Wide-Angle Electron-Pair Production

Blumenthal, Rik; Ehn, D. C.; Faissler, W.; Joseph, Patricia M.; Lanzerotti, L. J.; Pipkin, F. M.; Stairs, D. G.

doi:10.1103/physrev.144.1199

Cited by 49 publications

(8 citation statements)

References 22 publications

(5 reference statements)

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“…18. This plot compares the present experiment with previously published experiments in the same mass range 10 The best zero-order fit for the present experiment is i£=0.97±0.10.…”

Section: A Validity Of Qed At Small Distancessupporting

confidence: 81%

“…9 This experiment has been performed for both electrons and muons with interesting results. The first such experiment with electrons which probed significantly small distances was performed at the Cambridge Electron Accelerator (CEA) by Blumenthal et al 10 This experiment showed a severe breakdown of theory for highmomentum transfers to the electron propagator. A subsequent experiment at Cornell, 11 while inconclusive, seemed to be in qualitative agreement, at least, with Blumenthal et al At about the same time, another CEA experiment 12 looked at wide-angle muon pairs.…”

Section: -Mamentioning

confidence: 99%

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Wide-Angle Electron-Positron Pair Production

et al. 1968

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The yield of wide-angle electron-positron pairs was measured at the Cambridge Electron Accelerator for 7+C -> e + +e~-fC to test the validity of quantum electrodynamics (QED). Symmetric and asymmetric pairs were detected simultaneously, and the interference between the Bethe-Heitler and the Compton matrix elements was measured. Both the angle and the energy of each particle of a pair were measured. One particle was measured with a magnetic spectrometer, using a differential gas Cerenkov counter and shower counters to identify the electron. The other particle of the pair was measured with an array of lead-glass Cerenkov counters. Data were taken at machine energies of 3.0 GeV and 4.14 GeV, and cover an e + e~~ invariant mass range 250-650 MeV/c 2 . This experiment agrees with QED and the results of Asbury et al., and disagrees with the results of Blumenthal et al. The measured interference term is larger than predicted by a model using a p-dominated virtual Compton term.

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“…18. This plot compares the present experiment with previously published experiments in the same mass range 10 The best zero-order fit for the present experiment is i£=0.97±0.10.…”

Section: A Validity Of Qed At Small Distancessupporting

confidence: 81%

Section: -Mamentioning

confidence: 99%

Wide-Angle Electron-Positron Pair Production

et al. 1968

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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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“…There was also another possibility [Asbury 1967]. [Weinberg 1967] in which the symmetries of the weak and electromagnetic interactions are unified but spontaneously broken by a scalar boson leading to observable states of a massless 1 The Pipkin Effect [Blumenthal 1966] was wrong because they essentially divided by zero by making the measurement for exactly symmetric pairs, where the cross-section is identically zero by gauge invariance. Their detector Monte Carlo didn't miss by much but I don't think that they realized that the cross section they were trying to measure was exactly zero.…”

Section: Cern 1965-1966mentioning

confidence: 99%

“…I then went to Harvard as an Assistant Professor (eventually Associate Professor) and continued thinking about the "force (or quantum) of µ-ness". One of the reasons that I and others went to Harvard at this time was the Cambridge Electron Accelerator (CEA)-located close to the museum with the glass flowers on Oxford Street-at which the "Pipkin Effect", the anomalous photo-production of wide angle e + e − pairs had been discovered in 1965 [Blumenthal 1966]. Emilio and I got Norman Kroll (another of my Columbia teachers, who was visiting CERN) to explain to us for the paper from the g − 2 measurement [Farley 1966] why this apparent violation of QED could only be due to a violation of gauge invariance or, as suggested by Francis Low [Low 1965], the production of an excited electron, e * → e + γ.…”

Section: Cern 1965-1966mentioning

confidence: 99%

Waiting for the W

Tannenbaum

2016

EPJ H

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Abstract. The search for the left-handed W ± bosons, the proposed quanta of the weak interaction, and the Higgs boson, which spontaneously breaks the symmetry of unification of electromagnetic and weak interactions, has driven elementary-particle physics research from the time that I entered college to the present and has led to many unexpected and exciting discoveries which revolutionized our view of subnuclear physics over that period. In this article I describe how these searches and discoveries have intertwined with my own career.

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Wide-Angle Electron-Pair Production

Cited by 49 publications

References 22 publications

Wide-Angle Electron-Positron Pair Production

Wide-Angle Electron-Positron Pair Production

Electron–positron pair production by photons: A historical overview

Waiting for the W

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