A measurement of the neutron-proton capture cross-section

1958 ◽  
Vol 248 (1255) ◽  
pp. 539-559 ◽  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Recoil Proton ◽  
Statistical Error ◽  
Nuclear Research ◽  
Photographic Emulsion ◽  
Neutron Density ◽  
Capture Cross ◽  
Flux Measurements ◽  
Better Than

Measurements have been made of the neutron density as a function of distance from a polonium-beryllium source in effectively infinite tanks of water and aqueous boric acid. The ratio of the thermal-neutron capture cross-sections of boron and hydrogen was found to be 2317 ± 27. The cross-section of hydrogen calculated from this result, using the known cross-section of Harwell standard boron, 769 ± 4 barns (at a neutron velocity of 2200 m /s.), and the known cross-section of the boron used relative to Harwell standard boron, 0.985 + 0.002, was 0.327 + 0.004 barn (at 2200 m /s.) which is consistent with other recent accurate values. In preliminary experiments, it was shown that flux measurements reproducible to better than 3 % were possible with the disks of Ilford C2 nuclear research photographic emulsion used as detectors. The main source of error in the result was the statistical error for a total count of 200000 tracks. The only corrections necessary were 1.6% for recoil proton background, and 0.7 % for the disturbance of the neutron density by the detectors.

THERMAL NEUTRON CAPTURE CROSS-SECTION OF Na23 AND Mn55

1953 ◽  
Vol 31 (3) ◽  
pp. 204-206 ◽  
Author(s):  
Rosalie M. Bartholomew ◽  
R. C. Hawkings ◽  
W. F. Merritt ◽  
L. Yaffe
Keyword(s):  
Thermal Neutron ◽  
Cross Section ◽  
Cross Sections ◽  
Neutron Capture ◽  
Half Life ◽  
Capture Cross Section ◽  
Thermal Neutron Capture ◽  
Capture Cross ◽  
Neutron Capture Cross Section ◽  
Capture Cross Sections

The thermal neutron capture cross sections of Na23 and Mn55 have been determined using the activation method. The values are 0.53 ± 0.03 and 12.7 ± 0.3 barns respectively with respect to σAul97 = 93 barns. These agree well with recent pile oscillator results. The half-life for Mn56 is found to be 2.576 ± 0.002 hr.

MEASURING CAPTURE CROSS SECTIONS FOR HEAVY-ELEMENT PRODUCTION

2004 ◽  
Vol 13 (01) ◽  
pp. 293-300
Author(s):  
NEIL ROWLEY ◽  
NABILA GRAR
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Reaction Path ◽  
Superheavy Element ◽  
Evaporation Residue ◽  
Capture Cross ◽  
Total Capture ◽  
Capture Cross Sections

The creation of the nucleus of a superheavy element follows an extremely complex reaction path starting with the crossing of an external potential barrier (or distribution of barriers). This is followed by the evolution towards an equilibrated compound nucleus, which takes place in competition with pre-compound-nucleus fission (quasi-fission). Once formed the equilibrated compound nucleus must still survive against true fusion to yield a relatively long-lived evaporation residue. Much of this path is poorly understood, though recently, progress has been made on the role of the entrance-channel in quasi-fission. This will be briefly reported and a method proposed to measure the total capture cross section for such systems directly.

scholarly journals Application of the EGPT methodology in the analysis of small-sample reactivity worth experiments

2018 ◽  
Vol 4 ◽  
pp. 44 ◽  
Author(s):  
Pierre Leconte ◽  
Jean Tommasi ◽  
Alain Santamarina ◽  
Patrick Blaise ◽  
Paul Ros
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Capture Cross Section ◽  
Reference Sample ◽  
Small Sample ◽  
Capture Cross ◽  
Theoretical Formulation ◽  
Sensitivity Coefficients ◽  
Spectrum Experiment ◽  
The Impact

