* Supported by U.S. DoE grant # DE-FG02-01ER41175 # smikhail@fel.duke.edu COMMISSIONING OF THE BOOSTER INJECTOR SYNCHROTRON FOR THE HIGS FACILITY AT DUKE UNIVERSITY* S.F. Mikhailov # , M.D. Busch, M. Emamian, S.M. Hartman, Y. Kim, J. Li, V.G. Popov, G. Swift, P.W. Wallace, P.Wang, Y.K. Wu, FEL Laboratory, Duke University, Durham, NC 27708, USA C.R. Howell, Triangle Universities Nuclear Laboratory, Durham, NC, USA N.G. Gavrilov, G.Ya. Kurkin, Yu.Matveev, O.V. Anchugov, D.A. Shvedov, N.A. Vinokurov Budker Institute of Nuclear Physics, Novosibirsk, Russia Abstract A booster synchrotron (Duke booster) has been built and recently commissioned at Duke University Free Electron Laser Laboratory (DFELL) as part of the High Intensity Gamma-ray Source (HIGS) facility upgrade. HIGS is collaboration between the DFELL and Triangle Universities Nuclear Laboratory (TUNL). The booster provides top-off injection into the Duke FEL storage ring in the energy range of 0.24 - 1.2 GeV. When operating the Duke storage ring to produce high energy Compton gamma ray beams above 20 MeV, continuous electron beam loss occurs. The lost electrons are replenished by the booster injector operating in the top-off mode. The presentt operational injection and extraction rate of the machine allows us to routinely replenish up to 5·10 8 electrons per second. The compactness of the booster posed a challenge for its development and commissioning. The booster has been successfully commissioned in 2006. This paper reports experience of commissioning and initial operation of the booster. DUKE BOOSTER PARAMETERS The Duke booster is a compact 31.9 m circumference synchrotron with race-track shape [1,2,3]. Figure 1 shows the Duke booster enclosed in a radiation shielding vault. The booster is currently operates in either single bunch or two bunch mode. It has also been commissioned with a long electron pulse from the injection linac into all 19 buckets. The present operational parameters of the booster are listed in Table 1. The injection beam energy from the linac is 0.24 – 0.27 GeV. The injection and extraction is vertical using horizontal Lamberson injection and extraction septum magnets. A local orbit bump symmetrical for injection and extraction allows us to use a single injection and single extraction kicker. The extraction energy of the booster varies from 0.24 to 1.2 GeV. The booster and the storage ring are fully synchronized for the extraction. The RF frequency of the booster may be tuned independently or be phase-locked to the master oscillator of the main ring [4]. The odd ratio of the harmonic numbers of the booster and ring, 19/64, provides for extraction of any individual electron bunch from the booster into any selected RF bucket of the storage ring. The short pulse of extraction kicker supports the extraction of individual bunches without disturbing others. The lattice, design and injection features of the booster are described in detail in [5,6,7]. Figure 1: Duke University HIGS facility booster Proceedings of PAC07, Albuquerque, New Mexico, USA TUPMS014 02 Synchrotron Light Sources and FELs 1-4244-0917-9/07/$25.00 c 2007 IEEE A05 Synchrotron Radiation Facilities 1209