Radon-induced backgrounds in the NEXT-100 experiment

[摘要] The NEXT-100 detector at the LSC aims at the first competitive search for the 0νββ decay using a high-pressure 136Xe electroluminescent time projection chamber. The first low-background run of NEXT-100 at 3.95 bar has been devoted to the measurement of the radon-induced backgrounds impacting this search. The contributions from both the internal and external airborne radon have been evaluated. The internal 222Rn activity is found to be (0.95±0.04(stat)±0.09(sys)) Bq/m3, while no traces of 220Rn have been observed. Most of the 222Rn progeny plate-out on the surface of the cathode of the detector, leading to a rate of Rn-induced 214Bi of (0.97±0.05(stat)±0.10(sys)) Hz for visible energies above 400 keV. The corresponding background index in the 0νββ region of interest is evaluated as (7.3±1.5(stat)±0.8(sys))×10−4 counts/(keV·kg·yr) after selection of the fully contained events. This background index is reduced to ∼4×10−5 counts/(keV·kg·yr) by applying a topological selection requiring only one double-electron-like track in the events. This value is one order of magnitude below the total radiogenic background expectation in NEXT-100. By analyzing the correlation of the airborne radon activity and the measured rate of events in NEXT-100, it is concluded that the detector operates in a virtually radon-free environment thanks to the radon abatement system of the LSC.

[发布日期] 2026-09-07

[关键词] Dark Matter and Double Beta Decay (experiments);Rare Decay