Total Cross Sections Of Carbon Research Articles

Progress in measurements of fission cross sections and total cross sections at CSNS Back-n white neutron source

The neutron-induced cross sections are of great significance for the design of nuclear devices and advanced reactors for the nuclear energy production. At CSNS Back-n white neutron source, new measurements of the fission cross sections and total cross sections are performed with two sets of Day-one spectrometers based on the multi-cell fast fission ionization chamber (FIC). The neutron-induced 236,238U fission cross sections relative to 235U from the fission threshold energy to 200 MeV were measured by using the TOF method and the Fast Ionization Chamber Spectrometer for Fission Cross Section Measurement (FIXM) in the single/double bunch mode of Back-n. The experimental uncertainties are analyzed in detail, and the results from the two modes are consistent. The measured 236,238U/235U fission cross section ratios are compared with previous experiments and evaluations. The 236,238U(n,f) cross sections are obtained based on the standard 235U fission cross section. The neutron total cross sections of carbon and aluminum in the energy region from 1 eV to 20 MeV have been measured by using the TOF method and transmission method based on the Neutron Total Cross Section Spectrometer (NTOX) in the double bunch mode. The total cross section results after unfolding are in good agreement with the previous measurements as well as the broadening of the ENDF/B-Ⅷ.0 evaluation with Gaussian function within the experimental uncertainty. The present results provide the experimental data for further measurements, relevant evaluations and the design of nuclear system.

Measurement of the neutron total cross section of carbon at the Back-n white neutron beam of CSNS

To verify the performance of the neutron total cross-sectional spectrometer, the neutron total cross section of carbon is initially measured in the energy range of 1 eV to 20 MeV using the time-of-flight method. The measurement is performed at the Back-n white neutron source with a 76-m time-of-flight path using the China Spallation Neutron Source. A multilayer fast fission chamber with 235U and 238U is employed as the neutron detector. The diameter and thickness of the natural graphite sample are 70 mm and 40 mm, respectively. Signal waveforms are collected using a data acquisition system. Off-line data processing was used to obtain the neutron time-of-flight spectra and transmissions. The uncertainty of the counting statistics is generally approximately 3% for each bin in the energy range of 1–20 MeV. It is determined that the results for the neutron total cross section of carbon obtained using 235U cells are in good agreement with the results obtained using 238U cells within limits of statistical uncertainty. Moreover, the measured total cross sections show good agreement with the broadening evaluated data.

Scaling relative neutron depth-dose distributions from one phantom material to another: a comparison of experimental and theoretical results

To correct percentage depth-dose data from one phantom material to another, experimental and theoretical scaling factors (SF) are compared for different neutron beam qualities. Differences of up to 10% were observed for different phantom materials relative to water. The ratio SF/ rho was plotted as a function of H concentration by mass where rho is the mass density of the phantom material. A nearly linear relationship result at all energies for the theoretical scaling factors, while, for the experimental points, important deviations appeared at high energies for materials with relatively low H and high C concentrations. It can be shown that a single linear relationship for all compounds composed of H, C and O can only be valid if the ratio of total cross sections of carbon to oxygen is equal to 3/4. Experimental scaling factors will be more accurate than calculated values because of the uncertainty in the average total cross sections. If these factors for tissue equivalent (TE) liquid relative to water are converted to those of ICRU muscle by correcting to a mass density of 1.04 g cm-3, then the scaling factors are, within experimental uncertainty, equal to one.

A study of neutron detection efficiency of an organic scintillation detector through simulation of detection processes

Neutron detection efficiency of an organic scintillation detector has been studied through Rawal Monte Carlo programm coded in FORTRAN IV for energies of 0–15 MeV. The contribution from multiple scattering, carbon break-up and light pile-up have been investigated. The effect of resonances in the total cross-section of carbon on neutron detection efficiency as a function of neutron energy dispersion has also been studied. The comparison of calculated efficiency with reported measurements indicates that evaluated ENDF/B-IV alpha emission cross-sections below 15 MeV are higher and the corresponding evaluation reported by Lachkar et al. leads to better agreement.

