O. Méplan

Search for passing-through-walls neutrons constrains hidden braneworlds

Abstract In many theoretical frameworks our visible world is a 3-brane, embedded in a multidimensional bulk, possibly coexisting with hidden braneworlds. Some works have also shown that matter swapping between braneworlds can occur. Here we report the results of an experiment – at the Institut Laue-Langevin (Grenoble, France) – designed to detect thermal neutron swapping to and from another braneworld, thus constraining the probability p 2 of such an event. The limit, p 4.6 × 10 − 10 at 95% C.L., is 4 orders of magnitude better than the previous bound based on the disappearance of stored ultracold neutrons. In the simplest braneworld scenario, for two parallel Planck-scale branes separated by a distance d , we conclude that d > 87 in Planck length units.

Measurements of the mass and isotopic yields of the 233 U(n th , f) reaction at the Lohengrin spectrometer

Over the last 10 years, a vast campaign of measurements has been initiated to improve the precision of neutron data for the involved key nuclei (232Th, 233Pa and 233U) of the innovative Th−233U cycle. This latter might indeed provide cleaner nuclear energy than the present U-Pu one. New measurements of charge and mass distributions of the fission products have been achieved at the Lohengrin spectrometer of the Institute Laue-Langevin (ILL) during fall 2010 to complete the experimental data of 233U(n, f) that exist mainly for light fission fragments. That is why we performed measurements of mass and isotopic yields with a special focus on the heavy fission fragment part. Mass yields were measured by ion counting with an ionization chamber after separation by the Lohengrin spectrometer. Isotopic yields were derived from gamma spectrometry of mass-separated beams using HPGe clover detectors. This paper will present the results of these fission yield measurements along with details on the experimental set-up and the chosen analysis method.