Anomalous Positron Peaks from Supercritical Collision Systems

Cowan, T. E.; Backe, H.; Begemann, Marianne H.; Bethge, Κ.; Bokemeyer, H.; Folger, H.; Greenberg, Jay; Grein, H.; Gruppe, A.; Kido, Yoshiaki; Klüver, M.; Schwalm, D.; Schweppe, John E.; Stiebing, K. E.; Trautmann, Ν.; Vincent, P.

doi:10.1103/physrevlett.54.1761

Cited by 301 publications

(87 citation statements)

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“…As series of papers [7] have appeared describing sharp peaks in e + and e* singles spectra, and in coincidence, at approximately 180*. The experiments in question are again those involving heavy ions at low energies.…”

Section: Anomalous Position and Electron Peaksmentioning

confidence: 99%

Probing the vacuum with highly charged ions

Böttcher

Strayer

1988

Nuclear Instruments and Methods in Physics Research Section B:

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The physics of the Fermion vacuum is briefly described, and applied to pair production in heavy ion collisions. We consider in turn low energies (< 50 MeV/nucleon), intermediate energies (< 5 GeV/nucleon), and ultrahigh energies such as would be produced in. a ring collider. At high energies, interesting questions of Lorentz and gauge invariance arise. Finally, some applications to the structure of high Z atoms are examined. DISCLAIMER

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Section: Anomalous Position and Electron Peaksmentioning

confidence: 99%

Probing the vacuum with highly charged ions

Böttcher

Strayer

1988

Nuclear Instruments and Methods in Physics Research Section B:

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“…When the first peak structures were found in positron spectra from U+U, U+Th and U+Cm collisions (Schweppe et al 1983, Clemente et al 1984, it was attempted to interpret them as spontaneous positrons emitted from a longlived nuclear composite formed In the nuclear collision as a consequence of nuclear interactions at contact (Rafelski et al 1978, Reinhardt et al 1981b, U. Mfllier et al 1983, Heinz et al 1983a. Although this explanation has subsequently been excluded by the non-observance of the predicted shift with the combined nuclear charge of the energy at which the positron line occurs (Cowan et al 1985, Tsertos et al 1985, there is still some evidence that the appearance of the line structures (which now have been observed in many more, even subcritical systems, see talks at this conference by Bokemeyer, Cowan, Kienle, KBnig, and Kozhuharov) is connected in a sensitive way with the ion beam energy which has to be chosen close to the Coulomb barrier to see the peaks. A likely explanation is that nuclear contact or nuclear interactions play at least some role in the excitation mechanism for these peak structures.…”

Section: Introductionmentioning

confidence: 99%

Quantum Mechanical Theory of Positron Production in Heavy Ion Collisions with Nuclear Contact

Heinz

1987

Physics of Strong Fields

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SEf' 2 < !98t: ABSTRACTThe interplay between atomic and nuclear interactions in heavy ion collisions with nuclear contact is studied. The general theoretical description is outlined and analyzed in a number of different limits (semiclassical approximation, DWBA, fully quantal description). The two most important physical mechanisms for generating atomic-nuclear interference, i.e., energy conservation and the introduction of additional phase shifts by nuclear reactions, are extracted. The resulting typical coupling matrix elements are analyzed for their relative importance in atomic and nuclear excitations. The description of nuclear influence on atomic excitations in terms of a classical time delay caused by nuclear reactions is reviewed, and its relationship to the underlying quantal character of the nuclear reaction is discussed.The theory is applied to spontaneous positron emission in supercritical heavy-ion collisions (Z tot £ 173). It is shown that nuclear contact can lead to line structures in the positron energy spectra if the probability distribution for nuclear delay times caused by the contact has contributions for T c 10~ sec. We explicitly evaluate a model where a pocket in the internuclear potential near the touching configuration leads to formation of nuclear molecules, and predict a resonance-like excitation function for the positron peak.Invited talk presented at NATO Advanced Summer Institute PHYSICS OF STRONG FIELDS Maratea, Italy June 1 -14, 1986 This manuscript has been authored under contract DE-AC02-76CH00016 with the U.S. Department of Energy. Accordingly, the U. S. government retains a non-exclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U. S. government purposes. DISTRIBUTION OF THIS D'JCUMtNT & UNLIMITED -1 -QUANTUM MECHANICAL THEORY OF POSITRON PRODUCTION IN HEAVY ION COLLISIONS WITH NUCLEAR CONTACT Ulrich HeinzPhysics Department Brookhaven National Laboratory Upton, New York 11973, USA ABSTRACTThe interplay between atomic and nuclear interactions in heavy ion collisions with nuclear contact is studied. The general theoretical description is outlined and analyzed in a number of different limits (semiclassical approximation, DWBA, fully quantal description). The two most important .physical mechanisms for generating atomic-nuclear interference, i.e., energy conservation and the introduction of additional phase shifts by nuclear reactions, are extracted. The resulting typical coupling matrix elements are analyzed for their relative importance in atomic and nuclear excitations. The description of nuclear influence on atomic excitations in terms of a classical time delay caused by nuclear reactions is reviewed, and its relationship to the underlying quantal character of the nuclear reaction is discussed.The theory is applied to spontaneous positron emission in supercritical heavy-ion collisions (Z tot > 173). It is shown that nuclear contact can lead to line structures in the positron energy spectra if the pro...

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“…However, since the atom with Z 137 can be created for only a short time in heavy ion collision experiment, it is difficult to observe the phenomena experimentally at the quantitive level [3,4].…”

Section: Jhep02(2016)092mentioning

confidence: 99%

Bosonization approach for “atomic collapse” in graphene

Kagimura

Onogi

2016

J. High Energ. Phys.

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Abstract:We study quantum electrodynamics with 2+1 dimensional massless Dirac fermion around a Coulomb impurity. Around a large charge with atomic number Z > 137, the QED vacuum is expected to collapse due to the strong Coulombic force. While the relativistic quantum mechanics fails to make reliable predictions for the fate of the vacuum, the heavy ion collision experiment also does not give clear understanding of this system. Recently, the "atomic collapse" resonances were observed on graphene where an artificial nuclei can be made. In this paper, we present our nonperturbative study of the vacuum structure of the quasiparticles in graphene with a charge impurity which contains multi-body effect using bosonization method.

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Anomalous Positron Peaks from Supercritical Collision Systems

Cited by 301 publications

References 10 publications

Probing the vacuum with highly charged ions

Probing the vacuum with highly charged ions

Quantum Mechanical Theory of Positron Production in Heavy Ion Collisions with Nuclear Contact

Bosonization approach for “atomic collapse” in graphene

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