scholarly journals GAINS: neutron inelastic cross section measurements of interest for applications and reaction studies

2020 ◽  
Vol 239 ◽  
pp. 01005
Author(s):  
A. Negret ◽  
C Borcea ◽  
M. Boromiza ◽  
Ph. Dessagne ◽  
Gr. Henning ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Nuclear Structure ◽  
Cross Section ◽  
Cross Sections ◽  
Structural Materials ◽  
Reliable Data ◽  
Inelastic Cross Section ◽  
Nuclear Facilities ◽  
Materials Used

The paper represents an overview of the measurements performed using GAINS at GELINA (JRC-Geel, Belgium). While undergoing continuous upgrades, the setup produced highly precise cross sections. Our measurements are primarily driven by technological needs with an emphasis on structural materials used in the development of nuclear facilities. However, most cases offered the opportunity to investigate various reaction mechanism and/or nuclear structure issues. We concentrate on several specific experiments describing the particular difficulties we met and the solutions we adopted to infer reliable data and to draw significant conclusions.

scholarly journals Inelastic cross sections in relativistic deuterons on Lead reactions

2020 ◽  
Vol 19 ◽  
pp. 81
Author(s):  
M. Zamani ◽  
S. Stoulos ◽  
M. Fragopoulou ◽  
M. Krivopustov
Keyword(s):  
Experimental Data ◽  
Solid State ◽  
Attenuation Coefficient ◽  
Cross Section ◽  
Cross Sections ◽  
Inelastic Cross Section ◽  
Lead Target ◽  
Spallation Neutron Source ◽  
Interaction Length ◽  
Beam Attenuation

The inelastic cross section of deuterons hitting a Lead target has been determined by the beam attenuation technique. A spallation neutron source based on Lead target has been irradiated with 1.6 and 2.5 GeV deuterons. Solid state nuclear track detectors as well as the activation method were used in order to obtain the neutron and proton distribution along the surface of the source. The attenuation coefficient was estimated by fitting the experimental data taking into account the build up effect and the beam attenuation. Using the attenuation coefficient, the interaction length and then the inelastic cross section of deuterons on Lead reaction have been determined.

scholarly journals What can we learn from (n,xnγ) cross sections about reaction mechanism and nuclear structure?

2020 ◽  
Vol 239 ◽  
pp. 01023
Author(s):  
Maëlle Kerveno ◽  
Marc Dupuis ◽  
Catalin Borcea ◽  
Marian Boromiza ◽  
Roberto Capote ◽  
...  
Keyword(s):  
Nuclear Structure ◽  
Cross Section ◽  
Cross Sections ◽  
Level Density ◽  
Total N ◽  
Fission Process ◽  
Stringent Test ◽  
High Level ◽  
Scattering Cross Sections

Inelastic (n,n') cross section is a key quantity to accurately simulate reactor cores, and its precision was shown to need significant improvements. To bypass the experimental difficulties to detect neutrons from (n,xn) reaction and to discriminate inelastically scattered neutrons from those following the fission process in case of fissile targets, an indirect but yet powerful method is used: the prompt γ-ray spectroscopy. Along this line, our collaboration has developed the GRAPhEME setup, optimized for actinides, at the GELINA facility to measure partial (n,xn γ) cross sections, from which the total (n,xn) cross section can be inferred. (n,xn γ) experiments with actinides are still particularly challenging, as their structure presents a high level density at low energy, and the competing neutron-induced fission reaction contaminates the γ-energy distribution. New precise measurements of the partial (n,xn γ) cross sections provide a stringent test to theoretical model and offer a way to improve them. This is a path to a better determination of the total inelastic scattering cross sections. In this contribution we discuss modeling aspects of the 238U and 182W (n,n' γ) reactions, also measured with GRAPhEME, using the three codes TALYS, EMPIRE and CoH. We will highlight the needed/expected improvements on reaction modeling and nuclear structure input.

scholarly journals Inelastic cross sections of relativistic protons on Lead

2019 ◽  
Vol 18 ◽  
pp. 49
Author(s):  
M. Zamani ◽  
S. Stoulos ◽  
M. Fragopoulou ◽  
M. Manolopoulou ◽  
N. A. Sosnin ◽  
...  
Keyword(s):  
Cross Section ◽  
Neutron Source ◽  
Cross Sections ◽  
High Energy Physics ◽  
Analytical Calculation ◽  
High Energy ◽  
Inelastic Cross Section ◽  
Spallation Neutron Source ◽  
Fitting Procedure ◽  
Energy Physics

