C. Evans

AEgIS at ELENA: outlook for physics with a pulsed cold antihydrogen beam.

The efficient production of cold antihydrogen atoms in particle traps at CERN’s Antiproton Decelerator has opened up the possibility of performing direct measurements of the Earth’s gravitational acceleration on purely antimatter bodies. The goal of the AEgIS collaboration is to measure the value of g for antimatter using a pulsed source of cold antihydrogen and a Moiré deflectometer/Talbot–Lau interferometer. The same antihydrogen beam is also very well suited to measuring precisely the ground-state hyperfine splitting of the anti-atom. The antihydrogen formation mechanism chosen by AEgIS is resonant charge exchange between cold antiprotons and Rydberg positronium. A series of technical developments regarding positrons and positronium (Ps formation in a dedicated room-temperature target, spectroscopy of the n=1–3 and n=3–15 transitions in Ps, Ps formation in a target at 10 K inside the 1 T magnetic field of the experiment) as well as antiprotons (high-efficiency trapping of , radial compression to sub-millimetre radii of mixed plasmas in 1 T field, high-efficiency transfer of to the antihydrogen production trap using an in-flight launch and recapture procedure) were successfully implemented. Two further critical steps that are germane mainly to charge exchange formation of antihydrogen—cooling of antiprotons and formation of a beam of antihydrogen—are being addressed in parallel. The coming of ELENA will allow, in the very near future, the number of trappable antiprotons to be increased by more than a factor of 50. For the antihydrogen production scheme chosen by AEgIS, this will be reflected in a corresponding increase of produced antihydrogen atoms, leading to a significant reduction of measurement times and providing a path towards high-precision measurements. This article is part of the Theo Murphy meeting issue ‘Antiproton physics in the ELENA era’.

Physical Society of Japan : Overview of recent work on laser excitation of positronium for the formation of antihydrogen

P. Yzombard1, C. Amsler2, T. Ariga2, G. Bonomi3,4, P. Bräunig5, R. S. Brusa6,7, L. Cabaret1, M. Caccia8, R. Caravita9,10,14, F. Castelli8,11, G. Cerchiari12, D. Comparat1, G. Consolati8,13, A. Demetrio5, L. Di Noto9,10, M. Doser14, A. Ereditato2, C. Evans8,13, R. Ferragut8,13, J. Fesel14, A. Fontana4, S. Gerber14, M. Giammarchi8, A. Gligorova15, F. Guatieri6,7, S. Haider14, H. Holmestad16, T. Huse16, A. Kellerbauer12, D. Krasnický9,10, V. Lagomarsino9,10, P. Lansonneur17, P. Lebrun17, C. Malbrunot14,18, S. Mariazzi18, V. Matveev19,20, Z. Mazzotta8,11, G. Nebbia21, P. Nedelec17, M. Oberthaler5, N. Pacifico15, D. Pagano3,4, L. Penasa6,7, V. Petracek22, C. Pistillo2, F. Prelz8, M. Prevedelli23, L. Ravelli6,7, B. Rienaecker14, O.M. Røhne16, A. Rotondi4,24, M. Sacerdoti8,11, H. Sandaker16, R. Santoro8,25, P. Scampoli2,26, L. Smestad14,27, F. Sorrentino9,10, I. M. Strojek22, G. Testera10, I. C. Tietje14, S. Vamosi18, E. Widmann18, J. Zmeskal18, N. Zurlo4,28

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

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 Earths 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 moire 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 moire deflectometer.

submitter : Positron Manipulation and Positronium Laser Excitation in AEgIS

Production of antihydrogen by using the charge exchange reaction, as proposed by AEgIS (Antimatter Experiment: gravity, Interferometry, Spectroscopy), requires the formation of a dense cloud of positronium atoms excited to Rydberg states. In this work, the recent advances in AEgIS towards this result are described. Namely, the manipulation of positrons to produce bunches containing more than 108 particles and the laser excitation of positronium to Rydberg states, using n=3 as intermediate level, are presented.

The DAQ system for the AEḡIS experiment

In the sociology of small- to mid-sized (O(100) collaborators) experiments the issue of data collection and storage is sometimes felt as a residual problem for which well-established solutions are known. Still, the DAQ system can be one of the few forces that drive towards the integration of otherwise loosely coupled detector systems. As such it may be hard to complete with off-the-shelf components only. LabVIEW and ROOT are the (only) two software systems that were assumed to be familiar enough to all collaborators of the AEḡIS (AD6) experiment at CERN: working out of the GXML representation of LabVIEW Data types, a semantically equivalent representation as ROOT TTrees was developed for permanent storage and analysis. All data in the experiment is cast into this common format and can be produced and consumed on both systems and transferred over TCP and/or multicast over UDP for immediate sharing over the experiment LAN. We describe the setup that has been able to cater to all run data logging and long term monitoring needs of the AEḡIS experiment so far.