In the current paper, we investigate the application of the Equivalent Generalized Perturbation Theory (EGPT) to derive trends and associated covariances on the neutron capture cross section of one major fission product for both light water reactors and sodium-cooled fast reactors which is Rhodium-103. To do so, we have considered the ERMINE-V/ZONA1 & ZONA3 fast spectrum experiment and the MAESTRO thermal-spectrum experiment, where samples of these materials were oscillated in the MINERVE facility. In the paper, the theoretical formulation of EPGT is described and its derivation in the special case of the close loop oscillation technique where the reactivity worth is determined thanks to a power control system. A numerical benchmark is presented to assess the relevance of sensitivity coefficients provided by EGPT against direct perturbations where the microscopic cross sections are manually changed before calculating the adjoint and forward flux. The breakdown between direct and indirect contributions in the sensitivity analysis of the sample reactivity worth is presented and discussed, with the impact of using a calibration reference sample to normalize the measured reactivity worth. Finally, the assimilation of integral trends is done with the CONRAD code, using C/E comparisons between TRIPOLI4/JEFF3.2 calculations and experimental results and the sensitivity coefficients provided by the EGPT. Preliminary results of this study are showing that the JEFF3.2 evaluation of 103Rh gives satisfactory agreements in both thermal and fast spectrum experiments and that the combination of them can lead to a significant uncertainty reduction on the capture cross section, from ±5% to ±3% in the resolved resonance range (1 eV–10 keV) and from ±8% to ±5% in the unresolved resonance range (10 keV–1 MeV).

THE CAPTURE CROSS-SECTION FOR THERMAL NEUTRONS OF CADMIUM, LITHIUM6, BORON10, BARIUM, MERCURY AND HYDROGEN

1941 ◽  
Vol 19a (3) ◽  
pp. 33-41 ◽  
Author(s):  
E. L. Harrington ◽  
J. L. Stewart
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Capture Cross Section ◽  
Comparison Method ◽  
Thermal Neutrons ◽  
Capture Cross ◽  
Scattering Effect ◽  
Capture Cross Sections

A comparison method of measuring, by using solutions, the capture cross-sections for thermal neutrons is described. The chief advantages are directness, simplicity, and freedom from uncertainties as to direction of path, or as to the magnitude of the scattering effect. The method is best suited to nuclei of large cross-sections. Assuming the well checked value for the cadmium nucleus to be correct, the capture cross-sections of certain other nuclei were determined. The results for barium and for hydrogen differ widely from values previously published.

The 16O(p, γ)17F Direct Capture Cross Section with an Extrapolation to Astrophysical Energies

1975 ◽  
Vol 53 (17) ◽  
pp. 1672-1686 ◽  
Author(s):  
H. C. Chow ◽  
G. M. Griffiths ◽  
T. H. Hall
Keyword(s):  
Elastic Scattering ◽  
Excited States ◽  
Cross Section ◽  
Cross Sections ◽  
Capture Cross Section ◽  
Scattering Cross Section ◽  
Scattering Data ◽  
Capture Cross ◽  
Scattering Cross ◽  
Elastic Scattering Cross Section

The cross section for the direct radiative capture of protons by 16O has been measured relative to the proton elastic scattering cross section for energies from 800 to 2400 keV (CM). The elastic scattering cross section was normalized to the Rutherford scattering cross section at 385.5 keV. The capture cross section for the reaction 16O(p,γ)17F, which plays a role in hydrogen burning stars, has been extrapolated to stellar energies using a theoretical model which gives a good fit to the measured cross sections. The model involves calculation of electromagnetic matrix elements between initial and final state wave functions evaluated for Saxon–Woods potentials with parameters adjusted to fit both elastic scattering data and binding energies for the ground and first excited states of 17F. Cross sections for capture to the 5/2+ ground and 1/2+ first excited states of 17F in terms of astrophysical S factors valid for energies ≤ 100 keV have been found to be: S5/2+ = (0.317 + 0.0002E) keV b (± 8%); S1/2+ = (8.552 − 0.353E + 0.00013E2) keV b (± 5%).

Charge transfer in the presence of a radiation field

1998 ◽  
Vol 76 (3) ◽  
pp. 245-250 ◽  
Author(s):  
S -M Li ◽  
J -G Khou ◽  
Z -F Zhou ◽  
J Chen ◽  
Y -Y Liu
Keyword(s):  
Charge Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Born Approximation ◽  
Atomic Hydrogen ◽  
Capture Cross ◽  
Exchange Collision ◽  
Increasing Functions ◽  
Theoretical Results ◽  
Capture Cross Sections

In the first Born approximation, the dressing modification in laser-assisted charge exchange collision is investigated. The crosssections for electron capture by a proton from dressed atomic hydrogen and dressed helium targets are calculated within awide energy range. Theoretical results show that with impact energy increasing, the dressing effect leads to increasingly significant cross-section modifications. The modified capture cross sections are increasing functions of the ratio of laser strength to frequency. PACS Nos.: 34.50.Rk; 34.70.+e; 32.80.Wr; and 34.90.+q

