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Theoretical Analysis of Neutron Double—Differential Cross Section of n＋^10B at14.2MeV

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Communications in Theoretical Physics 2003年第1期39卷 433-438页

作者： zhangjing－shang ChinaInstituteofAtomicEnergy P.O.Box275（41）Beijing102413China

By using a new reaction model for light nuclei, the double-differential cross sections of n+ 10B reactions atEn ＝ 14.2 MeV have been analyzed. In the case of n+10B reactions there are over one hundred opened partial reactionchannels. Besides the sequential particle emissions, there is also the three-body breakup process, in which the kinematicsis classified into four types. In this paper the opened reaction channels are listed in detail with the LUNF code, withwhich the model calculation is performed to analyze the total outgoing neutron double-differential cross sections. All ofthe fittings agree fairly well with the measurements. The calculation results indicate that the pre-equilibrium mechanismdominates the whole reaction processes, and the recoil effect in light nuclear reaction is essentially important.

关键词：理论分析微分截面中子核反应模型反应过程 14.2MeV

Calculation of Double—Differential Cross Sections of n＋^7Li Reactions Below 20 MeV

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Communications in Theoretical Physics 2002年第4期37卷 465-474页

作者： zhangjing－shang HANYing－Lu ChinaInstituteofAtomicEnergy P.O.Box275（41）Beijing102413China

A new reaction model for light nuclei is proposed to analyze the measured data,especially for analysis of the double-differential cross sections of the outgoing *** channels arc opened in the n + 7Li reaction below En＜ 20 *** reaction mechanism is very complex,beside the sequential emissions there are also three-body breakup *** of a strong recoil effect of light nucleus reactions,the energy balance is strictly taken into *** comparisons of the calculated results with the double-differential measurements indicate that the model calculations are successful for the total outgoing neutrons.

关键词：低能核反应微分截面分立能级

Pre-formation Probability of ^5He Cluster in Pre-equilibrium Mechanism

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Communications in Theoretical Physics 2004年第4X期42卷 587-593页

作者： DUANJun-Feng YANYu-Liang zhangjing-shang ChinaInstituteofAtomicEnergy P.O.Box275(41)Beijing102413China

The possibility of 5He cluster emission has been affirmed theoretically. In order to describe the emission probability of 5He cluster, the pre-formation probability of 5He cluster in pre-equilibrium emission process is needed to be established. In terms of Iwamoto-Harada model, the theoretical formula of pre-formation probability of 5He cluster including 1p shell nucleon in pre-equilibrium mechanism has been established and calculated. In the case of low incident energies, the configuration of [1, m] for 5He cluster is the dominant part in the nuclear reaction. The calculated results indicate that pre-formation probability of configuration [1, m] for the unstable 5He cluster is much smaller than those of d, t, 3He, and 4He, i.e. the light stable composite particles, which are consisted of only 1s shell nucleons. However, it is propitious to the emission of 5He from the point of view on threshold energies, since the binding energies of 5He are generally lower than that of 3He in compound nucleus. The corresponding model formula has been given in this paper for described pre-formation probability of 5He cluster in pre-equilibrium mechanism.

关键词：原子核物理核反应复合粒子辐射氦束辐射费米面

Double-Differential Cross Section of ^5He Emission

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Communications in Theoretical Physics 2005年第2期43卷 299-304页

作者： YANYu-Liang DUANJun-Feng zhangjing-shang XUGuang ChinaInstituteofAtomicEnergy P.O.Box275（41）Beijing102413China InstituteofNuclearEnergyTechnology TsinghuaUniversityBeijing100086China

The probability of 5He particle emission has been affirmed theoretically [J.S. Zhang, Science in China G47 (2004) 137]. In order to describe the 5He emission, the theoretical formula of the double-differential cross section of emitted 5He is to be established. Based on the pick-up mechanism, used for calculating the formula of d, t, 3He, α emissions, the theoretical formula of double-differential cross section of 5 He is obtained, which is expressed in the form of Legendre coefficients. In the case of low incident energies, the configuration [J.S. Zhang, Science in China G47 (2004)137; J.S. Zhang, Commun. Theor. Phys. (Beijing, China) 39 (2003) 83] is the dominant part in the reaction *** calculated result indicates that the forward peaked angular distribution of the composite particle emission is weaker than that of the emitted single nucleon due to pick-up nucleon from the Fermi sea. As an example, the reactions of n + 14N have been calculated, and the Legendre coefficients of d, t, 3He, α, 5He emissions are obtained *** results show that the forward tendency is decided by the average momentum per nucleon in the emitted composite particles. The larger the average momentum is, the stronger the forward tendency is.

关键词： double-differential cross section composite particle emission nuclearreaction

Analytical Solution of Smoluchowski Equation in Harmonic Oscillator Potential

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Communications in Theoretical Physics 2005年第6期43卷 1099-1104页

作者： SUNXiao-Jun LUXiao-Xia YANYu-Liang DUANJun-Feng zhangjing-shang ChinaInstituteofAtomicEnergy P.O.Box275（41）Beijing102413China／／CollegeofPhysicsandInformationTechnologyGuangxiNormalUniversityGuilin541004China ChinaInstituteofAtomicEnergy P.O.Box275（41）Beijing102413China

Non-equilibrium fission has been described by diffusion model. In order to describe the diffusion process analytically, the analytical solution of Smoluchowski equation in harmonic oscillator potential is obtained. This analytical solution is able to describe the probability distribution and the diffusive current with the variable x and t. The results indicate that the probability distribution and the diffusive current are relevant to the initial distribution shape, initial position, and the nuclear temperature T; the time to reach the quasi-stationary state is proportional to friction coefficient beta, but is independent of the initial distribution status and the nuclear temperature T. The prerequisites of negative diffusive current are justified. This method provides an approach to describe the diffusion process for fissile process in complicated potentials analytically.

关键词： Smoluchowski equation probability distribution diffusive current

Analysis of Neutron Double-Differential Cross Section of n＋^14N at 14.2 MeV

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Communications in Theoretical Physics 2005年第1X期44卷 128-132页

作者： YANYu-Liang DUANJun-Feng SUNXiao-Jun WANGJi-Min zhangjing-shang ChinaInstituteofAtomicEnergy P.O.Box275(41)Beijing102413China ChinaInstituteofAtomicEnergy P.O.Box275(41)Beijing102413China//CollegeofPhysicsandInformationTechnologyGuangxiNormalUniversityGuilin541004China

By using a new reaction model for light nuclei, the double-differential cross section of n+14N reactions at En = 14.2 MeV has been analyzed. In the case of n+14N reactions, the reaction mechanism is very complex, there are over one hundred opened partial reaction channels even at incident energy En = 14.2 MeV. In this paper the opened reaction channels are listed in detail. With LUNF code the model calculation is performed to analyze the doubledifferential cross sections of total outgoing neutron. The calculated results agree fairly with the experimental data. The results indicate that the pre-equilibrium mechanism dominates the whole reaction processes, and the recoil effect in light nuclear reactions is essentially important. 5He emission has been considered, but it is only a small contribution to the double-differential cross section at incident energy En = 14.2 MeV.

关键词：核子反应双微分交叉截面轻子原子核