Cold antihydrogen atoms are a powerful tool to probe the validity of fundamental physics laws, and it's clear that colder atoms, generally speaking, allow an increased level of precision. After the first production of cold antihydrogen (
Hˉ) in 2002, experimental efforts have progressed continuously (trapping, beam formation, spectroscopy), with competitive results already achieved by adapting to cold antiatoms techniques previously well developed for ordinary atoms. Unfortunately, the number of
Hˉ atoms that can be produced in dedicated experiments is many orders of magnitude smaller than available hydrogen atoms, which are at hand in large amount, so the development of novel techniques that allow the production of
Hˉ with well defined conditions (and possibly control its formation time and energy levels) is essential to improve the sensitivity of the methods applied by the different experiments. We present here the first experimental results concerning the production of
Hˉ in a pulsed mode where the time when 90\% of the atoms are produced is known with an uncertainty of around 250~ns. The pulsed
Hˉ source is generated by the charge-exchange reaction between Rydberg positronium atoms (
Ps) and trapped antiprotons (
pˉ), cooled and manipulated in an electromagnetic trap:
pˉ+Ps∗→Hˉ∗+e− where Rydberg positronium atoms, in turn, are produced through the implantation of a pulsed positron beam into a mesoporous silica target, and are excited by two subsequent laser pulses, the first to
n=3, the second to the needed Rydberg level (
n≃17). The pulsed production allows the control of the antihydrogen temperature, and facilitates the tunability of the Rydberg states, their de-excitation by pulsed lasers and the manipulation through electric field gradients. In fact, the production of pulsed antihydrogen is a major milestone in the AEgIS experiment to perform direct measurements of the validity of the Weak Equivalence Principle for antimatter.
Abstract The GBAR (Gravitational Behaviour of Antihydrogen at Rest) experiment at CERN has been proposed to measure the gravitational acceleration of the ultracold antihydrogen atoms. This experiment produces antihydrogen ions through interactions between antiprotons and positronium atoms. Then, antihydrogen atoms are produced for the free-fall experiment after the photo-detachment of an excess positron from the cold antihydrogen ions. The energy of the antiproton beam before the positronium target chamber will be in the range of 1–10 keV. The cross-section for the reaction between the antiprotons and positroniums depends mainly on the energy of the antiprotons. Hence, to maximize the productivity of antihydrogen ions, a sufficient number of antiprotons should be provided with well-controlled energy. In this regard, an antiproton trap is considered to accumulate and slow down antiproton beams, and cool them utilizing the electron cooling technique. This trap is designed based on the Penning-Malmberg trap, which consists of a superconducting solenoid magnet and a series of ring electrodes including high-voltage electrodes to trap antiprotons. In addition, a set of extraction electrodes and optics for beam transport are used. Each electrode has been designed and optimized using the WARP PIC simulations. In this study, the design and simulation results of each trap component are presented.
Only our ATRAP Collaboration is yet able to accumulate and store 4.2 K antiprotons and positrons. The antiprotons come initially from the new Antiproton Decelerator facility at CERN. Good control of such cold antimatter plasmas is key to aspirations to produce and study antihydrogen atoms that are cold enough to confine by their magnetic moments. In the closest approach to cold antihydrogen realized to date, the cold positrons have been used to cool antiprotons, the first time that positron cooling has ever been observed. The Penning-loffe trap, one possibility for simultaneously confining antihydrogen and the cold ingredients from which it is formed, is introduced and discussed.
The goal of the AEGIS project at CERN is to create ultra-cold antihydrogen in order to perform precise measurments on the direction and magnitude of the gravitational force felt by antimatter. In order to provide the best results it is necessary to create as much antihydrogen as possible. The method of production chosen by AEGIS is a charge exchange process between excited positronium and ultra-cold antiprotons. In order to cool the antiprotons to well below mK temperatures, the AEGIS collaboration is attempting to sympathetically cool the antiprotons using laser cooled C2 anions. In order to ensure maximum efficiency of this process it is necessary to perform precise measurments on the position and energy of the antiproton beam we are attempting to cool. Unfortunately, it is almost impossible to perform these measurments using traditional methods of beam measurments, such as inserting a thin wire into the beam axis, since the antiprotons will annihilate upon contact with regular matter. It is for this reason that it is necessary to use non-intrusive methods. One of the proposed methods is using Compton Scattered photons to obtain an energy spectrum and position map of the beam. In this paper I will discuss the theory behind this idea and the way it might be implemented within the AEGIS experiment.
Precise manipulation of matter at the atomic or molecular level has provided the path for the nanotechnological revolution impacting diverse fields such as biology, medicine, material science, quantum technologies, and electronics. At the Antiproton Decelerator facility at CERN, the AEgIS experiment utilises state-of-the-art technology to store and manipulate synthesised exotic atoms containing both matter and antimatter. Such experiments lay the groundwork for a better understanding of the fundamental interactions and hold the potential to unravel the enigma of the absence of antimatter in our universe. Additionally, the developed techniques advance the technological frontier of controlling the quantum states of ions, a critical aspect of quantum sensing and quantum computing applications.