Analyzing powers of the ${}_{}{}^6{}_{}{}^{}\mathrm{Li}(\overrightarrow{n}, {}_{}{}^3{}_{}{}^{}\mathrm{H}){}_{}{}^4{}_{}{}^{}\mathrm{He}$ reaction have been measured at six angles for neutron energies from 0.2 to 1.5 MeV. A supplementary data set at two angles extends the energy range to 2.4 MeV. An energy continuum of neutrons was produced by bombarding a thick lithium metal target with a nanosecond-pulsed proton beam. Partially polarized neutrons emitted at 50° were incident on an evaporated ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ metal target. A silicon surface barrier detector was used to measure $\alpha$-particle and triton yields as a function of particle energy at angles of 30°, 60°, and 80°. For the supplementary data set the reaction angle was 55°. Tritons and $\alpha$ particles were distinguished by time-of-flight techniques. $\alpha$-particle yield asymmetries were converted to backward angle triton asymmetries. Analyzing powers were deduced from asymmetries. The data suggest interference between $s$ waves and the $p$-wave ${\frac{5}{2}}^{-}$ resonance at 0.247 MeV. Interference between the ${\frac{5}{2}}^{-}$ level and a broad ${\frac{3}{2}}^{-}$ state above 2 MeV also contributes. At higher energies interference between the ${\frac{3}{2}}^{-}$ state and $s$ waves results in analyzing powers close to +0.9 near 90° which vary slowly with neutron energy between 0.7 and 2.4 MeV.

NUCLEAR REACTIONS ${}_{}{}^6{}_{}{}^{}\mathrm{Li}(\overrightarrow{n}, {}_{}{}^3{}_{}{}^{}\mathrm{H})$, $E=0.2-2.4\mathrm{}$ MeV, measured $A_y\left(\theta \right)$,. $\theta =30-150\mathrm{}°$.

• Received 8 October 1976

DOI:https://doi.org/10.1103/PhysRevC.15.467