  Employing the momentum-sensitivity of time- and angle-resolved photoemission
spectroscopy we demonstrate the analysis of ultrafast single- and many-particle
dynamics in antiferromagnetic EuFe2As2. Their separation is based on a
temperature-dependent difference of photo-excited hole and electron relaxation
times probing the single particle band and the spin density wave gap,
respectively. Reformation of the magnetic order occurs at 800 fs, which is four
times slower compared to electron-phonon equilibration due to a smaller
spin-dependent relaxation phase space.