Total neutron cross section of carbon

An accurate determination of neutron total cross section of carbon has been made by the transmission method in the energy region 3 keV to 660 keV. No structure is observed in the total cross section over the whole energy region, and it is concluded that the upper limit of the width of the proposed level at 610 keV neutron energy must be 10 eV in order to escape detection in the present experiment. The observed total cross section has been analysed in terms of the effective range theory as well as the resonance theory, and the results are found to be in good agreement. The relative reduced width for the bound level at −1.86 MeV (i.e. the 3.09 MeV 2 s 1 2 state in C 13) is found to be θ 2 = 0.2, and the interaction radius is found to be 4.7 fm.

Measurement and Interpretation of Neutron Total Cross Sections of Carbon, Calcium, and Lead

The neutron tctal cross sections of carbon, calcium, and lead were determined in the energy region 200 to 960 kev using a time-of-flight technique. The observed cross section for carbon was analyzed in terms of the effective- range theory as well as the bound-level contribution. It is concluded that the upper limit for the total width of the proposed resonance in C/sup 13/ at 610 kev is 100 ev. For calcium and lead the data are analyzed for resonance parameters. It was found that the s-wave strength function for Ca/sup 40/ increased rapidly with increasing energy. It was concluded also that the course of the lead cross sections can be explained only by the presence of a broad s- wave resonance in Pb/sup 208/. (auth)

Total Cross Sections of Carbon, Oxygen, Fluorine and Thorium for Fast Neutrons

The neutron total cross sections of carbon, oxygen, fluorine and thorium have been measured in the energy range of 3.3 to 5.0 MeV. Measurements were made with a good-geometry arrangement and an energy resolution of about 20 keV, using a neutron detector which had a high efficiency and a good characteristic for gamma-ray discrimination. For carbon, oxygen and fluorine, several resonances in the cross sections were analyzed to give spin assignments. For thorium, a giant resonance was observed at 4.2±0.2 MeV.

Total Neutron Cross Sections near 14.1 Mev

Total cross sections of C, Ca, Ti, Ba, La, Ce, Nd, Sm, Gd, Er, Ta, Au, and Pb for neutrons of energies between 13.1 and 15.6 Mev have been measured by the transmission technique with good geometry. The range of neutron energy was achieved by observing neutrons at various angles from thin tritium targets bombarded by deuterons of energy up to 450 kev. Geometry was such that a scattering in the sample of more than about 2\ifmmode^\circ\else\textdegree\fi{} removed the neutron from the beam to the stilbene scintillation detector. The total cross section of carbon for neutrons was found to vary from 1.41 barns at 13.1 Mev to a minimum of 1.31 barns at 14.2 Mev to 1.49 barns at 15.6 Mev. Other elements showed smaller cross-section variation with energy.

XI. Neutron total cross sections between 30 and 153mev

Abstract The neutron total cross sections of carbon, aluminium, copper, cadmium and lead have been determined as a function of energy in the range 30 to 139 mev. The lead total cross section shows a dip at about 60 mev and corresponding dips in the cadmium and copper cross sections appear to occur between 30 and 40 mev. The neutron total cross section of hydrogen has been measured as 56·9±1·8×10-27 cm2 at a neutron energy of 126±2 mev.

Total Cross Sections of Carbon and Hydrogen for High Energy Neutrons

Total Cross Sections of Carbon and Hydrogen for High Energy Neutrons

XXXVIII. The hydrogen and carbon total cross-sections for neutron energies between39MeV. and156MeV.

Abstract The total cross-sections of carbon and hydrogen have been measured at neutron energies of 39, 64·5 and 97 MeV., using a recoil proton telescope as a neutron detector. At these three energies the hydrogen cross-sections are 223±7·6, 126±3 and 73·9±3·0 × 10 -27 cm.2 respectively. The corresponding carbon cross-sections are 1100±20, 784 ±5 and 508±5 × 10-27 cm.2.

The Total Cross Sections of Carbon and Hydrogen for Neutrons of Energies from 35 to 490 kev

The total cross sections of carbon and hydrogen have been measured at mean neutron energies of 35, 95, 265, and 490 kev.

75. On the Total Cross Section of Carbon for Various Resonance Neutrons

75. On the Total Cross Section of Carbon for Various Resonance Neutrons