  One of the possible sources of hadronic cosmic rays (CRs) are newborn
pulsars. If this is indeed the case, they should feature diffusive gamma-ray
halos produced by interactions of CRs with interstellar gas. In this paper we
try to identify extended gamma-ray emission around young pulsars, making use of
the 7-year Fermi-LAT data. For this purpose we select and analyze a set of
eight pulsars that are most likely to possess detectable gamma-ray halos. We
find extended emission that might be interpreted as a gamma-ray halo only in
the case of PSR J0007+7303. Its luminosity accords with the total energy of
injected cosmic rays $\sim 10^{50}$ erg, although other interpretations of this
source are possible. Irrespectively of the nature of this source we put bounds
on the luminosity of gamma-ray halos which suggest that pulsars' contribution
to the overall energy budget of galactic CRs is subdominant in the GeV-TeV
range.
