n−pTriple-Scattering ParameterDtat 197 MeV

Abstract

The $n-p$ triple-scattering parameter $D_t$ has been measured at 197 MeV at three angles. The measurements were made by bombarding a liquid-deuterium target with polarized protons, and spin-analyzing high-energy neutrons recoiling into forward angles. Spin analysis was accomplished by a charge-exchange scattering on C${\mathrm{H}}_2$. The measurements are related to the $D_t$ parameter for free $n-p$ scattering through an impulse-approximation calculation which includes the $s$-wave final-state interaction between the incident proton and the proton in the deuteron. Values obtained for the free $\mathrm{np} D_t$ parameter are: +0.095±0.068, -0.014±0.071, and +0.058±0.103 at free $n-p$ center-of-mass scattering angles of 147.4°, and 126.9°, respectively. These values are compared with the phase-shift solutions YLAN of Breit and collaborators, and the energy-independent solution of Arndt and MacGregor. Solutions YLAN 0, 1, 2, 2M, 3, and the Arndt-MacGregor solution do not agree with the data. Solutions YLAN 3M and 4M fit the data quite well.