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Search for the Invisible Decay of Neutrons with KamLAND

The KamLAND collaboration
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Abstract

The Kamioka Liquid scintillator Anti-Neutrino Detector (KamLAND) is used in a search for single neutron or two neutron intra-nuclear disappearance that would produce holes in the $\it{s}$-shell energy level of $^{12}$C nuclei. Such holes could be created as a result of nucleon decay into invisible modes ($inv$), e.g. $n \to 3ν$ or $nn \to 2ν$. The de-excitation of the corresponding daughter nucleus results in a sequence of space and time correlated events observable in the liquid scintillator detector. We report on new limits for one- and two-neutron disappearance: $τ(n\to inv)> 5.8\times 10^{29}$ years and $τ(nn \to inv)> 1.4 \times 10^{30}$ years at 90% CL. These results represent an improvement of factors of $\sim$3 and $>10^4$ over previous experiments.

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The KamLAND collaboration. 2006-02-07. Search for the Invisible Decay of Neutrons with KamLAND. https://doi.org/10.1103/physrevlett.96.101802

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