Velocity-selected production of 2S3 metastable positronium

Positronium in the 2 3 S metastable state exhibits a low electrical polarizability and a long lifetime (1140 ns), making it a promising candidate for interferometry experiments with a neutral matter-antimatter system. In the present work, 2 3 S positronium is produced, in the absence of an electric field, via spontaneous radiative decay from the 3 3 P level populated with a 205-nm UV laser pulse. Thanks to the short temporal length of the pulse, 1.5 ns full width at half maximum, different velocity populations of a positronium cloud emitted from a nanochanneled positron-positronium converter were selected by delaying the excitation pulse with respect to the production instant. 2 3 S positronium atoms with velocity tuned between 7 7 10 4 ms 121 and 10 7 10 4 ms 121 were thus produced. Depending on the selected velocity, a 2 3 S production efficiency ranging from 3c0.8% to 3c1.7%, with respect to the total amount of emitted positronium, was obtained. The observed results give a branching ratio for the 3 3 P-2 3 S spontaneous decay of (9.7 \ub1 2.7)%. The present velocity selection technique could allow one to produce an almost monochromatic beam of 3c1 7 10 3 2 3 S atoms with a velocity spread of <10 4 ms 121 and an angular divergence of 3c50 mrad

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 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 moir\ue9 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 moir\ue9 deflectometer

AEg̅IS latest results

The validity of the Weak Equivalence Principle (WEP) as predicted by General Relativity has been tested up to astounding precision using ordinary matter. The lack hitherto of a stable source of a probe being at the same time electrically neutral, cold and stable enough to be measured has prevented highaccuracy testing of the WEP on anti-matter. The AEg̅IS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) experiment located at CERN's AD (Antiproton Decelerator) facility aims at producing such a probe in the form of a pulsed beam of cold anti-hydrogen, and at measuring by means of a moiré deflectometer the gravitational force that Earth's mass exerts on it. Low temperature and abundance of the H̅ are paramount to attain a high precision measurement. A technique employing a charge-exchange reaction between antiprotons coming from the AD and excited positronium atoms is being developed at AEg̅IS and will be presented hereafter, alongside an overview of the experimental apparatus and the current status of the experimen

Gravity and antimatter: The AEgIS experiment at CERN

open62siFrom the experimental point of view, very little is known about the gravitational interaction between matter and antimatter. In particular, the Weak Equivalence Principle, which is of paramount importance for the General Relativity, has not yet been directly probed with antimatter. The main goal of the AEgIS experiment at CERN is to perform a direct measurement of the gravitational force on antimatter. The idea is to measure the vertical displacement of a beam of cold antihydrogen atoms, traveling in the gravitational field of the Earth, by the means of a moiré deflectometer. An overview of the physics goals of the experiment, of its apparatus and of the first results is presented.openPagano D.; Aghion S.; Amsler C.; Bonomi G.; Brusa R.S.; Caccia M.; Caravita R.; Castelli F.; Cerchiari G.; Comparat D.; Consolati G.; Demetrio A.; Noto L.D.; Doser M.; Evans A.; Fani M.; Ferragut R.; Fesel J.; Fontana A.; Gerber S.; Giammarchi M.; Gligorova A.; Guatieri F.; Haider S.; Hinterberger A.; Holmestad H.; Kellerbauer A.; Khalidova O.; Krasnicky D.; Lagomarsino V.; Lansonneur P.; Lebrun P.; Malbrunot C.; Mariazzi S.; Marton J.; Matveev V.; Mazzotta Z.; Muller S.R.; Nebbia G.; Nedelec P.; Oberthaler M.; Pacifico N.; Penasa L.; Petracek V.; Prelz F.; Prevedelli M.; Ravelli L.; Rienaecker B.; Robert J.; Rohne O.M.; Rotondi A.; Sandaker H.; Santoro R.; Smestad L.; Sorrentino F.; Testera G.; Tietje I.C.; Widmann E.; Yzombard P.; Zimmer C.; Zmeskal J.; Zurlo N.Pagano, D.; Aghion, S.; Amsler, C.; Bonomi, G.; Brusa, R. S.; Caccia, M.; Caravita, R.; Castelli, F.; Cerchiari, G.; Comparat, D.; Consolati, G.; Demetrio, A.; Noto, L. D.; Doser, M.; Evans, A.; Fani, M.; Ferragut, R.; Fesel, J.; Fontana, A.; Gerber, S.; Giammarchi, M.; Gligorova, A.; Guatieri, F.; Haider, S.; Hinterberger, A.; Holmestad, H.; Kellerbauer, A.; Khalidova, O.; Krasnicky, D.; Lagomarsino, V.; Lansonneur, P.; Lebrun, P.; Malbrunot, C.; Mariazzi, S.; Marton, J.; Matveev, V.; Mazzotta, Z.; Muller, S. R.; Nebbia, G.; Nedelec, P.; Oberthaler, M.; Pacifico, N.; Penasa, L.; Petracek, V.; Prelz, F.; Prevedelli, M.; Ravelli, L.; Rienaecker, B.; Robert, J.; Rohne, O. M.; Rotondi, A.; Sandaker, H.; Santoro, R.; Smestad, L.; Sorrentino, F.; Testera, G.; Tietje, I. C.; Widmann, E.; Yzombard, P.; Zimmer, C.; Zmeskal, J.; Zurlo, N

