Michael DoserCERN | CERN · Physics Department (PH)
Michael Doser
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621
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Introduction
Michael Doser currently works at the Physics Department (EP), CERN, with a particular focus on antimatter, antihydrogen and its coupling to gravity; positronium; and antiprotonic atoms / nuclear physics / HCI’s. In addition to being the spokesperson for the AEgIS experiment at CERN, he is involved in further related projects, such as Quantum sensing for HEP and an attempt to laser-cool anionic molecules.
Please send paper requests to michael.doser@cern.ch rather than through ResearchGate.
Publications
Publications (621)
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 evide...
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 evide...
The summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,717 new measurements from 869 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetr...
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 moir\'e deflectometer before annihilating onto a position-sensitive detector, which shall determine the vertical position of the annihil...
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 thos...
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 e...
This document presents a summary of the 2023 Terrestrial Very-Long-Baseline Atom Interferometry Workshop hosted by CERN. The workshop brought together experts from around the world to discuss the exciting developments in large-scale atom interferometer (AI) prototypes and their potential for detecting ultralight dark matter and gravitational waves....
To enhance the performance of micro-patterned gaseous detectors (MPGDs) to meet the challenging requirements of future high energy physics (HEP) experiments, two-dimensional (2D) materials are attractive candidates to address the back flow of positive ions, which affects detector performance by distorting electric field lines. In this context, grap...
The study of radioisotopes as well as of highly charged ions is a very active and dynamic field. In both cases, the most sensitive probes involve species trapped in Penning or Paul traps after a series of production and separation steps that limit the types and lifetimes of species that can be investigated. We propose a novel production scheme that...
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 b...
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 posit...
The study of radioisotopes as well as of highly charged ions is a very active and dynamic field. In both cases, the most sensitive probes involve species trapped in Penning or Paul traps after a lengthy series of production and separation steps that limit the types and lifetimes of species that can be investigated. We propose a novel production sch...
The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,143 new measurements from 709 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as super...
We present a hybrid imaging/timing detector for force sensitive inertial measurements designed for measurements on positronium, the metastable bound state of an electron and a positron, but also suitable for applications involving other low intensity, low energy beams of neutral (antimatter)-atoms, such as antihydrogen. The performance of the proto...
Interaction of low-energy antiprotons with nuclear targets provided fundamental knowledge about proton and neutron densities of many nuclei through the capture process, cascade on lower electron orbits, and annihilation with the nucleon. The expelled electrons produce X-rays and with the recoil particles after annihilation, thus, a sufficient amoun...
Developments in quantum technologies in the last decades have led to a wide range of applications, but have also resulted in numerous novel approaches to explore the low energy particle physics parameter space. The potential for applications of quantum technologies to high energy particle physics endeavors has however not yet been investigated to t...
A wide range of exotic bound systems incorporating antiprotons (atoms, atomic ions, molecules or molecular ions) can be formed, in many cases simply by replacing at least one electron of a matter system by an antiproton. A number of these systems have been studied over decades, while others (in particular antihydrogen) have only recently been the o...
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 memb...
We present the commissioning of the Fast Annihilation Cryogenic Tracker detector (FACT), installed around the antihydrogen production trap inside the 1 T superconducting magnet of the AE\=gIS experiment. FACT is designed to detect pions originating from the annihilation of antiprotons. Its 794 scintillating fibers operate at 4 K and are read out by...
In this work, we discuss the possibility of inertial sensing with positronium in the $2^3 S$ metastable state for the measurement of optical dipole, relativistic and gravitational forces on a purely leptonic matter-antimatter system. Starting from the characteristics of an available $2^3 S$ beam, we estimate the time necessary to measure accelerati...
We summarize the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic...
Co-producing scientific research with those who are affected by it is an emerging phenomenon in contemporary science. This article summarizes and reflects on both the process and outcome of a novel experiment to co-develop scientific research proposals in
the field of Open Innovation in Science (OIS), wherein scholars engaged in the study of open a...
