We report on a Q-switched alexandrite based- 100 ns long pulse duration ultra-violet laser system. The central wavelength of the fundamental pulse is set by a Volume Bragg Grating in reflection and can be tuned between 728 nm and 742 nm. The spectral bandwidth is- 130 GHz. This laser system was designed in view of Doppler cooling of a cloud of a near room temperature positronium by strongly saturating the 1 3 S- 2 3 P transition. In addition, we report on the development of a KD*P Pockels cell driver designed to both Q-switch the cavity and induce a sharp falling edge of the laser pulse so that the end of the positronium-laser interaction time can be controlled with nanosecond precision.

We report on laser cooling of a large fraction of positronium (Ps) in free flight by strongly saturating the 13S−23P transition with a broadband, long-pulsed 243 nm alexandrite laser. The ground state Ps cloud is produced in a magnetic and electric field-free environment. We observe two different laser-induced effects. The first effect is an increase in the number of atoms in the ground state after the time Ps has spent in the long-lived 23P states. The second effect is one-dimensional Doppler cooling of Ps, reducing the cloud’s temperature from 380(20) to 170(20) K. We demonstrate a 58(9)% increase in the fraction of Ps atoms with v1D<3.7×104 ms−1. Published by the American Physical Society 2024

Modern physics experiments are frequently very complex, relying on multiple simultaneous events to happen in order to obtain the desired result. The experiment control system plays a central role in orchestrating the measurement setup: However, its development is often treated as secondary with respect to the hardware, its importance becoming evident only during the operational phase. Therefore, the AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) collaboration has created a framework for easily coding control systems, specifically targeting atomic, quantum, and antimatter experiments. This framework, called Total Automation of LabVIEW Operations for Science (TALOS), unifies all the machines of the experiment in a single entity, thus enabling complex high-level decisions to be taken, and it is constituted by separate modules, called MicroServices, that run concurrently and asynchronously. This enhances the stability and reproducibility of the system while allowing for continuous integration and testing while the control system is running. The system demonstrated high stability and reproducibility, running completely unsupervised during the night and weekends of the data-taking campaigns. The results demonstrate the suitability of TALOS to manage an entire physics experiment in full autonomy: being open-source, experiments other than the AEgIS experiment can benefit from it.

The primary goal of the AEgIS experiment is to precisely measure the free fall of antihydrogen within Earth's gravitational field. To this end, a cold  50K antihydrogen beam has to pass through two grids forming a moiré deflectometer before annihilating onto a position-sensitive detector, which shall determine the vertical position of the annihilation vertex relative to the grids with micrometric accuracy. Here we introduce a vertexing detector based on a modified mobile camera sensor and experimentally demonstrate that it can measure the position of antiproton annihilations with an accuracy of 0.62^+0.40_-0.22μ m, which represents a 35-fold improvement over the previous state-of-the-art for real-time antiproton vertexing. Importantly, these antiproton detection methods are directly applicable to antihydrogen. Moreover, the sensitivity to light of the sensor enables the in-situ calibration of the moiré deflectometer, significantly reducing systematic errors. This sensor emerges as a breakthrough technology for achieving the scientific goals and has been selected as the basis for the development of a large-area detector for conducting antihydrogen gravity measurements.

Low-temperature antihydrogen atoms are an effective tool to probe the validity of the fundamental laws of Physics, for example the Weak Equivalence Principle (WEP) for antimatter, and -generally speaking- it is obvious that colder atoms will increase the level of precision. After the first production of cold antihydrogen in 2002 [1], experimental efforts have substantially progressed, with really competitive results already reached by adapting to cold antiatoms some well-known techniques pre- viously developed for ordinary atoms. Unfortunately, the number of antihydrogen atoms that can be produced in dedicated experiments is many orders of magnitude smaller than of hydrogen atoms, so the development of novel techniques to enhance the production of antihydrogen with well defined (and possibly controlled) conditions is essential to improve the sensitivity. We present here some experimental results achieved by the AEgIS Collaboration, based at the CERN AD (Antiproton Decelerator) on the production of antihydrogen in a pulsed mode where the production time of 90% of atoms is known with an uncertainty of ~ 250 ns [2]. The pulsed antihydrogen source is generated by the charge-exchange reaction between Rydberg positronium (Ps*) and an antiproton (p¯): p¯ + Ps* → H¯* + e−, where Ps* is produced via the implantation of a pulsed positron beam into a mesoporous silica target, and excited by two consecutive laser pulses, and antiprotons are trapped, cooled and manipulated in Penning-Malmberg traps. The pulsed production (which is a major milestone for AEgIS) makes it possible to select the antihydrogen axial temperature and opens the door for the tuning of the antihydrogen Rydberg states, their de-excitation by pulsed lasers and the manipulation through electric field gradients. In this paper, we present the results achieved by AEgIS in 2018, just before the Long Shutdown 2 (LS2), as well as some of the ongoing improvements to the system, aimed at exploiting the lower energy antiproton beam from ELENA [3].

