Collimator systems for the SNS ring

Abstract

The requirements and performance goals for the collimators are to reduce the uncontrolled beam loss by 2x104, absorb 2 kW of deposited heat, and minimize production and leakage of secondary radiation. In order to meet these requirements a self-shielding collimator configuration consisting of a layered structure was designed. The front layers (in the direction of the proton beam) are relatively transparent to the protons, and become progressively less transparent (blacker) with depth into the collimator. In addition, a high density (iron) shield is added around the outside. The protons will be stopped in the center of the collimator, and thus the bulk of the stxondary particles are generated at this location. The conceptual design described, the method of analysis discussed, and preliminary performance parameters outlined.

Low-loss design for the high-intensity accumulator ring of the Spallation Neutron Source

“…We expect the collimation efficiency to be around 90%. The secondary collimation units, comprising layers of steel, borated water, and the like, are designed to contain secondary charged and uncharged particles [28], as shown in Fig. 14.…”

The Collimation System of the High Energy Beam Transfer (HEBT) Line

“…To remove the transverse halo from the beam, we introduce adjustable carbon foils in the path of the beam to intercept the tails. After the passage of the À ion through the foil, the two electrons are removed and the À focusing lattice deviates the proton tails into large massive absorbers [4].…”

“…Besides diagnostics that characterize the beam, a collimation system is provided to protect the line and RF cavities and to avoid excessive transverse and longitudinal halo transported into the ring. The transverse system consists of two collimators [2,3,4] of fixed aperture preceded by horizontal and vertical pair of striper foils working as primary collimators. A longitudinal collimation system is also provided in the achromat with a pair of facing striper foils followed by an absorber.…”

The Collimation System of the Ring to Target Beam Transfer (RTBT) Line

“…A collimation system is provided to protect the line and the target from accidental losses mainly due to potential failure of the extraction kickers [1]. The system consists of two collimators [2,3,4] of fixed aperture with a relative phase advance of 90 degrees. Initially they were located after quadrupoles QH16 and QH18 after the bend.…”