  We present Herschel PACS mapping observations of the [OI]63 micron line
towards protostellar outflows in the L1448, NGC1333-IRAS4, HH46, BHR71 and
VLA1623 star forming regions. We detect emission spatially resolved along the
outflow direction, which can be associated with a low excitation atomic jet. In
the L1448-C, HH46 IRS and BHR71 IRS1 outflows this emission is kinematically
resolved into blue- and red-shifted jet lobes, having radial velocities up to
200 km/s. In the L1448-C atomic jet the velocity increases with the distance
from the protostar, similarly to what observed in the SiO jet associated with
this source. This suggests that [OI] and molecular gas are kinematically
connected and that this latter could represent the colder cocoon of a jet at
higher excitation. Mass flux rates (\.M$_{jet}$(OI)) have been measured from
the [OI]63micron luminosity adopting two independent methods. We find values in
the range 1-4 10$^{-7}$ Mo/yr for all sources but HH46, for which an order of
magnitude higher value is estimated. \.M$_{jet}$(OI) are compared with mass
accretion rates (\.M$_{acc}$) onto the protostar and with \.M$_{jet}$ derived
from ground-based CO observations. \.M$_{jet}$(OI)/\.M$_{acc}$ ratios are in
the range 0.05-0.5, similar to the values for more evolved sources.
\.M$_{jet}$(OI) in HH46 IRS and IRAS4A are comparable to \.M$_{jet}$(CO), while
those of the remaining sources are significantly lower than the corresponding
\.M$_{jet}$(CO). We speculate that for these three sources most of the mass
flux is carried out by a molecular jet, while the warm atomic gas does not
significantly contribute to the dynamics of the system.
