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The possibility of combining ultrafast laser direct writing and electrochemical etching in Si to produce a network of nanochannels connected to buried cavities was preliminary explored. The final goal is the efficient collection of positronium atoms inside the cavities for spectroscopy experiments and studies of positronium-positronium interaction. Positron Annihilation Spectroscopy measurements were performed to investigate the formation of buried cavities, their connection to nanochannels, the diffusion of positronium from the nanochannels to the cavities, and its collection inside the cavities. According to the measurements, at least around 7% of positrons implanted into the region of Si with nanochannels form positronium atoms that reach the cavities where they self-annihilate via 3γ emission.

Advanced spectroscopy experiments and new physics experiments with positronium atoms in vacuum will benefit from positronium production in an environment free of magnetic and electrostatic fields. Here, we present a novel scheme for generating a bunched positron beam. The positron bunches are prebunched before extraction from a buffer-gas trap, nonadiabatically extracted from a 700 G magnetic field, energy elevated up to 20 kV, and bunched on a target in a free field. According to simulations of the system, 60% of cooled positrons in the buffer-gas trap are extracted and focused on the target in a time spread of 2.5 ns full width tenth maximum (FWTM) and a spot of about 4 mm FWTM for positron implantation energy higher than 3 keV. These performance numbers are achieved in the same apparatus through a combination of several innovative beam manipulations.

The precise measurement of forces is one way to obtain deep insight into the fundamental interactions present in nature. In the context of neutral antimatter, the gravitational interaction is of high interest, potentially revealing new forces that violate the weak equivalence principle. Here we report on a successful extension of a tool from atom optics—the moiré deflectometer—for a measurement of the acceleration of slow antiprotons. The setup consists of two identical transmission gratings and a spatially resolving emulsion detector for antiproton annihilations. Absolute referencing of the observed antimatter pattern with a photon pattern experiencing no deflection allows the direct inference of forces present. The concept is also straightforwardly applicable to antihydrogen measurements as pursued by the AEgIS collaboration. The combination of these very different techniques from high energy and atomic physics opens a very promising route to the direct detection of the gravitational acceleration of neutral antimatter. Measuring forces on antimatter is vital to testing our understanding of fundamental physics. Towards this aim, Aghion et al. present a method to measure the deflection of antiprotons based on an atom optical tool, the moiré deflectometer, which could be extended to future antihydrogen gravity measurements.

The first successful demonstration of broadband laser cooling of positronium (Ps) atoms, obtained within the AEgIS experiment at CERN, is presented here. By employing a custom-designed pulsed alexandrite laser system at 243 nm featuring long-duration pulses of 70 ns and an energy able to saturate the 1 3 S–2 3 P transition over the broad spectrum range of 360 GHz, the temperature of a room-temperature Ps cloud was reduced from 380 K to 170 K in 70 ns. This advancement opens new avenues for precision spectroscopy, antihydrogen production, and fundamental tests with antimatter.

In the context of the Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEgIS) located at CERN, positron-positronium converters with a high positron-positronium conversion efficiency have been designed in both reflection and transmission geometries. The converters utilize nanochanneled silicon target technology with positron conversion efficiencies up to around 50% and around 16%, at room temperature and in the absence of magnetic fields, for reflection and transmission respectively. The positron-positronium converters allow for the pulsed production of antihydrogen ( H ¯ ) within the AEgIS experiment. This paper discusses the use of a pulsed H ¯ beam in a moiré deflectometer to perform a precise gravitational measurement on H ¯ at AEgIS. This work describes the principles and technical details of the current design of a moiré deflectometer using the pulsed H ¯ beam. The main goal of this work is to summarize the ongoing project of adding the described moiré deflectometer to the AEgIS experiment to further their efforts toward probing the material dependence of gravity and testing the weak equivalence principle (WEP).

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¯ + P s * → 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].

The AEgIS experiment located at the Antiproton Decelerator at CERN aims to measure the gravitational fall of a cold antihydrogen pulsed beam. The precise observation of the antiatoms in the Earth gravitational field requires a controlled production and manipulation of antihydrogen. The neutral antimatter is obtained via a charge exchange reaction between a cold plasma of antiprotons from ELENA decelerator and a pulse of Rydberg positronium atoms. The current custom electronics designed to operate the 5 and 1 T Penning traps are going to be replaced by a control system based on the ARTIQ & Sinara open hardware and software ecosystem. This solution is present in many atomic, molecular and optical physics experiments and devices such as quantum computers. We report the status of the implementation as well as the main features of the new control system.

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'.

A powerful and robust control system is a crucial, often neglected, pillar of any modern, complex physics experiment that requires the management of a multitude of different devices and their precise time synchronisation. The AEḡIS collaboration presents CIRCUS, a novel, autonomous control system optimised for time-critical experiments such as those at CERN’s Antiproton Decelerator and, more broadly, in atomic and quantum physics research. Its setup is based on Sinara/ARTIQ and TALOS, integrating the ALPACA analysis pipeline, the last two developed entirely in AEḡIS. It is suitable for strict synchronicity requirements and repeatable, automated operation of experiments, culminating in autonomous parameter optimisation via feedback from real-time data analysis. CIRCUS has been successfully deployed and tested in AEḡIS; being experiment-agnostic and released open-source, other experiments can leverage its capabilities.

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.