Nanochanneled silicon targets with high positron/positronium (Ps) conversion rate and efficient Ps cooling were produced. Morphological parameters of the nanochannels, such as their diameter and length, were adjusted to get a large fraction of thermalized Ps at room temperature being emitted into vacuum. Ps cooling measurements were conducted combi...
Antihydrogen atoms with K or sub-K temperature are a powerful tool to precisely probe the validity of fundamental physics laws and the design of highly sensitive experiments needs antihydrogen with controllable and well defined conditions. We present here experimental results on the production of antihydrogen in a pulsed mode in which the time when...
A main scientific goal of the ${\mathsf{AE}}\bar{{\mathsf{g}}}{\mathsf{IS}}$ experiment is the direct measurement of the Earth’s local gravitational acceleration g on antihydrogen. The Weak Equivalence Principle is a foundation of General Relativity. It has been extensively tested with ordinary matter but very little is known about the gravitationa...
The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,324 new measurements from 878 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as super...
The AE ḡ IS collaboration’s main goal is to measure the acceleration of antihydrogen ( H ¯ ) due to gravity. The experimental scheme is to form a pulsed beam whose vertical deflection is then measured by means of a moiré deflectometer [1]. Creating pulsed H ¯ is crucial since it allows a velocity measurement of the antiatoms via time of flight (ToF...
In this work, we discuss the possibility of inertial sensing with positronium in the 23S metastable state for the measurement of optical dipole, relativistic and gravitational forces on a purely leptonic matter-antimatter system. Starting from the characteristics of an available 23S beam, we estimate the time necessary to measure accelerations rang...
We propose in this White Paper a concept for a space experiment using cold atoms to search for ultra-light dark matter, and to detect gravitational waves in the frequency range between the most sensitive ranges of LISA and the terrestrial LIGO/Virgo/KAGRA/INDIGO experiments. This interdisciplinary experiment, called Atomic Experiment for Dark Matte...
In this work we present a hybrid detection method providing simultaneous imaging and timing informatiosuitable for fully monitoring positronium (Ps) formation, its laser excitation, and its spatial propagation for the first trials of pulsed antihydrogen production through a charge-exchange reaction with trapped antiprotons. This combined method, ba...
From 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 direc...
Forming a pulsed beam of cold antihydrogen using charge-exchange with Rydberg positronium (Ps) is the goal of the AEḡIS collaboration, which aims to a first gravity measurement on neutral antimatter. Recently achieved results in Ps formation and laser spectroscopy in the main AEḡIS apparatus are summarized. First, Ps has been produced using nanocha...
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 spontan...
Precision comparison experiments on bound states of matter and antimatter rely on the production of corresponding systems at low temperatures and in sufficient numbers. In this paper we propose a scheme for the pulsed production of highly excited protonium (Pn) in a Penning-Malmberg trap at low kinetic energies of tens of meV. The scheme relies on...
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...
In this article we present the production of a pulsed molecular C 2 ⁻ beam and the subsequent trapping of C 2 ⁻ in a digital ion trap (DIT). The anionic molecules were produced in a pulsed discharge valve from acetylene and carbon dioxide gas in a helium carrier. The mass spectrum of the pulsed anion beam is initially recorded using a Wien filter....
We characterized the pulsed Rydberg-positronium production inside the AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) apparatus in view of antihydrogen formation by means of a charge exchange reaction between cold antiprotons and slow Rydberg-positronium atoms. Velocity measurements on positronium along two axes in a cryogenic...
This correction provides updated acknowledgements: This work was supported by Istituto Nazionale di Fisica Nucleare; the Swiss National Science Foundation Ambizione Grant (No. 154833); a Deutsche Forschungsgemeinschaft research grant; an excellence initiative of Heidelberg University; Marie Sklodowska-Curie Innovative Training Network Fellowship of...
AE g ¯ IS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) is a CERN based experiment aiming to probe the Weak Equivalence Principle of General Relativity with antimatter by studying free fall of antihydrogen in the Earth’s gravitational field. A pulsed cold beam of antihydrogen produced by charge exchange between Rydberg positronium...
