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Alexandre Bigot

Publications and source records attributed to Alexandre Bigot.

2 recordsLinked to original sources

Measurement of 80-200 MeV/n $^{16}$O nuclear cross-section on Carbon and Polyethylene targets with the nuclear emulsion detector of the FOOT experiment

Accurate knowledge of nuclear fragmentation cross-sections is essential for optimizing charged particle therapy. In this study, conducted within the framework of the FOOT (FragmentatiOn Of Target) experiment, we present the first measurements with a large angular acceptance of total charge-changing cross-section and the cross-section for the production of fragments (production cross-section) for $^{16}$O ions interacting with Carbon (C) and Polyethylene (C$_2$H$_4$) targets in the kinetic energy range of 80 to 200 MeV/nucleon. Measurements were performed using the Emulsion Cloud Chamber (ECC) technique, which combines high spatial resolution and angular acceptance, up to 45$^\circ$. The results are compared with Monte Carlo model predictions. Moreover, the total charge-changing and fragment production cross-sections for $^{16}$O on Hydrogen in the same energy range are derived.

nucl-ex

Counter-rotation of magnetic beads in spinning fields

A magnetized bead in a magnetic field seeks to minimize its magnetic free energy by aligning its magnetic moment with the field direction and by moving towards the maximum of the field's intensity. However, when the bead is coupled to a substrate it is forced to roll. The two otherwise independent degrees of freedom, translation and rotation, become tightly coupled giving rise to subtle and often counterintuitive effects. Here we investigate one such, easily reproducible, yet stunning effect : A neodymium bead placed on top of a laboratory magnetic stirrer. When the stirrer's magnet spins at slow rates the bead naturally follows the field. However, surprisingly, at high spinning rates the bead suddenly inverts its direction and runs, to the surprise of the observer, in the opposite direction, against the driving field direction.This effect, experimentally investigated in [J.Magn.Magn.Matter, 476, 376-381, (2019)], is here comprehensively studied, with numerical simulations and a theoretical approach complementing experimental observations.

physics.class-ph