LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

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LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project
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Transcript of LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Page 1: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

LHC Ring Collimation– Overview –

R. Assmann, AB/ABP

for the LHC Collimation Project

Page 2: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Included in overview• Phases of LHC collimation with timeline

• Completing phase 1 collimation by 2007

– Components with spares

– Budget preliminary estimate and risks

– Manpower

– Schedule 2003/2004

– IR7 layout: optics and cleaning design

– Prototyping and tests

• Radiation and shielding

• Schedule beyond 2004

Page 3: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Main work flowStart of project

Definition of phased approachCollimator specifications for phase 1

System layout(optics, energydeposition, …)

Radiation,collimatorshielding

Collimatormechanical

design

Motors, controlelectronics

Budget

Prototyping, verification with SPS test

Series production

Phase 2 R&Ddesign, production

OCT02

JUL03

MAY-OCT04

2005-2006

Installation, commissioning2006-2007

Page 4: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Logic behind the phased approachNo single collimator solution corresponds to all LHC requirements:

• High robustness (withstand LHC beam)

• Low impedance (don’t disturb LHC beam)

• High efficiency (allow high beam intensities in SC ring)

Conflicting requirements More flexible approach required with specific

sub-systems for achieving nominal and

ultimate performance (hybrid sec. collimators)

Benefiting from natural evolution of LHC beam parameters:

STAGE the design, production & installation of LHC collimators

Phase 1: Compatible with injection&ramping up to ultimate intensities and with

requirements of commissioning and early 7 TeV physics run!

(accepting to run at the impedance limit at 7 TeV, fixed with phase 2)

Page 5: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Timeline for collimation phases

Timeline for phase 1 is on the critical path since start of the project: design,

prototyping, production, installation of a big and challenging system in 4 years.

Phase 1 is being realized…

- with a collimator concept as robust as possible and as simple as possible

- relying as much as possible on available experience

- completed as fast as possible

- for a quite low price

- with 50 × better efficiency than required at other machines (tighter tolerances)

Phased approach gives us room for learning and developing the LHC collimation.

Timeline for different phases extends until 2010/11.

Start phase 2 design early to allow for nominal performance with advanced design (wait until

phase is in series production)!

ID Task Name

1 Project set-up

2 Conceptual design

3 Phase 1

4 Phase 2

5 Phase 3

6 Phase 4 (optional)

Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q12002 2003 2004 2005 2006 2007 2008 2009 2010 2011

(without commissioning of the system – included in project mandate)

Page 6: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Size of system: Maximal 118 collimators installed comparable to LEP system which had 200 blocks!

Ultimate efficiency: With optional “Phase 4” (not required for nominal – to be confirmed for new optics).

Phasing of ring collimators (including spares)

Phase 1, 79

Phase 4, 16

Phase 3, 5

Phase 2, 33

(11 spares)(3 spares)

(1 spare)

(no spares)

Page 7: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Completing Phase 1 collimation by 2007Highest priority: Compatibility with LHC schedule without compromising

the system performance (…too much)(remember: in phase 1 we require 50× advancement in

cleaning efficiency beyond requirements elsewhere)

Strategy: Rely on solutions that worked before with similarmechanical specifications (resisting the temptationto just copy without verifying solutions are OK)! Use to maximum extent LEP solutions (no fancy stuff)

EST leads mechanical design and prototyping (LEP designer) Strong support from AB division for mechanical design See O. Aberle for details…

Reserve sufficient time for experimental tests: jaw materials, vacuum, heating and cooling, flatness, prototype tests (SPS, TT40)

Quality assurance is crucial (0.2 mm deformations over 1m jaw useless secondary collimator factor 10 in allowable intensity easily lost)

Page 8: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Concentrating on design of secondary collimators (TCS): most components and most difficult!

TCS design will serve as basis for TCP, TCSP, TCLP, and TCLI designs!

Collimators for Phase 1 (including spares)

TCP, 11

TCS, 33TCT, 18

TCLI, 5

TCLP, 5

TCSP, 7

(3 spares)

(3 spares)

(2 spares)

(1 spare)

(1 spare)

(1 spare)

Phase 1 is a big system:

• Total 79 components (95 in worst unlikely case).

