104 research outputs found
One-Particle Measurement of the Antiproton Magnetic Moment
\DeclareRobustCommand{\pbar}{\HepAntiParticle{p}{}{}\xspace}
\DeclareRobustCommand{\p}{\HepParticle{p}{}{}\xspace}
\DeclareRobustCommand{\mup}{{}{}\xspace}
\DeclareRobustCommand{\mupbar}{\mu_{\pbar}{}{}\xspace}
\DeclareRobustCommand{\muN}{{}{}\xspace
For the first time a single trapped \pbar is used to measure the \pbar
magnetic moment {\bm\mu}_{\pbar}. The moment {\bm\mu}_{\pbar} = \mu_{\pbar}
{\bm S}/(\hbar/2) is given in terms of its spin and the nuclear
magneton (\muN) by \mu_{\pbar}/\mu_N = -2.792\,845 \pm 0.000\,012. The 4.4
parts per million (ppm) uncertainty is 680 times smaller than previously
realized. Comparing to the proton moment measured using the same method and
trap electrodes gives \mu_{\pbar}/\mu_p = -1.000\,000 \pm 0.000\,005 to 5
ppm, for a proton moment ,
consistent with the prediction of the CPT theorem.Comment: 4 pages, 4 figures. arXiv admin note: substantial text overlap with
arXiv:1201.303
Trapped Antihydrogen in Its Ground State
Antihydrogen atoms are confined in an Ioffe trap for 15 to 1000 seconds --
long enough to ensure that they reach their ground state. Though
reproducibility challenges remain in making large numbers of cold antiprotons
and positrons interact, 5 +/- 1 simultaneously-confined ground state atoms are
produced and observed on average, substantially more than previously reported.
Increases in the number of simultaneously trapped antithydrogen atoms are
critical if laser-cooling of trapped antihydrogen is to be demonstrated, and
spectroscopic studies at interesting levels of precision are to be carried out
A semiconductor laser system for the production of antihydrogen
Laser-controlled charge exchange is a promising method for producing cold antihydrogen. Caesium atoms in Rydberg states collide with positrons and create positronium. These positronium atoms then interact with antiprotons, forming antihydrogen. Las er excitation of the caesium atoms is essential to increase the cross section of the charge-exchange collisions. This method was demonstrated in 2004 by the ATRAP collaboration by using an available copper vapour laser. For a second generation of charge-e xchange experiments we have designed a new semiconductor laser system that features several improvements compared to the copper vapour laser. We describe this new laser system and show the results from the excitation of caesium atoms to Rydberg states wit hin the strong magnetic fields in the ATRAP apparatus
Three Body Bound State in Non-Commutative Space
The Bethe-Salpeter equation in non-commutative QED (NCQED) is considered for
three-body bound state. We study the non-relativistic limit of this equation in
the instantaneous approximation and derive the corresponding Schr\"{o}dinger
equation in non-commutative space. It is shown that the experimental data for
Helium atom puts an upper bound on the magnitude of the parameter of
non-commutativity, .Comment: 10 pages, 3 figures, to appear in Phys. Rev.
Single-component plasma of photoelectrons ATRAP Collaboration
Abstract Ten-nanosecond pulses of photoelectrons liberated by intense UV laser pulses from a thin gold layer are captured into a single-component plasma that is ideally suited to cool antiprotons (p) for antihydrogen (H) production. Up to a billion electrons are accumulated using a series of laser pulses, more than are needed for efficientp cooling in the large traps now being used for loadingp forH production. The method is demonstrated within an enclosed vacuum space that is entirely at 4 K, and is thus compatible with the exceptional cryogenic vacuum that is desirable for the long-term storage of antihydrogen. The pitfalls of other electron accumulation methods are entirely avoided, including the particle heating and declining efficiency of field emission point loading, and the heat load and contamination of thermionic emission methods. © 2007 Elsevier B.V. All rights reserved. The quantum explanation of the surprising photoelectrons that light liberates from a metal surface was one of the early successes of a quantum view of the world Here we report the first use of short pulses of photoelectrons to quickly and robustly accumulate the large number of electrons needed to collisionally cool antiprotons (p)-a crucial step for slowH production [9-11]. CERN's unique Antiproton Decelerator facility (AD) delivers 5-MeVp. These are slowed to the keV energies at which they can be trapped-either i
The influence of host genetics on erythrocytes and malaria infection: is there therapeutic potential?
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