Positronium beam formation and manipulation are required in several fundamental experiments. Efficient positron/positronium conversion in transmission configuration would offer important geometrical advantages over the reflection one for these applications. A novel type of transmission positron/positronium converters, which consists of silicon membranes with pass-through nanochannels, was produced and tested. The amount of forward emitted positronium was studied as a function of the thickness of the membranes and the nanochannel size. A maximum of, at least, (16 +/- 4)% of positrons implanted in (3.5 +/- 0.5)-mu m-thick membrane with a nanochannel size of 5-8 nm were found to be forward emitted as positronium. A similar maximum amount of, at least, (16 +/- 5)%, was found to be emitted from a membrane (7.7 +/- 1.3)-mu m-thick with a nanochannel size of 7-10 nm. A preliminary evaluation shows that the maximum amount of forward emitted positronium with the entire kinetic energy distribution below 1 eV is, at least, 9% of the positrons implanted in the (3.5 +/- 0.5)-mu m-thick membrane.

The primary goal of the AEgIS collaboration at CERN is to measure the gravitational acceleration on neutral antimatter. Positronium (Ps), the bound state of an electron and a positron, is a suitable candidate for a force-sensitive inertial measurement by means of deflectometry/interferometry. In order to conduct such an experiment, the impact position and time of arrival of Ps atoms at the detector must be detected simultaneously. The detection of a low-velocity Ps beam with a spatial resolution of (88 ± 5) μm was previously demonstrated [1]. Based on the methodology employed in [1] and [2], a hybrid imaging/timing detector with increased spatial resolution of about 10 μm was developed. The performance of a prototype was tested with a positron beam. The concept of the detector and first results are presented.

G. Kornakov, M. Auzins, B. Bergmann, P. Burian, G. Bonomi, R. S. Brusa, f ,g A. Camper, R. Caravita, f ,g F. Castelli, j P. Cheinet, R. Ciuryło, D. Comparat, G. Consolati, M. Doser, H. Gjersdal, L. T. Glöggler, Ł. Graczykowski, F. Guatieri, f ,g S. Haider, S. Huck, M. Janik, G. Kasprowicz, G. Khatri, Ł. Kłosowski, L. Lappo, C. Malbrunot, S. Mariazzi, f G. Nebbia, L. Nowak, D. Nowicka, E. Oswald, D. Pagano, L. Penasa, f ,g V. Petracek, M. Piwiński, S. Pospisil, L. Povolo, f F. Prelz, S. Rangwala, B. Rienäcker, A. Rotondi, O. M. Røhne, H. Sandaker, I. Stekl, D. Tefelski, I. C. Tietje, M. Volponi, f ,g,n T. Wolz, M. Zawada, C. Zimmer and N. Zurlo

In this work, we show recent measurements of 2(3)S long-lived positronium production via spontaneous decay from the 3(3)P level. The possibility to tune the velocity of the 2(3)S positronium, excited following this scheme, is presented. In the light of these results, we discuss the use of the 3(3)P -> 2(3)S transition to realize a monochromatic pulsed 2(3)S positronium beam with low angular divergence. Preliminary tests of 2(3)S beam production are presented. The possibility to overcome the natural 3(3)P -> 2(3)S branching ratio via stimulated emission, and thus increasing the intensity of the 2(3)S source, is also shown. A position-sensitive detector for a pulsed beam of positronium, with spatial resolution of approximate to 90 mu m, is finally described in view of its possible application for the spatial characterization of the 2(3)S beam.

The AE (g) over bar IS experiment at CERN's Antiproton Decelerator is set up to precisely measure the gravitational interaction between matter and antimatter. For this purpose, antihydrogen will be formed from cold antiprotons and positronium, the hydrogen-like bound state of an electron and a positron. Subsequently, the free-fall acceleration of a cold horizontal beam of antihydrogen will be measured by a deflectometer. The present status, recent experimental progress and the medium-term plan of the AE (g) over bar IS experiment are presented.

