Investigation of Fine Structure in the Photoneutron Cross Sections of 16O and 208Pb

1975 ◽  
Vol 53 (15) ◽  
pp. 1434-1442 ◽  
Author(s):  
R. G. Johnson ◽  
J. D. Irish ◽  
K. G. McNeill
Keyword(s):  
Fine Structure ◽  
High Resolution ◽  
Differential Cross Section ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Center Of Mass ◽  
Energy Spectra ◽  
Neutron Time ◽  
Good Agreement

The structure in the photoneutron cross sections of 16O and 208Pb has been studied by the measurement of high resolution photoneutron energy spectra using the neutron time-of-flight technique and bremsstrahlung irradiations. For 16O, the ground state differential cross section at 98° has been deduced between 17.3 and 28.5 MeV and is in good agreement with most previous studies. Fine structure is seen throughout the cross section. Eight neutron energy spectra for 208Pb from bremsstrahlung endpoint energies in the range 11.0 to 15.5 MeV were obtained. Strong peaks are seen at center of mass neutron energies of 1.67, 1.85, 2.06, 2.19, 2.68, 3.15, 3.27, 3.50, 3.77, and 4.03 MeV with weaker peaks elsewhere. The energies of these peaks are in good agreement with previous measurements in this laboratory. The energies of peaks in the spectra are compared with recent cross section measurements.

Photoneutron cross sections in 7Li

1977 ◽  
Vol 55 (5) ◽  
pp. 428-433 ◽  
Author(s):  
H. Ferdinande ◽  
N. K. Sherman ◽  
K. H. Lokan ◽  
C. K. Ross
Keyword(s):  
Fine Structure ◽  
Excited State ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Reasonable Agreement ◽  
Branching Ratio ◽  
Energy Spectra ◽  
Average Value ◽  
First Excited State

Photoneutron energy spectra from 7Li have been measured by time-of-flight methods, for bremsstrahlung end-point energies increasing in 2 MeV steps from 13 to 25 MeV. The ground-state and approximate first-excited-state differential cross sections at 90° have been obtained from 8.5 to 23 MeV. No pronounced fine structure has been observed. The measured branching ratio to the first excited state falls from an average value of 0.70 between 10.3 and 14.5 MeV to an average of 0.29 between 14.5 and 18 MeV, and rises again to an average of 0.38 between 18 and 23 MeV. This behaviour can be explained by a crude theoretical model in which 1p → 2s and 1p → 1d single particle transitions dominate below 18 MeV. The calculation predicts a branching ratio of 0.50 near threshold, falling to 0.23 at higher energies, in reasonable agreement with the experiment. The integrated value of the ground-state cross section up to 23 MeV is about (38.7 ± 3.9) MeV mb, while that for the first excited state is about (17.2 ± 3.4) MeV mb. Together they account for 39% of the exchange-augmented dipole sum of 7Li.

Production cross-section of heavy flavored hadrons in pp collision at s = 7 TeV

2019 ◽  
Vol 34 (19) ◽  
pp. 1950150 ◽  
Author(s):  
Muhammad Ajaz ◽  
Irfan Khan ◽  
M. K. Suleymanov
Keyword(s):  
Experimental Data ◽  
Transverse Momentum ◽  
Differential Cross Section ◽  
Cross Section ◽  
Momentum Distribution ◽  
Cross Sections ◽  
Production Cross ◽  
Center Of Mass ◽  
Transverse Momentum Distribution ◽  
Mass Frame

The transverse momentum distribution of the differential production cross-sections of heavy flavored charm hadrons [Formula: see text], [Formula: see text] in pp collisions at 7 TeV are simulated. Predictions of DPMJETIII.17-1, HIJING1.383 and Sibyll2.3c are compared to the differential cross-section measurements of the LHCb experimental data presented in the region of [Formula: see text] and [Formula: see text], where the pp center of mass frame is used to measure the transverse momentum and rapidity. The models reproduce only some regions of [Formula: see text] and/or bins of [Formula: see text] but none of them predict completely all the [Formula: see text] bins over the entire [Formula: see text] range.

scholarly journals Cross Section Ionization By Electron Impact Of Helium Like Ions

2021 ◽  
Author(s):  
Manel Hariz Belgacem ◽  
Elhabib Guedda ◽  
Haikel Jelassi
Keyword(s):  
Electron Impact ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
The Cross ◽  
State 1 ◽  
Unstable States ◽  
Good Agreement

<sub></sub> In this paper we present our calculation of the cross section ionization by electron impact of C V, N VI and O VII. Using the Flexible Atomic Code (FAC), we obtain the cross sections for the ionization of these ions from the ground state 1<sup>1</sup>S, and from the unstable states 2<sup>1</sup>S and 2<sup>3</sup>S. Our results are in good agreement with those based on the Coulomb Born (CB) approximation and the available measurements.

