Motivation for 50 ns rise time injection
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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:

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Outline executive summary

Motivation for 50 ns rise time injection D.Manglunki, M.Schaumannwith lots of help fromTh.Bohl, H.Damerau, J.Jowett


Outline executive summary

Outline / Executive summary

  • Ion upgrade objectives and planning:

    • 10 nb-1Pb-Pb after LS2

  • Proposed baseline scenario and parameters:

    • Increase number of bunches while keeping bunch intensities and emitances constant (lumiburnoff)

    • 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

Ion upgrade objectives and planning

  • ALICE Upgrade approved for 50kHz (max 6x1027 cm-2s-1)

  • ECFA High Luminosity LHC Experiments Workshop:

    • “10 nb-1Pb-Pb physics run, x10 stats of Run 2”


Current scheme 2011 performance 2013

Current scheme (2011) & performance (2013)

Design

Intensity

Design

Horizontal /Vertical

Emittance


Assuming no improvement in injectors

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

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 msabort gap

    • 1248 bunches/ring (factor ~3.4)

    • >20’ filling time per ring on paper


Proposed pb pb 50 ns scheme for after ls2

Nb of bunches

Harmonic number / Frequency

6injections

2

2

16 – 14 – 12

2

4

21 – 25-30-36 -42

200 MHz

48

1248

400 MHz

Proposed Pb-Pb50 ns scheme for after LS2

Pb ions / (future) LHC bunch

LEIR

(1.6 109 Pb ions / 3.6 s)

4 108

200ns

PS batch expansion

100ns

PS bunch splitting followed by batch expansion(100ns bunch spacing)

12-24-21

4

50ns

PS batch compression(50ns bunch spacing)

3 108

4

50ns

50ns

SPS at injectionafter 12 transfers from PS, with 50ns batch spacing

2.2 108

50ns

50ns

LHC at injection,after 26 transfers from SPS

1.5 108


Upgrade options and improvement factors

Upgrade options and improvement factors

  • 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 factors1

Upgrade options and improvement factors

E = 7 Z TeV

Intensity scaling:

unsplit: = 1.15

split: = 0.85

50/50ns

Max. Luminosity

50/75ns

Baseline for after LS2

No Upgrade

100/225ns

After LS1


Conclusion projections on integrated luminosity

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.


Possible pb pb 50 75 ns scheme for after ls2

Nb of bunches

Harmonic number / Frequency

6injections

2

2

16 – 14 – 12

2

4

21 – 25-30-36 -42

200 MHz

48

1152

400 MHz

Possible Pb-Pb 50/75 ns scheme for after LS2

Pb ions / (future) LHC bunch

LEIR

(1.6 109 Pb ions / 3.6 s)

4 108

200ns

PS batch expansion

100ns

PS bunch splitting followed by batch expansion(100ns bunch spacing)

12-24-21

4

50ns

PS batch compression(50ns bunch spacing)

3 108

4

50ns

75ns

SPS at injectionafter 12 transfers from PS, with 75ns batch spacing

2.2 108

50ns

75ns

LHC at injection,after 24 transfers from SPS

1.5 108


12 injections in sps intensity scaling

12 injections in SPS: intensity scaling


Optimum number of injections into the sps 50 75ns

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


Estimates for after ls1 2011 scheme

Estimates for after LS1 – 2011 Scheme

E = 6.5 Z TeV

2011 filling scheme with

2013 bunch performance.

Max. peak luminosity


Estimates for after ls1 batch compression

Estimates for after LS1 – Batch Compression

  • 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.

max. Luminosity

max. Intensity

Max. peak luminosity


Estimates for after ls1 optimisation

Estimates for after LS1 – Optimisation

Scheme with max. peak luminosity

7 batches & 29 trains = 406 bunches

Scheme similar as in 2011

12 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 scheme

Estimates for after LS2 – 50/50ns Scheme

Option with highest luminosity achievable!

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


Estimates for after ls2 50 75ns scheme

Estimates for after LS2 – 50/75ns Scheme

Optimal Injection Scheme:

10 PS batches, 28 LHC trains

→ 1120 bunches/beam


Luminosity evolution w wo sps kicker upgrade

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 upgrade1

Luminosity Evolution w/wo SPS Kicker Upgrade

Peak 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

50/50ns split → 1200 bunches/beam

100/50ns unsplit → 748 bunches/beam

Integrated Luminosity

Number of Bunches/Beam


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