Post on 23-Feb-2016
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LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Motivation for 50 ns rise time injection D.Manglunki, M.Schaumann
with lots of help from Th.Bohl, H.Damerau, J.Jowett
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Outline / Executive summary
Ion upgrade objectives and planning: 10 nb-1 Pb-Pb after LS2
Proposed baseline scenario and parameters: Increase number of bunches while keeping bunch intensities and
emitances constant (lumi burnoff) 50 ns bunch & batch spacing to reach ~1200 bunches/ring
Upgrade options and improvement factors Issues / alternative schemes Any alternatives to 50 ns rise time injection?
(75 ns , 100ns, … 225ns)Conclusion: projections on integrated luminosity
75 ns maximum for 10 nb-1 in Runs 3+4
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Ion upgrade objectives and planning
ALICE Upgrade approved for 50kHz (max 6x1027 cm-2s-1)ECFA High Luminosity LHC Experiments Workshop:
“10 nb-1 Pb-Pb physics run, x10 stats of Run 2”
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Horizontal / VerticalEmittance
Design
Current scheme (2011) & performance (2013)
IntensityDesign
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Assuming no improvement in injectors
Using p-Pb February 2013 performance, and 2011 Pb-Pb luminosity data Extrapolating to 6.5 TeV/c/charge Peak L = 2.3x1027cm-2s-1
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Proposed baseline scenario and parameters:increasing total bunch number
Increase LEIR extracted intensity by ~40% Doubling Linac3 pulsing rate to 10Hz Mitigating LEIR intensity limitation
Implementing new RF gymnastics in PS Splitting followed by batch compression -> 4 bunches spaced by 50 ns
12 (tbc) injections into SPS spaced by 50 ns 2.4 ms train of 48 bunches spaced by 50 ns
26 injections/ring into LHC Taking into account 900ns for Injection Kicker and 3.3 ms abort gap 1248 bunches/ring (factor ~3.4) >20’ filling time per ring on paper
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Proposed Pb-Pb 50 ns scheme for after LS2
LEIR(1.6 109 Pb ions / 3.6 s)
PS batch expansion
SPS at injectionafter 12 transfers from PS, with 50ns batch spacing
LHC at injection,after 26 transfers from SPS
Pb ions / (future) LHC bunch
3 108
2.2 108
1.5 108
2
2
Nb of bunches
4
48
1248
Harmonic number /
Frequency
2
21 – 25-30-36 -42
16 – 14 – 12
200 MHz
400 MHz
6 injections
PS batch compression(50ns bunch spacing)
PS bunch splitting followed by batch expansion(100ns bunch spacing)
4 12-24-21
4 108
4 50ns
50ns
100ns
200ns
50ns
50ns50ns
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
ISSUES: LEIR intensity limitation may not be solved
− Either prevents splitting and forces to keep 2 bunches out of PS, also increasing LHC filling time
− Or results in lower intensity per bunch Nb
RF gymnastics in PS− Batch compression of 4 bunches to 50 ns need additional cavities
− Gymnastics close to transition simulated but not demonstrated
Feasibility of 50 SPS injection kicker rise time (this review) Hence, in parallel to longer injection kicker rise times (75, 100, …, 225 ns), we consider 3 alternative schemes, by decreasing order of resulting number of bunches in LHC:
2 bunches spaced by 50 ns− need batch compression close to transition in PS
− but can be done in one step by 13 MHz cavity for two bunches)
4 bunches spaced by 100 ns− demonstrated, but need LEIR intensity increase, or yields lower Nb
2 bunches spaced by 100 ns− demonstrated in February
For completeness: proposal to study stacking at low energy in PS Vacuum issues Necessitates accel/deceleration between injections
Upgrade options and improvement factors
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection 9
SPS Spacing [ns] PS Spacing [ns] No. Bunches/PS Batch
50 50 or 100 2 (unsplit) or 4 (split)
75 50 or 100 2 or 4
100 50 or 100 2 or 4
225 50 or 100 2 or 4
Intensity scaling:unsplit: = 1.15split: = 0.85
E = 7 Z TeV
No Upgrade100/225nsAfter LS1
50/50nsMax. Luminosity
50/75nsBaseline for after LS2
Upgrade options and improvement factors
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Conclusion: Projections on integrated luminosity
50/50ns spacing: (445h)50/75ns spacing: (365h) Statu quo, 100/225ns spacing: (5h) Assuming ~40 fills/yr, the goal of 10nb-1 can be reached in 6, 7, or 12 years.
