Positronium for Antihydrogen Production in the AEGIS Experiment
G. Consolati1,2, S. Aghion1,2, C. Amsler3, G. Bonomi4,5, R.S. Brusa6,7, M. Caccia2,8, R. Caravita9,10,11, F. Castelli2,12, G. Cerchiari13, D. Comparat14, A. Demetrio15, L. Di Noto9,10, M. Doser11, C. Evans1,2, M. Fanì9,10,11, R. Ferragut1,2, J. Fesel11, A. Fontana5, S. Gerber11, M. Giammarchi2, A. Gligorova3, F. Guatieri6,7, S. Haider11, A. Hinterberger11, H. Holmestad16, A. Kellerbauer13, O. Khalidova11, D. Krasnicky10, V. Lagomarsino9,10, P. Lansonneur17, P. Lebrun17, C. Malbrunot3,11, S. Mariazzi18, J. Marton3, V. Matveev19,20, Z. Mazzotta2,12, S.R. Müller15, G. Nebbia18, P. Nedelec17, M. Oberthaler15, N. Pacifico11, D. Pagano4,5, L. Penasa6,7, V. Petracek21, F. Prelz2, M. Prevedelli22, L. Ravelli6,7, B. Rienaecker11, J. Robert14, O.M. Røhne16, A. Rotondi5,23, H. Sandaker16, R. Santoro2,8, L. Smestad11,24, F. Sorrentino9,10, G. Testera10, I.C. Tietje11, E. Widmann3, P. Yzombard13, C. Zimmer11,13,25, J. Zmeskal3, N. Zurlo5,26
1Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
2INFN Milano, via Celoria 16, 20133, Milano, Italy
3Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
4Department of Mechanical and Industrial Engineering, University of Brescia, via Branze 38, 25123 Brescia, Italy
5INFN Pavia, via Bassi 6, 27100 Pavia, Italy
6Department of Physics, University of Trento, via Sommarive 14, 38123 Povo, Trento, Italy
7TIFPA/INFN Trento, via Sommarive 14, 38123 Povo, Trento, Italy
8Department of Science, University of Insubria, Via Valleggio 11, 22100 Como, Italy
9Department of Physics, University of Genova, via Dodecaneso 33, 16146 Genova, Italy
10INFN Genova, via Dodecaneso 33, 16146 Genova, Italy
11Physics Department, CERN, 1211 Geneva 23, Switzerland
12Department of Physics, University of Milano, via Celoria 16, 20133 Milano, Italy
13Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg, Germany
14Laboratoire Aime Cotton, Université Paris-Sud, ENS Paris-Saclay, CNRS, Université Paris-Saclay, 91405 Orsay Cedex, France
15Kirchhoff-Institute for Physics, Heidelberg University, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
16Department of Physics, University of Oslo, Sem Slandsvei 24, 0371 Oslo, Norway
17Institute of Nuclear Physics, CNRS/IN2p3, University of Lyon 1, 69622 Villeurbanne, France
18INFN Padova, via Marzolo 8, 35131 Padova, Italy
19Institute for Nuclear Research of the Russian Academy of Science, Moscow 117312, Russia
20Joint Institute for Nuclear Research, 141980 Dubna, Russia
21Czech Technical University, Prague, Brehov 7, 11519 Prague 1, Czech Republic
22University of Bologna, Viale Berti Pichat 6/2, 40126 Bologna, Italy
23Department of Physics, University of Pavia, via Bassi 6, 27100 Pavia, Italy
24The Research Council of Norway, P.O. Box 564, NO-1327 Lysaker, Norway
25Department of Physics, Heidelberg University, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
26Department of Civil, Environmental, Architectural Engineering and Mathematics, University of Brescia, via Branze 43, 25123 Brescia, Italy
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The primary goal of the Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEGIS) collaboration is to measure for the first time precisely the gravitational acceleration of antihydrogen, H̅, a fundamental issue of contemporary physics, using a beam of antiatoms. Indeed, although indirect arguments have been raised against a different acceleration of antimatter with respect to matter, nevertheless some attempts to formulate quantum theories of gravity, or to unify gravity with the other forces, consider the possibility of a non-identical gravitational interaction between matter and antimatter. We plan to generate H̅ through a charge-exchange reaction between excited Ps and antiprotons coming from the Antiproton Decelerator facility at CERN. It offers the advantage to produce sufficiently cold antihydrogen to make feasible a measurement of gravitational acceleration with reasonable uncertainty (of the order of a few percent). Since the cross-section of the above reaction increases with n4, n being the principal quantum number of Ps, it is essential to generate Ps in a highly excited (Rydberg) state. This will occur by means of two laser excitations of Ps emitted from a nanoporous silica target: a first UV laser (at 205 nm) will bring Ps from the ground to the n=3 state; A second laser pulse (tunable in the range 1650-1700 nm) will further excite Ps to the Rydberg state.

DOI: 10.12693/APhysPolA.132.1443
PACS numbers: 04.80.Cc, 07.77.-n, 36.10.Dr, 78.70.Bj