Measurement of the Solar Electron Neutrino Flux with the Homestake Chlorine Detector

TLDR

The Homestake Solar Neutrino Detector, based on the inverse beta‑decay reaction νe + ^37Cl → ^37Ar + e^−, has measured the solar neutrino flux since 1970. The study reviews all aspects of the detector, focusing on determining extraction and counting efficiencies and key parameters needed to convert the measured ^37Ar count rate into the solar neutrino production rate. The detector’s operation is examined in detail, including extraction and counting efficiencies, key conversion parameters, and systematic uncertainties such as nonsolar ^37Ar production. The detector operated stably over the period, yielding a combined solar neutrino‑induced ^37Ar production rate of 2.56 ± 0.16 (stat.) ± 0.16 (syst.) SNU.

Abstract

The Homestake Solar Neutrino Detector, based on the inverse beta-decay reaction νe +37Cl →37Ar + e-, has been measuring the flux of solar neutrinos since 1970. The experiment has operated in a stable manner throughout this time period. All aspects of this detector are reviewed, with particular emphasis on the determination of the extraction and counting efficiencies, the key experimental parameters that are necessary to convert the measured 37Ar count rate to the solar neutrino production rate. A thorough consideration is also given to the systematics of the detector, including the measurement of the extraction and counting efficiencies and the nonsolar production of 37Ar. The combined result of 108 extractions is a solar neutrino-induced 37Ar production rate of 2.56 ± 0.l6 (statistical) ± 0.16 (systematic) SNU.