arXiv subjects

Jules Grucker

Publications and source records attributed to Jules Grucker.

5 recordsLinked to original sources

arXiv2015

Cavitation Density of Superfluid Helium-4 around 1 K

Using an optical interferomertric method, the homogeneous cavitation density of superfluid helium at $T=0.96\,$K is measured and found to be $ρ_{cav}=0.1338\pm0.0002\rm\,g.cm^{-3}$. A well established equation of state for liquid helium at negative pressures converts this to the cavitation pressure $P_{cav}=-5.1\pm0.1\,$bar. This cavitation pressure is consistent with a model taking into account the presence of quantized vortices, but disagrees with previously published experimental values of $P_{cav}$.

cond-mat.other↗

arXiv2011

Observation of metastable hcp solid helium

We have produced and observed metastable solid helium-4 below its melting pressure between 1.1 K and 1.4 K. This is achieved by an intense pressure wave carefully focused inside a crystal of known orientation. An accurate density map of the focal zone is provided by an optical interferometric technique. Depending on the sample, minimum density achieved at focus corresponds to pressures between 2 and 4 bar below the static melting pressure. Beyond, the crystal undergoes an unexpected instability much earlier than the predicted spinodal limit. This opens a novel opportunity to study this quantum crystal in an expanded metastable state and its stability limits.

cond-mat.mtrl-sci↗

arXiv2010

Investigating metastable hcp solid helium below its melting pressure

We report a first attempt to produce metastable hcp solid helium below its melting pressure. A focused sound pulse is emitted along the c-axis of a mono-domain hcp helium-4 crystal starting from a static pressure just above the melting pressure. The sound pulse is made as simple as possible with one negative and one positive swing only. Density at focus is monitored by an optical interferometric method. Performed numerical simulations show that the crystal anisotropy splits the focused wave into two separate pulses, corresponding to a longitudinal wave along the c-axis and a radial one perpendicular to it. The amplification factor due to focusing remains nevertheless important. Negative pressure swings up to 0.9 bar have been produced, crossing the static melting pressure limit. Improvements in the detection method and in the focusing amplification are proposed.

cond-mat.other↗

arXiv2010

Time-resolved quantitative multiphase interferometric imaging of a highly focused ultrasound pulse

Interferometric imaging is a well established method to image phase objects by mixing the image wavefront with a reference one on a CCD camera. It has also been applied to fast transient phenomena, mostly through the analysis of single interferograms. It is shown that for repetitive phenomena multiphase acquisition brings significant advantages. A 1 MHz focused sound field emitted by a hemispherical piezotransducer in water is imaged as an example. Quantitative image analysis provides high resolution sound field profiles. Pressure at focus determined by this method agrees with measurements from a fiber-optic probe hydrophone. This confirms that multiphase interferometric imaging can indeed provide quantitative measurements.

physics.optics↗

arXiv2007

Nuclear spin interferences in bulk water at room temperature

Nuclear spin interference effects generated in a macroscopic sample of 10ml degassed water are detected in a simple NMR experiment. A π/2 - τ- π/2 RF double pulse sequence (Ramsey sequence) is applied to the water sample immersed in a static magnetic field B0 " 4.7T. For a homogeneity of B0 of the order of ΔB0/B0 = 2 . 10^{-8}, the nuclear spin interference term is controlled with a maximum relative deviation of 9.7 %. These results are a first step to manipulation of nuclear spin coherence of water molecules.

physics.comp-ph↗