Modeling $\bar{p}p$ and recent LHC pp total cross-sections

2014 ◽  
Vol 29 (08) ◽  
pp. 1450044 ◽  
Author(s):  
Amr Radi ◽  
Esraa El-Khateeb
Keyword(s):  
Neural Network ◽  
Total Cross Section ◽  
Cross Section ◽  
Cross Sections ◽  
Hadron Collider ◽  
Center Of Mass ◽  
High Energy ◽  
Ann Model ◽  
Predicted Values ◽  
Good Agreement

New technique is presented for modeling total cross-section of both pp and [Formula: see text] collisions from low to ultra high energy regions using an efficient artificial neural network (ANN). We have used the input (center-of-mass energy, [Formula: see text], and type of particle P) and output (total cross-section σ tot ) data to build a prediction model by ANN. The neural network has been trained to produce a function that studies the dependence of σ tot on [Formula: see text] and P. The trained ANN model shows a good performance in matching the trained distributions, predicts cross-sections that are not presented in the training set. The general trend of the predicted values shows a good agreement with the recent Large Hadron Collider (LHC) measurements, where the total cross-section at [Formula: see text] and 8 TeV are measured to be 98.6 mb and 101.7 mb, respectively. The predicted values of the total cross-section at [Formula: see text] and 14 TeV are found to be 105.8 mb and 111.7 mb, respectively. Those predictions are in good agreement with Block, Cudell and Nakamura.

scholarly journals Energy dependence of $$\phi $$ meson production at forward rapidity in pp collisions at the LHC

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
S. Acharya ◽  
D. Adamová ◽  
A. Adler ◽  
J. Adolfsson ◽  
G. Aglieri Rinella ◽  
...  
Keyword(s):  
Differential Cross Section ◽  
Energy Dependence ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Decay Channel ◽  
Center Of Mass ◽  
Meson Production ◽  
Pp Collisions ◽  
Rapidity Distributions

AbstractThe production of $$\phi $$ ϕ mesons has been studied in pp collisions at LHC energies with the ALICE detector via the dimuon decay channel in the rapidity region $$2.5< y < 4$$ 2.5 < y < 4 . Measurements of the differential cross section $$\mathrm{d}^2\sigma /\mathrm{d}y \mathrm{d}p_{\mathrm {T}}$$ d 2 σ / d y d p T are presented as a function of the transverse momentum ($$p_{\mathrm {T}}$$ p T ) at the center-of-mass energies $$\sqrt{s}=5.02$$ s = 5.02 , 8 and 13 TeV and compared with the ALICE results at midrapidity. The differential cross sections at $$\sqrt{s}=5.02$$ s = 5.02 and 13 TeV are also studied in several rapidity intervals as a function of $$p_{\mathrm {T}}$$ p T , and as a function of rapidity in three $$p_{\mathrm {T}}$$ p T intervals. A hardening of the $$p_{\mathrm {T}}$$ p T -differential cross section with the collision energy is observed, while, for a given energy, $$p_{\mathrm {T}}$$ p T spectra soften with increasing rapidity and, conversely, rapidity distributions get slightly narrower at increasing $$p_{\mathrm {T}}$$ p T . The new results, complementing the published measurements at $$\sqrt{s}=2.76$$ s = 2.76 and 7 TeV, allow one to establish the energy dependence of $$\phi $$ ϕ meson production and to compare the measured cross sections with phenomenological models. None of the considered models manages to describe the evolution of the cross section with $$p_{\mathrm {T}}$$ p T and rapidity at all the energies.

Photoneutron Reactions in 18O

1975 ◽  
Vol 53 (8) ◽  
pp. 786-794 ◽  
Author(s):  
J. D. Allan ◽  
J. W. Jury ◽  
R. G. Johnson ◽  
K. G. McNeill ◽  
J. G. Woodworth ◽  
...  
Keyword(s):  
Excited State ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Ground State ◽  
Energy Spectra ◽  
Continuum State ◽  
Average Value ◽  
First Excited State ◽  
Time Of Flight Spectroscopy

Photoneutron energy spectra from 18O have been measured by time-of-flight spectroscopy at bremsstrahlung endpoint energies from 11 to 18 MeV in 1 MeV steps to obtain the (γ, n0) and (γ, n1) differential cross sections. The ground state photoneutron cross section contains at least 8 major resonances in the region from 10 to 17 MeV and has an average value of 100 μb/sr. The cross section to the first excited state of 17O contains only two major resonances, at 11.4 and 14.4 MeV, and the average cross section in the region from 11 to 16 MeV is about 40 μb/sr. Of particular interest is a resonance at 14.4 MeV which appears to reflect a simple excitation of one of the valence neutrons to the 2p3/2 state. Analysis of the (γ, n0) and (γ, n1) cross sections for this continuum state leads to estimates of the configuration amplitudes of the 2s1/2 and 1d5/2 components of this state to be 0.62 ± 0.06 and 0.78 ± 0.08 respectively and the ratio of the (2s1/2)2 to (1d5/2)2 amplitudes in the ground state of 18O to be 0.39 ± 0.02.