Triple differential cross sections for the ionization of helium by intermediate-energy electrons

1988 ◽  
Vol 66 (1) ◽  
pp. 82-85
Author(s):  
K. S. Baliyan ◽  
M. K. Srivastava
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Intermediate Energy ◽  
Incident Electron Energy ◽  
Cross Section Data ◽  
Satisfactory Description ◽  
Triple Differential Cross Section ◽  
Section Data ◽  
Better Than

The recent triple differential cross-section data of Jung for the ionization of helium in the coplanar asymmetric geometry at 250 eV incident electron energy is analyzed within the framework of the second Born (B2) and modified Glauber (MG) approximations. At this energy B2 and MG results, although better than those obtained by using the first Born and Glauber approximations, do not lead to a satisfactory description of the experimental data in all the kinematic situations considered here.

scholarly journals Gravitational Capture Cross-Section of Particles by Schwarzschild-Tangherlini Black Holes

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 307
Author(s):  
Bobomurat Ahmedov ◽  
Ozodbek Rahimov ◽  
Bobir Toshmatov
Keyword(s):  
Black Hole ◽  
Cross Section ◽  
Cross Sections ◽  
Capture Cross Section ◽  
Higher Dimensions ◽  
Capture Cross ◽  
Circular Orbits ◽  
Test Particles ◽  
Dimensional Spacetime ◽  
Gravitational Capture

We study the capture cross-section of massless (photon) and massive test particles by the Schwarzschild–Tangherlini black hole, which is a solution of pure general relativity in higher dimensional spacetime with R×SD−2 topology. It is shown that an extra dimension weakens the gravitational attraction of a black hole, and consequently, radii of all the characteristic circular orbits, such as the radius of a photonsphere decrease in the higher dimensions. Furthermore, it is shown that in higher dimensions, there are no stable and bounded circular orbits. The critical impact parameters and capture cross-sections of photons and massive particles are calculated for several higher dimensions and it is shown that they also decrease with increasing dimension. Moreover, we calculate the capture cross-section of relativistic and non-relativistic test particles in the higher dimensions..

scholarly journals CRITICAL EXPERIMENT OF THORIUM LOADED THERMAL CORES AT KUCA (1) A NEW CRITICAL EXPERIMENT OF THORIUM LOADED CORE WITH HARDER NEUTRON SPECTRUM IN KUCA

2021 ◽  
Vol 247 ◽  
pp. 09013
Author(s):  
Tadafumi Sano ◽  
Jun-ichi Hori ◽  
Jeaong Lee ◽  
Yoshiyuki Takahashi ◽  
Kazuki Takahashi ◽  
...  
Keyword(s):  
Cross Section ◽  
Neutron Spectrum ◽  
Cross Sections ◽  
Capture Cross Section ◽  
The Other ◽  
Capture Cross ◽  
Delayed Neutron ◽  
Integral Evaluation ◽  
Critical Experiment ◽  
The Difference

In order to perform integral evaluation of 232Th capture cross section, a series of critical experiments for thorium-loaded and solid-moderated cores in KUCA had been carried out. In these experimental cores, H/235U nuclide ratio ranged about from 150 to 315, and 232Th/235U nuclide ratio ranged about from 13 to 19. In this study, a new critical experiment with Th loaded core in KUCA, which had about 70 of the H/235U ratio and 12.7 of 232Th/235U ratio, was carried out. As results, the excess reactivity was 0.086 ± 0.003 (% dk/k) and the keff was 1.0009 ± 0.0003, where the effective delayed neutron fraction was 7.656E-3. The keff was also calculated by MVP3.0 with different nuclear libraries. The respective calculations with JENDL-4.0, JENDL-3.3 and ENDF/B-VII.0 lead to 1.0056 ± 0.0086 (%), 1.0048 ± 0.0085 (%) and 1.0056 ± 0.0086 (%).On the other hand, the further MVP3.0 calculations, where only the 232Th cross sections were taken from JENDL-4.0, JENDL-3.3 or ENDF/B-VII.0 but all other nuclides were done from JENDL-4.0, were carried out to examine an impact of the difference of 232Th cross section among these nuclear libraries to the keff. The keff calculated with respective 232Th cross sections from JENDL-3.3 and ENDF/B-VII.0 was 1.0038 ± 0.0086 (%) and 1.0040 ± 0.0086 (%).

Sign in / Sign up

Export Citation Format

Share Document