Abstract
The collimation system for the Spallation Neutron Source accumulator ring is designed for a capture efficiency close to 95% of the proton beam halo, dissipating about 2 kW of beam power. The collimation system consists of a two-stage collimation system (one scraper and two absorbers) cleaning the transverse halo and a beam-in-gap kicker system cleaning the gap residual and longitudinal halo. Preliminary studies indicate that a maximum level of uncontrolled loss of 0.01% of the total beam is achievable. On the other hand, the energy lost in the primary scraper may kick protons outside the rf bucket concentrating uncontrolled losses in areas of maximum dispersion. We use Monte Carlo simulations to clarify some beam dynamic issues that may compromise the high efficiency required. The material interacting with the beam and the shape of the scraper and absorbers have been carefully chosen to maximize the collimation efficiency and to minimize radioactivation. Furthermore, a realistic distribution of losses around the machine is used to identify potential hot areas. Finally, we determine the sensitivity of the collimation efficiency to misalignments and closed orbit errors. This paper describes the latest design of the collimation system and summarizes the results of these numerical studies.
Highlights
The Spallation Neutron Source (SNS) is designed to deliver a proton beam with 2 MW of beam power to a liquid mercury target
The best performance regarding loss control in high intensity machines is achieved at the proton storage ring (PSR) at Los Alamos where the fractional uncontrolled beam loss is about 1023 [3]
A collimation scheme including transverse and longitudinal cleaning has been designed for the SNS accumulator ring
Summary
The Spallation Neutron Source (SNS) is designed to deliver a proton beam with 2 MW of beam power to a liquid mercury target. The expected fractional beam loss, due mainly to the strong space charge in the presence of magnetic errors, is of the order of 1023 without collimation system. To achieve hands-on maintenance, we place collimators at strategic positions around the ring to remove particles outside the beam core and to localize the beam loss. These locations become the only “hot spots” of the machine where remote handling is required. We study the dependence of the cleaning efficiency on parameters such as the impact parameter, the machine tune, and the primary aperture
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Physical Review Special Topics - Accelerators and Beams
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
