He4(π,π’p)3H reaction: Quasifree and resonance scattering
| Autor: | Christopher Morris, S. M. Sterbenz, M. A. Plum, S. K. Nanda, C. Fred Moore, M. J. Smithson, D. Crockett, D. S. Oakley, M. A. Bryan, M. A. Machuca, Shaul Mordechai, M. K. Jones, J. W. McDonald, D. Dehnhard, J. D. Zumbro, Fuentes Ah, Ahmed Hussein, M. Lynker, A. L. Williams |
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| Rok vydání: | 1990 |
| Předmět: | |
| Zdroj: | Physical Review C. 42:R807-R810 |
| ISSN: | 1089-490X 0556-2813 |
| Popis: | Exclusive $^{4}\mathrm{He}$(${\mathrm{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}$,${\mathrm{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}$'p${)}^{3}$H spectra in the excitation energy range between 21.5 and 44 MeV in $^{4}\mathrm{He}$ were measured at ${\mathit{T}}_{\mathrm{\ensuremath{\pi}}}$=180 MeV at several pion and proton angles. The cross section ratio ${\mathit{R}}_{\mathrm{\ensuremath{\pi}}\mathit{p}}$=\ensuremath{\sigma}(${\mathrm{\ensuremath{\pi}}}^{+}$,${\mathrm{\ensuremath{\pi}}}^{+}$'p)/\ensuremath{\sigma}(${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$,${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$'p) was found to be between 1 and 2 near 22 MeV which is in the region of the ${\mathit{J}}^{\mathrm{\ensuremath{\pi}}}$=${2}^{\mathrm{\ensuremath{-}}}$, T=0 state. Between 25 and 40 MeV in the continuum, which comprises the giant dipole resonance and broad ${2}^{\mathrm{\ensuremath{-}}}$ and ${2}^{+}$ states, ${\mathit{R}}_{\mathrm{\ensuremath{\pi}}\mathit{p}}$ ranges from 0.22 to 45 in sharp contrast to the predicted values of \ensuremath{\approxeq}1 from a model assuming the entire yield is due to the sequential decay of a state of good isospin, and 6 to 9 from a distorted-wave impulse approximation calculation assuming quasifree proton knockout. |
| Databáze: | OpenAIRE |
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