  The search for neutrinoless double beta decay requires increasingly advanced
methods of background reduction. A bold approach to solving this problem, in
experiments using Xe-136, is to extract and identify the daughter Ba-136 ion
produced by double beta decay. Tagging events in this manner allows for a
virtually background-free verification of double beta decay signals. Various
approaches are being pursued by the nEXO collaboration to achieve Ba-tagging. A
Multi-Reflection Time-of-Flight Mass Spectrometer (MR TOF) has been designed
and optimized as one of the ion-identification methods, where it will
investigate the ion-extraction efficiency, as well as provide further
identification of the Ba isotope. The envisioned mode of operation allows the
MR TOF to achieve a quickly adjustable mass-range and resolution, with
simulations suggesting that a mass-resolving power of 140,000 is within reach.
This work will discuss the MR TOF design and the methods employed to simulate
and optimize it.
