Ion-extraction polarimetry for polarized internal targets

We discuss ion extraction from an internal target in a storage ring, separation of atomic and molecular species, and subsequent measurement of the polarization of the atomic ions. This technique can be applied to internal targets of polarized hydrogen, deuterium, 3He and other gases. Here, we report on the development of such a device for a tensor polarized deuterium gas target internal to a medium-energy electron storage ring. Ions were extracted from a storage cell using a spherical deflector and transported to a mass analyzer. In a prototype setup, using electrons from a gun to simulate the electron beam from a storage ring, the tensor polarization of the atomic ions was measured using the 3H(d̄, n) α reaction. The data show that the extraction of ions from a storage-cell target, followed by their mass and polarization analysis, allows the determination of the nuclear polarization of the target independent of its spatial and temporal variations.