{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/25777"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/25777","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"A-2 meson production in pi-minus proton interactions at five BeV","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 transver.se 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.\"","abstract_html":""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 transver.se 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."","abstract_has_math":false,"creators":["Schafer, Elton Duane"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Ascoli, Giulio"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-07-12T17:32:11Z","date_published":"2011-07-12T17:32:11Z","updated_at":"2026-07-22T22:25:26Z","subjects":["A2 mesons","hydrogen bubble chamber","incident pions"],"languages":["en"],"rights":["Copyright 1969 Elton Duane Schafer"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["2959302"],"render_values":[{"text":"2959302","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/25777","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Ascoli, Giulio"]},{"key":"dc:creator","label":"Author","values":["Schafer, Elton Duane"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-07-12T17:32:11Z","10000-01-01","1969"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation / Thesis","text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["A2 mesons","hydrogen bubble chamber","incident pions"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1969 Elton Duane Schafer"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["2959302","http://hdl.handle.net/2142/25777"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["\"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 transver.se 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.\"","Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-07-12T17:32:11Z No. of bitstreams: 1 1969_schafer.pdf: 4436296 bytes, checksum: 53eac4ad8815329979a87475817607e5 (MD5)","Made available in DSpace on 2011-07-12T17:32:11Z (GMT). No. of bitstreams: 1 1969_schafer.pdf: 4436296 bytes, checksum: 53eac4ad8815329979a87475817607e5 (MD5) Previous issue date: 1969","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-07-12T17:32:11Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:32:42-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis","Thesis","U of I Only"]},{"key":"dc:title","label":"Title","values":["A-2 meson production in pi-minus proton interactions at five BeV"]}]}],"canonical_facts":{"dc:contributor":["Ascoli, Giulio"],"dc:creator":["Schafer, Elton Duane"],"dc:date":["2011-07-12T17:32:11Z","10000-01-01","1969"],"dc:description":["\"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 transver.se 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.\"","Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-07-12T17:32:11Z No. of bitstreams: 1 1969_schafer.pdf: 4436296 bytes, checksum: 53eac4ad8815329979a87475817607e5 (MD5)","Made available in DSpace on 2011-07-12T17:32:11Z (GMT). No. of bitstreams: 1 1969_schafer.pdf: 4436296 bytes, checksum: 53eac4ad8815329979a87475817607e5 (MD5) Previous issue date: 1969","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-07-12T17:32:11Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:32:42-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis","Thesis","U of I Only"],"dc:identifier":["2959302","http://hdl.handle.net/2142/25777"],"dc:language":["en"],"dc:rights":["Copyright 1969 Elton Duane Schafer"],"dc:subject":["A2 mesons","hydrogen bubble chamber","incident pions"],"dc:title":["A-2 meson production in pi-minus proton interactions at five BeV"],"dc:type":["Dissertation / Thesis","text"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:26Z"}