The inelastic cross section of relativistic protons in Lead was determined indirectly by measuring the neutron distribution along a Lead spallation neutron source. The spallation neutron source was irradiated by 1, 1.5 and 2 GeV protons. The experimental results were taken using passive methods. A fitting procedure has been applied to the experimental data and the results have been compared with analytical calculation of the produced hadrons’ spatial distribution based on High Energy Physics concepts. Using the beam attenuation coefficient the inelastic cross section of protons in Pb was estimated.

scholarly journals The 58Ni(n,p)58Co, 58Ni(n,2n)57Ni, and 58Ni(n,np)57Co Cross Sections at 14·1 MeV

1959 ◽  
Vol 12 (1) ◽  
pp. 103 ◽  
Author(s):  
KH Purser ◽  
EW Titterton
Keyword(s):  
Reaction Mechanism ◽  
Energy Spectrum ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Estimate ◽  
Experimental Results ◽  
Relative Importance

The energy spectrum of the protons which are emitted when nickel is bombarded with 14 �1 MeV neutrons has been studied recently by several workers-Allan (1957), Colli, Facchini, et al. (1958), and Colli, Pignanelli, et al. (1958). The results of these experiments do not allow an accurate estimate of the relative importance of contributions from the (n,p) reaction and the (n,np) reaction. Such information is necessary when any reaction mechanism is postulated to account for the experimental results. In these experiments, therefore, activation techniques have been used to measure these two cross sections separately for the isotope 58Ni at 14�1 MeV; in addition, the 68Ni(n,2n)57Ni cross section has been remeasured.

Electron Irradiation Effects in Polyoxymethylene Crystals Grown Inside Trioxane Crystals

1971 ◽  
Vol 29 ◽  
pp. 78-79
Author(s):  
J. P. Colson ◽  
D. H. Reneker
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Detailed Examination ◽  
The Other ◽  
Electron Micrograph ◽  
Irradiation Effects ◽  
Threefold Axis ◽  
Typical Sample ◽  
Polymer Crystals ◽  
Chain Axis

Polyoxymethylene (POM) crystals grow inside trioxane crystals which have been irradiated and heated to a temperature slightly below their melting point. Figure 1 shows a low magnification electron micrograph of a group of such POM crystals. Detailed examination at higher magnification showed that three distinct types of POM crystals grew in a typical sample. The three types of POM crystals were distinguished by the direction that the polymer chain axis in each crystal made with respect to the threefold axis of the trioxane crystal. These polyoxymethylene crystals were described previously.At low magnifications the three types of polymer crystals appeared as slender rods. One type had a hexagonal cross section and the other two types had rectangular cross sections, that is, they were ribbonlike.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Oxygen K near edge structures studied with multiple scattering calculations

1988 ◽  
Vol 46 ◽  
pp. 504-505
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Partial Cross Section ◽  
Energy Window ◽  
Edge Structure ◽  
Fine Structures ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
Quantitative Chemical

In electron energy loss spectroscopy, quantitative chemical microanalysis is performed by comparison of the intensity under a specific inner shell edge with the corresponding partial cross section. There are two commonly used models for calculations of atomic partial cross sections, the hydrogenic model and the Hartree-Slater model. Partial cross sections could also be measured from standards of known compositions. These partial cross sections are complicated by variations in the edge shapes, such as the near edge structure (ELNES) and extended fine structures (ELEXFS). The role of these solid state effects in the partial cross sections, and the transferability of the partial cross sections from material to material, has yet to be fully explored. In this work, we consider the oxygen K edge in several oxides as oxygen is present in many materials. Since the energy window of interest is in the range of 20-100 eV, we limit ourselves to the near edge structures.

Absolute inner-shell cross section determination for EELS analysis

1988 ◽  
Vol 46 ◽  
pp. 534-535
Author(s):  
P.A. Crozier
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absolute Cross Section ◽  
Specimen Thickness ◽  
Mass Thickness ◽  
Scattering Cross ◽  
Before And After ◽  
Estimated Error ◽  
Scattering Cross Sections ◽  
Electron Microscopist

Absolute inelastic scattering cross sections or mean free paths are often used in EELS analysis for determining elemental concentrations and specimen thickness. In most instances, theoretical values must be used because there have been few attempts to determine experimental scattering cross sections from solids under the conditions of interest to electron microscopist. In addition to providing data for spectral quantitation, absolute cross section measurements yields useful information on many of the approximations which are frequently involved in EELS analysis procedures. In this paper, experimental cross sections are presented for some inner-shell edges of Al, Cu, Ag and Au.Uniform thin films of the previously mentioned materials were prepared by vacuum evaporation onto microscope cover slips. The cover slips were weighed before and after evaporation to determine the mass thickness of the films. The estimated error in this method of determining mass thickness was ±7 x 107g/cm2. The films were floated off in water and mounted on Cu grids.

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