• Much work overhead:6 different types, not counting different azimuthal orientations for TCS!

Page 9: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Collimation project for Phase 1

• Budget and risks

• Manpower

• Schedule

Page 10: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Budget LHC Collimation – Phase 1 –

Number of components Cost/component Total costmachine spares [kSFr] [kSFr]

TCP 8 3 103 1133TCS 30 3 133 4389TCT 16 2 133 2394TCLI 4 1 133 665TCLP 4 1 133 665TCSP 6 1 63 441General costs 2247Installation/alignm./transp./… 68 5 340

Total 68 11 12274

• Preliminary budget estimate (final estimate only after building prototype).

• Budget was allocated by LHC management (to be put into EVM).

• Prices appear favorable if compared with costs of existing (simpler) designs (SNS).

Page 11: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Budget risks phase 1 The carbon jaws can be fixed on a metallic cooling support with a technique of clamping.

If state-of-the-art techniques (as used for the ITER fusion project) need to be applied significant cost increase would result (on the order of 2-3MSFr).

The cost for motors, electronics, and local control is based on the LEP technology and prices. If this technology cannot be used (e.g. due to higher radiation at LHC) significant cost increase can result.

It is assumed that no local shielding is put at the collimators. Otherwise advanced handling tools for shielding and collimators might be required with a significant increase in budget.

A flexible collimator design is assumed (collimators can be used for any plane), resulting in a minimum number of spares. More spares for less flexible designs would cause an increase in budget.

It is assumed that 5 out of 8 prototypes to be built can be installed into the LHC as collimators. Prototyping cost therefore takes into account only 3 components.

Significant R&D for phase 2 collimators is done by SLAC as part of the US-LHC collaboration (LARP) . Additional budget would be required if this R&D work would need to be performed at CERN.

Production and installation cost for phase 2 and phase 3 collimators is not included. Phase 2 collimators need to be installed after one year of LHC operation. However, the costs of services for phase 2 and 3 are included, as they should be installed for day 1 of LHC (minimizing human intervention in IR3 and IR7).

Page 12: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

0

1

2

3

4

5

6

7

8FTE

Manpower Collimation Project

2003

2004

2003 1.6 4.8 0.5

2004 4.5 8 0.5

HW sim/design/exp proj. management

Manpower: 6.9 FTE (2003) 13.0 FTE (2004)

AB-division: 3.3 FTE (2003) 6.9 FTE (2004)

1.0 from PhDstudent

w/oions

Page 13: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Manpower per group

0

0.5

1

1.5

2

2.5

3

3.5

4

20032004

2003 1.6 1.5 0.2 0 0.3 0.8 1 1 0.7

2004 3.4 1.8 1.2 0.5 0.3 2.4 2 0.7 0.7

AB/ABP AB/ATB AB/CO AB/RF AT/MT EST IHEP TIS/RP TRIUMF

Total: 27 persons involved from 9 groups in 2004

Average FTE/person: 0.3 (2003) 0.5 (2004)

FT

E

Page 14: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Manpower status• We are still building up manpower to tackle the collimation challenge

(almost double in 2004).

• About 50% of manpower from AB.

• Still most resources on simulation/system design:

This illustrates the big challenge of non-trivial beam loss signatures.

2004: Shielding in IR3 and IR7 is a major work challenge (see later).

Still not at all easy to meet deadlines!

• Hardware resources tripling next year (stronger increase than simulation).

Healthy sign: Further increase might be required as we start to produce

hardware!

• Average FTE/person goes from 0.3 to 0.5: Average person works 50% of

its time on collimation! Healthy development! Still struggling with other

priorities!

Page 15: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Schedule• Collimation project not in steady state.

• Schedule must adapt to available manpower, free resources, priorities, encountered difficulties, ….

• No time reserve in schedule.

