Production and detection of cold antihydrogen atoms

Physik-Institut, Zürich University, CH-8057 Zürich, Switzerland
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment (Impact Factor: 1.22). 02/2004; DOI: 10.1016/j.nima.2003.10.072


The production and observation of cold antihydrogen atoms have been recently reported by the ATHENA experiment at the CERN Antiproton Decelerator. The antiatoms were produced by mixing low-energy antiprotons and positrons in an electromagnetic trap. The antihydrogen detection is based on the observation of a characteristic signature in the annihilation of the neutral antiatoms on the trap walls by means of an imaging particle detector. An overview of the apparatus is given and the results obtained are discussed.

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    • "Instead, we rely on two other arguments: (1) As will be discussed in Section 7, the temporal-spatial characteristics of the candidate events are not compatible with mirror-trapped antiprotons. (2) By heating the positron plasma, we can shut off the production of antihydrogen [20]. When we do this, we observe essentially no trapped antihydrogen candidates (one candidate in 246 trials, as opposed to 38 candidates in 335 trials in [1]). "
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    ABSTRACT: Recently, antihydrogen atoms were trapped at CERN in a magnetic minimum (minimum-B) trap formed by superconducting octupole and mirror magnet coils. The trapped antiatoms were detected by rapidly turning off these magnets, thereby eliminating the magnetic minimum and releasing any antiatoms contained in the trap. Once released, these antiatoms quickly hit the trap wall, whereupon the positrons and antiprotons in the antiatoms annihilate. The antiproton annihilations produce easily detected signals; we used these signals to prove that we trapped antihydrogen. However, our technique could be confounded by mirror-trapped antiprotons, which would produce seemingly identical annihilation signals upon hitting the trap wall. In this paper, we discuss possible sources of mirror-trapped antiprotons and show that antihydrogen and antiprotons can be readily distinguished, often with the aid of applied electric fields, by analyzing the annihilation locations and times. We further discuss the general properties of antiproton and antihydrogen trajectories in this magnetic geometry, and reconstruct the antihydrogen energy distribution from the measured annihilation time history.
    New Journal of Physics 01/2012; 14(1):015010. DOI:10.1088/1367-2630/14/1/015010 · 3.56 Impact Factor
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    • "A hollow electron column with axial mirrors has also been considered [7]. Penning–Malmberg traps have been recently used in experiments for the production of antihydrogen [8] [9] and are being considered, with mirror fields added, for future experiments to confine the anti-hydrogen itself [10] [11]. Recently, the effects of a multipole magnetic field intended to trap the anti-hydrogen radially in such a trap have been studied experimentally [12], theoretically [13], and with simulations [14]. "
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    ABSTRACT: Computer simulation studies of the stability and transport properties of trapped non-neutral plasmas require the numerical realization of a three-dimensional plasma distribution. This paper presents a new numerical method for obtaining, without an explicit model for physical collisions in the code, a low noise three-dimensional computational equilibrium distribution. This requires both the loading of particles into an idealized distribution and the relaxation from that distribution toward an approximate numerical equilibrium. The equilibrium can then be modified through a slow change of system parameters, to generate other equilibria. In the present, work we apply this method to a UC Berkeley experiment on electron confinement in magnetic geometries appropriate for the ALPHA anti-hydrogen experiment, using the three-dimensional particle-in-cell code WARP. WARP’s guiding center mover and its option to switch between different solvers during a simulation are highly valuable because they speed up the simulations; they enable the practical use of the new technique for generating numerical equilibrium states of trapped non-neutral plasmas.
    Journal of Computational Physics 01/2006; 225(2-225):1736-1752. DOI:10.1016/ · 2.43 Impact Factor
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    ABSTRACT: Copyright: 2006 Academy of Science of South Africa Early proposals for laser propulsion were surveyed. Propulsion theory and laboratory momentum coupling experiments demonstrate how it is possible to choose the target material so as to optimize payload efficiency, with a possible order-of-magnitude reduction in launch costs. American, German and Japanese experimental ‘lightcraft’ are described as well as the Orion programme to de-orbit space debris. Marx’s seminal paper on laser-driven, relativistic space propulsion and the ensuing controversy was also discussed.
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