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

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

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

A scheme with 140 bunches/ring Collision pattern (scheduling)

• 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

First bunch(both rings)

Abort gapring 1

Abort gapring 2

LHC-BCWG, 28th September 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 4/6

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 block

1050 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

A scheme with 124 bunches/ring Collision pattern (scheduling)

• 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 First bunch

(both rings)

Abort gapring 1

Abort gapring 2

LHC-BCWG, 28th September 2010 Filling Schemes proposed for the 2010 Ion Run C.Carli and J.Jowett 6/6