Efficient 2 S 3 positronium production by stimulated decay from the 3 P 3 level

We investigate experimentally the possibility of enhancing the production of 2S3 positronium atoms by driving the 1S3-3P3 and 3P3-2S3 transitions, overcoming the natural branching ratio limitation of spontaneous decay from 3P3 to 2S3. The decay of 3P3 positronium atoms toward the 2S3 level has been efficiently stimulated by a 1312.2 nm broadband IR laser pulse. The dependence of the stimulating transition efficiency on the intensity of the IR pulse has been measured to find the optimal enhancement conditions. A maximum relative increase of ×(3.1±1.0) in the 2S3 production efficiency, with respect to the case in which only spontaneous decay is present, was obtained

Calibration and equalisation of plastic scintillator detectors for antiproton annihilation identification over positron/positronium background

none53In this contribution, the system of the external plastic scintillator slabs of the AEgIS experiment is presented. These slabs, surrounding the superconducting magnet and operating at room temperature, are read out by photomultiplier tubes (PMTs) that are calibrated and equalised to be exploited as a whole detector with useful segmentation and redundancy to effectively detect single antiparticle annihilations. In particular, thanks to periodically recurring calibrations with cosmic rays and to a detailed study of the system in different operational conditions, including extensive Monte Carlo (MC) simulations, these scintillators can be used to identify antiproton annihilations over the constant background represented by cosmic rays and over the strongly time-dependent background due to positrons/positronium annihilations. By means of the sampling and digitization of the analog signal produced by each phototube and the consequent analysis of the amplitude of the recorded events, the energy released by the particle in the scintillator slab can be estimated consistently and with good accuracy. As a consequence, we are able to identify an amplitude range where positrons/positronium annihilations can be univocally excluded. This prerequisite allows us to exploit the array of external plastic scintillators for antihydrogen annihilations tagging.noneZurlo N.; Amsler C.; Antonello M.; Belov A.; Bonomi G.; Brusa R.S.; Caccia M.; Camper A.; Caravita R.; Castelli F.; Cerchiari G.; Comparat D.; Consolati G.; Demetrio A.; Di Noto L.; Doser M.; Fani M.; Ferragut R.; Gerber S.; Giammarchi M.; Gligorova A.; Gloggler L.; Guatieri F.; Haider S.; Hinterberger A.; Kellerbauer A.; Khalidova O.; Krasnicky D.; Lagomarsino V.; Malbrunot C.; Mariazzi S.; Matveev V.; Muller S.R.; Nebbia G.; Nedelec P.; Oberthaler M.; Oswald E.; Pagano D.; Penasa L.; Petracek V.; Prelz F.; Prevedelli M.; Rienaecker B.; Rohne O.M.; Rotondi A.; Sandaker H.; Santoro R.; Testera G.; Tietje I.C.; Toso V.; Wolz T.; Yzombard P.; Zimmer C.Zurlo, N.; Amsler, C.; Antonello, M.; Belov, A.; Bonomi, G.; Brusa, R. S.; Caccia, M.; Camper, A.; Caravita, R.; Castelli, F.; Cerchiari, G.; Comparat, D.; Consolati, G.; Demetrio, A.; Di Noto, L.; Doser, M.; Fani, M.; Ferragut, R.; Gerber, S.; Giammarchi, M.; Gligorova, A.; Gloggler, L.; Guatieri, F.; Haider, S.; Hinterberger, A.; Kellerbauer, A.; Khalidova, O.; Krasnicky, D.; Lagomarsino, V.; Malbrunot, C.; Mariazzi, S.; Matveev, V.; Muller, S. R.; Nebbia, G.; Nedelec, P.; Oberthaler, M.; Oswald, E.; Pagano, D.; Penasa, L.; Petracek, V.; Prelz, F.; Prevedelli, M.; Rienaecker, B.; Rohne, O. M.; Rotondi, A.; Sandaker, H.; Santoro, R.; Testera, G.; Tietje, I. C.; Toso, V.; Wolz, T.; Yzombard, P.; Zimmer, C

