Filling Schemes proposed for the 2010 Heavy Ion Run

1. Filling Schemes proposed for the 2010 Heavy Ion Run Content Introduction A scheme with 140 bunches/ring (minimum spacing 500 ns) Filling scheme and pattern Collision pattern (scheduling) A scheme with 124 bunches/ring (minimum spacing 600 ns) Filling scheme and pattern Collision pattern (scheduling) Summary and Conclusions Alternative filling schemes to increase Luminosity … adaptations of EARLY scheme Increase of (minimum) filling time to ~7 mins/ring Further steps (if decision to in increase the number of LHC ion bunches in 2010): Which scheme to be used … may-be further variant to be studied? Discuss with relevant SPS and LHC (RF, BI, machine protection …?) experts LHC-BCWG, 28th September 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 1/6

2. Introduction • EARLY scheme adopted in 2003 for the first ion run(s): • Luminosity 5×1025 cm-2 s-1 (instead of NOMINAL 1027 cm-2 s-1) • Running conditions (b*=3.5 m instead of 1.0 m and half the design energy): • Further drop of the luminosity to ~0.7×1025 cm-2 s-1 • Compensate partly by increasing (roughly doubling for the schemes presented here) the number of bunches • “Only” adaptation of the EARLY scheme • No variants of the NOMINAL scheme proposed … keep it simple • 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 data request non-colliding bunches LHC-BCWG, 28th September 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 2/6

3. A scheme with 140 bunches/ring Filling scheme and pattern Very regular filling pattern (is this a real advantage?): • Basic building block - SPS accumulates 4 bunches (1 per transfer from PS) spaced by 500 ns - 975 ns for LHC injection kicker - total duration: 2475 ns or 99 “25ns positions” • 35 times this basic building block (36 times would fill an LHC ring 36*99 = 3564) • longer gap for the dump kicker LHC-BCWG, 28th September 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 3/6

4. A scheme with 140 bunches/ring Collision pattern (scheduling) Abort gap ring 2 First bunch (both rings) Abort gap ring 1 • First bunches of trains must NOT encounter at one of the IPs (to have non colliding bunches) • Collision patterns, if first bunches encounter (just an example) at point 7 • Black: collisions • Red and Blue: bunches in ring 1 and 2 not colliding with bunch in other ring LHC-BCWG, 28th September 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 4/6

5. A scheme with 124 bunches/ring Filling scheme and pattern • Basic building block: • Four bunches spaced by 600 ns • LHC injection kicker 975 ns • Total duration: 2775 ns or 111x25 ns • Filling of one regular quarter: • Eight of above blocks plus 75 ns (increase spacing to 1050 ns • Abort gap: for one quarter leave one building block1050 ns + 2775 ns = 3825 ns LHC-BCWG, 28th September 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 5/6

6. A scheme with 124 bunches/ring Collision pattern (scheduling) Abort gap ring 2 First bunch (both rings) Abort gap ring 1 • First bunches (again) of trains must NOT encounter at one of the exps (to have non colliding bunches) • Collision patterns, if first bunches encounter (e.g.) at point 6 • Black: collisions • Red and Blue: bunches in ring 1 and 2 not colliding with bunch in other ring LHC-BCWG, 28th September 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 6/6