2025-09-29 カリフォルニア大学サンタバーバラ校（UCSB）
Photo Credit:Matt Kapust/Sanford Underground Research Laboratory
The outer detector of the LZ dark matter experiment
＜関連情報＞
- https://news.ucsb.edu/2025/022028/physicists-tighten-net-elusive-dark-matter
- https://journals.aps.org/prl/abstract/10.1103/4dyc-z8zf
ダークマター検索結果4。2 トン−年LUX-ZEPLIN（LZ）実験の曝露 Dark Matter Search Results from 4.2 Tonne−Years of Exposure of the LUX-ZEPLIN (LZ) Experiment
J. Aalbers, D. S. Akerib, A. K. Al Musalhi, F. Alder, C. S. Amarasinghe, A. Ames, T. J. Anderson, N. Angelides, H. M. Araújo et al. (LZ Collaboration)
Physical Review Letters Published: 1 July, 2025
DOI: https://doi.org/10.1103/4dyc-z8zf
Abstract
We report results of a search for nuclear recoils induced by weakly interacting massive particle (WIMP) dark matter using the LUX-ZEPLIN (LZ) two-phase xenon time projection chamber. This analysis uses a total exposure of 4.2 ±0.1 tonne-years from 280 live days of LZ operation, of which 3.3 ±0.1 tonne-years and 220 live days are new. A technique to actively tag background electronic recoils from 214Pb decays is featured for the first time. Enhanced electron-ion recombination is observed in two-neutrino double electron capture decays of 124Xe, representing a noteworthy new background. After removal of artificial signal-like events injected into the dataset to mitigate analyzer bias, we find no evidence for an excess over expected backgrounds. World-leading constraints are placed on spin-independent (SI) and spin-dependent WIMP-nucleon cross sections for masses ≥9 GeV/2. The strongest SI exclusion set is 2.2×10−48 cm2 at the 90% confidence level and the best SI median sensitivity achieved is 5.1 ×10−48 cm2, both for a mass of 40 GeV/2.