Positronium (Ps), the unstable bound state of electron and positron, is a valuable system for neutral antimatter spectroscopic studies and for antihydrogen production. Forming a pulsed beam cold antihydrogen using charge-exchange with the Rydberg Ps is the goal of the AEgIS Collaboration, which aims to measure gravity on neutral antimatter. Recent results achieved in producing, manipulating and studying Ps are summarized. Ps has been first produced with mesoporous silica targets in a reflection geometry. Spectroscopy of Ps n = 3 state has been conducted, yielding as a byproduct an independent estimate of the produced Ps temperature. Efficient laser excitation to the Rydberg levels was then achieved, validating the proof-of-concept of AEgIS. Subsequently, production of Ps from a new class of transmission targets was also achieved, opening the possibility for future experiments.

In this work a characterization study of forward emission from a thin, meso-structured silica positron/positronium (Ps) converter following implantation of positrons in light of possible antihydrogen production is presented. The target consisted of a ∼1μm thick ultraporous silica film e-gun evaporated onto a 20nm carbon foil. The Ps formation and emission was studied via Single Shot Positron Annihilation Lifetime Spectroscopy measurements after implantation of pulses with 3-4·107 positrons and 10ns temporal width. The forward emission of implanted positrons and secondary electrons was investigated with a micro-channel plate – phosphor screen assembly, connected either to a CCD camera for imaging of the impinging particles, or to a fast photomultiplier tube to extract information about their time of flight. The maximum Ps formation fraction was estimated to be ∼10%. At least 10% of the positrons implanted with an energy of 3.3keV are forward-emitted with a scattering angle smaller than 50° and maximum kinetic energy of 1.2keV. At least 0.1–0.2 secondary electrons per implanted positron were also found to be forward-emitted with a kinetic energy of a few eV. The possible application of this kind of positron/positronium converter for antihydrogen production is discussed.

S. Aghion,1,2 C. Amsler,3 A. Ariga,3 T. Ariga,3 G. Bonomi,4,5 P. Bräunig,6 J. Bremer,7 R. S. Brusa,8,9 L. Cabaret,10 M. Caccia,2,11 R. Caravita,12,13 F. Castelli,2,14 G. Cerchiari,15 K. Chlouba,16 S. Cialdi,2,14 D. Comparat,10 G. Consolati,1,2 A. Demetrio,6 L. Di Noto,12,13 M. Doser,7 A. Dudarev,7 A. Ereditato,3 C. Evans,1,2 R. Ferragut,1,2 J. Fesel,7 A. Fontana,5 O. K. Forslund,7 S. Gerber,7 M. Giammarchi,2,3 A. Gligorova,17 S. Gninenko,18 F. Guatieri,8,9 S. Haider,7 H. Holmestad,19 T. Huse,19 I. L. Jernelv,7 E. Jordan,15 A. Kellerbauer,15 M. Kimura,3 T. Koettig,7 D. Krasnicky,12,13 V. Lagomarsino,12,13 P. Lansonneur,23 P. Lebrun,23 S. Lehner,20 J. Liberadzka,7 C. Malbrunot,7,20 S. Mariazzi,20,* L. Marx,7 V. Matveev,18,21 Z. Mazzotta,2,14 G. Nebbia,22 P. Nedelec,23 M. Oberthaler,6 N. Pacifico,17 D. Pagano,4,5 L. Penasa,8,9 V. Petracek,16 C. Pistillo,3 F. Prelz,2 M. Prevedelli,24 L. Ravelli,8,9 L. Resch,7 B. Rienäcker,7 O. M. Røhne,19 A. Rotondi,5,25 M. Sacerdoti,2,14 H. Sandaker,19 R. Santoro,2,11 P. Scampoli,3,26 L. Smestad,7,27 F. Sorrentino,12,13 M. Spacek,16 J. Storey,3 I. M. Strojek,16 G. Testera,13 I. Tietje,7 S. Vamosi,20 E. Widmann,20 P. Yzombard,10 J. Zmeskal,20 and N. Zurlo5,28 (AEgIS Collaboration) 1Politecnico of Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy, 2Istituto Nazionale di Fisica Nucleare Milano, via Celoria 16, 20133 Milano, Italy 3Laboratory for High Energy Physics, Albert Einstein Center for Fundamental Physics,

The present status of the AEGIS experiment at CERN (AD-06), on the way of forming anti-hydrogen for a first gravity measurement, is reviewed. Recent results in trapping and cooling positrons and antiprotons in the main electromagnetic traps are presented, including the storage time measurement obtained during the 2014 run with antiprotons, the observation of centrifugal separation of a mixed antiproton/electron plasma and positron accumulation and transfer results obtained during 2015.

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