报告题目：Few Body Effects in Electron impact ionization

报 告 人：Colm T Whelan，Department of Physics, old Dominion University, Norfolk, Virginia,USA

报告时间：2017年7月14日，星期五上午10：30

报告地点：理科楼C302（三楼报告厅）

报告摘要：An (e,2e) measurement is one where an electron, of well defined energy and momentum, is fired at a target, ionizes it and the two exiting electrons are detected in coincidence. The energies and positions in space of these electrons are determined by the experiment so in effect all but the spin quantum numbers are then known. We can, therefore, describe it as a kinematically complete experiment; if we could also measure all the spins we would have all the information on a scattering experiment that quantum mechanics will allow. The technique offers both the possibility of a direct determination of the target wavefunction and profound insights into the nature of few body interactions. What information you extract from such an experiment really depends on the kinematics you chose and the target you use. What is measured is the cross section, i.e. the ratio of the number of measured events corresponding to two final state electrons being detected at fixed position in space with well-defined energies per unit time per unit scatterer as compared to the incident flux. Technically we are talking here about a triple differential cross section, TDCS, as opposed to one where we have integrated over one or more electron co-ordinates. Integrated cross sections can be crude things and you need the full power of a highly differential measurement to tease out the delicacies of the interactions. In the last few years, revolutionary advances in experimental techniques and spectacular increases in computer power have offered unique opportunities to develop a much more profound understanding of the atomic few body problem.

In this talk I will consider the contribution that distortion, post collisional interactions and exchange effects make to the shape and absolute size of the TDCS