outline / executive summary

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


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


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”


Horizontal / VerticalEmittance

Design

Current scheme (2011) & performance (2013)

IntensityDesign


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


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


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


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


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.


THANK YOU FOR YOUR ATTENTION!


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


12 injections in SPS: intensity scaling


Optimum number of injections into the SPS(50/75ns)


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


Estimates for after LS1 – Batch Compression

Batch Compression @ = 6.5Z TeV = 0.5m = 1.15

Spacing PS [ns] 100

Spacing SPS [ns] 225


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.


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.


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. LHC trains 35


Option with highest luminosity achievable!

Flat Peak Luminosity Evolution for more than 12 batches/train.


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. LHC trains 24


𝐿𝑝𝑒𝑎𝑘=4×1027 cm− 2 s− 2

Optimal Injection Scheme:10 PS batches, 28 LHC trains→ 1120 bunches/beam


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.


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

outline / executive summary

Documents

time injection d

pbpb physics

time injection issues

sps injection kicker

ns scheme

ns batch spacinglhc

schaumann motivation

bunch intensities