Shapes of Rotating ³He Droplets

Recent advent of X-ray free electron lasers (XFEL) has enabled the study of rotation in free isolated superfluid ⁴He droplets.[1] The work presented here extends our study of rotating quantum fluids to non-superfluid ³He droplets. Sub micrometer sized ³He droplets were obtained from free jet expansion of liquid ³He at temperatures less than 3 K and studied via X-ray scattering at the LCLS XFEL.[2] The obtained shapes and sizes of rotating ⁴He and ³He droplets have been compared. In contrast to superfluid ⁴He droplets, ³He droplets (T = 0.15 K) are devoid of quantum vortices. Tracing of quantum vortices inside ⁴He droplets have been previously achieved by doping with large number of Xe atoms.[3] This work presents the first experimental study of the formation dynamics of atomic clusters in a homogenous, vortex-free quantum fluid.

[1] Bernando, C. et. al. 2017, Phys. Rev. B 95, 064510
[2] Gomez, L. F. et. al. 2014, Science 354, 906
[3] Jones, C. F. et. al. 2016, Phys. Rev. B 93, 180510