The scattering of polarized neutrons from statically polarized solid 3He

We have constructed a 0.4 mole solid 3He target, cryogenically polarized at 12 mK in a field of 7 T. The 0.04 atoms/b target reached a polarization of 38% in 35 h. Such a target may be applied to any experiment which is tolerant of the large ambient magnetic field and which produces target heating of less than a microwatt. High energy neutron and photon scattering experiments meet these requirements. The targetʹs figure of merit for neutron transmission measurement exceeds that of polarized gas targets by greater than 35. At the Triangle Universities Nuclear Laboratory we have used the target to measure the total cross section differences ΔσT and ΔσL for incident polarized neutrons of energies 2–8 MeV. The cross section difference is sensitive to the excited state structure of the n-3He system. The results have been compared to a recent R-matrix analysis of R = 4 scattering and reaction data, and provide support for the 4He level scheme derived from that analysis.