High-yield positron systems for linear colliders

It is noted that the SLC (Standford Linear Collider), having electron energies up to 50 GeV, presents the possibility of generating positron bunches with a useful charge even exceeding that of the initial electron bunch. The exact positron yield to be obtained depends on the particular capture, transport, and damping system used. Using 31-GeV electrons impinging on a W-type converter target, and with adequate matching of the positron beam phase-space at the target to the acceptance of the capture RF section, the SLC source is capable of producing, for every electron, up to two positrons within the acceptance of the positron damping ring. The design of this source and the performance of the positron system as built are described. Also, future prospects and limitations for high-yield positron systems are discussed