H. Aurass et al., THE FLARE OF 1989 SEPTEMBER 9, 09 09 UT - DOES CORONAL LOOP COLLISIONINITIATE EFFICIENT GAMMA-RAY EMISSION/, The Astrophysical journal. Supplement series, 90(2), 1994, pp. 707-711
Vector magnetogram data and Ha pictures together with data published b
y Chupp et al. lead us to conjecture that in the presented case a cont
act between the rising two-ribbon flare current sheet and a coronal lo
op connecting two nearby plage regions initiates efficient high-energy
gamma-ray emission.