  Atom probe tomography (APT) is a valuable near-atomic scale imaging
technique, which yields mass spectrographic data. Experimental correctness can
often pivot on the identification of peaks within a dataset, this is a manual
process where subjectivity and errors can arise. The limitations of manual
procedures complicate APT experiments for the operator and furthermore are a
barrier to technique standardisation. In this work we explore the capabilities
of computer-guided ranging to aid identification and analysis of mass spectra.
We propose a fully robust algorithm for enumeration of the possible identities
of detected peak positions, which assists labelling. Furthermore, a simple
ranking scheme is developed to allow for evaluation of the likelihood of each
possible identity being the likely assignment from the enumerated set. We
demonstrate a simple, yet complete work-chain that allows for the conversion of
mass-spectra to fully identified APT spectra, with the goal of minimising
identification errors, and the inter-operator variance within APT experiments.
This work chain is compared to current procedures via experimental trials with
different APT operators, to determine the relative effectiveness and precision
of the two approaches. It is found that there is little loss of precision (and
occasionally gain) when participants are given computer assistance. We find
that in either case, inter-operator precision for ranging varies between 0 and
2 "significant figures" (2{\sigma} confidence in the first n digits of the
reported value) when reporting compositions. Intra-operator precision is weakly
tested and found to vary between 1 and 3 significant figures, depending upon
species composition levels. Finally it is suggested that inconsistencies in
inter-operator peak labelling may be the largest source of scatter when
reporting composition data in APT.
