scholarly journals Charge-exchange isobaric resonances

2018 ◽  
Vol 194 ◽  
pp. 02009 ◽  
Author(s):  
Yu.S. Lutostansky
Keyword(s):  
Experimental Data ◽  
Charge Exchange ◽  
Cross Sections ◽  
Microscopic Theory ◽  
Average Deviation ◽  
Resonance Energies ◽  
Strength Functions ◽  
Experimental Values ◽  
Gamow Teller ◽  
Good Agreement

Three types of the charge-exchange isobaric resonances - giant Gamow-Teller (GTR), the analog (AR) and pygmy (PR) ones are investigated using the microscopic theory of finite Fermi systems and its approximated version. The calculated energies of GTR, AR and three PR’s are in good agreement with the experimental data. Calculated differences ΔEG-A=EGTR-EAR go to zero in heavier nuclei indicating the restoration of Wigner SU(4)-symmetry. The average deviation for ΔEG-A is 0.30 MeV for the 33 considered nuclei where experimental data are available. The comparison of calculations with experimental data on the energies of charge-exchange pygmy resonances gives the standard deviation δE<0:40 MeV. Strength functions for the 118Sn, 71Ga, 98Mo and 127I isotopes are calculated and the calculated resonance energies and amplitudes of the resonance peaks are close to the experimental values. Strong influence of the charge-exchange resonances on neutrino capturing cross sections is demonstrated.

Gamow–Teller strength functions from scattering experiments

1987 ◽  
Vol 65 (6) ◽  
pp. 691-698 ◽  
Author(s):  
O. Häusser
Keyword(s):  
Shell Model ◽  
Cross Sections ◽  
Mean Field ◽  
Wave Functions ◽  
Structure Information ◽  
Model Wave ◽  
Spin Flip ◽  
Strength Functions ◽  
Gamow Teller ◽  
Good Agreement

We present here recent [Formula: see text] results from TRIUMF that are relevant to the determination of spin-flip isovector strength functions in nuclei. Distortion factors needed for the extraction of nuclear-structure information have been deduced from cross sections and analyzing powers in elastic scattering for several energies and targets. Nonrelativistic optical potentials obtained by folding effective nucleon (N)–nucleus interactions with nuclear densities are found to overpredict both elastic and reaction cross sections, whereas Dirac calculations that include Pauli blocking are in good agreement with the data. Spin observables (Snn and Ay) for the quasi-elastic region in 54Fe[Formula: see text] at 290 MeV provide some evidence for the reduction of the effective proton mass predicted in relativistic mean-field theories as a consequence of the attractive scalar field in the nuclear medium. The energy dependence of the effective N–nucleus interaction at small momentum transfers has been investigated using isoscalar and isovector 1+ states in 28Si as probe states. We find that the cross sections for the isovector transitions are in good agreement with predictions for the dominant Vστ part of the Franey–Love interaction. Gamow–Teller (GT) strength functions have been obtained in 24Mg and 54Fe from measurements of both cross sections and spin–flip probabilities Snn. The spin-flip cross sections σSnn are particularly useful in heavier nuclei to discriminate against a continuous background of ΔS = 0 excitations. In the (s, d) shell where full shell-model wave functions are available, the GT quenching factors [Formula: see text] are in good agreement with those from recent (p, n) and (n, p) experiments. We show that a state-by-state comparison of (p, p′) and (e, e′) results has the potential of identifying pionic current contributions in (e, e′). The GT quenching factors in 54Fe are smaller than in the (s, d) shell probably because of severely truncated shell-model wave functions, particularly those of the nuclear ground state.

scholarly journals Four-body one-channel distorted-wave theories for single electron transfer

2003 ◽  
Vol 2 (5) ◽  
pp. 301-309
Author(s):  
Ivan Mancev
Keyword(s):  
Experimental Data ◽  
Electron Transfer ◽  
Charge Exchange ◽  
Cross Sections ◽  
Differential Cross ◽  
Scattering Theory ◽  
Single Electron Transfer ◽  
Distorted Wave ◽  
Single Charge ◽  
Good Agreement

The two versions of the Born distorted wave (BDW) models are formulated within the framework of the four-body scattering theory. As an illustration the BDW approximation is applied to compute the differential cross sections for a single charge exchange in p + H e collision at 500 keV. The present calculated results are found to be in good agreement with experimental data.

scholarly journals Energy Dependence of Total Cross Sections for Reactions with 4, 6he, 6, 7, 9li Nuclei

KnE Energy ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 21
Author(s):  
Yu Penionzhkevich ◽  
Yu Sobolev ◽  
V Samarin ◽  
M Naumenko
Keyword(s):  
Experimental Data ◽  
Energy Range ◽  
Numerical Solution ◽  
Energy Dependence ◽  
Cross Sections ◽  
Beam Energy ◽  
Microscopic Analysis ◽  
Time Dependent ◽  
Total Cross Sections ◽  
Good Agreement

The paper presents the results of measurement of the total cross sections for reactions 4,6He + Si and 6,7,9Li + Si in the beam energy range 5−50 A⋅MeV. The enhancements of the total cross sections for reaction 6He + Si compared with reaction 4He + Si, and 9Li + Si compared with reactions 6,7Li + Si have been observed. The performed microscopic analysis of total cross sections for reactions 6He + Si and 9Li + Si based on numerical solution of the time-dependent Schrödinger equation for external neutrons of projectile nuclei 6He and 9Li yielded good agreement with experimental data.

