Title: WIMPS, Neutrino-less Double-beta Decay, and Xenon


I present a simple analysis of important factors that limit energy resolution in xenon in liquid and gaseous state. Xenon exhibits a rich phenomenology, especially in the anomalously large fluctuations between scintillation and ionization in liquid xenon (LXe). Pursuing the goal of an optimized detector design for 0-\nu ββ decay, I reached the conclusion that a high-pressure gaseous xenon (instead of liquid) xenon detector will offer much superior energy resolution for the 0-ν ββ decay search in 136Xe, and likely offmuch superior γ-background rejection in the search for WIMPs. If this scenario is correct, two identical HPXe TPCs differing only in isotopic content may provide significantly more robust evidence for the existence of either signal. In this case, the arguably optimum detector for next generation searches at the few hundred kg level, for both purposes, is the same high-pressure xenon gas (HPXe) TPC. An unresolved issue is whether the WIMP and 136Xe 0-\nu double beta community would approach such a common approach.