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Model Calculation of n + 6Li Reactions Below 20 MeV

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Communications in Theoretical Physics 2001年第10期36卷 437-442页

作者： zhang jing-shang HAN Yin-Lu China Nuclear Data Center China Institute of Atomic Energy Beijing 102413 China China Nuclear Data Center China Institute of Atomic Energy Beijing 102413 China

Based on the unified Hauser-Feshbach and exciton model for light nuclei, the calculations of reaction cross sections and the double-differential cross sections for n + 6Li are performed. Since all of the first-particle emissions are from the compound nucleus to the discrete levels, the angular momentum coupling effect in pre-equilibrium mechanism must be taken into account. The fitting of the measured data indicates that the three-body break-up process needs to be involved, and the pre-equilibrium reaction mechanism dominates the reaction processes. In light nucleus reactions the recoil effect must be taken into account.

关键词： pre-equilibrium emission, discrete levels, three-body break-up process

Study of Pre-equilibrium Fission Based on Diffusion Model

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Communications in Theoretical Physics 2006年第2期45卷 325-331页

作者： SUN Xiao-Jun zhang jing-shang College of Physics and Information Technology Guangxi Normal University Guilin 541004 China China Institute of Atomic Energy P.O. Box 275（41） Beijing 102413 China

In terms of numerical method of Smoluchowski equation the behavior of fission process in diffusion model has been described and analyzed, including the reliance upon time, as well as the deformation parameters at several nuclear temperatures in this paper. The fission rates and the residual probabilities inside the saddle point are calculated for fissile nucleus n＋^238U reaction and un-fissile nucleus p＋^208Pb reaction. The results indicate that there really exists a transient fission process, which means that the pre-equillbrium fission should be taken into account for the fissile nucleus at the high temperature. Oppositely, the pre-equilibrlum fission could be neglected for the un-fissile nucleus. In the certain case the overshooting phenomenon of the fission rates will occur, which is mainly determined by the diffusive current at the saddle point. The higher the temperature is, the more obvious the overshooting phenomenon is. However, the emissions of the light particles accompanying the diffusion process may weaken or vanish the overshooting phenomenon.

关键词： pre-equilibrium fission diffusion model fissile nucleus un-fissile nucleus

Theoretical Analysis of the Neutron Double Differential Cross Section of n+16O at En=14.1 MeV

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Communications in Theoretical Physics 2001年第5期35卷 579-584页

作者： zhang jing-shang Han Yin-Lu Fan Xiao-Li China Nuclear Data Center CIAE Beijing 102413 China Department of Physics Northwest University Xi'an 710069 China

Based on the unified Hauser-Feshbach and exciton model,a new model has been developed for the light nucleus *** analysis of the ne u tron energy-angular spectra of n+ 1 6 O reaction has been *** fit ting of the experimental data indicates that this method is successful for calculating the double-differential cross section of thelight nucleus.

关键词：中子物理 N+^16O微分截面理论分析

Exciton-Dependent Pre-formation Probability of Composite Particles

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Communications in Theoretical Physics 2007年第6期47卷 1106-1110页

作者： zhang jing-shang WANG Ji-Min DUAN Jun-Feng China Institute of Atomic Energy P.O. Box 275（41） Beijing 102413 China

In Iwamoto-Harada model the whole phase space is full of fermions. When the momentum distributions of the exciton states are taken into account, the pre-formation probability of light composite particles could be improved, and the exciton state-dependent pre-formation probability has been proposed. The calculated results indicate that the consideration of the momentum distribution enhances the pre-formation probability of [1, m] configuration, and suppresses that of [ι 〉 1, m] configurations seriously.

关键词： pre-formation probability pre-equilibrium emission

Theoretical Model Calculation for d+~8Li Reaction

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Communications in Theoretical Physics 2008年第8期50卷 463-467页

作者： HAN Yin-Lu GUO Hai-Rui zhang Yue zhang jing-shang China Institute of Atomic Energy P.O. Box 275（41） Beijing 102413 China

Based on the theoretical models for light nuclei, the calculations of reaction cross sections and the angular distributions for d ＋^8Li reaction are performed. Since all of the particle emissions are from the compound nucleus to the discrete levels, the angular momentum coupling effect in pre-equilibrium mechanism is taken into account. The three- body break-up process and the recoil effect are involved. The theoretical calculated results are compared to existing experimental data.

