Slightly Inelastic Proton-Deuteron Scattering

Abstract

Measurements of the inelastic $p\ensuremath{-}d$ cross section, in the region of very small momentum transfer, have been made at laboratory scattering angles of 5\ifmmode^\circ\else\textdegree\fi{}, 10\ifmmode^\circ\else\textdegree\fi{}, 15\ifmmode^\circ\else\textdegree\fi{}, and 20\ifmmode^\circ\else\textdegree\fi{}. The elastic $p\ensuremath{-}d$ cross section has also been measured at these angles and compared with Postma's data. These measurements have been performed with a high-resolution magnetic spectrometer designed especially for this experiment. The $p\ensuremath{-}d$ cross sections have been obtained by normalizing the $p\ensuremath{-}d$ spectra to $p\ensuremath{-}p$ spectra obtained by filling the same target with liquid hydrogen. The shape of the $p\ensuremath{-}p$ spectrum, at a particular angle, was used to effect the separation of the inelastic $p\ensuremath{-}d$ from the elastic $p\ensuremath{-}d$ spectrum. The over-all energy resolution at small angles was about 0.75%.A comparison of the elastic $p\ensuremath{-}d$ data with the impulse-approximation calculation of Kerman, McManus, and Thaler yielded a value of ${\ensuremath{\Sigma}}_{t}$, the triplet amplitude sum, at the four angles measured. The singlet amplitude sum, ${\ensuremath{\Sigma}}_{s}$, was obtained by fitting Cromer's theory to the inelastic $p\ensuremath{-}d$ cross section. The experimental values of the parameters ${\ensuremath{\Sigma}}_{s}$ and ${\ensuremath{\Sigma}}_{t}$ are compared with the predictions of the most recent phase-shift analyses. ${\ensuremath{\Sigma}}_{s}$ appears to be particularly sensitive to the values of the $T=0$ amplitudes and thus experimental values of ${\ensuremath{\Sigma}}_{s}$ may be useful in future phase-shift analyses.