A fountain of droplets

A vessel is plunged upside down into a pool of 50 cSt silicone oil. An air bell is then created. This bell is vertically shaken at 60 Hz that leads to the oscillation of the air/oil interface. The edges of the immersed vessel generate surface waves that propagate towards the center of the bell. When the amplitude of the oscillation increases, wave amplitude increases. We study the influence of the angle between successive sides on the wave patterns. Two kinds of vessel have been studied: a triangular and a square prism. The shape of the air/oil meniscus depends on the angle between the sides of the considered prism. As the amplitude of the oscillation is increased, the triple line, which is the contact line between the solid and the air/oil interface, moves up and down. Above a given acceleration that depends on the immersion depth and on the shape vessel, wave goes under the corner edge of the bell. During the oscillation, the wave generates at the edges presents a singularity that leads eventually to a jet and a drop ejection. A drop is ejected at each oscillation. More complicated ejection can be produced with further increase of the amplitude. This is a sample arXiv article illustrating the use of fluid dynamics videos.Comment: 3 pages, 2 figures, 2 movies (high-res and low-res

Temps Moderns 1996, no. 20

Abstract not availabl

Probing the braneworld hypothesis with a neutron-shining-through-a-wall experiment

The possibility for our visible world to be a 3-brane embedded in a multidimensional bulk is at the heart of many theoretical edifices in high-energy physics. Probing the braneworld hypothesis is thus a major experimental challenge. Following recent theoretical works showing that matter swapping between braneworlds can occur, we propose a neutron-shining-through-a-wall experiment. We first show that an intense neutron source such as a nuclear reactor core can induce a hidden neutron flux in an adjacent hidden braneworld. We then describe how a low-background detector can detect neutrons arising from the hidden world and quantify the expected sensitivity to the swapping probability. As a proof of concept, a constraint is derived from previous experiments.Comment: 12 pages, 4 figures, final version published in Physical Review

Cross section measurements of the reactions induced by deuteron particles on ¹³C

Nuclear reactions induced by deuterons have been found to be an ideal analysis tool for depth profiling of light elements in the first microns of materials. In particular, the nonresonant nuclear reactions (d, p), (d, α) and (d, t) are well adapted to determine depth distributions of C and C in a single measurement. Nevertheless, only the cross section of the C(d, p)C nuclear reaction is well known for various experimental configurations. Thus, we measured the differential cross sections of the C(d, p)C, C(d, α)B, C(d, α)B and C(d, t)C nuclear reactions. A thin C foil (83 nm thick) was used and the measurements were performed at deuteron energies from 0.5 to 1.65 MeV for different laboratory angles of detection (135°, 150° and 165° with respect to the incident beam). Then, the results obtained in this work were compared to cross sections measured by Marion and Weber for a detection angle of 135°. © 2006 Elsevier B.V. All rights reserved