Photoproduction of Wide-Angle Electron-Positron Pairs at High Energies

Asbury, J.G.; Bertram, William K.; Becker, U.; Joos, P.; Rohde, M.; Smith, A. J. S.; Friedlander, Sheldon K.; Jordan, C. L.; Ting, Samuel C.C.

doi:10.1103/physrev.161.1344

Cited by 21 publications

(9 citation statements)

References 10 publications

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“…Some wide-angle electron-positron pair production measurements in C in the region 1 to 2 GeV were made at DESY by Blumenthal et al (1966), Asbury et al (1967) and Alvenslaben et al (1968). More recently, some other measurements have been made at intermediate and extreme high photon energies for pair production aspects other than cross section data.…”

Section: Pair and Triplet Measurements: A Brief History And Surveymentioning

confidence: 99%

Electron–positron pair production by photons: A historical overview

Hubbell

2006

Radiation Physics and Chemistry

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This account briefly traces the growth of our theoretical and experimental knowledge of electron-positron pair production by photons, from the prediction of the positron by Dirac [1928a can interact with the Coulomb field of an atomic nucleus to be transformed into an electron-positron pair, the probability increasing with increasing photon energy, up to a plateau at high energies, and increasing with increasing atomic number approximately as the square of the nuclear charge (proton number). This interaction can also take place in the field of an atomic electron, for photons of energy in excess of 4m e c 2 (2.044 MeV), in which case the process is called triplet production due to the track of the recoiling atomic electron adding to the tracks of the created electron-positron pair. The last systematic computations and tabulations of pair and triplet cross sections, which are the predominant contributions to the photon mass attenuation coefficient for photon energies 10 MeV and higher, were those of Hubbell et al. [Pair, triplet, and total atomic cross sections (and mass attenuation coefficients) for 1 MeV-100 GeV photons in elements Z ¼ 1-100. J. Phys. Chem. Ref. Data 9, 1023Data 9, -1147, from threshold (1.022 MeV) up to 100 GeV, for all elements Z ¼ 1-100. These computations required some ad hoc bridging functions between the available low-energy and high-energy theoretical models. Recently (1979Recently ( -2001, Sud and collaborators have developed some new approaches including using distorted wave Born approximation (DWBA) theory to compute pair production cross sections in the intermediate energy region (5.0-10.0 MeV) on a firmer theoretical basis. These and other recent developments, and their possible implications for improved computations of pair and triplet cross sections, are discussed. Published by Elsevier Ltd.

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Section: Pair and Triplet Measurements: A Brief History And Surveymentioning

confidence: 99%

Electron–positron pair production by photons: A historical overview

Hubbell

2006

Radiation Physics and Chemistry

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“…p 00 Cp (2) As shown in Fig. 2 There were a few typographical errors in this paper: On p. 1026, in the equation in column one, i^-(k) should be F^k) =ir^ j(k).…”

Section: Km T(p^ee)=m T(u)-~ee) + M T(cp~»ee)mentioning

confidence: 99%

“…2 To first order, both the Bethe-Heitler (BH) and Compton diagrams contribute to the reaction y + C-~C+e + + e (4)…”

Section: Br = T(mentioning

confidence: 99%

Leptonic Decays of Vector Mesons: the Branching Ratio of the Electron-Positron Decay Mode of the Phi Meson

et al. 1968

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An experiment designed to measure the branching ratio of the phi meson to e e~~ was performed at DESY by measuring phi production and phi decay to e^e"" with the same apparatus. The results of this experiment, based on 10 4 cp-*K + K"-events and 41 (p-+e + eevents on carbon, yield a branching ratio of (2.9±0.8)xl0~4. with various theoretical predictions. This result is comparedAt the DESY 7.5-GeV electron synchrotron, experiments are in progress to investigate the leptonic decays of vector mesons. 1 We report here a measurement of the branching ratio

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“…3 The separation of K + K~ from the background of 77+77" and e*e' was accomplished by four large-aperture threshold Cherenkov counters and two lead-Lucite shower counters. Protons were rejected by time-offlight techniques.…”

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confidence: 99%

Photoproduction and Forbidden Decays ofϕMesons

et al. 1972

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in which all low-lying hadron states have zero isospin. Below the threshold for production of states with nonzero isospin, only the isoscalar component of the electromagnetic current would be observed. This isoscalar probe would not distinguish between proton and neutron. Low-energy experiments would indicate a deuteron made of two identical spin-i nucleons, each with charge 2, and peculiar statistics allowing two identical particles in a symmetric state. Only after the excitation of the isovector states of the two-nucleon system would it be clear that there was a hidden degree of freedom and two kinds of nucleons with integral charges. 8 This result is expected, since the three-triplet model was constructed to give all the Gell-Mann-Zweig properties of observed particles. Given a set of hadron states in the conventional quark model, corresponding hadron states in the three-triplet model can be constructed for which the matrix elements of the electromagnetic current operator are identical to those of the quark model.Photoproduction of (p mesons from hydrogen and carbon was studied at 5.2 GeV by observing ) -y -*p -2TT with corresponding partial widths r w-*2ir~1 0 keV, r^-^2 7r «0.6 keV. Our previously measured width r w -27r is a factor of 10 larger than the simple predicted value. It is of interest to see if the cp^2ir width is also correspondingly larger.The K + K" pairs were detected by a double-arm magnetic spectrometer which has been described in a previous publication. 3 The separation of K + K~ from the backgrou...

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Photoproduction of Wide-Angle Electron-Positron Pairs at High Energies

Cited by 21 publications

References 10 publications

Electron–positron pair production by photons: A historical overview

Electron–positron pair production by photons: A historical overview

Leptonic Decays of Vector Mesons: the Branching Ratio of the Electron-Positron Decay Mode of the Phi Meson

Photoproduction and Forbidden Decays ofϕMesons

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