RELATIVISTIC OPTICAL MODEL FOR PROTON-NUCLEUS ELASTIC SCATTERING

2002 ◽  
Vol 11 (05) ◽  
pp. 425-436 ◽  
Author(s):  
M. Y. H. FARAG ◽  
M. Y. M. HASSAN
Keyword(s):  
Experimental Data ◽  
Elastic Scattering ◽  
Cross Sections ◽  
Differential Cross ◽  
Optical Potential ◽  
Optical Model ◽  
Potential Model ◽  
Optical Potential Model ◽  
Relativistic Description ◽  
Good Agreement

The relativistic description of the proton-nucleus elastic scattering can be considered within the framework of a relativistic optical potential model. The elastic scattering of proton with the nuclei 12 C , 16 O , 20 Ne , and 24 Mg at 800 MeV and 1.04 GeV are studied for relativistic and nonrelativistic treatments. The real optical potentials and the differential cross sections of these reactions are calculated. The obtained results are compared with the corresponding results obtained from the calculation depending on the Woods–Saxon optical potential which were adjusted to fit the experimental data. The present results are in good agreement with the experimental data.

Microscopic spin-orbit potential for p +6He elastic scattering

2019 ◽  
Vol 28 (09) ◽  
pp. 1950074
Author(s):  
Zakaria M. M. Mahmoud ◽  
Awad A. Ibraheem ◽  
M. A. Hassanain
Keyword(s):  
Experimental Data ◽  
Elastic Scattering ◽  
Cross Sections ◽  
Optical Model ◽  
Spin Orbit ◽  
Current Form ◽  
Density Distributions ◽  
Orbit Potential ◽  
Scattering Cross Sections ◽  
Good Agreement

In this work, we simultaneously reanalyzed the differential elastic scattering cross-sections ([Formula: see text]) and the vector analyzing power ([Formula: see text]) of [Formula: see text]He elastic scattering. This analysis was performed using the folded optical model for both real central and spin-orbit (SO) potentials, respectively. For the imaginary central, we used the usual Woods-Saxon (WS) form. Three different model density distributions are used to calculate the potential. We aimed to examine the applicability of the microscopically derived SO potential and the structure effect of 6He nucleus. The presence of the [Formula: see text] experimental data of [Formula: see text]He makes it interesting for this study. Our calculations showed that the three densities gave similar predictions for the cross-sections data. The three microscopic SO potentials calculations of [Formula: see text] are not in a good agreement with the experimental data. We concluded that the SO formalism in its current form needs more investigations for exotic halo nuclei.

K-, L-, and M-shell ionization of atoms by electron and positron impact

1996 ◽  
Vol 74 (7-8) ◽  
pp. 376-383 ◽  
Author(s):  
S. P. Khare ◽  
J. M. Wadehra
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Positron Impact ◽  
Electrons And Positrons ◽  
Virtual Photons ◽  
Plane Wave Born Approximation ◽  
Ionization Cross Sections ◽  
Impact Energies ◽  
Shell Ionization ◽  
Good Agreement

The plane-wave Born approximation with Coulomb, relativistic, and exchange corrections is employed to obtain the K-, L1-, L2-, L3-, and M-shell ionization cross sections of a number of atoms bombarded by electrons and positrons in the energy range varying from the threshold of ionization to 1 GeV. Transverse interaction of virtual photons with atoms is also included and it is found to be of great significance for impact energies greater than about 1 MeV. For K- and L-shell ionization, good agreement between the theoretical values and various experimental data for electron-impact cross sections is obtained. However, for the M shell, the theory overestimates the experimental cross sections. For positron impact the agreement between the present results and the limited experimental data is found to be quite satisfactory.

scholarly journals Improved Performance Prediction of Marine Propeller: Numerical Investigation and Experimental Verification

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Yue Tan ◽  
Jing Li ◽  
Yuan Li ◽  
Chunbao Liu
Keyword(s):  
Experimental Data ◽  
Performance Prediction ◽  
Outer Boundary ◽  
Tangential Velocity ◽  
Marine Propeller ◽  
Computational Performance ◽  
Accurate Performance ◽  
Improved Performance ◽  
Experimental Values ◽  
Good Agreement