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
THANK YOU FOR YOUR ATTENTION!
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Possible Pb-Pb 50/75 ns scheme for after LS2
LEIR(1.6 109 Pb ions / 3.6 s)
PS batch expansion
SPS at injectionafter 12 transfers from PS, with 75ns batch spacing
LHC at injection,after 24 transfers from SPS
Pb ions / (future) LHC bunch
3 108
2.2 108
1.5 108
2
2
Nb of bunches
4
48
1152
Harmonic number /
Frequency
2
21 – 25-30-36 -42
16 – 14 – 12
200 MHz
400 MHz
6 injections
PS batch compression(50ns bunch spacing)
PS bunch splitting followed by batch expansion(100ns bunch spacing)
4 12-24-21
4 108
4 75ns
50ns
100ns
200ns
50ns
75ns50ns
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
12 injections in SPS: intensity scaling
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Optimum number of injections into the SPS(50/75ns)
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Estimates for after LS1 – 2011 Scheme2011 Filling Scheme @ = 6.5Z TeV
= 0.5m = 1.15
Spacing PS [ns] 200
Spacing SPS [ns] 200
No. bunches/PS batch 2
No. PS batches/train 12
No. LHC trains 15
No. bunches/beam 358
E = 6.5 Z TeV
2011 filling scheme with 2013 bunch performance.
Max. peak luminosity
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Estimates for after LS1 – Batch Compression
Batch Compression @ = 6.5Z TeV = 0.5m = 1.15
Spacing PS [ns] 100
Spacing SPS [ns] 225
No. bunches/PS batch 2
No. PS batches/train 7 / 9
No. LHC trains 29 / 24
No. bunches/beam 406 / 432
max. Luminosity
max. Intensity
Max. peak luminosity
Filling schemes are not exact!Takes into account:• Not more than 40% of the SPS is filled.• 3.3μs abort gap.• 900ns LHC kicker gap.• All bunches are colliding with an equal
partner.
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Estimates for after LS1 – OptimisationScheme with max. peak luminosity7 batches & 29 trains = 406 bunches
Scheme similar as in 201112 batches & 18 trains = 432 bunches
• 15% improvement in peak luminosity due to batch compression in the PS.
• Another 10% by shortening the trains.
→ 30% more as for 2011 scheme.
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Estimates for after LS2 – 50/50ns Scheme50/50ns SchemePS Bunch Splitting
@ = 7Z TeV = 0.5m = 1.15
Spacing PS [ns] 50
Spacing SPS [ns] 50
No. bunches/PS batch 2
No. PS batches/train 16
No. LHC trains 35
No. bunches/beam 1120
Option with highest luminosity achievable!
Flat Peak Luminosity Evolution for more than 12 batches/train.
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Estimates for after LS2 – 50/75ns Scheme50/75ns SchemePS Bunch Splitting
@ = 7Z TeV = 0.5m = 0.85
Spacing PS [ns] 50
Spacing SPS [ns] 75
No. bunches/PS batch 4
No. PS batches/train 12
No. LHC trains 24
No. bunches/beam 1152
𝐿𝑝𝑒𝑎𝑘=4×1027 cm− 2 s− 2
Optimal Injection Scheme:10 PS batches, 28 LHC trains→ 1120 bunches/beam
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Luminosity Evolution w/wo SPS Kicker Upgrade
Takes into account different • initial bunch luminosities, • bunch luminosity decay times.
Without any upgrade (black curve):• Almost 50% integrated luminosity
less (after 5h) compared to 50/50ns case.
• 40% less compared to 50/75ns cases.
LIU-SPS Pb Injection System Review - D.Manglunki, M.Schaumann - Motivation for 50 ns rise time injection
Luminosity Evolution w/wo SPS Kicker UpgradePeak luminosity higher for 100ns PS spacing with unsplit bunches.→ Higher brightness bunches decay faster.→ Higher integrated luminosity for 50ns PS
spacing with split bunches.
Peak Luminosity
Integrated Luminosity
50/50ns split → 1200 bunches/beam100/50ns unsplit → 748 bunches/beam
Number of Bunches/Beam