A data acquisition system for fast ion-atom collision experiments

A new data acquisition system has been created. It is designed to let the experimenter make full use of the capabilities of several multi-spectrometer apparatus. By accessing two digital I/O interfaces which have been installed in a personal computer, the new system is capable of simultaneously counting events from six different sources and can acquire two-dimensional spectra which may be measured in coincidence with four different events. The new system reads, processes, displays, and stores all of these data.

In order to demonstrate and test some of the capabilities of the new data acquisition system, we have measured the elastic scattering cross section for electrons incident upon argon gas and scattered into the angular range from 45° to 135° with respect to the beam axis for two different electron energies (500 eV, 800 eV). We have also measured the angular distribution of L_2,3M_2,3M_2,3 Auger electrons produced in coincidence with Ar²⁺ target recoil ions.

Our experimentally measured elastic scattering cross sections are compared with previously published cross sections and the agreement is quite good. The Auger electron-recoil ion results have poor statistics but prove that the new data acquisition system can successfully make coincidence measurements. The versatility of the new system will allow it to be used with many different experimental setups which may be required for future ion-atom collision experiments.