Ionization cross-section ratios at low energies near Z=79

The ratio of the L) to L) ionization cross sections for low-energy α particles has been remeasured, with better experimental precision, to lower energies than our previous data. Two additional elements near gold, namely tungsten and lead, have been included. While all the elements studied deviate from PWBA calculations, the anomalous behavior of the gold and platinum ratios reported earlier is still observed