Tag: Refereed Publication
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Be+ assisted, simultaneous confinement of more than 15000 antihydrogen atoms
Antihydrogen, the bound state of a positron and an antiproton, is the only pure anti-atomic system ever studied. It is produced exclusively in the laboratory, as it has never been observed in nature. This unique system is of great interest for searching for tentative differences between matter and antimatter. Anti-hydrogen has been routinely trapped since
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Evaluation of a caesium fountain frequency standard for antihydrogen spectroscopy
The performance of a caesium fountain frequency reference for use in precision measurements of trapped antihydrogen in the ALPHA experiment at CERN is evaluated. A description of the fountain is provided together with a characterisation of systematic effects. The impact of the magnetic environment in the Antimatter Factory, where the fountain is installed, on the
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The ALPHA-2 apparatus – facilitating experimentation with trapped antihydrogen
This paper describes the ALPHA-2 apparatus, used at the CERN Antiproton Decelerator facility for the study of trapped antihydrogen atoms. Details of both the construction and performance are included. Prominence is given to both the new and the improved features, with respect to the original ALPHA assembly, of the apparatus including a stand-alone antiproton catching
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Precision spectroscopy of the hyperfine components of the 1S–2S transition in antihydrogen
The antimatter equivalent of atomic hydrogen—antihydrogen—is an outstanding testbed for precision studies of matter–antimatter symmetry. Here we report on the simultaneous observation of both accessible hyperfine components of the 1S–2S transition in trapped antihydrogen. We determine the 2S hyperfine splitting in antihydrogen and—by comparing our results with those obtained in hydrogen—constrain the charge–parity–time-reversal symmetry-violating coefficients
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Shot-noise-induced lower temperature limit of the nonneutral plasma parallel temperature diagnostic
We develop a new algorithm to estimate the temperature of a nonneutral plasma in a Penning-Malmberg trap. The algorithm analyzes data obtained by slowly lowering a voltage that confines one end of the plasma and collecting escaping charges, and is a maximum likelihood estimator based on a physically-motivated model of the escape protocol presented in
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Adiabatic expansion cooling of antihydrogen
Magnetically trapped antihydrogen atoms can be cooled by expanding the volume of the trap in which they are confined. We report a proof-of-principle experiment in which antiatoms are deliberately released from expanded and static traps. Antiatoms escape at an average trap depth of 0 . 0 8 ± 0 . 0 1 K (statistical errors
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Measurements of Penning-Malmberg trap patch potentials and associated performance degradation
Antiprotons created by laser ionization of antihydrogen are observed to rapidly escape the ALPHA trap. Further, positron plasmas heat more quickly after the trap is illuminated by laser light for several hours. These phenomena can be caused by patch potentials—variations in the electrical potential along metal surfaces. A simple model of the effects of patch
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Observation of the effect of gravity on the motion of antimatter
Einstein’s general theory of relativity (GR), from 19151, remains the most successful description of gravitation. From the 1919 solar eclipse2 to the observation of gravitational waves3, the theory has passed many crucial experimental tests. However, the evolving concepts of dark matter and dark energy illustrate that there is much to be learned about the gravitating
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Design and performance of a novel low energy multispecies beamline for an antihydrogen experiment
The ALPHA Collaboration, based at the CERN Antiproton Decelerator, has recently implemented a novel beamline for low energy (<100 eV) positron and antiproton transport between cylindrical Penning traps that have strong axial magnetic fields. Here, we describe how a combination of semi analytical and numerical calculations was used to optimize the layout and design of
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Efficient calculations of magnetic fields of solenoids for simulations
This paper examines different models for calculating the magnetic field of solenoids. Accuracy and computation time are compared for a range of different simplified models: a current loop and a thin shell solenoid, and solenoids with finite length and thickness. There is no definitive answer to “what model is the best”, as it depends on