The Exposure-Background Duality in the Searches of Neutrinoless Double Beta Decay
Abstract
Tremendous efforts are required to scale the summit of observing neutrinoless double beta decay (0 β β). This article quantitatively explores the interplay between exposure (target mass X data taking time) and background levels in 0 β β experiments. In particular, background reduction can substantially alleviate the necessity of unrealistic large exposure as the normal mass hierarchy (NH) is probed. The non-degenerate (ND)-NH can be covered with an exposure of O(100) ton-year, which is only an order of magnitude larger than those planned for next generation projects - provided that the background could be reduced by 0(10-6) relative to the current best levels. It follows that background suppression will be playing increasingly important and investment-effective, if not determining, roles in future 0 β β experiments with sensitivity goals of approaching and covering ND-NH.