ATS MDs Experience from Run I Perspective for

ATS MDs: Experience from Run I & Perspective for Run II S. Fartoukh for the ATS MD team The Achromatic Telescopic Squeeze (ATS): Basic principles 2011 & 2012 ATS MDs: Highlights and lessons Priority list for Run II Acknowledgements S. Fartoukh LSWG Day, September 2 th, 2014 1

The basic principles of the ATS • A new injection optics (~ p/2 FODO lattice new integer tunes) • A squeeze in 2 steps 1) An “almost” standard squeeze, the Pre-squeeze: acting on the matching quads of IR 1 and IR 5, with new matching constraints on the left/right IR phase till reaching some limits (sextupoles, matching section). 2) A further reduction of b*, the Squeeze: acting on IR 2/8 for squeezing IR 1 and IR 4/6 for IR 5, inducing b-beating bumps in sectors 81/12/45/56 to boost the sextupole efficiency at constant strength. S. Fartoukh LSWG Day, September 2 th, 2014 2

Reaching b*=10 cm in the existing LHC for ATLAS & CMS … a small animation /afs/cern. ch/eng/lhc/optics/ATS_V 6. 503 IR 4 IR 5 IR 6 Beam size [mm] and dispersion (IR 4 IR 6) at 3. 5 Te. V (for ge=3. 5 mm) S. Fartoukh Tunes vs. dp IR 5 aperture (compared to 4 sigma's (X-angle OFF) Chromatic Montague functions over the LSWG Day, September 2 th, 2014 full ring (off-momentum b-beating) 3

ATS MDs over 2011&2012 A full program deployed in 2011 &2012, with a total of 8 h spent for dry runs (w/o beam) + 35 h with beam: 1. 2011 -Bloc 1 (2 h+8 h): ATS injection optics and ramp (new integer tunes, new arc and IR optics). successful The ATS MD Part I, CERN-ATS-Note-2011 -033 MD, 2011 2. 2011 -Bloc 2 (3 h+9. 5 h): Pre-squeeze to b*=1. 2 m in IR 1&5 (no X-angle), and telescopic squeeze for IR 1 only to reach b*= 30 cm successful The ATS MD Part II, CERN-ATS-Note-2011 -060 MD, 2011 3. 2011 -Bloc 4 (2 h+4. 5 h): Pre-squeeze to b*=40 cm in IR 1&5 (no X-angle) and telescopic squeeze of IR 1 and IR 5 down to b*= 10 cm. Pre-squeeze successful, beam lost when preparing the squeeze The ATS MD Part III, CERN-ATS-Note-2011 -132 MD, 2011 4. 2012 -Bloc 2 (12 h): idem as above successful The 10 cm b* MD, CERN-ATS-Note-2013 -004 MD, 2013 S. Fartoukh LSWG Day, September 2 th, 2014 4

• Chromatic measurements of the pre-squeezed optics at b*=1. 2 m (MD 2). The Tunes are linear vs. dp over a momentum window of +/- 1. 5 permil S. Fartoukh The off-momentum b-beating wave induced by the IT starts to show up but is contained in s 81/12/45/56 Perf. Workshop, Chamonix 2012 5

• Telescopic principle (× 4) demonstrated in IR 1(MD 2) (starting from b*=1. 2 m). S. Fartoukh LSWG Day, September 2 th, 2014 6

• Optics measurements and correction for the pre-squeezed optics at b*= 40 cm (MD 3) Qx(d) at b*=40 cm Qy(d) at b*=40 cm 15 -20% level reached for the b-beating after one single correction iteration (only Beam 1) S. Fartoukh No (small) Q’’, Q’’’ … Perf. Workshop, Chamonix 2012 7

• Optics measurements for the telescopic optics at b*= 10 cm (MD 4) barc 800 m! bmax 25 km ! V H. . . zoomed in the arcs b*=10 cm bmax = 23. 8 km in the triplet (21. 1 km for BPMS). . . the b-beating was not ‘ideal’ (MD time missing!) but b* was probably around 12. 5(V)-14. 5(H) cm, so still 5 mm better than the HL-LHC baseline! 2/20/2021 S. Fartoukh, LSWG 7/3/2012 8

Lessons • For the LHC The nominal b* (55 cm) or below (40 cm) is well within reach (from the optics point of view)! • For the ATS So far so good …but ``only’’ demonstrated with pilot bunches (although nothing special is expected with nominal bunches) S. Fartoukh LSWG Day, September 2 th, 2014 9

Plans & possibilities for Run II 1. Fully Commission a pre-squeezed ATS optics with high intensity beam: either in long MD sessions or because the ATS-compatible optics is directly put in operation in 2015. 2. Develop Telescopic flat optics AND validate with a few nominal bunches either LHC compatible (IT aperture) for performance maximization beyond 2016 (e. g. 80/25 cm with X-angle), or beyond (e. g. 50/10 cm w/o X-angle to prepare for the HL-LHC Plan B). 3. Develop and validate special telescopic round optics for maximizing the MO efficiency (with higher b’s in the arcs) AND validate with a few nominal bunches e. g. with a pre-squeezed ``downgraded’’ to 1 -1. 2 m and the rest of the squeeze performed in a telescopic manner to reach 50 -40 cm. 4. Develop ``anti-ATS’’ optics for very large b* (up to 5 km). S. Fartoukh LSWG Day, September 2 th, 2014 10

Acknowledgments … Many thanks for these results which are the fruit of the work of many people: in particular the OP team and the OMC team, but also the MD coordination team and many others C. Alabau, M. Albert, R. Alemany Fernandez, R. Assmann, R. Bruce, A. Butterworth, R. Giachino, B. Goddard, P. Hagen, W. Hofle, D. Jacquet, M. Giovannozzi, V. Kain, G. Kruk, M. Lamont, Y. Levinsen, E. Maclean, A. Macpherson, R. de Maria, R. Miyamoto, G. Mueller, L. Normann, G. Papotti, T. Persson, M. Pojer, L. Ponce, S. Redaelli, N. Ryckx, P. Skowronski, M. Solfaroli, R. Steinhagen, M. Strzelczyk, R. Suykerbuyk, E. Todesco, R. Tomas, D. Valuch, V. Venturini, G. Vanbavinckhove, J. Wenninger, D. Wollmann, F. Zimmermann S. Fartoukh LSWG Day, September 2 th, 2014 11