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Title: Design of a high yield positron source

Conference · · IEEE Trans. Nucl. Sci.; (United States)
OSTI ID:6119020

The Stanford Linear Collider (SLC) requires a positron source with a yield large enough to give equal number of positrons and electrons at the interaction point. In addition, the colliding positrons must have an emittance and bunch length similar to the electron beam. This report describes the design of a high yield positron source to give these characteristics. Reference 1 contains more details of the systems of the SLC and positron source. The overall positron production system in relation to the SLC is shown in Fig. 1. A single bunch of electrons of 33 GeV is extracted from the Linac at the two-thirds point by means of a fast kicker magnet and a pair of septum magnets. The extracted electron beam is transported into the positron vault where it is focused to a spot size of + or -0.6 mm at the target. Spoiler foils are placed in the extracted beam path to increase the emittance so that the spot size cannot be made so small that target damage would occur. Positrons are collected in a focusing solenoid system using an iron shaped solenoidal field of 1 Tesla at the target and a pulsed solenoidal field from a flux concentrator with a peak field of 5 Tesla. The positron beam emerging from the focusing solenoid system is accelerated to 200 MeV in a 1.5 meter high-gradient-accelerator of 50 MeV/meter and three 3.05 m standard accelerator sections. The positrons are contained in the accelerator aperture using a 0.5 Tesla solenoidal field in the beginning and quadrupole focusing in the final two standard accelerator sections. The positrons are then transported back to the beginning of the Linac for further acceleration to 1.2 GeV, whereupon they are sent to the positron damping ring. Later they are removed from the damping ring, accelerated to the end of the Linac, and transported around the e/sup +/ arc to the interaction point.

Research Organization:
Stanford Linear Accelerator Center, Stanford University, Stanford, CA
OSTI ID:
6119020
Report Number(s):
CONF-850504-
Journal Information:
IEEE Trans. Nucl. Sci.; (United States), Vol. NS-32:5; Conference: Particle accelerator conference, Vancouver, Canada, 13 May 1985
Country of Publication:
United States
Language:
English