The superbubble model for Li, Be and B production and Galactic evolution
  We show that the available constraints relating to $^{6}$LiBeB Galactic evolution can be accounted for by the so-called superbubble model, according to which particles are efficiently accelerated inside superbubbles out of a mixture of supernova ejecta and ambient interstellar medium. The corresponding energy spectrum is required to be flat at low energy (in E^-1 below 500 MeV/n, say), as expected from Bykov's acceleration mechanism. The only free parameter is also found to have the value expected from standard SB dynamical evolution models. Our model predicts a slope 1 (primary) and a slope 2 (secondary) behaviour at respectively low and high metallicity, with all intermediate slopes achieved in the transition region, between 10^-2 and 10^-1 Z_sol. 
Etienne Parizot and Luke Drury (Dublin Institute for Advanced Studies)