Production of long-lived positronium states via laser excitation to 33P level

The 33P state of positronium is an intermediate level suitable for producing long-lived positronium states. On one hand, it can be used in a two-step laser excitation scheme from the ground state to Rydberg levels. On the other hand, excitation of positronium to 33P level is a simple pathway for producing metastable 23S positronium atoms by spontaneous radiactive decay. In this work, experiments showing the production of such long-lived levels, using the 33P state as intermediate state, are presented. The characteristics of the two long-lived levels, in view of experiments of deflectometry/interferometry with positronium, are discussed

Gravity and antimatter: the AEgIS experiment at CERN

International audienceFrom the experimental point of view, very little is known about the gravitational interaction between matter and antimatter. In particular, the Weak Equivalence Principle, which is of paramount importance for the General Relativity, has not yet been directly probed with antimatter. The main goal of the AEgIS experiment at CERN is to perform a direct measurement of the gravitational force on antimatter. The idea is to measure the vertical displacement of a beam of cold antihydrogen atoms, traveling in the gravitational field of the Earth, by the means of a moiré deflectometer. An overview of the physics goals of the experiment, of its apparatus and of the first results is presented

Production of long-lived positronium states via laser excitation to 33P level

The 3P3 state of positronium is an intermediate level suitable for producing long-lived positronium states. On one hand, it can be used in a two-step laser excitation scheme from the ground state to Rydberg levels. On the other hand, excitation of positronium to 3P3 level is a simple pathway for producing metastable 2S3 positronium atoms by spontaneous radiactive decay. In this work, experiments showing the production of such long-lived levels, using the 3P3 state as intermediate state, are presented. The characteristics of the two long-lived levels, in view of experiments of deflectometry/interferometry with positronium, are discussed

AEg̅IS latest results

The validity of the Weak Equivalence Principle (WEP) as predicted by General Relativity has been tested up to astounding precision using ordinary matter. The lack hitherto of a stable source of a probe being at the same time electrically neutral, cold and stable enough to be measured has prevented highaccuracy testing of the WEP on anti-matter. The AEg̅IS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) experiment located at CERN's AD (Antiproton Decelerator) facility aims at producing such a probe in the form of a pulsed beam of cold anti-hydrogen, and at measuring by means of a moiré deflectometer the gravitational force that Earth's mass exerts on it. Low temperature and abundance of the H̅ are paramount to attain a high precision measurement. A technique employing a charge-exchange reaction between antiprotons coming from the AD and excited positronium atoms is being developed at AEg̅IS and will be presented hereafter, alongside an overview of the experimental apparatus and the current status of the experimen