【115/10/06 物理論壇-演講公告】

◎ 演講者 (Speaker)：Dr. Ying-Ting Lin (林盈廷)
Institute for Nuclear physics, University of Münster

◎ 講題 (Topic)：First Measurement of Solar Neutrinos through Elastic
Neutrino-Electron Scattering at the keV Scale

◎ 日期與時間 (Date & Time)：115年10月06日(二) 15:10 (15:10, Tuesday, Oct. 6, 2026)

◎ 地點 (Place)：育成中心 3-2 (Incubation Center 3-2)

◎ 邀請者 (Host)：劉承邦教授 (Prof. Cheng-Pang Liu)

◎ 摘要 (Abstract)：

The XENONnT experiment utilizes a dual-phase liquid xenon (LXe) time
projection chamber (TPC) to search for dark matter and other rare
events. In addition to its primary nuclear-recoil (NR) search channel,
XENONnT has achieved unprecedentedly low background rates in the
electron-recoil (ER) channel. With extensive mitigation and active
reduction efforts, the dominant ER background from radon and krypton
has been reduced to levels comparable to the non-shieldable background
induced by proton–proton (pp) chain solar neutrinos, effectively
entering the irreducible neutrino background regime. This low ER
background allows competitive probes of solar axions, axion-like
particles, and dark photons as dark matter candidates.

The key techniques that enabled this performance includes the
cryogenic distillation column that reduced the krypton level below 100
ppq in Science Run 0 and the continuous removal system that reached an
order of 1 μBq/kg radon level in Science Run 1. Also required are the
high-precision measurement methods of the ultra-low backgrounds in the
TPC, including the Rare Gas Mass Spectrometer (RGMS) for natural Kr
and dedicated alpha analysis on radon calibrations for 222Rn/220Rn. As
a result of all these efforts, XENONnT has achieved the lowest energy
threshold to date for detecting solar neutrinos down to 17 keV through
elastic neutrino-electron scattering.