Extracting information about few-body breakup thresholds from high-energy collisions

We show that the analysis of high-energy collisions provides an alternative, and sometimes advantageous, method of gathering information on a breakup system at threshold. We demonstrate the applicability of this approach by extracting the s-wave scattering length a0 for the collision of electrons by neutral atoms in metastable states from measurements of photo- and collisional detachment of electrons from negative ions and electron capture to continuum states of neutral projectiles in atomic ionization collisions. Finally, we discuss how to generalize these ideas to gather information about an N-body threshold behavior. (author)