Energetic (HXR/GR) Emission from Flares: Implication for Particle Acceleration and Transport

This paper reviews a selection of observations in hard X-rays (HXR) and gamma-rays (GR) that allow us to derive quantitative constraints on the energetic electrons and ions accelerated during solar flares. We shall focus on the results obtained for the relative energy contents in electrons and ions in strong gamma-ray line (GRL) events as well as on the chemical composition of accelerated ions. We shall discuss new estimates of the upper limit of the energy contained in ions for electron-dominated events and briefly summarize new results concerning the relationship found between centimetric-millimetric emitting electrons and HXR/GR bremsstrahlung emitting ones