Neutron Polarization fromH2(p,n→)andH1(d,n→)

Measurements of the neutron polarization in the $p-d$ breakup reaction are reported. The polarization of breakup neutrons from ${}_{}{}^2{}_{}{}^{}\mathrm{H}(p,\overrightarrow{n})$ has been measured at $E_p=21.4\mathrm{}$ MeV, ${\theta }_{\mathrm{lab}}={18}^{\circ }$, as a function of neutron energy with an accuracy of approximately ±0.01. The measurement is consistent with zero from 8 to 13 MeV, but shows a small but significant positive polarization from 14 to 18 MeV. A similar measurement of the breakup neutrons from the ${}_{}{}^1{}_{}{}^{}\mathrm{H}(d,\overrightarrow{n})2p$ reaction at the same center-of-mass momentum ($E_d=42.8\mathrm{}$ MeV), also at ${\theta }_{\mathrm{lab}}={18}^{\circ }$, shows nonzero polarization over the neutron energy region 8 to 25 MeV, reaching a maximum of about -0.05±0.01. In both cases, the polarization of the breakup neutrons is opposite in sign to that expected if the dominant process is simple quasifree scattering.