747 research outputs found
Evidence For The Production Of Slow Antiprotonic Hydrogen In Vacuum
We present evidence showing how antiprotonic hydrogen, the quasistable
antiproton-proton (pbar-p) bound system, has been synthesized following the
interaction of antiprotons with the hydrogen molecular ion (H2+) in a nested
Penning trap environment. From a careful analysis of the spatial distributions
of antiproton annihilation events, evidence is presented for antiprotonic
hydrogen production with sub-eV kinetic energies in states around n=70, and
with low angular momenta. The slow antiprotonic hydrogen may be studied using
laser spectroscopic techniques.Comment: 5 pages with 4 figures. Published as Phys. Rev. Letters 97, 153401
(2006), in slightly different for
Detection of antihydrogen annihilations with a Si-micro-strip and pure CsI detector
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).Comment: 7 pages, 5 figures; Proceedings for the 8th ICATPP Conference on
Astroparticle, Particle, Space Physics, Detectors and Medical Physics
Applications (Como, Italy October 2003) to be published by World Scientific
(style file included
ATHENA -- First Production of Cold Antihydrogen and Beyond
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 cor
Cold-Antimatter Physics
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 tabl
Three Dimensional Annihilation Imaging of Antiprotons in a Penning Trap
We demonstrate three-dimensional annihilation imaging of antiprotons trapped
in a Penning trap. Exploiting unusual feature of antiparticles, we investigate
a previously unexplored regime in particle transport; the proximity of the trap
wall. Particle loss on the wall, the final step of radial transport, is
observed to be highly non-uniform, both radially and azimuthally. These
observations have considerable implications for the production and detection of
antihydrogen atoms.Comment: Invited Talk at NNP03, Workshop on Non-Neutral Plasmas, 200
Positron plasma diagnostics and temperature control for antihydrogen production
Production of antihydrogen atoms by mixing antiprotons with a cold, confined,
positron plasma depends critically on parameters such as the plasma density and
temperature. We discuss non-destructive measurements, based on a novel,
real-time analysis of excited, low-order plasma modes, that provide
comprehensive characterization of the positron plasma in the ATHENA
antihydrogen apparatus. The plasma length, radius, density, and total particle
number are obtained. Measurement and control of plasma temperature variations,
and the application to antihydrogen production experiments are discussed.Comment: 5 pages, 4 figures, to be published in Phys. Rev. Let
Maladies infectieuses - Acquis, nouveautés et perspectives en 2021 [Infectious diseases: Achievements, new Developments and Perspectives in 2021]
The substantial progresses during the last decades in the field of infectious diseases have significantly improved their prevention, diagnosis and treatment. Basic and medical sciences have efficiently dealt with the challenges of emerging infections, infectious complications related to the increasing complexity of medical practices and marked slow-down in the development of new antimicrobial agents. During the worldwide crisis related to the COVID-19 pandemic, the « medical normality » has been put in stand-by, but medical advances have fortunately continued. In the present article we present new knowledge in the field of bacterial, viral and fungal infections, which may modify hospital and ambulatory practices. Significant achievements in the field of COVID-19 will be presented in a future article
First Production and Detection of Cold Antihydrogen Atoms
The ATHENA experiment recently produced the first atoms of cold antihydrogen.
This paper gives a brief review of how this was achieved.Comment: Invited talk at Int. Conf. on Low Energy Antiprotons 2003 (LEAP03),
to be published in NIM
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