来自HFIR冷中子束的n→n'变换的新极限
New Limits on $n \rightarrow n'$ Transformation from HFIR Cold Neutron Beam
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中文总结 AI 辅助
本研究利用HFIR冷中子束搜寻n→n'变换，采用含Δm和θ₀参数的理论模型，通过超导磁体与镉片开展实验，未观测到信号，将对应概率下限提升一个数量级。
中文摘要 AI 辅助
假想的中子n到惰性中子n'的变换会重子数B，指向暗物质的本质。我们利用橡树岭国家实验室高通量同位素反应堆（HFIR）产生的强冷中子束，对n→n'开展了新的搜寻。我们采用了描述n→n'变换的理论模型，该模型包含两个参数：相互作用态n与n'之间的小质量差Δm，以及混合真空角θ₀。我们在超导6.6T磁体中心放置了薄镉吸收片，该磁体为非绝热n→n'变换提供了大梯度。在磁体下游20米处的³He中子探测器中，未观测到超出本底的信号。该结果在Δm处于0.1neV至1000neV的范围内，将真空下n→n'变换概率2θ₀²的下限提升了一个数量级。
英文摘要
Hypothetical neutron $n$ to sterile neutron $n'$ transformations would violate baryon number $\mathcal{B}$ and point to the nature of Dark Matter. We performed a new search for $n \rightarrow n'$ using an intense cold neutron beam from the High Flux Isotope Reactor at Oak Ridge National Laboratory. We used a theoretical model that describes the transformation $n \rightarrow n'$ with two parameters: a small mass difference $Δ{m}$ between the interaction states $n$ and $n'$ and a mixing vacuum angle $θ_0$. A thin absorbing cadmium wafer was used in the center of the superconducting 6.6 T magnet which provided a large gradient for the non-adiabatic $n \rightarrow n'$ transition. No signal was observed above background in the $^{3}\text{He}$ neutron detector 20 meters downstream of the magnet. This result gives an order of magnitude improvement in the lower limit for the probability $2θ_0^2$ of the $n \rightarrow n'$ transformation in vacuum in the range of $Δ{m}$ between $0.1$ neV and $1000$ neV.
