Error Sources in the ETA Energy Analyzer Measurement

At present the ETA beam energy as measured by the ETA energy analyzer and the DARHT spectrometer differ by {approx}12%. This discrepancy is due to two sources, an overestimate of the effective length of the ETA energy analyzer bending-field, and data reduction methods that are not valid. The discrepancy can be eliminated if we return to the original process of measuring the angular deflection of the beam and use a value of 43.2cm for the effective length of the axial field profile.