关键词： deuteron-induced reaction cross sections light nuclei of the 1p shell angular momentum andparity dependence exciton model improved Iwamoto-Harada model

Theoretical Analysis of Neutron Double-Differential Cross Section of n ＋^19F at 14.2 MeV

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Communications in Theoretical Physics 2007年第1期47卷 102-106页

作者： YAN Yu-Liang SUN Xiao-Jun zhang Yue zhang jing-shang China Institute of Atomic Energy P.O. Box 275（41） Beijing 102413 China College of Physics and Information Technology Guangxi Normal University Guilin 541004 China

A new light nuclear reaction model has been developed and the double-differential measurements of lp shell nuclei have been analyzed successfully. Now, the application of this model is expanded to 19F of the 2s-ld shell nucleus. The double-differential cross section of total outgoing neutron for n ＋^19F reactions at En=14.2 MeV has been calculated and analyzed, which agrees fairly well with the experimental measurements. In this paper, the contributions from different reaction channels to the double-differential cross sections have been analyzed in detail. The calculations indicate that this light nudear reaction model is also able to be used for the 2s-ld shell nucleus so long as the related level scheme couM be provided sufficiently.

关键词： light nuclear reaction double-differential cross section pre-equillbrium emission discrete level

^5He Emission in Neutron-Induced ^10B Reactions

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Communications in Theoretical Physics 2006年第3X期46卷 527-532页

作者： WANG Ji-Min DUAN Jun-Feng YAN Yu-Liang SUN Xiao-Jun zhang jing-shang China Institute of Atomic Energy P.O. Box 275(41) Beijing 102413 China College of Physics and Electronic Engineering Guangxi Normal University Guilin 541004 China

In n ＋^10B reactions, ^5He cluster emission has been discussed with the updated level scheme and the new optical model parameters. In this paper the reaction channels related to ^5He emission are listed in detail. By using the new reaction model for light nuclei, the double-differential cross sections of total outgoing neutrons for n ＋ ^10 B reactions at En= 14.2 MeV have been calculated, and the results agree fairly well with the measurements. Particularly, in the energy-angular spectra the contribution from the 5He-emission to the total outgoing neutron double-differential cross sections has also been analyzed, and the partial energy-angular spectra of 60° at En= 14.2 MeV have been given. The calculated results indicate that once the 5He emission is taken into account, the fitting with the double-differential measurements of total outgoing neutrons at the low energy region could be improved. Therefore, to consider the ^5He emission properly in the reaction processes of light nuclei is necessary.

关键词： ^ 5He emission double-differential cross section pre-equilibrium emission

Further Analysis of Neutron Double-Differential Cross Section of n ＋ ^16O at 14.1 MeV and 18 MeV

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Communications in Theoretical Physics 2005年第4X期44卷 701-706页

作者： DUAN Jun-Feng YAN Yu-Liang WANG Ji-Min SUN Xiao-Jun zhang jing-shang China Institute of Atomic Energy P.O. Box 275(41) Beijing 102413 China College of Physics and Information Technology Guangxi Normal University Guilin 541004 China

By using a new reaction model for light nuclei, the double-differential cross section of total outgoing neutron with LUNF code for n＋^16O reactions at En=14.1 MeV and 18 MeV have been calculated and analyzed. In this paper the opened reaction channels, which have contribution to emitting the neutrons, are listed in detail. To improve the fitting results the direct inelastic scattering mechanism is involved. The calculating results agree fairly well with the experimental data at E,~ = 14.1 MeV and the deviation from calculated results and experimental data in low energy region at En= 18 MeV has been analyzed. Since the possibility of 5He has been affirmed theoretically [J.S. zhang, Sci. Chin. G 47 （2004） 137], so 5He emission from n＋ ^16O reaction is taken into account, which plays an important role at the region of the outgoing neutron energy εn〈3 MeV in total outgoing neutron energy-angular spectrum. The calculated results indicate that the pre-equilibrium mechanism dominates the whole reaction processes, and the recoil effect in light nuclear reactions is essentially important.

关键词： total outgoing neutron energy-angular spectrum light nucleus reaction

Analyses of p-^(11)B,p-^(11)C and d-^(11)C Reactions

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Chinese journal of nuclear physics 1995年第1期17卷 60-66页

作者： Shen Qing-biao zhang jing-shang Han Yin-lu Bai Xi-xiang (China Institute of Atomic Energy,P.O.Box 275(41),Beijing 102413) 中国原子能科学院北京

Aiming at the production of 11C radioactive beam,various nuclear data ofp+11B reaction at incident proton energies spanning 1-25 MeV were obtained by calcu-lation with quasiquantum multistep direct （QMSD） theory and Hauser-Feshbach （HF）*** calculations basically agree with the experimental *** angular distri-butions in lab frame of 11C produced in the reversed geometry reaction 1H(11B,11C)nwere *** cross sections of p+11C and d+11C reactions induced by 11C beamwere also *** results show that the experimental measurement for 11C+d re-action is more feasible than for 11C+p reaction at HI-13 tandem accelerator.

关键词： 11C Radioactive beam Analyses