Showing papers by "Gorm Bruun Andresen published in 2011"
Aarhus University1, Simon Fraser University2, University of California, Berkeley3, Swansea University4, CERN5, Federal University of Rio de Janeiro6, University of Calgary7, TRIUMF8, University of British Columbia9, University of Tokyo10, Stockholm University11, York University12, University of Liverpool13, Auburn University14
TL;DR: Antihydrogen has been created, trapped and stored for 1,000 years and the improved holding time means that we now have access to the ground state of antimatter, long enough to test whether matter and antimatter obey the same physical laws as mentioned in this paper.
Abstract: Antihydrogen has been created, trapped and stored for 1,000 s. The improved holding time means that we now have access to the ground state of antimatter—long enough to test whether matter and antimatter obey the same physical laws.
241 citations
TL;DR: It is demonstrated that controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive produces Antihydrogen and starts atomic recombination.
Abstract: We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination.
59 citations
TL;DR: In this article, the authors present the results of an experiment to search for trapped anti-hydrogen atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator.
45 citations
TL;DR: The first detailed measurements of such states in an electron-antiproton plasma are reported, and the first observations of the separation dynamics in any centrifugally separated system are made.
Abstract: Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments.
36 citations
01 Jan 2011
TL;DR: In this paper, the authors investigate the interplay between storage and balancing in a future, highly renewable European power system, and show that the synergy between storing and balancing is significant, and that even a small but efficient storage reduces balancing needs significantly due to its influence on intra-day mismatches.
Abstract: We model the mismatches between wind and solar power generation and load for any combination of wind and solar power generation and for any level of penetration of these. The approach is based on high-resolution tempo-spatial meteorological and electricity load data. Based on these mismatch time series, we analyze the balancing needs and the effect of introducing both large and smaller scale energy storages. We investigate the interplay between storage and balancing in a future, highly renewable European power system, and we show that the synergy between storage and balancing is significant. Even a small but efficient storage reduces balancing needs significantly due to its influence on intra-day mismatches. We show that a combination of a smaller, efficient storage in combination with a larger, lowefficiency hydrogen storage and hydro balancing is feasible with an excess generation of only 3‰ at an optimal wind-solar mix of around 60-40.
3 citations
Swansea University1, Aarhus University2, Simon Fraser University3, University of California, Berkeley4, Federal University of Rio de Janeiro5, University of Calgary6, TRIUMF7, University of British Columbia8, University of Tokyo9, Stockholm University10, York University11, University of Liverpool12, Auburn University13
TL;DR: In this article, the authors reviewed the sources of positrons and antiprotons that are currently used for the formation of antihydrogen with low kinetic energies, mostly in the context of the ALPHA collaboration and its predecessor ATHENA.
Abstract: Sources of positrons and antiprotons that are currently used for the formation of antihydrogen with low kinetic energies are reviewed, mostly in the context of the ALPHA collaboration and its predecessor ATHENA. The experiments were undertaken at the Antiproton Decelerator facility, which is located at CERN. Operations performed on the clouds of antiparticles to facilitate their mixing to produce antihydrogen are described. These include accumulation, cooling and manipulation. The formation of antihydrogen and some of the characteristics of the anti-atoms that are created are discussed. Prospects for trapping antihydrogen in a magnetic minimum trap, as envisaged by the ALPHA collaboration, are reviewed.
2 citations
01 Jan 2011
TL;DR: In this article, the authors introduce a top-down stylized model to analyze the impact of a transition to a European power system based only on wind and solar power, and find that wind power generation can replace conventional power generation and power capacity to a large degree if power transmission across the continent is made possible.
Abstract: We introduce a top-down stylized model to analyze the impact of a transition to a European power system based only on wind and solar power. Wind and solar power generation is calculated from high-resolution weather data and based on the country specific electricity demand alone, we introduce a model of the conventional power system that facilitates simple spatio-temporal modeling of its macroscopic behavior without direct reference to the underlying technological, economical, and political development in the system. Using this model, we find that wind and solar power generation can replace conventional power generation and power capacity to a large degree if power transmission across the continent is made possible.
2 citations
TL;DR: The ALPHA anti-hydrogen trap at CERN's Antiproton Decelerator has been used to measure the antiproton temperature and a new technique to cool them to below 10 K as mentioned in this paper.
Abstract: Spectroscopy of antihydrogen has the potential to yield high-precision tests of the CPT theorem and shed light on the matter-antimatter imbalance in the Universe. The ALPHA antihydrogen trap at CERN's Antiproton Decelerator aims to prepare a sample of antihydrogen atoms confined in an octupole-based Ioffe trap and to measure the frequency of several atomic transitions. We describe our techniques to directly measure the antiproton temperature and a new technique to cool them to below 10 K. We also show how our unique position-sensitive annihilation detector provides us with a highly sensitive method of identifying antiproton annihilations and effectively rejecting the cosmic-ray background.
Swansea University1, Aarhus University2, Simon Fraser University3, University of California, Berkeley4, Federal University of Rio de Janeiro5, University of Calgary6, TRIUMF7, University of British Columbia8, University of Tokyo9, Stockholm University10, York University11, University of Liverpool12, Auburn University13
TL;DR: The ALPHA anti-hydrogen trap at CERN's Antiproton Decelerator has been used to measure the antiproton temperature and a new technique to cool them to below 10 K as discussed by the authors.
Abstract: Spectroscopy of antihydrogen has the potential to yield high-precision tests of the CPT theorem and shed light on the matter-antimatter imbalance in the Universe. The ALPHA antihydrogen trap at CERN’s Antiproton Decelerator aims to prepare a sample of antihydrogen atoms confined in an octupole-based Ioffe trap and to measure the frequency of several atomic transitions. We describe our techniques to directly measure the antiproton temperature and a new technique to cool them to below 10 K. We also show how our unique position-sensitive annihilation detector provides us with a highly sensitive method of identifying antiproton annihilations and effectively rejecting the cosmic-ray background.
TL;DR: Antihydrogen spectroscopy offers precise tests of the symmetry of matter and antimatter, and can possibly offer new insights into the baryon asymmetry of the universe as mentioned in this paper.
Abstract: Antihydrogen spectroscopy promises precise tests of the symmetry of matter and antimatter, and can possibly offer new insights into the baryon asymmetry of the universe. Antihydrogen is, however, d...