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..

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.

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%).

scholarly journals Magnetized particle capture cross section for braneworld black hole

2011 ◽  
Vol 335 (2) ◽  
pp. 499-504 ◽  
Author(s):  
O. G. Rahimov ◽  
A. A. Abdujabbarov ◽  
B. J. Ahmedov
Keyword(s):  
Black Hole ◽  
Cross Section ◽  
Capture Cross Section ◽  
Capture Cross ◽  
Particle Capture

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 (%).

REACTOR NEUTRON CAPTURE CROSS SECTION OF 51-DAY Sr89

1957 ◽  
Vol 35 (10) ◽  
pp. 1215-1219 ◽  
Author(s):  
L. P. Roy ◽  
J. C. Roy
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Neutron Capture ◽  
Capture Cross Section ◽  
High Flux ◽  
Capture Cross ◽  
Neutron Capture Cross Section ◽  
Naturally Occurring ◽  
Reactor Spectrum ◽  
Capture Cross Sections

The neutron capture cross section of Sr89 has been measured by an activation method. Naturally occurring strontium was irradiated in different high flux positions in the NRX reactor at Chalk River and the amount of Sr90 formed by successive neutron capture in Sr88 was determined by separating and measuring its daughter Y90. Using values of 36.6 and 0.005 barns for the respective neutron capture cross sections of Co59 and Sr88, the capture cross section of Sr89 for reactor spectrum neutrons was found to be 0.49 ± 0.10 barn.

Oxidation Induced ON1, ON2a/b Defects in 4H-SiC Characterized by DLTS

2014 ◽  
Vol 778-780 ◽  
pp. 281-284 ◽  
Author(s):  
Ian D. Booker ◽  
Hassan Abdalla ◽  
Louise Lilja ◽  
Jawad ul Hassan ◽  
Peder Bergman ◽  
...  
Keyword(s):  
Correlation Function ◽  
Energy Level ◽  
Electron Capture ◽  
Cross Section ◽  
Cross Sections ◽  
Capture Cross Section ◽  
Capture Cross ◽  
Electron Capture Cross Section ◽  
Pulse Measurement ◽  
Capture Cross Sections

The deep levels ON1and ON2a/bintroduced by oxidation into 4H-SiC are characterized via standard DLTS and via filling pulse dependent DLTS measurements. Separation of the closely spaced ON2a/bdefect is achieved by using a higher resolution correlation function (Gaver-Stehfest 4) and apparent energy level, apparent electron capture cross section and filling pulse measurement derived capture cross sections are given.

scholarly journals The 154Gd neutron capture cross section measured at the n_TOF facility and its astrophysical implications

2020 ◽  
Vol 239 ◽  
pp. 07003
Author(s):  
M. Mastromarco ◽  
A. Mazzone ◽  
C. Massimi ◽  
S. Cristallo ◽  
N. Colonna ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Neutron Capture ◽  
Nuclear Physics ◽  
Capture Cross Section ◽  
Close Correlation ◽  
Capture Cross ◽  
Neutron Capture Cross Section ◽  
Capture Process ◽  
Process Region

The (n, γ) cross sections of the gadolinium isotopes play an important role in the study of the stellar nucleosynthesis. In particular, among the isotopes heavier than Fe, 154Gd together with 152Gd have the peculiarity to be mainly produced by the slow capture process, the so-called s-process, since they are shielded against the β-decay chains from the r-process region by their stable samarium isobars. Such a quasi pure s-process origin makes them crucial for testing the robustness of stellar models in galactic chemical evolution (GCE). According to recent models, the 154Gd and 152Gd abundances are expected to be 15-20% lower than the reference un-branched s-process 150Sm isotope. The close correlation between stellar abundances and neutron capture cross sections prompted for an accurate measurement of 154Gd cross section in order to reduce the uncertainty attributable to nuclear physics input and eventually rule out one of the possible causes of present discrepancies between observation and model predictions. To this end, the neutron capture cross section of 154Gd was measured in a wide neutron energy range (from thermal up to some keV) with high resolution in the first experimental area of the neutron time-of-flight facility n_TOF (EAR1) at CERN. In this contribution, after a brief description of the motivation and of the experimental setup used in the measurement, the preliminary results of the 154Gd neutron capture reaction as well as their astrophysical implications are presented.

Neutron Activation Resonance Integral of 74Ge and 76Ge and Evaluation of the 74Ge keV Neutron Radiative Capture Cross Section and Resonance Integral

1972 ◽  
Vol 50 (17) ◽  
pp. 1978-1986
Author(s):  
M. D. Ricabarra ◽  
R. Turjanski ◽  
G. H. Ricabarra
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Capture Cross Section ◽  
Radiative Capture ◽  
Resonance Integral ◽  
Neutron Resonance ◽  
Capture Cross ◽  
Resonance Parameters ◽  
Radiative Capture Cross Section ◽  
Average Resonance

Values of the reduced activation resonance integral relative to the thermal cross section I′/σ0 of 74Ge and 76Ge were determined relative to gold by measuring cadmium ratios in a reactor spectrum.A lithium-drifted germanium γ-ray spectrometer was used to resolve the activities of the samples.The results for 74Ge are I′/σ0 = 1.514 ± 0.031 and I′ = 0.681 ± 0.123 b with an assumed σ0 = 0.45 ± 0.08 b; for 76GeI′/σ0 = 12.00 ± 0.16 and I′ = 1.992 ± 0.359 with an assumed σ0 = 0.166 ± 0.030 b.The values obtained for I′ are in serious disagreement with the values calculated with neutron resonance parameters and confirm previous results obtained in similar keV average resonance spacing isotopes.Due to this fact a careful evaluation of the keV neutron radiative capture cross section and resonance integral for 74Ge was undertaken.The evaluation and comparison with the experimental value of the resonance integral shows first that for nuclides with an average resonance spacing of keV the unresolved resonance integral has been seriously underestimated in many evaluations, and second that between 10 and 100 keV, resonance integrals calculated with smooth low resolution activation cross sections give a better calculation of neutron captures than that obtained with neutron resonance parameters.

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