Bound-State Beta Decay of ${}^{205}{\mathrm{Tl}}^{81+}$ Ions and the LOREX Project

Abstract

Stable ${}^{205}$Tl ions have the lowest known energy threshold for capturing electron neutrinos (${\nu }_e$) of $E_{{\nu }_e}\ge 50.6$\,keV. The Lorandite Experiment (LOREX), proposed in the 1980s, aims at obtaining the longtime averaged solar neutrino flux by utilizing natural deposits of Tl-bearing lorandite ores. To determine the ${\nu }_e$ capture cross section, it is required to know the strength of the weak transition connecting the ground state of ${}^{205}$Tl and the 2.3 keV first excited state in ${}^{205}$Pb. The only way to experimentally address this transition is to measure the bound-state beta decay (${\beta }_b$) of fully ionized ${}^{205}\mathrm{T}{\mathrm{l}}^{81+}$ ions. After three decades of meticulous preparation, the half-life of the ${\beta }_b$ decay of ${}^{205}\mathrm{T}{\mathrm{l}}^{81+}$ has been measured to be $291_{-27}^{+33}$ days using the Experimental Storage Ring (ESR) at GSI, Darmstadt. The longer measured half-life compared to theoretical estimates reduces the expected signal-to-noise ratio in the LOREX, thus challenging its feasibility.

References in corpus (2)

• High-temperature ${}^{205}$Tl decay clarifies ${}^{205}$Pb dating in early Solar System
• Status of Direct Determination of Solar Neutrino Fluxes after Borexino

Cited by in corpus (4)

• Bayesian and Monte Carlo approaches to estimating uncertainty for the measurement of the bound-state $\beta$ decay of ${}^{205}{\mathrm{Tl}}^{81+}$
• Software Defined Radio for on-line interaction with beam processes in the heavy ion storage ring ESR
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• A novel method of half-life determination for highly charged ions based on isochronous mass spectrometry