Beam energy measurement using the Hall C beamline (CEBAF)

We propose to use the curved transport line into Hall C at CEBAF to measure the beam energy. With only dipoles powered, this transport arc has a dispersion of 12 cm/%. We propose to insert pairs of wire scanners at the entrance and exit of the arc to measure beam position and direction. These measurements, together with a calibrated dipole field, obtain an absolute beam energy measurement with /spl sim/10/sup -3/ accuracy, according to error analyses. In operational mode, arc quads and sextupoles are powered to obtain a second order achromat with a dispersion of 2.1 cm/% at the arc center. A wire scanner at the arc center then obtains a relative energy measurement of /spl sim/10/sup -4/ accuracy.<>