  We study the dynamics of neutrally buoyant particles with diameters varying
in the range [1, 45] in Kolmogorov scale units (eta) and Reynolds numbers based
on Taylor scale between 580 and 1050. One component of the particles' velocity
is measured using extended Laser Doppler Velocimetry at the center of a
Von-Karman (VK) flow, acceleration is derived by differentiation. We find that
although the particle acceleration variance decreases with increasing their
diameter with scaling close to (D/eta)^-2/3, in agreement with previous
observations, the characteristic time of acceleration autocorrelation increases
much strongly than previously reported, and linearly with D/eta. A new analysis
of the probability density functions of the acceleration shows smaller wings
for larger particles; the flatness indeed decreases as also expected from the
behavior of Eulerian pressure increments in the VK flow. We contrast our
measurements with former observations in wind-tunnel turbulent flows and
numerical simulations, and discuss if the observed differences arise from
inherent properties of the VK flow.
