  We have characterized an electron-irradiated Ba1-xKxFe2As2 (x = 0.53)
single-crystal using two different experimental techniques: magneto-optic
measurements and microwave measurements. The crystal has been measured before
as well as after the 2.5 MeV electron irradiation process. After irradiation it
was annealed in a number of steps, between 90 deg C and 180 deg C, and measured
after each annealing step. Most microwave measurements were performed by means
of a copper cavity, taking advantage of the TE011 and TM110 modes, allowing for
the determination of the London penetration depths changes
{\delta}{\lambda}ab(T) and {\delta}{\lambda}c(T), i.e. perpendicular and
parallel to the sample c-axis. Appropriate equations, based on perturbation
theory, were derived to calculate the penetration depths changes
{\delta}{\lambda}ab and {\delta}{\lambda}c for a rectangular prism geometry.
The sample showed a full recovery of its Tc, however the observed behavior of
{\delta}{\lambda}c and {\delta}{\lambda}ab was not monotonic vs annealing
temperature, displaying a minimum of {\delta}{\lambda}c and {\delta}{\lambda}ab
at 120 deg C. This finding was confirmed by magneto-optic measurements, where
besides verifying the sample uniformity and the absence of visible defects, the
lower critical field Hc1 of the Ba1-xKxFe2As2 single-crystal was obtained and
the London penetration depth {\lambda}ab(0) was calculated.