Emphasis in 2003:

• Put resources together to make quick progress

• Develop a coherent picture of collimation in the LHC rings

• Fix basic technical design parameters (materials, lengths, …)

• First round of new layout in IR3 and IR7

• Get mechanical design going on most difficult collimator

Schedule and tasks defined in detail until end of 2004…

Page 16: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

ID Task Name

1 Project set-up

2 Conceptual design

3 Optics & cleaning design IR7

4 Feedback from AT/VAC, EST/IC

5 Energy deposition IR7: Absorbers

6 ECR IR7

7 Optics & cleaning design IR3

8 Energy deposition IR3: Absorbers

9 ECR IR3

10 Prepare ECR tertiary collimators

11 ECR tertiary collimators

12 Shielding study

13 Decision on shielding design

14 Mechanical pre-design

15 Acquiring&Measuring C samples

16 Mechanical design TCS

17 Drawings TCS jaws

18 Ordering TCS jaw material

19 Motorization/local control

20 Integration into LHC controls

21 Heating/cooling test

22 Prototypes construction

23 Test: Mechanical tolerances

24 Test: Outbaking/Vacuum

25 Test: Mechanical tolerances

26 Test: Impedance

27 Integrate with motorization

28 Integrate local controls

29 Remote control tests

30 Proposal SPS/TT40 test

31 Pre-installation SPS

32 Pre-installation TT40

33 Test installation

34 SPS/TT40 beam tests

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep OctQtr 4, 2002 Qtr 1, 2003 Qtr 2, 2003 Qtr 3, 2003 Qtr 4, 2003 Qtr 1, 2004 Qtr 2, 2004 Qtr 3, 2004 Qtr 4, 2004

Phased approach

LHC layout for phased approach and nominal

performance

Mechanical design for phase 1 TCS collimators

(prototypes for SPS/TT40 test)

SPS/TT40 test

Page 17: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

IR7 layout: Optics and cleaning design

Much larger movements

for collimators!

Goal: Space allocations for secondary collimators (2 beams×16×2m), phase 2 hybrid collimators (2 beams×16×2m) with all upgrade phases.

Keep good cleaning efficiency.

Minimize impedance.

Decision for proposal: Has been taken 14.11.03. Being finalized in optics team.

Quadrupole movements

Page 18: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Space in IR7 "RBEND" "MBW.A6L7.B1" 376.7491258

2TCS + 1TCS = 12m 24.7m

"QUADRUPOLE" "MQWA.E5L7.B1" 405.1216258

"QUADRUPOLE" "MQWA.A5L7.B1" 423.6216258

2TCS + 5TCS = 28m 35.9m

"QUADRUPOLE" "MQWA.E4L7.B1" 463.2116258

"QUADRUPOLE" "MQWA.D4L7.B1" 466.9

1TCS = 4m 5.0m

"QUADRUPOLE" "MQWA.C4L7.B1" 475.6

"QUADRUPOLE" "MQWA.A4L7.B1" 486.7116258

5TCS + 5TCS = 40m 117.3m

"QUADRUPOLE" "MQWA.A4R7.B1" 607.6636258

"QUADRUPOLE" "MQWA.C4R7.B1" 618.8

1TCS = 4m 5.0m

"QUADRUPOLE" "MQWA.D4R7.B1" 627.5

"QUADRUPOLE" "MQWA.E4R7.B1" 631.1636258

5TCS + 2TCS = 28m 35.9m

"QUADRUPOLE" "MQWA.A5R7.B1" 670.7536258

"QUADRUPOLE" "MQWA.E5R7.B1" 689.2536258

1TCS + 2TCS = 12m 24.6m

"RBEND" "MBW.A6R7.B1" 717.6261258

All space included!

40% of space in IR7 reserved for collimation

Sufficient space for correctors, BPM’s, …

Lowest free space between quads: 7.9 m

Lowest free space with collimator in between modules: 1.0m

Dogleg L

Q5 L

Q4 L

Q4 L

Q4R

Q4R

Q5

Dogleg R

Page 19: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Cleaning design IR7

Phase 1 with all collimators: Roughly as good as old system…

Now to be done: Remove collimators from phase 1!

Ultimate reach with Cu hybrids: Factor 3-4 better in inefficiency!

Larger collimator gaps: Expect factor 2-3 gain in impedance!

Target inefficiency

Page 20: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Radiation & collimator shieldingThe LHC management has confirmed its policy to limit environmental impact of LHC operation to less than the low 10Sv/y limit.

This implies that shielding will be installed in IR3/IR7, also on the collimators, if required to achieve this goal (also implementing ventilation changes).

