Neutron reflection from the surfaces of liquid 4 He and a Dilute 3 He- 4 He solution
Neutron reflection from the surfaces of liquid 4 He and a Dilute 3 He- 4 He solution
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液体 4 He 和稀 3 He- 4 He 溶液表面的中子反射
DOI：
10.1088/1742-6596/150/3/032022
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
Charlton T
中科院分区：
文献类型：
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作者：
Charlton T
我们报告和讨论的第一次中子反射测量正常和超流4 He和液体3 He-4 He混合物的自由表面。在液体4 He的情况下，表面粗糙度在λ转变的上方和下方是不同的，在超流状态下更平滑。对于超流体，我们还观察到一个200 μ m厚的表面层的形成，它具有微妙不同的中子散射截面。结果可以解释为靠近氦表面的玻色-爱因斯坦凝聚分数的增强。我们发现，3 He同位素杂质的加入导致在低温下Andreev能级的形成。
We report and discuss the first neutron reflection measurements from the free surfaces of normal and superfluid 4 He and of a liquid 3 He-4 He mixture. In case of liquid 4 He the surface roughness is different above and below the lambda transition, being smoother in the superfluid state. For the superfluid, we also observe the formation of a surface layer∼ 200 Å thick which has a subtly different neutron scattering cross-section. The results can be interpreted as an enhancement of the Bose-Einstein condensate fraction close to the helium surface. We find that the addition of 3 He isotopic impurities leads to the formation of Andreev levels at low temperatures.