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Positron Production In Heavy Ion Collisions
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Book Synopsis Positron Production in Heavy Ion Collisions: Current Status of the Problem-II. by :
Download or read book Positron Production in Heavy Ion Collisions: Current Status of the Problem-II. written by and published by . This book was released on 1994 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ATLAS Positron Experiment APEX was built to study positron emission in collisions between very heavy ions. Narrow peaks were observed in such collisions at GSI, Darmstadt in the spectra of positrons and in the sum-energy spectra of electron-positron coincidences. APEX is a second-generation experiment which was specifically designed to look for the coincidence events and measure the opening angle between electrons and positrons. The first beam-induced positrons were detected using APEX in March 1993, and since then three additional runs were carried out. The first results for the collision system 238U + 181Ta show no evidence for sharp peaks in the electron-positron sum-energy spectrum. The current emphasis in this work is to obtain a complete understanding of the APEX apparatus. The atomic group is studying events involving coincidences between heavy ions and electrons. Since APEX measures the laboratory angles and energies of both electrons and heavy ions, it is possible to make an event-by-event Doppler correction of the electron spectra. These Doppler-corrected spectra show a number of lines which are attributed to conversion electrons which are emitted when a nuclear excited state decays by ejecting an inner-shell electron. The study of these spectra provide an important confirmation of the proper functioning of APEX. We are particularly concerned with the atomic physics aspects of this process. In order to understand the electron spectra, it is necessary to account for the change in binding energy of the inner-shell electrons as a function of ionic charge. We are utilizing the GRASP relativistic atomic structure program to calculate the binding energies. This information, together with the measured gamma-ray energies, allows us to calculate the expected energies of the conversion electrons which we can then compare with the observed Doppler-corrected conversion electron energies.
Book Synopsis Positron Production in Heavy Ion Collisions by : H. Backe
Download or read book Positron Production in Heavy Ion Collisions written by H. Backe and published by . This book was released on 1977 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Quantum Mechanical Theory of Positron Production in Heavy Ion Collisions with Nuclear Contact by :
Download or read book Quantum Mechanical Theory of Positron Production in Heavy Ion Collisions with Nuclear Contact written by and published by . This book was released on 1986 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A New Look at Positron Production from Heavy-ion Collisions by :
Download or read book A New Look at Positron Production from Heavy-ion Collisions written by and published by . This book was released on 1995 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new solenoidal spectrometer, designed to study the production mechanism of electrons and positrons in heavy-ion collisions, has been constructed at Argonne National Laboratory. The spectrometer has been used to study the 238U + 181Ta system at 5.95, 6.10, and 6.30 MeV/u and the 238U + 232Th system at 5.95 MeV/u. These bombarding energies cover the energy region where previous experiments have reported sharp sum-energy lines. No evidence is found for sharp peaks in the present data. For the specific case of the isolated decay of a neutral particle of mass 1.4--2.1 MeV/c2 the upper limits on cross sections obtained from the present data are significantly less than the previously reported cross sections.
