| Popis: |
The spin dependence of the ${\mathrm{He}}^{3}(n, p)\mathrm{T}$ reaction was investigated by studying the transmission of polarized thermal neutrons through a polarized ${\mathrm{He}}^{3}$ target which consisted of ${\mathrm{He}}^{3}$ adsorbed on zeolite. It was found that the interaction cross section was essentially all associated with an $I\ensuremath{-}\frac{1}{2}=0$ channel, i.e., $\frac{{\ensuremath{\sigma}}_{I\ensuremath{-}\frac{1}{2}}}{{\ensuremath{\sigma}}_{0}}=1.010\ifmmode\pm\else\textpm\fi{}0.032$. Once the spin dependence of the cross section was established, polarized neutrons provided a convenient method of studying the nuclear spin susceptibility of ${\mathrm{He}}^{3}$. Susceptibility measurements were made on our adsorbed-phase target over the temperature range 0.06-1.0\ifmmode^\circ\else\textdegree\fi{}K. It was found that the nuclear susceptibility began to fall below Curie's law at about 0.2\ifmmode^\circ\else\textdegree\fi{}K, indicating the onset of some type of antiparallel ordering in the nuclear spin system. |
