Direct Determination of Nuclear Polarization Produced by Beam-Foil Interaction for the Short-LivedβEmitterB12

Nuclear polarization $P$ of the short-lived $\beta$ emitter ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ was produced by the beam-foil interaction and directly determined via asymmetric $\beta$ decay. For a single tilted foil, at boron energy $E_{\mathrm{B}}=1.0\mathrm{}$ MeV, $\mathrm{}\left|P\right|=1.82\mathrm{}\left(14\right)\%$. This was enhanced to $\mathrm{}\left|P\right|=4.69\mathrm{}\left(46\right)\%$ by stacking four tilted foils. The dependence of $P$ vs $E_{\mathrm{B}}$ was observed for a single tilted foil in the range of $E_{\mathrm{B}}=0.6\mathrm{} \mathrm{to} 1.3$ MeV. The sign of $P$ followed that of the tilt angle and was consistent with predictions from electron-density-gradient models.