Restoration of the signals from multi-hit three-layer delay-line anode position-sensitive detector

Multi-hit 3-layer delay-line anode (Hexanode) has an increased ability to detect multi-hit events in a collision experiment. Coupled with a pair of micro-channel plates, it can provide position information of the particles even if the particles arrive at the same time or within small time dwell. But it suffers from some ambiguous outputs and signal losses due to timing order and triggering thresholds etc. We have developed a signal reconstruction program to correct those events. After the program correction, the dead time only exists when 2 paxticles arrive at the same time and the same position within a much smaller range. With the combination of Hexanode and the program, the experimental efficiencies will be greatly improved in near threshold double ionization on He collisions

Emission characteristics of three final continuum electrons produced in low-energy double ionization of helium

The double ionization of helium by electron impact for 106 eV incident energy was studied in a kinematically complete experiment by using a reaction microscope. The pattern of the angular correlation of the three emitted electrons was analyzed by selecting different values of the recoil ion longitudinal momentum. The Wannier predicted geometry appears when the recoil ion carries the full initial projectile momentum. It was found that at this low impact energy, the outgoing electrons still remember the initial-state collision information

Correlation of emitted electrons in near threshold double ionization of helium by electron impact

We have performed an experiment on near threshold double ionization of helium by 106 eV electron impact with an improved reaction microscope. In this experiment the momenta of three particles after ionization were measured, and the information on correlation of emitted electrons was obtained. Detailed descriptions of the experimental setup and the methods of reconstruction of electron momentum were given. We focused on the analysis of momentum and energy distributions and the angular correlation of the emitted electrons. The experimental results were compared with Wannier's prediction, and it was found that the experimental results showed some characteristic features predicted by Wannier theory