The Fluorescence Chamber: New Approach to 3-d Event Spectroscopy in LENS

Given that the technology of choice for 2) is LS, the first generation plan for 1) was a piled array of longitudinal logs where the event vertex within a log is inferred from differential times of flight of signals observed at the ends of the log. In the second generation strategy true 3-d event localization could be achieved directly and digitally. In a “scintillation lattice chamber” . Two basic strategies have influenced the design of the LENS detector from the beginning: 1) high granularity, i.e. precise localization of low energy events in real-time; and 2) a detection medium with well established usage in low energy nuclear spectroscopy that offers a good platform for requirement 1). Over the years of LENS development several approaches for 1) have been considered. In this Note I consider a new approach, which still uses the long-adopted liquid scintillation (LS) for 2). Since the only type of valid signal event is a coincidence event, the only background is random coincidences of candidate tags (from any internal or external source) with vertex events --electrons of the solar signal and the beta decay of In, the high rate of which demands detector granularity as a general remedy. It can be readily shown that the signal/noise S/N varies as 1/m, the mass of In in the vertex cell. The cell resolution is then N = M/m where M is the total mass of In.