Several extensions of the Standard Model predict the existence of charged, very

massive, and long-lived particles. Because of their high masses these particles

would propagate non-relativistically through the ATLAS pixel detector and would

therefore be identifiable through a measurement of large specific energy loss.

Measuring heavy, long-lived particles through their track parameters in the pixel

detector allows sensitivity to particles with lifetimes in the nanosecond range

and above. This dissertation presents an inner detector driven method for identifying

such particles in proton-proton collisions at 13 TeV with the 2015 LHC

dataset corresponding to an integrated luminosity of 3.5 pb−1.