Experimental Study of Antiproton-Proton Annihilation Into an Electron-Positron Pair and Antiproton-Proton Annihilation Into Two γ-Rays for Incident Antiproton Momenta of 1.50 GeV/c and 2.50 GeV/c

Citation

Hartill, Donald LeRoy (1967) Experimental Study of Antiproton-Proton Annihilation Into an Electron-Positron Pair and Antiproton-Proton Annihilation Into Two γ-Rays for Incident Antiproton Momenta of 1.50 GeV/c and 2.50 GeV/c. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/76YC-XC89. https://resolver.caltech.edu/CaltechETD:etd-09172002-150943

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Upper limits for the differential cross sections at 90 [degrees] in the center of mass system for the reaction [...] have been measured for incident antiproton momenta of 1.50 geV/c and 2.50 geV/c. These limits to the 90% confidence level were [...] respectively. Two thin foil spark chambers were used to measure the laboratory angles of the electron and positron and two lead plate spark chambers were used to identify the electron and positron by their characteristic electromagnetic showers produced in such chambers. Assuming a one photon exchange mechanism for the annihilation, upper limits equal to 0.2 if [...] for the electric and magnetic form factors of the proton for time-like momentum transfers of +5.2(GeV/c)[superscript 2] and +6.8(GeV/c)[superscript 2] were obtained from the cross section limits. The differential cross section at 90 [degrees] in the center of mass system for the reaction [...] has been tentatively measured for an incident antiproton momentum of 1.50 geV/c and an upper limit for this cross section has been measured for an incident antiproton momentum of 2.50 geV/c. The differential cross section at 1.50 geV/c is based on two events giving [...]. The upper limit to a 90% confidence level at 2.50 geV/c is [...]. Upper limits for the cross sections of the process [...] for incident [..] momenta ranging from 1.00 geV/c to 2.50 geV/c have been measured. Differential cross sections for the process [...] have been tentatively measured for center of mass angles from 55[degrees] to 90[degrees] and for incident [...] momenta ranging from 1.00 geV/c to 2.50 geV/c. The results for the [...] final state could, however, contain up to 50% background from the [...] final states. The relative rates between the [...] and the [...] final states and between the [...] and the [...] final state appear to be at least a factor of two smaller than would be expected for a simple statistical model for the annihilation.

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