Estimation of the ATLAS Inner Detector material budget by use of hadronic interactions

The dominant inefficiency in track reconstruction comes from particle interactions with the material in the detector. A good understanding of the material in the Inner Detector (ID) of the ATLAS detector is therefore a vital part of track and object reconstruction. In recent years a new technique has been developed, which by reconstructing nuclear interactions with the detector material allows one to quantify the material budget. The relatively low momentum interactions yields large opening angles between the outgoing particles. This makes it feasible to pinpoint the location of the interaction with excellent spatial resolutions, both perpendicular and parallel to the beam axis, permitting detailed comparisons of even minute detector elements. Utilising a second-pass tracking, specially designed to reconstruct secondary tracks with large impact parameters, the technique maps 0.3 $m^{3}$ of the ID volume. The collected results from the Run-1 and the Run-2 analyses will be presented.