POLARIZATION MEASUREMENTS ON A MAGNETIC QUADRUPOLE LINE IN NE-LIKE BARIUM

We have measured the absolute polarization of the 2p(6) S-1(0)- 2p(5)( (20)(3/2))3s[3/2](0)(2) magnetic quadrupole transition in Ne-like bari um, excited in an electron-beam ion trap at a variety of energies. We find strong evidence for the existence of resonant excitation processe s that are not explained by our collisional-radiative calculations eve n when the polarization arising from impact excitation is included. At energies well away from where the resonances occur, the agreement bet ween experiment and theory is good.