A Further Study Of Antiproton Interactions And The Annihilation Process Thesis PDF Download

The antiproton annihilation process in complex nuclei was studied in photographic emulsions. When a 19.8 gr/ cm/sup 2/ LiH absorber was introduced in an existing antiproton beam, the antiproton-to-meson ratio improved by a factor of about 10, becoming 1/50,000. Thus in a single stack exposed to this improved beam, 165 antiprotons were found. These together with 20 more found in other stacks and the 36 reported in the Antiproton Collaboration Experiment'' (a total of 221 analyzed stars) are included in this analysi. From this analysis the annihilation process in complex nuclei can be interpreted to proceed as follows: The antiproton annihilates itself with one nucleon, transforming all the available energy mainly into The effects of mesons of average multiplicity 5.36 sintering time 0.28 with an occasional K-K emission of frequeney (3.5 sintering time 1.5%) per star. The mesons interact with the nucleus leaving it in an excited state. The nucleus releases the excitation energy through nucleon emission. On the average, the stars in flight have more excitation than those at rest. By the use of this experimental data and available information on pion interactions in nuclear matter, the fraction of interacting pions was deduced for the stars in flight and at rest separately. It is shown that with a better knowledge of the pion interactions in nuclear matter, antiproton annihilations can be used to investigate the nucleon distribution at the surface of the nucleus. The pion-pion angular distribution was deduced on the basis of energy-momentum conservation, by the use of the Fermi statistical model of the annihilation with Lorentz-invariant phase space. The theoretical distribution agrees with the experimental one if an adjustment of the interaction volume is made to account for the observed pion multiplicity. A strong pionpion interaction is thus unlikely. (auth).