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Experience with SPS scrapers. G. Arduini Acknowledgements: C. Fischer, R. Jung and F. Zimmermann. Main uses. Beam scraping to produce “Poor man pilot” To reduce intensity for impedance measurement To measure diffusion rate for BBLR experiment (most demanding ….up to now).
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Experience with SPS scrapers G. Arduini Acknowledgements: C. Fischer, R. Jung and F. Zimmermann
Main uses • Beam scraping to produce “Poor man pilot” • To reduce intensity for impedance measurement • To measure diffusion rate for BBLR experiment (most demanding ….up to now)
H & V scraper (BSHV5145) H&V Primary collimators (2 jaws each): BRCH51710- BRCV5169 H&V Secondary collimators (2 jaws each): BRCZ5193 H beam V SPS Scraping system
H-scraping (as I understood it…) Larger parking – target position difference longer delay to start scraping in the cycle SLOW 0.5-1.5 s Target Parking 570 ms How many mm? Scraper – how does it work?
HW limitations • Scraping takes ~ 100 ms (~4000 turns) • During the slow motion from parking to target position the scraper might become an aperture limiter in the other plane and induce background (observed during BBLR studies) • The direction of the fast movement does not coincide with the direction where the scraper would constitute a well-define aperture limit. • Scraper (BSHV 5145) at position with dispersion (2.2 m).
SW limitations • Not multicycling (normally set-up for MD cycle – lengthy procedure to set it for main cycle) something done for the start-up? • Only one plane at a time • Quite some thinking to set correct parameters to account for the slow movement from parking to target position and still observe scraping at the desired timing Documentation is existing… • No correlation among scraper and collimator settings to obtain proper collimation of the secondaries
What would be needed? • Define the transverse aperture with the scraper and then retract by a few 100 mm to see re-emergence of back ground signal. Fast scraper motion over the above short distance (ms – 10 ms?) and V(H) aperture limit should extend over the full H(V) range.
Other issues • How can we measure tails? • Are BLM the only way? • Dedicated profile monitors?