic cross section, an optimal set of proton optical potential parameters for ⁵⁸Ni has been obtained. All cross sections, elastic and inelastic scattering angular distributions, energy spectra and especially double differential cross sections for neutrons, protons, deuterons, tritons, helium particles and alpha particles emission have been calculated, using nuclear models theory. Theoretical calculations have been compared with existing experimental data, in most cases, the calculated results are in good agreement with the experimental data.     

Determination of differential cross-sections for the natK(p, p0) and 39K(p, α0) reactions in the backscattering geometry

In the present work, new, differential cross-section values are presented for the ^natK(p, p₀) reaction in the energy range E_lab = 3000–5000 keV (with an energy step of 25 keV) and for detector angles between 140° and 170° (with an angular step of 10°). A qualitative discussion of the observed cross-section variations through the influence of strong, closely spaced resonances in the p + ³⁹K system is also presented. Information has also been extracted concerning the ³⁹K(p,α₀) reaction for E_lab = 4000–5000 keV in the same angular range. As a result, more than ～500 data points will soon be available to the scientific community through IBANDL (Ion Beam Analysis Nuclear Data Library – http://www-nds.iaea.org/ibandl/) and could thus be incorporated in widely used IBA algorithms (e.g. SIMNRA, WINDF, etc.) for potassium depth profiling at relatively high proton beam energies.     

Calculation and analysis of n+Zr reactions in the En ⩽ 250 MeV energy range

All of reaction cross sections, angular distributions, energy spectra, γ-ray production cross sections, and the double differential cross section for neutron, proton, deuteron, triton, helium and alpha emission are calculated and analyzed for n+^{90,91,92,94,96,nat}Zr at incident neutron energies from 0.1 to 250 MeV. The optical model, intranuclear cascade model, the unified Hauser–Feshbach theory and the exciton model which included the improved Iwamoto–Harada model are used. Theoretical calculated results are compared with existing experimental data and other evaluated data from ENDF/B-VI.8, ENDF/B-VII.0 and JENDL-3.3. The optical model potential parameters are obtained according to the experimental data of total, nonelastic cross sections and elastic scattering angular distributions.     

The elastic He+d cross section of relevance for knock-on effects in radio frequency heated (He)D plasmas

The cross section for d+³He elastic scattering has been determined for the angular range 20-180° (CM) for beam energies E_d = 0.05 to 11 MeV through combined use of experimental data, Coulomb scattering and extrapolations. The results are used to study, for instance, how the cross section is affected by nuclear interaction contributions. Implications of these results on the calculation of knock on effects in (³He)D plasmas subjected to RF heating and their manifestations in the spectrum of the d + d fusion neutron emission are discussed.     

Theoretical electron-atom elastic scattering cross sections: Selected elements, 1 keV to 256 keV

Calculated differential elastic electron scattering cross sections for 24 selected elements are presented in tabular form in the energy range 1 to 256 keV at values of 2ⁿ keV. The total elastic and momentum-transfer cross sections are tabulated also. Parameters for 12-parameter analytic fits to the differential values are given for 80 elements in a second table. The calculations were done in the relativistic static approximation with relativistic atomic wavefunctions for the heavier elements (Z > 35).     

Stopping of 0.3-1.2 MeV/u protons and alpha particles in Si

The stopping cross sections ε(E) of silicon for protons and alpha particles have been measured over the velocity range 0.3-1.2 MeV/u from a Si//SiO₂//Si (SIMOX) target using the Rutherford backscattering spectrometry (RBS) with special emphasis put on experimental aspects. A detection geometry coupling simultaneously two solid-state Si detectors placed at 165° and 150° relative to each side of the incident beam direction was used to measure the energies of the scattered ions and determine their energy losses within the stopping medium. In this way, the basic energy parameter, E_x, at the Si/SiO₂ interface for a given incident energy E₀ is the same for ions backscattered in the two directions off both the Si and O target elements, and systematic uncertainties in the ε(E) data mainly originating from the target thickness are significantly minimized. A powerful computer code has been elaborated for extracting the relevant ε(E) experimental data and the associated overall uncertainty that amounts to less than 3%. The measured ε(E) data sets were found to be in fair agreement with Paul’s compilation and with values calculated by the SRIM 06 computer code. In the case of ⁴He⁺ ions, experimental data for the γ effective charge parameter have been deduced by scaling the measured stopping cross sections to those of protons crossing the same target with the same velocity, and compared to the predictions of the SRIM 06 computer code. It is found that the γ-parameter values generated by the latter code slightly deviate from experiment over the velocity region around the stopping cross section maximum where strong charge exchanges usually occur.     

