Double differential cross sections for ionization of H by 75 keV proton impact:Assessing the role of correlated wave functions

The effect of final-state dynamic correlation is investigated for ionization of atomic hydrogen by 75-keV proton impact by analyzing double differential cross sections.The final state is represented by a continuum correlated wave(CCW-PT)function which accounts for the interaction between the projectile and the target nucleus(PT interaction).The correlated final state is nonseparable solutions of the wave equation combining the dynamics of the electron motion relative to the target and projectile,satisfying the Redmond’s asymptotic conditions corresponding to long range interactions.The transition matrix is evaluated using the CCW-PT function and the undistorted initial state.Both the correlation effects and the PT interaction are analyzed by the present calculations.The convergence of the continuous correlated final state is examined carefully.Our results are compared with the absolute experimental data measured by Laforge et al.[Phys.Rev.Lett.103,053201(2009)]and Schulz et al.[Phys.Rev.A 81,052705(2010)],as well as other theoretical models(especially the results of the latest non perturbation theory).We have shown that the dynamic correlation plays an important role in the ionization of atomic hydrogen by proton impact.While overall agreement between theory and the experimental data is encouraging,detailed agreement is still lacking.However,such an analysis is meaningful because it provides valuable information about the dynamical correlation and PT interaction in the CCW-PT theoretical model.

Light fragment and neutron emission in high-energy proton induced spallation reactions

The dynamics of high-energy proton-induced spallation reactions on target nuclides of 56Fe,58Ni,107Ag,112d,184W,181Ta,197Au,and 208Pb are investigated with the quantum molecular dynamics transport model motivated by the China initiative Accelerator Driven System(CiADS)in Huizhou and the China Spallation Neutron Source(CSNS)in Dongguan.The production mechanism of light nuclides and fission fragments is thoroughly analyzed,and the results obtained thereby are compared with available experimental data.The statistical code GEMINI is employed in conjunction with a transport model for describing the decay of primary fragments.For the treatment of cluster emission during the preequilibrium stage,a surface coalescence model is implemented into the model.It is found that the available data in terms of total fragment yields are well reproduced in the combined approach for spallation reactions both on the heavy and light targets.The energetic light nuclides(deuteron,triton,helium isotopes etc)mainly created during the preequilibrium stage are treated within the framework of surface coalescence,whereas their evaporation is described in the conventional manner by the GEMINI code.With this combined approach,a good overall description of light clusters and neutron emission is obtained,and some discrepancies with the experimental data are discussed.Possible production of radioactive isotopes in the spallation reactions is also analyzed,i.e.,the 6.8He energy spectra.