The feasibility of using neural networks to obtain cross sectionsfrom electron swarm data

The use of an artificial neural network as an optimization technique for treating the inverse problem of obtaining electron collision cross section from electron transport data is explored in which electron-impact cross sections from measured drift velocities, characteristic energies, and other swarm data are obtained. Momentum transfer cross sections obtained for a model problem and for xenon using a neural network are presented     

Resonance States in Scattering of Slow Particles with Nonzero Orbital Angular Momentum by the Pöschl-Teller Potential

The scattering of slow particles with nonzero orbital angular momentum in the field of a finite potential is considered. The respective scattering problem is solved in the Pais approximation. The inverse problem is solved for the Pöschl-Teller equation, and a general scheme for Pais resonances and a procedure for calculating scattering cross sections for resonance particles are formulated.

     

Influence of nuclear excitations on absorption cross sections

From the mean free path in excited nuclear matter a temperature dependent optical model is derived. With its help the approximation of inverse cross sections by ground state absorption cross sections is studied.     

Estimation of Electrical Source Localization Using the Temporal Correlation between Magnetic Field Measurements

It is well known that an inverse problem of biomagnetic imaging is generally ill-posed. Recently several attempts using biocoherence have been reported, but the ill-condition is not considered in these previous methods. If the conventional reconstruction formula is under the ill-condition, the reconstruction problem is also ill-posed and the ill-posedness cannot be improved. In this paper, we propose an approach to estimate the location of current sources under the condition that sources of different positions have little or weak correlation. Our method is based on a well-known regularization method, the truncated SVD method. Compared with the conventional method, our technique allows accurate determination of the location of current sources because it improves the ill-posedness of the inverse problem. We carried out computer simulations using the half-space conducting model and confirmed the effectiveness of our method.     

On the capture of protons by magnetic monopoles

The cross sections for the formation of monopole proton bound states are calculated in the dipole approximation and found to be of the order of the proton Compton wavelength squared, weakly dependent on the relative velocity and on the binding energy of the system. Cross sections for the inverse (photodetachment) process are also given.     

Pair production of doubly heavy diquarks

The differential and total cross sections for the pair production of doubly heavy diquarks are calculated analytically within the diquark model. The cases of electron-positron and quark-antiquark annihilation are considered. The ratios of the total cross sections to the corresponding cross sections for annihilation into two heavy quarks are estimated numerically.     

Simulated annealing algorithm for ill-posed or ill-conditioning deconvolution problem

I.IlitroductiollDeconvolutionisesselltialinsomeenglneeringapplications.Forexample,toexaminethepropertiesofmaterial8withoutbrealdngthemdownNonDestructiveEvaluationTechniquesNDETareusuallyusedandmainlybasedontheultrasonicmeasurementwherebroadbandultrasonicpulsesaJrecoupledintothematerichandtheechoesarecollected.Thenthepulseresponseofthematerialisdeconvolutedandthecharacteristicsofthehiddenflawsinthematerialscanbeidentifiedbypatternrecoghtiontechulqllesl1l.DeconvolutionisaIsoencounteredinthe…     

Separation of continuous lines mutually overlapping and smoothed by the instrumental function

Direct and inverse spectroscopy problems concerning superposition of overlapping continuous spectral lines, as well as smoothing of the total spectrum by the instrumental function, are considered. The direct problem is formulated in two stages: initially, the total spectrum is formed by lines with a given intensity distribution, and, then, a smoothed by the spectrometer instrumental function and noisy spectrum is obtained. The inverse problem is also formulated in two stages: initially, the Fredholm integral equation of the first kind is solved by the Tikhonov regularization method (an ill-posed problem), and, then, the problem of reconstruction of separate line-component shapes from the total spectrum is solved, which is the problem of line separation (division). The individual line components are modeled by Gaussians and Lorentzians. Numerical illustrations are shown. Gaussian and dispersion (Lorentz) instrumental functions are considered.     

Calculation of the photoionization cross sections for the ions of the rubidium isoelectronic sequence by the Dirac-Fock method

The photoionization cross sections for the ground and some excited states of 11 ions of the rubidium isoelectronic sequence from Rb through Ag¹⁰⁺ are calculated by the relativistic Dirac-Fock self-consistent field method. The energy dependence of the photoionization cross sections and the changes in the threshold values along the isoelectronic sequence are considered. The influence of the exchange effect and the choice of gauge on the calculated values of photoionization cross sections is examined. For practical use, the calculated cross sections are approximated by an analytical expression. Along with the total photoionization cross sections, the asymmetry parameter in the angular distribution of photoelectrons and the degree of their polarization are also calculated.     

Formation of metastable molecular states at the resonance scattering of two atoms in a laser radiation field

Using the Dirac’s method, the formation of metastable molecular states at the resonance scattering of two atoms in the laser radiation field is considered. Expressions for the metastable level populations and the resonance scattering cross sections are obtained. In the case of an exact resonance with the laser radiation, the graphs for populations and resonance scattering cross sections, which have two peaks due to the Autler–Townes effect, are obtained. These results play an important role in the study of the controlled chemical reaction and for the understanding of the processes in the quantum systems of the Bose–Einstein condensate at low temperatures, as well as in the various optical processes in atomic gases.     

Cascade-exciton model analysis of level density parameter dependence in proton induced fission cross sections of some sub-actinide nuclei

Fission cross sections strongly depend on the ratio of the level density parameter in fission to neutron emission, a_f/a_n. In this work, a cascade-exciton model implemented in the code CEM95 has been used to observe this effect for proton induced fission cross sections of tungsten, lead and bismuth. The method was employed using different level density parameter ratios for each fission cross section calculation. The calculated fission cross sections are compared with the available experimental data in the literature. It has been observed that a change of the ratio of the level density parameter, a_f/a_n, is necessary with the incident energy of the proton, to best estimate the fission cross sections in CEM95.     