scholarly journals Spin Effects in the (e, 2e) Cross Section of Xenon

1996 ◽  
Vol 49 (2) ◽  
pp. 383 ◽  
Author(s):  
B Granitza ◽  
X Guo ◽  
JM Hum ◽  
J Lower ◽  
S Mazevet ◽  
...  
Keyword(s):  
Electron Beam ◽  
Fine Structure ◽  
Electron Impact ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Closed Shell ◽  
Spin Effects ◽  
Incident Electron Beam ◽  
Series Of Experiments

In a series of experiments investigating the spin-dependent aspects of electron impact induced ionisation of atoms with a spin-resolved incident electron beam we have measured spin-resolved (e, 2e) cross sections for xenon. By experimentally resolving the fine structure levels of the ground state residual ion the existence of an effect analogous to the fine structure effect in excitation has been established, whereby strong and opposite polarisation effects are observed in the ionisation of a spinless closed shell target leading to a fine structure doublet.

Cross Section Analysis of Cu Filled TSVs Based on High Throughput Plasma-FIB Milling

2012 ◽  
Author(s):  
Frank Altmann ◽  
Jens Beyersdorfer ◽  
Jan Schischka ◽  
Michael Krause ◽  
German Franz ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
High Throughput ◽  
Cross Sections ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Electron Backscatter ◽  
Section Surface ◽  
Backscatter Diffraction ◽  
Section Analysis

Abstract In this paper the new Vion™ Plasma-FIB system, developed by FEI, is evaluated for cross sectioning of Cu filled Through Silicon Via (TSV) interconnects. The aim of the study presented in this paper is to evaluate and optimise different Plasma-FIB (P-FIB) milling strategies in terms of performance and cross section surface quality. The sufficient preservation of microstructures within cross sections is crucial for subsequent Electron Backscatter Diffraction (EBSD) grain structure analyses and a high resolution interface characterisation by TEM.

scholarly journals Photoionization Cross-Sections of Carbon-Like N+ Near the K-Edge (390–440 eV)

Atoms ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 27
Author(s):  
Jean-Paul Mosnier ◽  
Eugene T. Kennedy ◽  
Jean-Marc Bizau ◽  
Denis Cubaynes ◽  
Ségolène Guilbaud ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
Cross Sections ◽  
Experimental Studies ◽  
Photoionization Cross Section ◽  
Theoretical Work ◽  
Rydberg Series ◽  
R Matrix ◽  
Resonance Strengths ◽  
Nitrogen Ion

High-resolution K-shell photoionization cross-sections for the C-like atomic nitrogen ion (N+) are reported in the 398 eV (31.15 Å) to 450 eV (27.55 Å) energy (wavelength) range. The results were obtained from absolute ion-yield measurements using the SOLEIL synchrotron radiation facility for spectral bandpasses of 65 meV or 250 meV. In the photon energy region 398–403 eV, 1s⟶2p autoionizing resonance states dominated the cross section spectrum. Analyses of the experimental profiles yielded resonance strengths and Auger widths. In the 415–440 eV photon region 1s⟶(1s2s22p2 4P)np and 1s⟶(1s2s22p2 2P)np resonances forming well-developed Rydberg series up n=7 and n=8 , respectively, were identified in both the single and double ionization spectra. Theoretical photoionization cross-section calculations, performed using the R-matrix plus pseudo-states (RMPS) method and the multiconfiguration Dirac-Fock (MCDF) approach were bench marked against these high-resolution experimental results. Comparison of the state-of-the-art theoretical work with the experimental studies allowed the identification of new resonance features. Resonance strengths, energies and Auger widths (where available) are compared quantitatively with the theoretical values. Contributions from excited metastable states of the N+ ions were carefully considered throughout.

Differential cross-section measurements in positron–argon collisions

1996 ◽  
Vol 74 (7-8) ◽  
pp. 505-508 ◽  
Author(s):  
R. M. Finch ◽  
Á. Kövér ◽  
M. Charlton ◽  
G. Laricchia
Keyword(s):  
Elastic Scattering ◽  
Differential Cross Section ◽  
Inelastic Scattering ◽  
Energy Range ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Coupling Effect ◽  
Channel Coupling ◽  
Scattering Cross

Differential cross sections for elastic scattering and ionization in positron–argon collisions as a function of energy (40–150 eV) are reported at 60°. Of particular interest is the energy range 55–60 eV, where earlier measurements by the Detroit group found a drop in the elastic-scattering cross section of a factor of 2. This structure has been tentatively attributed to a cross channel-coupling effect with an open inelastic-scattering channel, most likely ionization. Our results indicate that ionization remains an important channel over the same energy range and only begins to decrease at an energy above 60 eV.

Sign in / Sign up

Export Citation Format

Share Document