Linac-based positron source and generation of a high density positronium cloud for the GBAR experiment

16th International Conference on Positron Annihilation

Liszkay, L.^1 ; Comini, P.^1 ; Corbel, C.^2 ; Debu, P.^1 ; Dupré, P.^3 ; Grandemange, P.^3 ; Pérez, P.^1 ; Rey, J.-M.^1 ; Ruiz, N.^1 ; Sacquin, Y.^1

CEA, Irfu, Centre de Saclay, F-91191 Gif-sur-Yvette, France^1

Laboratoire des Solides Irradiés, Ecole Polytechnique, 91128 Palaiseau, France^2

CSNSM-IN2P3/CNRS, Université de Paris Sud, 91406 Orsay, France^3

关键词: Antiproton decelerator;    Converter structure;    Experimental scheme;    Gravitational fields;    Linear electron accelerator;    Mesoporous silica film;    Penning-Malmberg trap;    Pore configuration;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/443/1/012006/pdf
DOI  :  10.1088/1742-6596/443/1/012006

来源: IOP

【 摘 要 】

The aim of the recently approved GBAR (Gravitational Behaviour of Antihydrogen at Rest) experiment is to measure the acceleration of neutral antihydrogen atoms in the gravitational field of the Earth. The experimental scheme requires a high density positronium cloud as a target for antiprotons, provided by the Antiproton Decelerator (AD)-Extra Low Energy Antiproton Ring (ELENA) facility at CERN. We introduce briefly the experimental scheme and present the ongoing efforts at IRFU CEA Saclay to develop the positron source and the positron-positronium converter, which are key parts of the experiment. We have constructed a slow positron source in Saclay, based on a low energy (4.3 MeV) linear electron accelerator (linac). By using an electron target made of tungsten and a stack of thin W meshes as positron moderator, we reached a slow positron intensity that is comparable with that of22Na-based sources using a solid neon moderator. The source feeds positrons into a high field (5 T) Penning-Malmberg trap. Intense positron pulses from the trap will be converted to slow ortho-positronium (o-Ps) by a converter structure. Mesoporous silica films appear to date to be the best candidates as converter material. We discuss our studies to find the optimal pore configuration for the positron-positronium converter.