The AEgIS experiment at CERN: measuring antihydrogen free-fall in earth’s gravitational field to test WEP with antimatter

R S Brusa ,V Matveev ,I C Tietje ,Z Mazzotta ,G Bonomi ,M Sacerdoti ,Markus K Oberthaler ,D Comparat ,H Holmestad ,G Nebbia ,F Guatieri ,R Ferragut ,S Haider ,T Ariga ,G Cerchiari ,A Ereditato ,C Amsler ,C Pistillo ,C Evans ,P Lansonneur ,M Caccia ,A Demetrio,T Huse ,D Pagano ,J Zmeskal ,V Petráček ,A Fontana ,M Prevedelli ,L Di Noto ,L Smestad ,I Strojek ,P Nédélec ,F Castelli ,P Scampoli ,N Pacifico ,C Malbrunot ,J Fesel ,R Santoro ,M Doser ,F Prelz ,P Yzombard ,P Bräunig ,P Lebrun ,D Krasnický ,H Sandaker ,E Widmann ,S Mariazzi ,G Testera ,S Vamosi ,A Gligorova ,R Caravita ,B Rienäcker ,G Consolati ,L Ravelli ,L Penasa ,V Lagomarsino ,S Gerber ,A Kellerbauer ,M Giammarchi ,A Rotondi ,O Røhne ,L Cabaret ,F Sorrentino ,N Zurlo

doi:10.1088/1742-6596/791/1/012014

Abstract

The AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) experiment is designed with the objective to test the weak equivalence principle with antimatter by studying the free fall of antihydrogen in the Earth’s gravitational field. A pulsed cold beam of antihydrogen will be produced by charge exchange between cold Ps excited in Rydberg state and cold antiprotons. Finally the free fall will be measured by a classical moiré deflectometer. The apparatus being assembled at the Antiproton Decelerator at CERN will be described, then the advancements of the experiment will be reported: positrons and antiprotons trapping measurements, Ps two-step excitation and a test-measurement of antiprotons deflection with a small scale moiré deflectometer.

Highlights

The weak equivalence principle (WEP), known as universality of free fall (UFF), states that in a gravitational field all bodies, irrespective of their mass and composition, fall with the same acceleration
The apparatus being assembled at the Antiproton Decelerator at CERN will be described, the advancements of the experiment will be reported: positrons and antiprotons trapping measurements, Ps two-step excitation and a testmeasurement of antiprotons deflection with a small scale moiré deflectometer
UFF of matter in the field of Earth has been tested by measuring the dimensionless parameter Δ ⁄ where Δ is the relative acceleration between two proof masses as they fall with an acceleration towards the Earth; validity of UFF-WEP requires 0

Summary

Introduction

The weak equivalence principle (WEP), known as universality of free fall (UFF), states that in a gravitational field all bodies, irrespective of their mass and composition, fall with the same acceleration. UFF of matter in the field of Earth has been tested by measuring the dimensionless parameter Δ ⁄ where Δ is the relative acceleration between two proof masses as they fall with an acceleration towards the Earth; validity of UFF-WEP requires 0. In spite of very precise experiments done with matter, none has been carried out to test UFF-WEP with antimatter. The AEgIS experiment, set up at the Antiproton Decelerator (AD) at CERN, is designed with the primary scientific goal of measuring for the first time the free fall of antihydrogen ( ) in the Earth’s gravitational field with percent order precision [2]. In this paper the current progress towards forming a cold antihydrogen beam and measuring gravity will be summarized

The AEgIS experiment: method and set-up

Positronium formation and excitation in the secondary chamber

Moiré deflectometer: concept proof with antiprotons

Conclusions

Methods