1. 1 CAN WE KEEP THE CURRENT SYSTEM FOR LIU BEAMS ? Francesco Cerutti, Alessio Mereghetti, Joao Saraiva LIU-SPS Beam Scraping System Review 2013 Jan 22 contributions from O. Aberle, J. Borburgh, N. Conan, K. Cornelis, L. Ducimetiere, B. Goddard, R. Losito, A. Masi, M. Meddahi, E. Veyrunes, H. Vincke

2. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 2 reviewing the current scraping system with regard to some (experienced and overcome) weaknesses expectations from tracking – energy deposition coupled simulations with regard to possible active material damage OUTLINE

3. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 3 PRESENT SPS SCRAPERS three pairs of H&V scrapers [essential for clean injection into the LHC]: one in LSS5 (BSHV.51659), recuperated from ISR (early 1970s) blade exchange in 2010, from 3cm copper to 1cm graphite (by reason of robustness) currently spare of the spare

4. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 4 LSS5 SCRAPER old assembly with risk of component failures significant increase of the local radiation levels (dose to machine and equipment, activation) impact of 2010 operation wrt 2009 and 2011

5. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 5 LSS1 SCRAPERS [I] two pairs in LSS1 (BSHV.11759 and BSHV.11771), used since spring 2011 1cm graphite blades, new assembly spare insignificant impact on the LSS1 radiation levels, more than two orders of magnitude higher than in LSS5 mainly because of the high energy dump[see numbers in the Helmut Vincke’s presentation]

6. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 6 LSS1 SCRAPERS [II] Concerns: lifetime of edge-welded bellows, step motors challenged by fast movement However, mechanics/controls do not look as a critical limitation for the present system (spare could be produced and – timely, wrt to access RP constraints – installed) 2012 operation Jan 16, 2012 Jan 14, 2013 20k cycles in April 2012 to study the scrapers impact on LSS1 cables (dose measurements downstream cell 117, not pointing to a dramatic effect) 100k cycles

7. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 7 SCRAPING MECHANISM 1cm 3cm 20 cm/s 0.008  y /turn z z scraper (≡beam) movement implemented in FLUKA coupled to tracking code [actually at 3 cm/s]

8. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 8 ICOSIM/SIXTRACK – FLUKA COUPLING ICOSIM [by Hans Braun, up to sextupoles included] Idea: to develop a two-in-one tool allowing the most accurate and efficient treatment both of beam transport (by the tracking code) and beam-matter interaction (by FLUKA), accounting for multiturn and moving devices, and preventing interface files and conflicting aperture models SixTrack [by Frank Schmidt] one tracking process and one FLUKA process take over each from the other at the geometry interfaces, communicating through a network port [by David Sinuela Pastor and Vasilis Vlachoudis]

9. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 9 SCRAPER HEATING [I] 1cm 3.5  x = 2.2mm 288 nominal (1.15E11) bunches vertical sweeping at 20cm/s (in reality 3cm/s) 1.8 g/cm 3 graphite  y = 0.58mm past ICOSIM-FLUKA simulation of nominal LHC injection Gaussian beam Q26 optics BSHV.51659 3.5um є n (similar beam size – not so crucial – at BSHV.11771 with Q20 optics and max LIU emittance)

10. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 10 SCRAPER HEATING [II] peak values for 288 nominal (1.15E11) bunches, 100um x 100um tranverse resolution

11. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 11 INTENSITY LIMIT ROUGH GUESS 288 1.15E11 bunches adiabatic approximation ( neglecting heat diffusion over 50um within several ten ms → pessimistic ) thermomechanical analysis still to be carried out 4.4% scraped fraction 0.22% scraped fraction Copper limit

12. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 12 SCRAPER HEATING [III] integral values for 288 nominal (1.15E11) bunches

13. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 13 CLEANING DURATION exp(-N 2 /2) for N=3.5 3000 turns ~ 75ms scraping at 3.5  x

14. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 14 LOSS PATTERN 1cm graphite blade illustrative (synchrotron motion not included here)

15. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 15 CONCLUSIONS recent (2012) operation experience demonstrated the current (LSS1) device reliability, for regular scraping of several % of a full (50ns spaced) train of ~1.5E11 proton bunches induced radiation is not a real issue in LSS1 blade heating represents on paper a concern to be more accurately studied especially in view of maximum LIU intensities (the new scraping concept offers some more margin in this respect, see the Alessio Mereghetti’s presentation) is a faster/more flexible system, as with dedicated bumpers and a fixed absorber, desirable from the operation point of view?

16. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 16 BACKUP SLIDES

17. 2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 17 IMPACT ON LSS1 CABLES Scrapers LSS1 : 31/08/2011 -> 03/11/2011 Scrapers LSS5 : 03/11/2011 -> 24/04/2012