  In laboratory experiments we determine the mass gain and loss in central
collisions between cm to dm-size SiO2 dust targets and sub-mm to cm-size SiO2
dust projectiles of varying mass, size, shape, and at different collision
velocities up to ~56.5 m/s. Dust projectiles much larger than 1 mm lead to a
small amount of erosion of the target but decimetre targets do not break up.
Collisions produce ejecta which are smaller than the incoming projectile.
Projectiles smaller than 1 mm are accreted by a target even at the highest
collision velocities. This implies that net accretion of decimetre and larger
bodies is possible. Independent of the original size of a projectile
considered, after several collisions all fragments will be of sub-mm size which
might then be (re)-accreted in the next collision with a larger body. The
experimental data suggest that collisional growth through fragmentation and
reaccretion is a viable mechanism to form planetesimals.