Temperature effect of the integral flux of cosmic-ray muons at high energies

The temperature coefficients of the integral fluxes of cosmic-ray muons arriving at sea level vertically and horizontally with energies of 10², 10⁴, and 3 × 10⁶ GeV are calculated. Decays of pions, kaons, and charmed particles are considered as sources of muon generation in the atmosphere (according to current data on the generation cross sections of pions, kaons, and charmed particles in interactions between nucleons and the nuclei of atmospheric atoms, obtained in experiments on accelerators and in quantum chromodynamics models). The uncertainties in the generation cross sections of charmed particles are quite high.     

闭通道对氦氢碰撞激发分波截面影响的研究

采用精确度较高的密耦近似方法计算了不同能量下的氯原子与氢分子碰撞体系的振转激发分波截面.在计算时依次考虑了入射通道中耦合态的数目为开通道数加上1个闭通道数,2个闭通道数,3个闭通道数,直到7个闭通道数的情况.结果表明:在研究氦氢碰撞体系的弹性碰撞、纯转动激发时,可以只考虑1个闭通道的影响,但在研究振转激发分波截面时,至少要考虑5个闭通道,才能得到比较准确的计算结果.     

Mechanism of elastic and inelastic proton scattering on a 15C nucleus in diffraction theory

The amplitudes for elastic and inelastic proton scattering on the neutron-rich nucleus ¹⁵C (to its J ^?? = 5/2⁺ level in the latter case) in inverse kinematics were calculated within Glauber diffraction theory. First- and second-order terms were taken into account in the multiple-scattering operator. The ¹⁵C wave function in the multiparticle shell model was used. This made it possible to calculate not only respective differential cross sections but also the contribution of proton scattering on nucleons occurring in different shells. The differential cross sections for elastic and inelastic scattering were calculated at the energies of 0.2, 0.6, and 1 GeV per nucleon.     

碳对α的非卢瑟福背散射截面研究

报道了散射角为１７０°±１．５°，α粒子能量在５－９．０ＭｅＶ之间，ｃ的背散射截面的实验测量值；用Ｒ矩阵理论，通过与实验数据拟合，分析、给出了一套能级参数，并计算了能量范围在２－９．０ＭｅＶ，ｃ的背散射截面；讨论了对背散射分析感兴趣的窄而孤立的强共振峰４２５０±１０ＫｅＶ随靶厚、角度的变化关系以及截面变化缓慢的平坦区３．６－４．２０ＭｅＶ，６．４２５－６．７００ＭｅＶ能区的截面值与背散射角度的关系。 关键词：     

Some features of the production of heavy-quark-containing baryons in electron-positron collisions

The production of various heavy-quark-containing baryons in electron-positron annihilation is considered. On the basis of exact formulas that we obtained previously within full perturbation theory, new numerical calculations of the respective cross sections are performed, and simple approximate expressions are then constructed for the results of these calculations. The dependence of the total cross sections on the masses of constituent quarks is discussed. The application of the Peterson fragmentation function and a Reggeon-type fragmentation function to describing differential cross sections is analyzed.     

Analysis of Neutron Double-Differential Cross Sections for n + 12C Reaction Below 30 MeV

Based on the light nucleus reaction model (Nucl. Sci. Eng. l33 (1999) 218), four aspects (neutron incident energy region, reaction channel analysis, the renewed level schemes and the optical model parameters) of n 12 C reaction are improved to calculate total outgoing neutron double-differential cross sections with modified LUNF code below 30 MeV. The calculated results agree fairly well with the experimental data at En = 14.1 MeV and 18 MeV. The analysis shows that the pre-equilibrium mechanism, which is exactly considered the conservation of energy, momentum and parity, dominates the whole reaction process. The contribution of the neutron emission from 5He to total energyangular spectra is also considered properly. This modified LUNF code will be a useful tool to set up the file of neutron double-differential cross sections below 30 MeV in the neutron evaluation nuclear data library.     

Transitions between the components of the fine structure in He and He-Like ions colliding with protons

The cross sections for the transitions between the components of the fine structure of triplet levels with n = 2 and 3 in He and He-like ions colliding with protons have been considered. The feature of the problem is the presence of a virtual level coupled with the components of the multiplet by dipole-allowed transitions. As a result, the cross section at intermediate collision velocities has a peak, which is sometimes much higher than the cross section for the transition induced by collisions with electrons. The cross sections for He and C⁴⁺ and Fe²⁴⁺ ions have been calculated by the tight-binding method.     

Dinuclear systems in complete fusion reactions

Formation and evolution of dinuclear systems in reactions of complete fusion are considered. Based on the dinuclear system concept, the process of compound nucleus formation is studied. Arguments confirming the validity of this concept are given. The main problems of describing the complete fusion in adiabatic approximation are listed. Calculations of evaporation residue cross sections in complete fusion reactions leading to formation of superheavy nuclei are shown. Isotopic trends of the cross sections of heavy nuclei formation in complete fusion reactions are considered.     

He-HI碰撞的转动激发分波截面

基于作者所发展的分子间相互作用势,采用密耦方法计算了入射He原子能量分别为40,75和100　meV时与HI分子碰撞的弹性和非弹性分波截面.研究表明：激发分波截面比弹性分波截面收敛得快;激发态越高,激发分波截面收敛得越快;能量越高,激发分波截面收敛得越慢. 关键词： 分波截面 密耦方法 He-HI复合物