  1s(Lambda) hypernuclear formation rates in stopped K- reactions on several
p-shell targets are derived from hypernuclear formation spectra measured
recently by the FINUDA Collaboration and are compared with calculated
1s(Lambda) formation rates based on a KbarN coupled channels chiral model. The
calculated rates are about 15% of the derived rates, depending weakly on the
depth of the threshold K- nuclear potential. The A dependence of the calculated
rates is in fair agreement with that of the derived rates, showing a slight
preference for a deep density dependent K- nuclear potential of depth (150-200)
MeV at nuclear matter density over a shallow potential of depth about 50 MeV.
These new features originate from a substantial energy and density dependence
found for the in-medium subthreshold (K- n --> pi- Lambda) branching ratio that
serves as input to the K- capture at rest calculations.
