1. Filling Schemes for the 2010 Heavy Ion Run Updated (3 rd iteration) version of BCWG presentation initially on 28 September, updated after discussions with P. Baudrenghien, E. Carlier, B. Goddard, J. Wenninger.  Abort gap keeper constraint taken into account already.  Given that bunch 1 is always the one following the abort gap, and that the beam dump kicker systems receive the proper timing signal from RF when bunch 1 passes IP1, there is no need to change the beam dump kicker timing set-up.  The kicker timing is independent in the two rings so we can choose the relative timing of the two beams so that bunch 1 of Beam 1 collides with bunch 1 of Beam 2 at any point around the rings. October 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 1/7

2. Recap EARLY scheme adopted in 2003 for the first ion run(s): – Luminosity 5×10 25 cm -2 s -1 (instead of NOMINAL 10 27 cm -2 s -1 ) Running conditions (  * =3.5 m instead of 1.0 m and half the design energy): –Further drop of the luminosity to ~0.7×10 25 cm -2 s -1 Compensate partly by increasing (roughly doubling) the number of bunches Only consider adaptations of the EARLY scheme in 2010 –No variants of the NOMINAL scheme for now.. –Transparent for Linac3, LEIR and PS (one LHC ion bunch per cycle) –SPS accumulates four PS transfers … keep SPS magnetic cycle –Decrease distance between bunches in SPS (some change for RF, timings) to create space –Increase number of SPS cycles to fill one LHC ring …. and, thus, the LHC filling time to a minimum of ~7 min/ring –All three experiments (ALICE, CMS and ATLAS) taking ion collisionsrequest non-colliding bunches –Consider adding single bunch for LHCb ? Low intensity in “keeper space.” October 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 2/7

3. 128 bunches/ring variant respecting kicker restrictions (Recap) Based on previous140 bunch scheme –Reduced number of batches to cope with injection kicker limitations Basic building block: –Four bunches spaced by 500 ns –Injection kicker: 975 ns 9 such blocks fill exactly one LHC quarter Very long abort gap removing four batches at the end October 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 3/7

4. Collision schedule with 128 bunches/ring Collision patterns optimized with first bunches of trains encountering close to ALICE (±5 0 ) –Black: collisions –Red and Blue: bunches in ring 1 and 2 not colliding with bunch in other ring 124 bunch encounters for ALICE and 112 for CMS and ATLAS ➠ Uses free choice of point where 1 st bunches of the two rings collide. First bunch (both rings 5 o from ALICE) Abort gap ring 1 Abort gap ring 2 October 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 4/7

5. Variants of the 140 bunches/ring scheme presented on 28 th Sept. 120 bunches/ring variant … if 1 st bunches encounter at point 1 Based on the 140 bunches/ring and 128 bunches/ring schemes If 1 st bunches of 128 bunch pattern collide in point 1: –Abort gaps encounter in point 1 and 5 –no non-colliding bunches for CMS and many (16 per ring) non-colliding bunches for ALICE Remove two batches/ring batches such that CMS/ATLAS see non-colliding bunches –120 bunches/ring, 112 bunch encounters/revolution, different patterns for ring 1 and 2 October 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 5/7 -No need for this scheme now

6. Variants of the 140 bunches/ring scheme presented on 28 th Sept. 120 bunches/ring variant … if 1 st bunches encounter at point 1 First bunches encounter at point 1 and 5 –Black: collisions –Red and Blue: bunches in ring 1 and 2 not colliding with bunch in other ring 112 bunch encounters for ALICE, CMS and ATLAS October 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 6/7 -No need for this scheme now

7. Summary and Conclusions  New filling scheme with 128 bunches per ring meets all requireements  Abort gap keeper  Bunch 1 collides with Bunch 1 at a point near ALICE (arranged by RF dephasing)  No change to beam dump kicker timing set-up  Provides non-colliding bunches to all 3 experiments  124 bunch encounters for ALICE and 112 for CMS and ATLAS  Need to verify acceptability to experiments October 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 7/7

8. BACKUP SLIDES

9. Appendix: Limitations on Injection Kicker Timings from Abort Gap Keeper Issue raised by J. Wenninger at the LHC-BCWG on 18 th September 2010 with detailed explanations by B. Goddard Aim: make sure that the abort gap cannot be filled accidentally by restricting injection kicker timings LHC injection kickers possibly filling the abort gap are not allowed –Implies minimum distance between first bunch of last batch and first bunch of first batch … value between 11 225 ns and 11 350 ns (precise value could be found if needed) –No restriction for LHC filling with typical proton bunch trains (SPS accumulates 4 PS batches) –A limitation with short ion bunch trains as envisaged for the “EARLY” ion scheme Injection kicker 7.8  s fixed w.r.t. 1 st bunch of batch Dump Kicker 3.0  s Minimum distance between 1 st bunches of last and first batch between 11 225 ns and 11 350 ns 1 st bunch of 1 st batch in bucket 1 1 st bunch of last batch bucket 31 101 o.k, bucket 31 201 not o.k. time or bunch position October 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett