Expanded data and improved calibrations for measurements of electron-ion collision rates in magnetized ultracold neutral plasmas

Ultracold neutral plasmas (UNPs) can have cold electron temperatures (as low as 1K) and low densities (10⁷ cm^-3) that allow the achievement of extreme degrees of electron magnetization with only moderate laboratory fields.  We have conducted measurements of the AC conductivity of electrons in UNPs as a function of magnetization for high-frequency fields and found a variation in conductivity that is not explained by AC conductivity theories.  Since this AC conductivity is related to electron-ion collision rates, this discrepancy indicates a difference between predicted and measured electron-ion collision rates in these magnetized systems.  We report additional measurements at more magnetic fields as well as describe improvements to multiple calibrations necessary for interpreting these measurements.