Polarization of the Proton from the γ + n → p + π − Reaction
1963; American Institute of Physics; Volume: 129; Issue: 5 Linguagem: Inglês
10.1103/physrev.129.2259
ISSN1536-6065
Autores Tópico(s)Atomic and Molecular Physics
ResumoThe polarization of the proton from the $\ensuremath{\gamma}+n\ensuremath{\rightarrow}p+{\ensuremath{\pi}}^{\ensuremath{-}}$ reaction in deuterium has been experimentally measured at 90\ifmmode^\circ\else\textdegree\fi{} in the center-of-mass system for photon energies near 715 MeV by using a counter technique to observe the left to right asymmetry in the scattering of the protons from carbon. A value of -0.26\ifmmode\pm\else\textpm\fi{}0.06 was observed, with the direction of the polarization defined by $\stackrel{^}{n}=\frac{(\stackrel{^}{k}\ifmmode\times\else\texttimes\fi{}\stackrel{^}{q})}{|\stackrel{^}{k}\ifmmode\times\else\texttimes\fi{}\stackrel{^}{q}|}$, where $\stackrel{^}{k}$ and $\stackrel{^}{q}$ are, respectively, unit vectors in the directions of the photon momentum and the pion momentum. The result is interpreted as an indication that the interference between the ${P}_{\frac{3}{2}}$ (325 MeV) and ${D}_{\frac{3}{2}}$ (750 MeV) resonances may not be the dominant contribution to the polarization at this energy. Significant contributions from either an interference between the ${P}_{\frac{3}{2}}$ (325 MeV) resonance and the possible new resonance suggested by the $\ensuremath{\pi}$, $p$ scattering measurements, or an interference between the ${D}_{\frac{3}{2}}$ (750 MeV) and ${F}_{\frac{5}{2}}$ (1050 MeV) resonances, or a combination of these two possibilities seem to be required.
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