Publications (10)0 Total impact
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Article: Cold-Antimatter Physics
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ABSTRACT: The CPT theorem and the Weak Equivalence Principle are foundational principles on which the standard description of the fundamental interactions is based. The validity of such basic principles should be tested using the largest possible sample of physical systems. Cold neutral antimatter (low-energy antihydrogen atoms) could be a tool for testing the CPT symmetry with high precision and for a direct measurement of the gravitational acceleration of antimatter. After several years of experimental efforts, the production of low-energy antihydrogen through the recombination of antiprotons and positrons is a well-established experimental reality. An overview of the ATHENA experiment at CERN will be given and the main experimental results on antihydrogen formation will be reviewed. Comment: Proceedings of the XLIII International Meeting on Nuclear Physics, Bormio (Italy), March 13-20 (2005). 10 pages, 4 figures, 1 table03/2005; -
Article: Antihydrogen Formation using Cold Plasmas
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ABSTRACT: Antihydrogen, the antimatter counterpart of the hydrogen atom, can be formed by mixing cold samples of antiprotons and positrons. In 2002 the ATHENA collaboration succeeded in the first production of cold antihydrogen. By observing and imaging the annihilation products of the neutral, non‐confined, antihydrogen atoms annihilating on the walls of the trap we can observe the production in quasi‐real‐time and study the dynamics of the formation mechanism. The formation mechanism strongly influences the final state of the formed antihydrogen atoms, important for future spectroscopic comparison with hydrogen. This paper briefly summarizes the current understanding of the antihydrogen formation in ATHENA. © 2004 American Institute of PhysicsAIP Conference Proceedings. 10/2004; 730(1):13-22. -
Article: ATHENA -- First Production of Cold Antihydrogen and Beyond
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ABSTRACT: Atomic systems of antiparticles are the laboratories of choice for tests of CPT symmetry with antimatter. The ATHENA experiment was the first to report the production of copious amounts of cold antihydrogen in 2002. This article reviews some of the insights that have since been gained concerning the antihydrogen production process as well as the external and internal properties of the produced anti-atoms. Furthermore, the implications of those results on future prospects of symmetry tests with antimatter are discussed. Comment: Proc. of the Third Meeting on CPT and Lorentz Symmetry, Bloomington (Indiana), USA, August 2004, edited by V. A. Kostelecky (World Scientific, Singapore). 10 pages, 5 figures, 1 table. Author affiliations corr09/2004; -
Article: Production of Cold Antihydrogen with ATHENA for Fundamental Studies
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ABSTRACT: Since the beginning of operations of the CERN Antiproton Decelerator in July 2000, the successful deceleration, storage and manipulation of antiprotons has led to remarkable progress in the production of antimatter. The ATHENA Collaboration were the first to create and detect cold antihydrogen in 2002, and we can today produce large enough amounts of antiatoms to study their properties as well as the parameters that govern their production rate.07/2004; -
Article: Detection of antihydrogen annihilations with a Si-micro-strip and pure CsI detector
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ABSTRACT: In 2002, the ATHENA collaboration reported the creation and detection of cold (~15 K) antihydrogen atoms [1]. The observation was based on the complete reconstruction of antihydrogen annihilations, simultaneous and spatially correlated annihilations of an antiproton and a positron. Annihilation byproducts are measured with a cylindrically symmetric detector system consisting of two layers of double sided Si-micro-strip modules that are surrounded by 16 rows of 12 pure CsI crystals (13 x 17.5 x 17 mm^3). This paper gives a brief overview of the experiment, the detector system, and event reconstruction. Reference 1. M. Amoretti et al., Nature 419, 456 (2002). -
Article: A novel aerogel Cherenkov detector for DIRAC-II
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ABSTRACT: We present a new threshold Cherenkov detector using silica aerogel radiators with wavelength shifter. A duplex design was chosen to discriminate between kaons and protons in the momentum range 4–8 GeV/c for the DIRAC-II experiment at CERN. The counter consists of overlapping modules with two different refractive indices, 1.015 and 1.008, covering the low and high momentum regions, respectively. The detector performance was optimized with cosmic rays and Monte-Carlo simulations. Thereby we developed a new design of alternating layers of aerogel tiles and diffusive reflector foils coated with wavelength shifter. The best results were obtained with p-terphenyl giving 50% increase in light yield. A pyramidal shape of the aerogel radiator was also adopted for the best signal uniformity over a large sensitive area.Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. -
Article: A new aerogel Čerenkov detector with wavelength shifter
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ABSTRACT: We present a new threshold Čerenkov detector using silica aerogel radiators with wavelength shifter. A duplex design was chosen to discriminate between kaons and protons in the momentum range 4 – 8 GeV/c for the DIRAC-II experiment at CERN. The counter consists of overlapping modules with two different refractive indices, 1.015 and 1.008, covering the low and high momentum regions, respectively. The detector performance was optimized with cosmic rays and Monte-Carlo simulations. Thereby we developed a new design of alternating layers of aerogel tiles and diffusive reflector foils coated with wavelength shifter. The best results were obtained with p-terphenyl giving 50% increase in light yield. A pyramidal shape of the aerogel radiator was also adopted for the best signal uniformity over a large sensitive area.Ln. 823360(85). -
Article: A measurement of the Lorentz angle in silicon strip sensors at cryogenic temperature
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ABSTRACT: A geometric model of charge collection has been developed to measure the Lorentz angle in silicon sensors. The model relates the track inclination to the average cluster width. A Lorentz angle of 19.6 ± 0.27 +1.0 −0.5 • was measured by fitting the model to cosmic ray data collected with the double–sided silicon strip sensors of the ATHENA antihydrogen detector. These measurement corresponds to holes drifting in sensors operated at 130 K, in a 3 T magnetic field and with an average internal electric field of 1.3 kV/cm. Comparisons of charge sharing between strips and track residuals for data taken with and without magnetic field are also presented and support this measurement. -
Article: Sideband cooling of ions in a non-neutral buffer gas
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ABSTRACT: We have investigated an extension of the buffer gas cooling technique to a non-neutral buffer gas. The proposed scheme will allow efficient mass-selective centering of ions confined in a Penning trap in situations where the use of a neutral damping agent is not possible. The present paper reviews the principle of the technique and reports on evidence for sideband cooling of antiprotons in an electron gas, obtained with the ATHENA apparatus at CERN's Antiproton Decelerator facility. -
Article: Antihydrogen production temperature dependence
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ABSTRACT: Cold antihydrogen atoms were produced by mixing cold samples of antiprotons and positrons. The temperature of the positron plasma was increased by controlled radio-frequency (RF) heating, and the antihydrogen production was measured. Formation is observed to decrease with increased temperature but a simple power law scaling is not observed. Significant production is still present at room temperature.Physics Letters B.
Top co-authors
Institutions
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2004
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University of Zurich
Zürich, ZH, Switzerland
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