Towards the first measurement of matter-antimatter gravitational interaction

¹ LNESS, Department of Physics, Politecnico di Milano, via Anzani 42, 22100, Como, Italy
² INFN Milano, via Celoria 16, 20133, Milano, Italy
³ Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
⁴ Department of Mechanical and Industrial Engineering, University of Brescia, via Branze 38, 25123 Brescia, Italy
⁵ INFN Pavia, via Bassi 6, 27100 Pavia, Italy
⁶ Department of Physics, University of Trento, via Sommarive 14, 38123 Povo, Trento, Italy
⁷ TIFPA/INFN Trento, via Sommarive 14, 38123 Povo, Trento, Italy
⁸ Department of Science, University of Insubria, Via Valleggio 11, 22100 Como, Italy
⁹ Department of Physics, University of Genova, via Dodecaneso 33, 16146 Genova, Italy
¹⁰ INFN Genova, via Dodecaneso 33, 16146 Genova, Italy
¹¹ Department of Physics, University of Milano, via Celoria 16, 20133 Milano, Italy
¹² Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg, Germany
¹³ Laboratoire Aimé Cotton, Université Paris-Sud, ENS Paris Saclay, CNRS, Université Paris-Saclay, 91405 Orsay Cedex, France
¹⁴ Department of Aerospace Science and Technology, Politecnico di Milano, via La Masa 34, 20156, Milano, Italy
¹⁵ Kirchhoff-Institute for Physics, Heidelberg University, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
¹⁶ Physics Department, CERN, 1211 Geneva 23, Switzerland
¹⁷ Department of Physics, University of Oslo, Sem Slandsvei 24, 0371 Oslo, Norway
¹⁸ Institute of Nuclear Physics, CNRS/IN2p3, University of Lyon 1, 69622 Villeurbanne, France
¹⁹ Institute for Nuclear Research of the Russian Academy of Science, Moscow 117312, Russia
²⁰ Joint Institute for Nuclear Research, 141980 Dubna, Russia
²¹ INFN Padova, via Marzolo 8, 35131 Padova, Italy
²² Department of Physics, Heidelberg University, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
²³ Institute of Physics and Technology, University of Bergen, Allégaten 55, 5007 Bergen, Norway
²⁴ Czech Technical University, Prague, Brehov 7, 11519 Prague 1, Czech Republic
²⁵ University of Bologna, Viale Berti Pichat 6/2, 40126 Bologna, Italy
²⁶ Department of Physics, University of Pavia, via Bassi 6, 27100 Pavia, Italy
²⁷ The Research Council of Norway, P.O. Box 564, NO-1327 Lysaker, Norway
²⁸ Department of Civil Engineering, University of Brescia, via Branze 43, 25123 Brescia, Italy

^a e-mail: craig.evans@polimi.it

Published online: 3 August 2018

Abstract

The AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) is a CERN based experiment with the central aim to measure directly the gravitational acceleration of antihydrogen. Antihydrogen atoms will be produced via charge exchange reactions which will consist of Rydberg-excited positronium atoms sent to cooled antiprotons within an electromagnetic trap. The resulting Rydberg antihydrogen atoms will then be horizontally accelerated by an electric field gradient (Stark effect), they will then pass through a moiré deflectometer. The vertical deflection caused by the Earth's gravitational field will test for the first time the Weak Equivalence Principle for antimatter. Detection will be undertaken via a position sensitive detector. Around 103 antihydrogen atoms are needed for the gravitational measurement to be completed. The present status, current achievements and results will be presented, with special attention toward the laser excitation of positronium (Ps) to the n=3 state and the production of Ps atoms in the transmission geometry.