Molecular many-body dissociation: Data reduction strategies in translational spectroscopy

Abstract:

Advanced time- and position-sensitive multi-hit detectors allow to study molecular breakup processes into two, three, and more massive fragments by translational spectroscopy. We discuss the feasibility to perform kinematically complete final state analysis of complex molecular dissociation processes using such detectors. We have developed new algorithms to determine - for an arbitrary number of fragments - the fragment momentum vectors in the center-of-mass frame from the measured positions and arrival time differences. These algorithms can easily be implemented to perform online data reduction in coincidence experiments. We have tested the new data reduction strategies in an experimental study and in Monte-Carlo simulations of realistic experimental conditions. We show that the new algorithms can discriminate between two-, three-, and four-body decay of a four-atomic molecule and can uniquely determine the momentum vectors of all fragments. For two-body decay, we find that the accuracy of the new algorithm is superior to the frequently used approximate formula introduced by DeBruijn and Los. We demonstrate this improvement in the evaluation of experimental data for the decay of laser-excited triatomic hydrogen H₃ 3s (N=1,K=0) into H + H₂(v,J) fragment pairs.