Important trade-off in radiation protection in IR3/7:

Low personnel exposure Low environmental impact

Less shielding More shielding

Detailed shielding studies and proposals middle of next year between TIS/RP, collimation project, vacuum, …!

Just a few slides as a warning!

Page 21: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Collimator tank with motors(~100kg)

Collimator integration without shielding:

Compact dimensions in order to respect inter-beam distance and support various azimuthal orientations:

0˚ 90˚(all angles possible)

Details: O. Aberle

R. Perret, EST

Page 22: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Collimator integration with shielding:

R. Perret, EST

Example of 20cm shielding(illustrative only, no design)

Collimator design for SPS prototypes continues w/oshielding.

Start thinking aboutLHC design now:

• Motors (inside/ouside)• Moving mechanism• Handling tools (crane)

Decide aboutshielding detailsmiddle of next year!(start study Feb04)

Impact on collimator design and insertion layout!(integration)

Next AB project review!?

Page 23: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Prototyping & TestsPrototyping and tests are very important in view of the challenges:

• Build a prototype for every type of collimator!

• Assume 8 prototypes (already for TCS + 1 other overhead).

• Budget assumes that 5 of them can be installed into the LHC!

Biggest challenge tackled first (in terms of tolerances, dimensions, flexibility):

• Secondary collimators TCS with 1.2 m jaw (details O. Aberle).

• Two prototypes to be completed in May 2004 (EST).

• Thorough program of testing and design verification for TCS prototypes:

• Laboratory measurements (see planning)

• Beam measurements (TT40: robustness, SPS: functionality/impedance)

Page 24: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

ID Task Name

1 Project set-up

2 Conceptual design

3 Optics & cleaning design IR7

4 Feedback from AT/VAC, EST/IC

5 Energy deposition IR7: Absorbers

6 ECR IR7

7 Optics & cleaning design IR3

8 Energy deposition IR3: Absorbers

9 ECR IR3

10 Prepare ECR tertiary collimators

11 ECR tertiary collimators

12 Shielding study

13 Decision on shielding design

14 Mechanical pre-design

15 Acquiring&Measuring C samples

16 Mechanical design TCS

17 Drawings TCS jaws

18 Ordering TCS jaw material

19 Motorization/local control

20 Integration into LHC controls

21 Heating/cooling test

22 Prototypes construction

23 Test: Mechanical tolerances

24 Test: Outbaking/Vacuum

25 Test: Mechanical tolerances

26 Test: Impedance

27 Integrate with motorization

28 Integrate local controls

29 Remote control tests

30 Proposal SPS/TT40 test

31 Pre-installation SPS

32 Pre-installation TT40

33 Test installation

34 SPS/TT40 beam tests

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep OctQtr 4, 2002 Qtr 1, 2003 Qtr 2, 2003 Qtr 3, 2003 Qtr 4, 2003 Qtr 1, 2004 Qtr 2, 2004 Qtr 3, 2004 Qtr 4, 2004

Phased approach

LHC layout for phased approach and nominal

performance

Mechanical design for phase 1 TCS collimators

(prototypes for SPS/TT40 test)

SPS/TT40 test

Page 25: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Schedule beyond middle 2004More complete schedule will be prepared in January 2004:1) Mechanical design of TCP, TCSP, TCT, TCLI, TCLP:

Possible after completing design of TCS in 2/04…2) Prototyping beyond the SPS test requirements:

Possible after delivering TCS prototypes in 5/04…3) Feedback from TCS tests, design optimizations

After SPS tests in 11/04…

4) Preparation for series production:Starting in 1/04…

… later in 2004 (knowing about local shielding)…5) Schedule for ordering components, assembly, …6) Schedule of test and quality assurance for series production7) Installation schedule

Still strong uncertainties until end of 2004:• Delivery delays• Assembly and testing• Shielding and additional handling tools

Page 26: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Conclusion• Project for LHC collimation is gathering momentum, relying on good

support from about 9 groups at CERN.

• A path to nominal LHC performance has been defined.

• Project is not in steady state dynamic process (not everything is defined, scheduled, or documented in detail adjust to reality).

