BLM thresholds in the IR5 Q6 region L.S. Esposito and F. Cerutti, - - PowerPoint PPT Presentation

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BLM thresholds in the IR5 Q6 region L.S. Esposito and F. Cerutti, - - PowerPoint PPT Presentation

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BLM thresholds in the IR5 Q6 region L.S. Esposito and F. Cerutti, CERN FLUKA team, EN-STI-EET LHC Collimation Working Group meeting #182, Oct 27, 2014 Summary from previous meetings - 1 with respect to 10 These considerations were first

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SLIDE 1

BLM thresholds in the IR5 Q6 region

L.S. Esposito and F. Cerutti, CERN FLUKA team, EN-STI-EET LHC Collimation Working Group meeting #182, Oct 27, 2014

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SLIDE 2

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Summary from previous meetings - 1

2

with respect to 10 σ These considerations were first verified with respect to collision debris

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SLIDE 3

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Summary from previous meetings - 2

3

Later, the contribution from beam gas (and TCL6 impact on RR electronics) was discussed at Collimation WG #168

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SLIDE 4

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Roman Pot operation and vacuum levels - 1

Gas profile approximated by a rectangular spike of 8 × 1016 H2/m3

  • ver 5 m centered at the RP220m location

The effect of this simple gas spike is limited by construction to the Q6-Q7 region

From these data, it can be concluded that an important pressure gradient is present around RP stations

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SLIDE 5

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Roman Pot operation and vacuum levels - 2

what about vacuum levels?

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SLIDE 6

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Roman Pot operation and vacuum levels - 3

7 10-8 mbar

VGPB.235.6R5.B.PR VGI.77.6R5.B.PR VGPB.2.6R5.B.PR VGPB.4.6R5.B.PR

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SLIDE 7

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Let’s assume that pressure spikes are prevented - 1

impact on Q6 and Q7 from collision debris

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SLIDE 8

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Let’s assume that pressure spikes are prevented - 2

BLM signals from collision debris

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SLIDE 9

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Layout & FLUKA model refreshing - 1

9

Q5 Q6 Q7 DQR RP stations RPT

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SLIDE 10

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Layout & FLUKA model refreshing - 2

10

RPT

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SLIDE 11

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014 11

normalisation is given by #interactions/s = I × ρ × σp-H2 × L where: I = 0.581/e A σp-H2 = 2 × σp-p ≃ 2 × 38.6 mb ρ = 8 × 1016 molecules/m3 L = 5.0 m that gives ~ 1.1 × 107 interactions/s

Back to a pressure spike scenario - 1

impact on Q6 and Q7 from rectangular gas spike centered around FH220m

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SLIDE 12

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014 12

normalisation is given by #interactions/s = I × ρ × σp-H2 × L where: I = 0.581/e A σp-H2 = 2 × σp-p ≃ 2 × 38.6 mb ρ = 8 × 1016 molecules/m3 L = 5.0 m that gives ~ 1.1 × 107 interactions/s

Back to a pressure spike scenario - 2

BLM signals from rectangular gas spike centered around FH220m

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SLIDE 13

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

BLM signals: debris vs pressure spike

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SLIDE 14

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

DS protection by TCL6

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10 σ aperture of the TCL6 external jaw is necessary to protect Q9 This setting reduces the contribution of TCL6 to the impedance budget

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SLIDE 15

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Summary

  • Losses in 2012 and 2011 due to pressure spike induced by RP insertion
  • RP operation not harmful for Q6 and Q7, even with TCL6 open
  • BLM signals expected with 7 TeV beams at nominal lumi as well as in

presence of a pressure spike have been evaluated

  • If TCL6 is closed at 10 sigma, significant increase of the Q6 BLM signal
  • TCL6 protects very effectively the DS, also in case of an asymmetric

aperture

15

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SLIDE 16

Spares

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SLIDE 17

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Contribution from timing RPs - 1

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RPT disk 7.25 cm radius along z, 30 um thick RP rect 12.5 along z, 15 um thick

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SLIDE 18

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Contribution from timing RPs - 2

18

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SLIDE 19

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Comparison 4 TeV vs 7 TeV: debris

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TCL4 helps to reduce the BLM losses along the entire Matching Section

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SLIDE 20

Roman Pots operation and BLM signals

  • F. Cerutti

CWG # 182, Oct 27, 2014

Comparison 4 TeV vs 7 TeV: pressure spike

20

No strong dependence on energy