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RESEARCH PRODUCT

Calculated solar-neutrino capture rate for a radiochemical Tl205 -based solar-neutrino detector

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Radiochemical experiments for low-energy solar-neutrino detection have been making headlines by exploiting the isotopes $^{37}\mathrm{Cl}$ and $^{71}\mathrm{Ga}$. Such a very low-threshold measurement of this type can also be performed using $^{205}\mathrm{Tl}$, which has been considered for decades for this purpose. A unique feature of this detector nucleus is the integration in the solar-neutrino flux over ${10}^{6}$ of years owing to its long-living daughter $^{205}\mathrm{Pb}$. In this Rapid Communication, we have calculated for the first time the cross section for the charged-current solar-neutrino scattering off $^{205}\mathrm{Tl}$. Taking into account the solar-model-predicted neutrino fluxes and the electron-neutrino survival probabilities, a solar-neutrino capture rate of $62.2\ifmmode\pm\else\textpm\fi{}8.6\phantom{\rule{0.28em}{0ex}}\mathrm{solar}\ensuremath{-}\mathrm{neutrio}\phantom{\rule{0.28em}{0ex}}\mathrm{units}$ is determined, a value significantly smaller than in previous estimates.