An approach was presented to improve the performance prediction of marine propeller through computational fluid dynamics (CFD). After a series of computations were conducted, it was found that the passage in the former study was too narrow, resulting in the unnecessary radial outer boundary effects. Hence, in this study, a fatter passage model was employed to avoid unnecessary effects, in which the diameter was the same as the length from the propeller to the downstream outlet and the diameter was larger than the previous study. The diameter and length of the passage were 5D and 8D, respectively. The propeller DTMB P5168 was used to evaluate the fat passage model. During simulation, the classical RANS model (standard k-ε) and the Multiple Reference Frame (MRF) approach were employed after accounting for other factors. The computational performance results were compared with the experimental values, which showed that they were in good agreement. The maximum errors of Kt and Kq were less than 5% and 3% on different advance coefficients J except 1.51, respectively, and that of η was less than 2.62%. Hence the new model obtains more accurate performance prediction compared with published literatures. The circumferentially averaged velocity components were also compared with the experimental results. The axial and tangential velocity components were also in good agreement with the experimental data. Specifically, the errors of the axial and tangential velocity components were less than 3%, when the r/R was not less than 3.4. When the J value was larger, the variation trends of radial velocity were consistent with the experimental data. In conclusion, the fat passage model proposed here was applicable to obtain the highly accurate predicted results.

Total-to-K-shell photoelectric cross-section ratios in some rare-earth and high-Z elements

1989 ◽  
Vol 67 (2-3) ◽  
pp. 139-142 ◽  
Author(s):  
S. Chandra Lingam ◽  
K. Suresh Babu ◽  
V. Prakash Kumar ◽  
D. V. Krishna Reddy
Keyword(s):  
Rare Earth ◽  
Cross Section ◽  
Atomic Number ◽  
Cross Sections ◽  
Cross Section Ratio ◽  
Section Ratio ◽  
Photoelectric Cross Section ◽  
Normal Transmission ◽  
Experimental Values ◽  
Good Agreement

The total photoelectric cross-sections in the elements gadolinium, dysprosium, erbium, lutetium, tantalum, tungsten, gold, and lead have been obtained by using the normal transmission experiments, and the results are reported. Using these total photoelectric cross sections, we have found the K-shell photoelectric cross sections, the K-jump ratios, and the total-to-K-shell photoelectric cross-section ratios at the K edges for the above elements. These values are compared with the available theoretical and experimental values. The results are in good agreement with the Storm and Israel results and the Scofield theoretical values, within the limits of experimental uncertainties. Furthermore, the variation of the total-to-K-shell photoelectric cross-section ratio with energy and atomic number is discussed.

A novel multiaxial three-dimensional woven preform: Process and structure

2017 ◽  
Vol 37 (4) ◽  
pp. 247-266 ◽  
Author(s):  
Xinmiao Wang ◽  
Li Chen ◽  
Junshan Wang ◽  
Xintao Li ◽  
Zhongwei Zhang
Keyword(s):  
Cross Sections ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Woven Composite ◽  
Cell Geometry ◽  
Geometry Model ◽  
End Use ◽  
Experimental Values ◽  
Composite Samples ◽  
Good Agreement

A novel multiaxial three-dimensional woven preform and the weaving technique have been developed in this study. The preform exhibits remarkable designs, which is formed by multiple layers of different yarn sets, including bias (+bias/−bias), warp, and filling, and all layers are locked by Z-yarns These layers are arranged in a rectangular fashion and the layer number and the position of bias layer can be determined by the end-use requirements. A weaving process and machine are proposed to produce the preform. The weaving technique enables the insertion of many warp layers between two opposite bias layers. The microstructure of the preform was also studied. Microscopic evidence of the microstructure reveals that the cross-sections of Z-yarn are variable along its central axis due to the lateral compression forces of adjacent yarns from different directions. On the basis of microscopic observation, a unit cell geometry model of multiaxial three-dimensional woven preform is established, and a good agreement has been obtained between the theoretical and experimental values of the structural parameters of woven composite samples.

Identification of Natural Frequency of Bearing Rotor Based on GA-SVM

2012 ◽  
Vol 443-444 ◽  
pp. 27-33
Author(s):  
Tian Ran Ma ◽  
Fei Hu Qin ◽  
Rui Xue Liu ◽  
Feng Jie Zhang
Keyword(s):  
Experimental Data ◽  
Support Vector Machine ◽  
Natural Frequency ◽  
Rolling Bearing ◽  
Linear Mapping ◽  
Support Vector ◽  
Non Linear ◽  
Experimental Values ◽  
Rotor Structure ◽  
Good Agreement

During identify natural frequency of bearing rotor, due to the complex non-linear relationship among the factors which influence natural frequency, so it is hard to establish a complete and accurate theoretical model. Based on the generalization and approximation of non-linear mapping capability of support vector machine (SVM) and the powerful ability of global optimization of the genetic algorithm (GA), the paper through optimizing the SVM by GA, establishes combined Genetic Support Vector Machine (GA-SVM). The method establishes the mapping between the natural frequency of a rolling bearing rotor and the various parameters, which reduces the rotor structure for the study similar to the natural frequency of the calculation of the workload greatly. Using the model to indentify the natural frequency of bearing rotor under different parameters, then compare identification value with experimental values shows that projections in good agreement with the experimental data.

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