  We report results on all-optical Thomson scattering intercepting the
acceleration process in a laser wakefield accelerator. We show that the pulse
collision position can be detected using transverse shadowgraphy which also
facilitates alignment. As the electron beam energy is evolving inside the
accelerator, the emitted spectrum changes with the scattering position. Such a
configuration could be employed as accelerator diagnostic as well as reliable
setup to generate x-rays with tunable energy.
