Calibration of a superconducting beta spectrometer using 66Ga

We have constructed a new superconducting Wu spectrometer with roughly 1sr. acceptance and 2{\%} FWHM momentum resolution. The spectrometer measures the energy deposited into a 4MeV thick Si(Li) detector by betas that have been magnetically selected for their momentum. This simultaneous measurement of both momentum and energy deposition allows scattering effects to be accounted for, and provides an opportunity to compare data to Monte-Carlo simulations. These comparisons have been performed with both 207Bi and 66Ga, and the 66Ga results will be presented.