Photoproduction of Charged Pion Pairs and N*(U38)⁺⁺ in Hydrogen from 0.9 to 1.3 GEV

Citation

Hauser, Michael George (1967) Photoproduction of Charged Pion Pairs and N*(U38)⁺⁺ in Hydrogen from 0.9 to 1.3 GEV. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/YA2S-Z261. https://resolver.caltech.edu/CaltechETD:etd-09182002-112358

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The momentum spectrum and angular distribution of negative pions produced in the reaction [...] have been measured at eight incident photon energies from from 0.9 to 1.3 GeV. The reaction was produced in a liquid hydrogen target illuminated by a bremsstrahlung beam from the Caltech synchrotron. Negative pions were detected and momentum analyzed with a magnetic spectrometer employing a combination of scintillation counters and Cherenkov counters. The incident photon energy was fixed by using the technique of bremsstrahlung subtraction. The cross section for the pseudo-two-body reaction [...] was obtained by fitting the [pi(superscript-)] momentum spectrum at each angle and energy with a linear combination of a resonance term and a three-body phase space term. The angular distribution of the [pi(superscript-)] in [...] production is in good qualitative and fair quantitative agreement with predictions of the Drell (OPE) model. Gauge invariant models are in poorer agreement with the data. The total cross section for pion pair production decreases smoothly from 78.9 ? 2.9[...] at .93 GeV to 59.1 ? 5.2 [...] at 1.29 GeV, whereas the [...] part of the cross section decreases from 45.0 ? 2.4 [...] to 18.2 ? 3.5 [...] over the same range. A slight shoulder in each of these cross sections suggests formation of [nucleon resonance(1688)] as an intermediate state.

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