Cover Story (Issue 9, 2024) Measurement of solar pp neutrino flux using electron recoildata from PandaX-4T commissioning run
Author: Prof. Ben-Da Xu (Tsinghua University, Beijing)
The most abundantsolar neutrino from the proton-proton (pp) fusion provides us the uniqueprobe to the stellar core and is the only component that propagates to theearth through the vacuum oscillation mode. Though Borexino in 2012 managed topenetrate the C-14 beta decay curtain with clever tricks of energy spectrafitting, it is crucial to make precise and clean measurement of pp solarneutrino flux and energy spectrum. More than 20 years has passed since Professor Y. Suzuki, one of the main figures behind the solar neutrinomeasurement at Super-KamiokaNDE and the solution of the solar neutrino problem,proposed to use liquid xenon for real-time detection of elastic scattering of pp solar neutrino on electrons. The vision was a 10-ton liquid xenon that are free of inevitably hindersome C-14 with organic liquid scintillators. Today, thevision is about to come true.
The PandaX collaboration utilized the PandaX-4T dual-phased liquid-xenon TPC to search for pp neutrinos. Although the electron-scattering signals areindistinguishable from the overwhelming beta and double-beta decays of Kr-85 and Xe-136, the collaboration managed to set a meaningful limit of 23.3×1010 s-1cm-2 with a central value of 8×1010 s-1cm-2,consistent with the prediction of standard solar model. It marks the beginningof a new era to detect solar neutrino with direct dark-matter searchexperiments, with more excitement ahead of us when PandaX-4T finishes full
data-taking, afterthe upgrade of distillation tower to suppress Kr, or possibly deploying separate Xe-136 depleted and enriched liquid xenon sub-detectors optimized forsolar neutrino and neutrinoless double-beta decay.
References
[1] Xiaoying Lu etal. (PandaX Collaboration), Chin. Phys. C 48, 091001 (2024), arXiv: 2401.07045[hep-ex]
