  We present a fingerprint-like method to analyze material defects after
energetic particle irradiation by computing a rotation invariant descriptor
vector for each atom of a given sample. For ordered solids this new method is
easy to use, does not require extreme computational resources, and is largely
independent of the sample material and sample temperature. As illustration we
applied the method to molecular dynamics simulations of deuterated and pristine
tungsten lattices at 300 K using a primary knock-on atom (PKA) of 1 keV with
different velocity directions to emulate a neutron bombardment process. The
number of W atoms, that are affected after the collision cascade, have been
quantified with the presented approach. At first atoms at regular lattice
positions as well as common defect types like interstitials and vacancies have
been identified using precomputed descriptor vectors. A principal component
analysis (PCA) is used to identify previously overlooked defect types and to
derive the corresponding local atomic structure. A comparison of the
irradiation effects for deuterated and pristine tungsten samples revealed that
deuterated samples exhibit consistently more defects than pristine ones.