We investigate experimentally the possibility of enhancing the production of $2^3S$ positronium atoms by driving the $1^3S$-$3^3P$ and $3^3P$-$2^3S$ transitions, overcoming the natural branching ratio limitation of spontaneous decay from $3^3P$ to $2^3S$. The decay of $3^3P$ positronium atoms towards the $2^3S$ level has been effciently stimulated...
Positronium in the 23S 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, 23S positronium is produced, in the absence of an electric field, via spontaneous radiative decay from the 33P le...
The AEgIS experiment aims at producing antihydrogen (and eventually measuring the effects of the Earth gravitational field on it) with a method based on the charge exchange reaction between antiproton and Rydberg positronium. To be precise, antiprotons are delivered by the CERN Antiproton Decelerator (AD) and are trapped in a multi-ring Penning tra...
We report on recent developments in positronium work in the frame of antihydrogen production through charge exchange in the AEgIS collaboration [1]. In particular, we present a new technique based on spatially imaging a cloud of positronium by collecting the positrons emitted by photoionization. This background free diagnostic proves to be highly e...
The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,873 new measurements from 758 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as super...
Positronium in the 23S 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, 23S positronium is produced via spontaneous radiative decay from the 33P level populated with a 205 nm UV laser pu...
Producing positronium (Ps) in the metastable 23S state is of interest for various applications in fundamental physics. We report here on an experiment in which Ps atoms are produced in this long-lived state by spontaneous radiative decay of Ps excited to the 33P level manifold. The Ps cloud excitation is obtained with a UV laser pulse in an experim...
Studies of antimatter are important for understanding our universe at a fundamental level. There are still unsolved problems, such as the matter-antimatter asymmetry in the universe. The AEgIS experiment at CERN aims at measuring the gravitational fall of antihydrogen in order to determine the gravitational force on antimatter. The proposed method...
We describe a multi-step “rotating wall” compression of a mixed cold antiproton–electron non-neutral plasma in a 4.46 T Penning–Malmberg trap developed in the context of the AEḡIS experiment at CERN. Such traps are routinely used for the preparation of cold antiprotons suitable for antihydrogen production. A tenfold antiproton radius compression ha...
Producing positronium (Ps) in the metastable $2^3\text{S}$ state is of interest for various applications in fundamental physics. We report here about an experiment in which Ps atoms are produced in this long-lived state by spontaneous radiative decay of Ps excited to the $3^3\text{P}$ level manifold. The Ps cloud excitation is obtained with a UV la...
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 an...
We propose to extend laser-cooling techniques, so far only achieved for neutral molecules, to molecular anions. A detailed computational study is performed for molecules stored in Penning traps using GPU based Monte Carlo simulations. Two cooling schemes—Doppler laser cooling and photodetachment cooling—are investigated. The sympathetic cooling of...
The AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) is a CERN based experiment with the central aim to measure directly the gravitational acceleration of antihydrogen. Antihydrogen atoms will be produced via charge exchange reactions which will consist of Rydberg-excited positronium atoms sent to cooled antiprotons within an el...
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...
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, Hbar , a fundamental issue of contemporary physics, using a beam of antiatoms. Indeed, although indirect arguments have been raised against a differen...
In the sociology of small- to mid-sized (O(100) collaborators) experiments the issue of data collection and storage is sometimes felt as a residual problem for which well-established solutions are known. Still, the DAQ system can be one of the few forces that drive towards the integration of otherwise loosely coupled detector systems. As such it ma...
In this paper we report on measurements and simulations of superconducting tubes in the presence of inhomogeneous externally applied magnetic fields in a cryogenic environment. The shielding effect is studied for two different tube materials, Pb and Nb, employing Hall sensors in a tabletop experiment. The measured internal and external fields of th...
We discuss the possibility of using optical dipole forces for Sisyphus cooling of ions stored in a Penning trap by addressing the specific case of the molecular cooling candidate C2−. Using a GPU accelerated code for Penning trap simulations, which we extended to include the molecule-light interaction, we show that this scheme can decrease the time...