THEORY OF PION INDUCED NUCLEON REMOVAL IN THE (3,3) RESONANCE REGION; MULTINUCLEON REMOVAL REACTIONS IN THE INTERACTION OF IODINE-127 WITH 60-350 MEV PIONS
Abstract
A Benioff-type calculation has been performed to calculate the ((pi)('(+OR-)),(pi)N) reaction cross sections in the (3,3) resonance region (100-300 MeV) for ('12)C, ('25)Mg, ('127)I, and ('197)Au, treating the nucleon charge exchange probability P as an adjustable parameter. For ('12)C P has also been estimated using the free particle-free particle picture. Nucleon charge exchange appears to be needed to explain the anomaly seen in the cross section ratio for light nuclei, whereas it is unimportant for heavy nuclei as the consequence of two effects, i.e. nuclear shell effect and size effect. An experiment has been performed to measure the ('127)I((pi)('(+OR-)),X)('127-x)I reaction cross sections in the (3,3) resonance region (60-350 MeV), using activation techniques. The results obtained have been compared with the ISOBAR-DFF calculation. Pion inelastic scattering followed by evaporation is the dominant mechanism except for ('126)I, i.e. single-nucleon removal, for which the importance of this mechanism and that of direct knockout are comparable. The mass loss in the evaporation process appears to be more significant than that in the cascade process. The cross sections due to (pi)('+) absorption have been estimated phenomenologically. Pion absorption is significant only for the formation of low mass iodine isotopes at low energies. the ISOBAR-DFF code reproduces the overall features in the reactions studied. However, this code generally underestimates the cross sections and may overestimate those associated with pion absorption.
Degree
Ph.D.
Subject Area
Nuclear chemistry
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