Book Synopsis Electron-positron Pair Production in Ultrarelativistic Heavy Ion Collisions by : Gerhard Baur
Download or read book Electron-positron Pair Production in Ultrarelativistic Heavy Ion Collisions written by Gerhard Baur and published by . This book was released on 2007 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Systematic Studies of Positron Production in Heavy-ion Collisions Near the Coulomb Barrier by :
Download or read book Systematic Studies of Positron Production in Heavy-ion Collisions Near the Coulomb Barrier written by and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Systematic Studies of Positron Production in Heavy Ion Collisions Near the Coulomb Barrier by : Haralabos Tsertos
Download or read book Systematic Studies of Positron Production in Heavy Ion Collisions Near the Coulomb Barrier written by Haralabos Tsertos and published by . This book was released on 1991 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Influence of Strong Magnetic Fields on Positron Production in Heavy-ion Collisions by : K. Rumrich
Download or read book The Influence of Strong Magnetic Fields on Positron Production in Heavy-ion Collisions written by K. Rumrich and published by . This book was released on 1987 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Electron-positron Production in Ultra-peripheral Heavy-ion Collisions with the STAR Experiment by :
Download or read book Electron-positron Production in Ultra-peripheral Heavy-ion Collisions with the STAR Experiment written by and published by . This book was released on 2003 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a measurement of the cross-section of the purely electromagnetic production of e+e- pairs accompanied by mutual nuclear Coulomb excitation AuAu → Au*Au* + e+e-, in ultra-peripheral gold-gold collisions at RHIC at the center-of-mass collision energy of √SNN = 200 GeV per nucleon. These reactions were selected by detecting neutron emission by the excited gold ions in the Zero Degree Calorimeters. The charged tracks in the e+e- events were reconstructed with the STAR Time Projection Chamber. The detector acceptance limits the kinematical range of the observed e+e- pairs; therefore the measured cross-section is extrapolated to 4? with the use of Monte Carlo simulations. We have developed a Monte Carlo simulation for ultra-peripheral e+e- production at RHIC based on the Equivalent Photon Approximation, the lowest-order QED e+e- production cross-section by two real photons and the assumption that the mutual nuclear excitations and the e+e- production are independent (EPA model). We compare our experimental results to two models: the EPA model and a model based on full QED calculation of the e+e- production, taking the photon virtuality into account. The measured differential cross-section d?/dMinv (Minv - e+e- invariant mass) agrees well with both theoretical models. The measured differential cross-section d?/dp $tottop{perp}$ (p$tottop{perp}$- e+e- total transverse momentum) favors the full QED calculation over the EPA model.
Book Synopsis Quantum Mechanical Theory of Positron Production in Heavy Ion Collisions with Nuclear Contact by :
Download or read book Quantum Mechanical Theory of Positron Production in Heavy Ion Collisions with Nuclear Contact written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The 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/sub tot/ greater than or equal to 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 greater than or equal to 10−19 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. 25 refs., 7 figs.
Book Synopsis Theory of positron production in heavy ion collision by :
Download or read book Theory of positron production in heavy ion collision written by and published by . This book was released on 1978 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Positron Production in Heavy Ion-atom Collisions by : P. Kienle
Download or read book Positron Production in Heavy Ion-atom Collisions written by P. Kienle and published by . This book was released on 1985 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Non-perturbative Character of Electron-positron Pair Production in Relativistic Heavy Ion Collisions by : Klaus Mitverf Rumrich
Download or read book Non-perturbative Character of Electron-positron Pair Production in Relativistic Heavy Ion Collisions written by Klaus Mitverf Rumrich and published by . This book was released on 1991 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Search for Spontaneous Positron Production in Heavy Ion-Atom Collisions by : John Edward Schweppe
Download or read book A Search for Spontaneous Positron Production in Heavy Ion-Atom Collisions written by John Edward Schweppe and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Electromagnetic Production of Electron Positron Pairs in Relativistic Heavy Ion Collisions by : Kai Hencken
Download or read book Electromagnetic Production of Electron Positron Pairs in Relativistic Heavy Ion Collisions written by Kai Hencken and published by . This book was released on 1994 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Light-fronts Approach to Electron-positron Pair Production in Ultrarelativistic Heavy-ion Collisions by :
Download or read book Light-fronts Approach to Electron-positron Pair Production in Ultrarelativistic Heavy-ion Collisions written by and published by . This book was released on 1998 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors solve, in an ultrarelativistic limit, the time-dependent Dirac equation describing electron-positron pair production in peripheral relativistic heavy ion collisions using light front variables and a light-fronts representation, obtaining nonperturbative results for the free pair-creation amplitudes in the collider frame. Their result reproduces the result of second-order perturbation theory in the small charge limit while nonperturbative effects arise for realistic charges of the ions.
Book Synopsis APEX: An Experiment to Study Correlated Positron-electron Production in Heavy Ion Collisions by : Nicholas Ioannis Koloskamis
Download or read book APEX: An Experiment to Study Correlated Positron-electron Production in Heavy Ion Collisions written by Nicholas Ioannis Koloskamis and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
