Design and Status of the 1.5 GeV-Harmonic Double Sided Microtron for MAMI

A Harmonic Double Sided Microtron (HDSM) is presently under construction to increase the end energy of the three staged cw Race-Track Microtron (RTM) cascade MAMI from 0.855 to 1.5GeV. This new accelerator, scheduled to come into operation in 2004, consists mainly of two pairs of 90° bending magnets and two linear accelerators (see Fig. 1). Special features of the HDSM are the operation of the two linacs at different frequencies, 2.45GHz and 4.90GHz, for higher longitudinal stability, and a relatively strong field gradient in the bending magnets for the compensation of vertical edge defocu sing. In this paper we will present the main design considerations and report the status of construction. L IN A C I (4 .9 0 G H z) L IN A C II (2 .4 5 G H z) 1 0 m 4 3 re c irc u la tio n s B = 1 .5 3 9 T max Ijec tio n 8 5M eV Extrac tion 1 507M eV Fig. 1: General layout of HDSM