CDR2 – Injection System 1.12 - Injection system overview (Seeman) (2 pages) 1.12.1 - Source (Brachmann) (3 p) 1.12.2 - Linac (Boni) (6 p) 1.12.2.1 - General description 1.12.2.2 - Low energy conversion linac 1.12.2.3 - High energy conversion option 1.12.2.4 - Buncher RF system 1.12.2.5 – S-band accelerating structures 1.12.2.6 - RF power sources 1.12.2.7 - RF power distribution 1.12.2.8 - Low level RF 1.12.2.9 - The C-band option 1.12.3 - Damping ring & T.L.’s (Preger) (3 p) 1.12.4 – Injection into the rings (Guiducci) (3 p)

1.12 Injection System Overview The injection system for SuperB is capable of injecting electrons and positrons into their respective rings at full energies. The HER needs positrons at 6.7 GeV and the LER 4.18 GeV polarized electrons. At full luminosity and beam currents, up to 3.5 A, the HER and LER have expected beam lifetimes as low as 5 minutes. Thus, the injection process must be continuous, called top-up injection, to keep nearly constant beam current and luminosity. Multiple bunches (~five) will be injected on each linac pulse into one or the other of the two rings. Positron bunches are generated by striking a high charge electron bunch onto a positron convertor target and collecting the emergent positrons. The transverse and longitudinal emittances of the electron bunches and, especially, of the generated positron bunches are larger than the LER and HER acceptances and must be predamped. A specially designed damping ring at 1 GeV is used to reduce the injected beam emittances. This damping ring is shared for the two particle types to reduce costs. An overview of the injection system is shown in Figure 1. Fig. 1 Figure 1 Overall layout of the SuperB Injection System Figure 2 Injection and extraction from the shared Damping Ring

The transport lines into and out of the damping ring are shown in Figure 2. The electron to positron conversion is done at about 0.6 GeV using a newly designed target and capture section to produce a yield of about 10% (?). The electrons from the gun source are longitudinally polarized. The particle spins are rotated to the vertical plane in a special transport section downstream of the gun. The spins now remain vertical for the rest of the injection system and injected in this vertical state into the LER. The specific injection parameter values are described here. The linac operates at 50 Hz. A short train of 5 bunches (1 to 20 possible) at a time are produced for each beam type, stored for 20 msec in the damping ring, and then extracted and accelerated to full injection energy. The nominal stored beam current in each ring is 2.1 A, but the injector is designed to accommodated the maximum stored current of 3.5 A. At 3.5 A the number of stored particles are about 1014 particles total per SuperB ring. With a 5 minute lifetime, 1.23 x 1011 particles are lost per second per ring. With 5 injected bunches per pulse and an injection rate of 16 Hz, each injected bunch has a charge of 1.5 x 109. This charge is about 1.5% of the SuperB stored bunch charge and, thus, the rms bunch current will be constant to about 0.5% over time. The vertical polarization averaged over the electron bunch is expected to be about 88%. The details of the injection system are described in the following sections.