AEIS Experiment: Measuring the acceleration g of the earth’s gravitational field on antihydrogen beam

¹ Università Degli Studi di Brescia, Dipartimento di Ingegneria Meccanica e Industriale, Via Branze 38, 25133 Brescia, Italy
² Istituto Nazionale di Fisica Nucleare, Sez. di Pavia, Via Agostino Bassi 6, 27100 Pavia, Italy
³ Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan, Italy
⁴ Istituto Nazionale di Fisica Nucleare, Sez. di Milano, Via Celoria 16, 20133 Milan, Italy
⁵ European Organization for Nuclear Research, Physics Dept., 1211 Geneva 23, Switzerland
⁶ Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics, University of Bern, 3012 Bern, Switzerland
⁷ Institute for Nuclear Research of Russian Academy of Sciences, Moscow, 117312, Russia
⁸ University of Heidelberg, Kirchoff Institute for Physics, Im Neuenheimer Feld 227, 69120, Heidelberg, Germany
⁹ Dipartimento di Fisica, Universitàdi Trento & INFN, Gruppo Collegato di Trento, Via Sommarive 14, 38050 Povo, Trento, Italy
¹⁰ Laboratoire Aimé Cotton, CNRS, Université Paris Sud, ENS Cachan, Bâtiment 505, Campus d’Orsay, 91405 Orsay Cedex, France
¹¹ University of Zurich, Physics Institute, Winterthurerstrasse 190, 8057 Zurich, Switzerland
¹² Università Degli Studi di Milano, Dipartimento di Fisica, Via Celoria 16, 20133 Milan, Italy
¹³ Istituto Nazionale di Fisica Nucleare, Sez. di Genova, Via Dodecaneso 33, 16146 Genova, Italy
¹⁴ University of Bergen, Institute of Physics and Technology, Alleegaten 55, 5007 Bergen, Norway
¹⁵ University College London, Dept. of Physics and Astronomy, Gower Street, London, WC1E 6BT, UK
¹⁶ University of Oslo, Dept. of Physics, Semælands vei 24, 0371 Oslo, Norway
¹⁷ Max Plank Institute for Nuclear Physics, Saupfercheckweg 17, 69117 Heidelberg, Germany
¹⁸ Università Degli Studi di Genoa, Dipartimento di Fisica, Via Dodecaneso 33, 16146 Genova, Italy
¹⁹ Joint Institute for Nuclear Research, 141980 Dubna, Russia
²⁰ ETH Zurich, Laboratory for Physical Chemistry, 8093 Zurich, Switzerland
²¹ Istituto Nazionale di Fisica Nucleare, Sez. di Padova, Via Marzolo 8, 35131 Padova, Italy
²² Claude Bernard University Lyon 1, Institut de Physique Nucléaire de Lyon, 4 Rue Enrico Fermi, 69622 Villeurbanne, France
²³ Czech Technical University in Prague, FNSPE, Břehová 7, 11519 Praha 1, Czech Republic
²⁴ Università Degli Studi di Bologna, Dipartimento di Fisica, Via Irnerio 46, 40126 Bologna, Italy
²⁵ Università Degli Studi di Pavia, Dipartimento di Fisica Nucleare e Teorica, Agostino Bassi 6, 27100 Pavia, Italy
²⁶ Università di Napoli Federico II, Dipartimento di Fisica, Via Cinthia, 80126 Napoli, Italy

^a e-mail: martin.alfonso.subieta.vasquez@cern.ch

Published online: 29 April 2014

Abstract

The AEIS experiment [1] aims at directly measuring the gravitational acceleration g on a beam of cold antihydrogen () to a precision of 1%, performing the first test with antimatter of the (WEP) Weak Equivalence Principle. The experimental apparatus is sited at the Antiproton Decelerator (AD) at CERN, Geneva, Switzerland. After production by mixing of antiprotons with Rydberg state positronium atoms (Ps), the atoms will be driven to fly horizontally with a velocity of a few 100 ms⁻¹ for a path length of about 1 meter. The small deflection, few tens of μm, will be measured using two material gratings (of period ∼ 80 μm) coupled to a position-sensitive detector working as a moiré deflectometer similarly to what has been done with matter atoms [2]. The shadow pattern produced by the beam will then be detected by reconstructing the annihilation points with a spatial resolution (∼ 2 μm) of each antiatom at the end of the flight path by the sensitive-position detector. During 2012 the experimental apparatus has been commissioned with antiprotons and positrons. Since the AD will not be running during 2013,during the refurbishment of the CERN accelerators, the experiment is currently working with positrons, electrons and protons, in order to prepare the way for the antihydrogen production in late 2014.