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Title:A-2 meson production in pi-minus proton interactions at five BeV
Author(s):Schafer, Elton Duane
Doctoral Committee Chair(s):Ascoli, Giulio
Department / Program:Physics
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):A2 mesons
hydrogen bubble chamber
incident pions
Abstract:A study of the A2 meson has been made on data obtained from pi p interactions at 5 BeV/c in the 72"Alvarez liquid hydrogen bubble chamber. The p pi decay mode in the 4-constraint, p pi+ pi- pi- final state is treated in detail. Fit.s to the 3TI invariant mass spectrum yield a central mass value and width of 1.296±.008 and .l05±.035 BeV. respectively, for the A2 when the events are treated as constituting a single resosant particle. Limited statistics render inconclusive an investigation of a possible mass splitting at the center of the A2 peak. A production crosS section of l20±46 ub. for the quasi-two-body reaction. pi- p -> A-2 p, is also obtained from X2 fits to the 3TI mass spectrum. This result is in good agreement with cross. section measurements reported at other incident pion momenta. The spin-parity analysis of the Ppi decay mode yields results p + which are consistent with a J = 2 assignment for both halves of the A2" The angular distribution of the decay plane indicates a J = 2 spin state with alkl = 1 component along the normal to the decay plane. A projection of the P helicity state population is consistent with a completely polarization (i.e. t helicity, I A I = 1) for the intermediate p!s from the A2 decay. A calculation of the spin-density matrix elements, assuming a JF= 2+ assignment for the A2, yields results consistent with resonance production via p meson exchange. The values for the density matrix elements are also in.general agreement with those computed from the npi decay mode.
Issue Date:1969
Genre:Dissertation / Thesis
Rights Information:Copyright 1969 Elton Duane Schafer
Date Available in IDEALS:2011-07-12
Identifier in Online Catalog:2959302

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