Correlated east time structures at millimeter waves and hard X-rays duringa solar burst

We present an analysis of the time profiles detected during a solar impulsi ve flare, observed at one-millimeter radio frequency (48 GHz) and in three hard X-ray energy bands (25-62, 62-111, and 111-325 keV) with high sensitiv ity and time resolution. The time profiles of all emissions exhibit fast ti me structures of 200-300 ms half power duration which appear in excess of a slower component varying on a typical time scale of 10 s. The amplitudes o f both the slow and fast variations observed at 48 GHz are not proportional to those measured in the three hard X-ray energy bands. However, the fast time structures detected in both domains are well correlated and occur simu ltaneously within 64 ms, the time resolution of the hard X-ray data. In the context of a time-of-flight flare model, our results put strong constraint s on the acceleration time scales of electrons to MeV energies.