Related papers: Molecular Tagging Velocimetry in Superfluid Helium…
The flow of liquid helium through a single nanohole with radius smaller than 25 nm was studied for the first time. Mass flow was induced by applying a pressure difference of up to 1.4 bar across a 50 nm thick Si3N4 membrane and was measured…
Visualization using tracer particles is a relatively new tool available for the study of superfluid turbulence and flow, which is applied here to oscillating objects submerged in the liquid. We report observations of a structure seen in…
In this paper, we propose a microflow velocimetry based on particle tracking with the aid of optical trapping of tracers, namely, optically-trapped particle tracking velocimetry (ot-PTV). The ot-PTV has two phases: a trap phase, in which…
This article describes two independent developments aimed at improving the Particle Tracking Method for measurements of flow or particle velocities. First, a stereoscopic multicamera calibration method that does not require any optical…
The formation of twin images in digital inline holography (DIH) prevents the placement of the focal plane in the center of a sample volume for DIH-based particle tracking velocimetry (DIH-PTV) with a single camera. As a result, it is…
The SPICE/HeRALD collaboration is performing R&D to enable studies of sub-GeV dark matter models using a variety of target materials. Here we report our recent progress on instrumenting a superfluid $^4$He target mass with a transition-edge…
A density functional theory is used to investigate the instability arising in superfluid $^4$He as it flows at velocity u just above the Landau critical velocity of rotons v_c. Confirming an early theoretical prediction by one of us [JETP…
Low temperature water electrolyzers (LTWEs) and low temperature hydrogen fuel cells (LTFCs) present a promising technological strategy for the productions and usages of green hydrogen energy towards a net-zero world. However, the…
Gas behavior in systems at microscale has been receiving significant attention from researchers in the last two decades [1-4]. Today, there is an enhanced emphasis on developing new experimental techniques to capture the local temperature…
We have studied the interaction of metastable $^4$He$_2^*$ excimer molecules with quantized vortices in superfluid $^4$He in the zero temperature limit. The vortices were generated by either rotation or ion injection. The trapping diameter…
I present here a microscopic theory for the superfluidity of $^4$He (He II) derived from experiments, and answer its essential questions. With a "momenton" model, the superfluid is shown to feature as a "harmonic superfluid". In which a new…
Recent advances in ultrafast measurement in cold atoms, as well as pump-probe spectroscopy of $K_3 C_{60}$ films, have opened the possibility of rapidly quenching systems of interacting fermions to, and across, a finite temperature…
Using inelastic electron tunneling spectroscopy with the scanning tunneling microscope (STM-IETS) and density functional theory calculations (DFT), we investigated properties of a single H2 molecule trapped in nanocavities with controlled…
We report a new kind of experiment in which we generate a known superfluid velocity in a straight tube and directly determine the phase difference across the tube's ends using a superfluid matter wave interferometer. By so doing, we…
Measurements of molecular hydrogen (H_2) column densities are presented for the first six rotational levels (J=0 to 5) for 73 extragalactic targets observed with FUSE. All of these have a final signal-to-noise ratio larger than \snlimit,…
Helium is recognized as a model system for the study of phase transitions. Of particular interest is the superfluid phase in two dimensions. We report measurements on superfluid helium films adsorbed on the surface of a suspended carbon…
This paper demonstrates particle tracking velocimetry performed for a model system wherein particle-laden liquid metal flow about a cylindrical obstacle was studied. We present the image processing methodology developed for particle…
Contrary to conventional frame-based imaging, event-based vision (EBV) or dynamic vision sensing (DVS) asynchronously records binary signals of intensity changes for given pixels with microsecond resolution. The present work explores the…
Metastable He$_{2}^{*}$ excimer molecules have been utilized as tracer particles of the normal component in superfluid $^4$He (He II) which can be imaged via laser-induced fluorescence. These excimer molecules form tiny bubbles in He II and…
Microscopic-level understanding of the separation mechanism for two-dimensional (2D) membranes is an active area of research due to potential implications of this class of membranes for various technological processes. Helium (He)…