Dispersion Suppressor Protection Alexander Krainer CERN May 5th, - - PowerPoint PPT Presentation

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Dispersion Suppressor Protection Alexander Krainer CERN May 5th, 2017 Why is Protection necessary? M. Fiascaris, Rome 2016 from tentative scaling of LHC lossrate about O(70) too high D. Schulte, Rome 2016 Alexander Krainer (CERN) FCC

SLIDE 1

Dispersion Suppressor Protection

Alexander Krainer

CERN

May 5th, 2017

SLIDE 2

Why is Protection necessary?

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 2 / 14

M. Fiascaris,

Rome 2016 from tentative scaling of LHC lossrate about O(70) too high

D. Schulte, Rome 2016

SLIDE 3

Why is Protection necessary?

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 2 / 14

M. Fiascaris,

Rome 2016 from tentative scaling of LHC lossrate about O(70) too high

D. Schulte, Rome 2016

First Sixtrack simulations from last year show high losses in the Dispersion Suppressors

SLIDE 4

Lossmaps with Merlin

Lattice and Optics have changed
Merlin uses a different scattering model for

single diffractive processes than Sixtrack

The model in Sixtrack has been updated
differences in DS losses are now in the order of a

factor 2 (James Molson IPAC17)

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 3 / 14

SLIDE 5

Lossmaps with Merlin

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 4 / 14

109 Particles over 20 turns

SLIDE 6

Lossmaps with Merlin

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 5 / 14

1.99 · 109 Particles over 250 turns

SLIDE 7

Lossmaps with Merlin

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 5 / 14

1.99 · 109 Particles over 250 turns

TCLD Cell 8

SLIDE 8

Lossmaps with Merlin

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 5 / 14

1.99 · 109 Particles over 250 turns

TCLD Cell 8

Summed relative losses on TCLD: 8.898 · 10-5

SLIDE 9

Lossmaps with Merlin

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 5 / 14

1.99 · 109 Particles over 250 turns

TCLD Cell 8

Summed relative losses on TCLD: 8.898 · 10-5 12 min beam lifetime ≈ 1kW total load

SLIDE 10

Geometry for FLUKA simulations

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 6 / 14

1 Meter Collimator

SLIDE 11

Geometry for FLUKA simulations

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 6 / 14

1 Meter Collimator

Material: Inermet 180 Halfgap: 1.3 mm

SLIDE 12

Geometry for FLUKA simulations

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 6 / 14

1 Meter collimator + 50 cm Mask

Material: Inermet 180

SLIDE 13

Geometry for FLUKA simulations

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 6 / 14

1 Meter collimator + 1 Meter collimator + 50 cm Mask

Material: Inermet 180 Halfgap: 2.6 mm

SLIDE 14

Geometry for FLUKA simulations - Magnets

Simplified MQ coil model (based on P. Vedrine, Rome 2016)

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 7 / 14

50%Nb3Sn 50%Cu

SLIDE 15

Geometry for FLUKA simulations - Magnets

Simplified MB coil model (based on V. Marinozzi, Rome 2016)

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 7 / 14

50%Nb3Sn 50%Cu

SLIDE 16

FLUKA simulations

Input distribution is generated from Merlin tracking
Every turn the whole bunch is recorded before the collimator.
Particles which hit the collimator are selected.
This distribution is loaded into FLUKA

and particles are randomly selected from it.

Energy deposition is scored in a meshgrid of bins.
Scoring in the coils with 0.5 cm radial,

2◦ angular and 5 - 10 cm longitudinal binning.

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 8 / 14

SLIDE 17

Energy Deposition - Quadrupole

Maximum Energy deposition in the Quadrupole coils (MQDA.8RJ)

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 9 / 14

5-10 mW /cm3 magnet limits

E. Todesco

SLIDE 18

Energy Deposition - Dipole

Maximum Energy deposition in the Dipole coils (MB.A9RJ)

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 10 / 14

5-10 mW /cm3 magnet limits

E. Todesco

SLIDE 19

Energy Deposition

Merlin and Sixtrack show discrepancies of a factor ∼ 2.

(J. Molson IPAC17) Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 11 / 14

SLIDE 20

Energy Deposition

Maximum Energy deposition in the Quadrupole coils (MQDA.8RJ)

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 11 / 14

5-10 mW /cm3 magnet limits

E. Todesco

Factor 2

(Sixtrack)

SLIDE 21

Energy Deposition

Maximum Energy deposition in the Dipole coils (MB.A9RJ)

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 11 / 14

5-10 mW /cm3 magnet limits

E. Todesco

Factor 2

(Sixtrack)

SLIDE 22

Energy Deposition

Merlin and Sixtrack show discrepancies of a factor ∼ 2.

(J. Molson IPAC17)

Comparisons of simulations and measurements at the LHC show a

factor 2-3 discrepancy.

(R. Bruce et. al. Phys. Rev. ST Accel. Beams 17, 081004 (2014)) Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 11 / 14

SLIDE 23

Energy Deposition

Maximum Energy deposition in the Quadrupole coils (MQDA.8RJ)

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 11 / 14

5-10 mW /cm3 magnet limits

E. Todesco

Factor 4

(Sixtrack + discrepancy)

SLIDE 24

Energy Deposition

Maximum Energy deposition in the Dipole coils (MB.A9RJ)

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 11 / 14

5-10 mW /cm3 magnet limits

E. Todesco

Factor 4

(Sixtrack + discrepancy)

SLIDE 25

Energy Deposition around IP

Energy deposition in the dispersion suppressors after IPA from

collision debris.

Input distribution from H. Rafique.

(H. Rafique, A. Krainer, IPAC17) Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 12 / 14

SLIDE 26

Energy Deposition around IP

Maximum Energy deposition in the Quadrupole coils (MQDA.8RA)

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 12 / 14

5-10 mW /cm3 magnet limits

E. Todesco

SLIDE 27

Conclusion

Combination of updated tracking codes and changes in optics

gives a factor ∼ 5 reduction.

With 2 collimators and masks in cell 8 and 10, even a big

underestimation should not pose a problem.

Losses in the DS after the experiments are easily manageable

with the same system.

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 13 / 14

SLIDE 28

Outlook

Collimator gaps have not been optimized
Not sure if energy collimation hierarchy is violated
Look if this system can be used in other critical places, like injection
Run simulations for cell 10 to show that it is also not a problem

Alexander Krainer (CERN) FCC Collimation Meeting May 5th, 2017 14 / 14