• However, documentation in LHC design report…

• Advancing on freezing layout (IR7 optics and cleaning design completed) with good LHC performance reach.

• Advancing on mechanical design and prototyping.

• Detailed work tasks and schedule for 2003/2004 has been defined, including thorough testing without and with beam.

• New budget has been requested and allocated.

• Local shielding imposes risks for changes in design, budget, schedule.

• Next version of schedule (more complete) in Feb2004 and Nov2004?

• We will have a reasonably well performing Phase 1 collimation in 2007, but we cannot (yet) relax!

O. Aberle will present the engineering details…

Page 27: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Collimation projectLeader: R. Assmann

Project engineer: O. AberleOrganization, schedule, budget, milestones, progress monitoring,

design decisions

Project steeringE. Chiaveri report to

AB division(S. Myers, LTC)

LHC project(L. Evans)

Beam aspects R. Assmann, LCWG

System design, optics, efficiency, impedance (calculation, measure-ment), beam impact, tolerances, diffusion,

beam loss, beam tests, beam commissioning, functional specification

(8/03), operational scenarios, support of

operation

Energy deposition, radiation

A. Ferrari (collimator design, ions)

J.B Jeanneret (BLM’s, tuning)

M. Brugger(radiation impact)

FLUKA, Mars studies for energy deposition around the rings. Activation and handling requirements.

Collimator engineering & HW

support O. Aberle

Sen. advice: P. SieversConceptual collimator de-

sign, ANSYS studies, hardware commissioning, support for beam tests,

series production, installation,

maintenance/repair, electronics&local control, phase 2 collimator R&D

Mechanical eng-ineering (EST)Coord.: M. Mayer

Engin.: A. BertarelliSen. designer: R. PerretTechnical specification,

space budget and mecha-nical integration, thermo-mechanical calculations

and tests, collimator mechanical design, prototype testing,

prototype production, drawings for series

production.

Resources/planningR. Assmann, E. Chiaveri,

M. Mayer, J.P. Riunaud

Machine ProtectionR. Schmidt

VacuumM. Jimenez

Beam instrum.B. Dehning

Dump/kickersB. Goddard

Integration into operationM. Lamont

Supply & orderingO. Aberle, A. Bertarelli

Local feedbackJ. Wenninger

ControlsAB/CO

Electronics/radiationT. Wijnands rearranged Aug03

Page 28: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Budget for a TCSItem Quantity Cost/item Total cost

[kSFr] [kSFr]Jaw material (65x45x1200

mm3) 2 5 10

Coating 2 0.6 1.2

Motor (micron stepping motors) 6 1.5 9

Controls + Power supplies 1 13 13

Cables 8 8

Machining (jaws/tank/RF/support/…) 1 50 50

Easy handling equipment 1 10 10

Cooling 10 kW 1 27 27

Sensoring 1 5 5

Total 133.2

Page 29: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

General costsItem Cost

[kSFr]

EST design work 6300 h 321

Prototyping 8 components, 5 into LHC 400

General design studies + tests 250

Vacuum heat treatment 1-2 batches 4

Assembly, testing, bake-out (1 month x 2 people / object) 13.2 FTE (a 50kSFr) 660

Cabling, handling equipment and services in preparation for phases 2 and 3 34 times 18kSFr 612

Total 2247

Page 30: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Manpower 2003 2004

1 AB/ABP R. Assmann 1.0 1.0 sim/design/management2 J.B. Jeanneret 0.3 0.3 sim/design3 E. Metral/L. Vos 0.2 0.1 sim 4 S. Redaelli 0.0 1.0 sim/exp5 D. Schulte 0.1 0.2 sim 6 G. Robert-Demolaize 0.0 0.8 sim/exp

7 AB/ATB O. Aberle 0.8 0.6 HW8 E. Chiaveri 0.1 0.2 management9 F. Dercorvet 0.0 0.5 HW

10 A. Ferrari 0.3 0.3 sim 11 V. Vlachoudis 0.3 0.3 sim

12 AB/CO V. Kain 0.2 0.2 sim/exp13 M. Jonker 0.0 0.2 HW14 F. Carollo 0.0 0.6 HW15 F. Locci 0.0 0.2 HW

16 AB/RF M. