Beam Chopping Control using Digital Pulse Generators

In experimental measurements of statistical nature, signal must be extracted from background noise. This applies to the previous absolute cross section measurements of charge transfer [1] with the merged beams technique at the Oak Ridge National Laboratory Multicharged Ion Research Facility. Improvements to the chopping scheme is required to prepare for new high-resolution X-ray measurements from charge transfer between H and highly charged ions using merged beams.  This is accomplished by chopping the two beams with pulses from a pair of digital pulse generators.  Signal is measured with beam pulses in phase and merged while the background is measured with beam pulses out of phase and de-merged. Once the pulse generators are programmed, electronic counters are used to ensure there are an equal amount of merged and de-merged pulses. 

Research is supported by NASA Astrophysics Research and Analysis Grant No. NNH18ZDA001N.

[1] V. M. Andrianarijaona, L. M. Wegley, A. Z. Watson, M. Andrianarijaona, C. P. DeGuzman, K. Kim, E. J. Nuss, J. J. Taylor, R. L. Wilson, R. T. Zhang, D. G. Seely, C. C. Havener, AIP Conference Proceedings, 2160, 070005 (2019).