The calculation of the differential cross sections for recoil protons in 4He-p Scattering

The equation relating phase shift to energy given by the effective range theory for charged particle reactions and the effective range parameters which can well fit the experimental data of P-⁴He elastic scattering have been used to obtain the phase shifts and differential cross sections of protons in p-⁴He elastic scattering. Thereafter the differential cross section of recoil protons in ⁴He-p elastic scattering are calculated through the principle of detailed balance and compared with the experimental data and Rutherford cross sections. Better consistency between experimental and theoretical values than in previous work is achieved.     

Evaluation of non-Rutherford proton elastic scattering cross section for nitrogen

The available experimental information on the proton elastic scattering from ¹⁴N in the energy range up to 5 MeV was compiled. The critical analysis of the revealed discrepancies was performed taking into account the applied experimental technique and possible error sources. Based on this, the apparently reliable experimental points were selected. Model calculations with comparison and fitting to the experimental data were used for parameterization of the cross section. The R-matrix theory was employed in the calculations, the phase shifts calculated for Saxon-Woods potential well being substituted for commonly used hard-sphere ones in order to take into account direct potential scattering. The result of the evaluation is that the required excitation functions for proton elastic scattering from nitrogen may be calculated for any scattering angle with reliability exceeding that for any individual measurement. The evaluated cross sections are provided by the SigmaCalc web site at www-nds.iaea.org/sigmacalc/.     

Neutron Nuclear Data Evaluation for Thorium-232

An evaluation was made on the neutron cross sections, resonance parameters and average neutron yield in fission for ²³²Th in the energy range from thermal energy to 20 MeV. The fission and capture cross sections were evaluated on the basis of the experimental data by converting the relative ratio data into cross section values by making use of recent evaluations for reference cross sections. The total cross section was determined from experimental data in the region from 24 keV to 15 MeV and then extrapolated to lower and higher energies by using the optical model whose parameters had been adjusted as so to reproduce the measured data. The elastic and inelastic scattering, (n, 2n) and (n, 3n) reaction cross sections were calculated by means of the statistical model combined with the optical model. A set of resonance parameters were recommended in the energy range below 3.5 keV and average resonance parameters were deduced in the unresolved resonance region. A value of 7.40 b was chosen for the capture cross section at 0.025 eV, and the picket-fence negative-energy levels were introduced so as to reproduce the non-l/v behavior of the capture cross section in the epithermal region.

The results were incorporated in the Japanese Evaluated Nuclear Data Library, Version 2 (JENDL-2). Comparison was made between the present and other evaluations such as ENDF/B-V and possible reasons for the discrepancy were discussed.     

On the investigation of alpha-particle resonance elastic scattering from the 16O nucleus

Solid target measurements are conducted in order to investigate ¹⁶O(α, α₀)¹⁶O resonances in the energy region 2.0–3.6 MeV. Excitation functions are reported for scattering angles of 145° (θ_cm = 153°) and 165° (θ_cm = 168°), and resonances are observed at 2.522, 3.042, 3.082 and 3.372 MeV. The deduced widths of these resonances in the centre-of-mass frame are 19.00, 8.20, 3.36, and 15.10 keV respectively. It is reported that the widths of the first three resonances are in agreement with previous data, but the width of the 3.372 MeV resonance exceeds an early gas target result due to Cameron [5]. In addition, elastic scattering cross sections are compared with the gas target data and found to be consistent. It is concluded that the width of the 3^? resonance at 3.042 MeV is in agreement with the prediction due to multiparticle cluster calculations for ²⁰Ne.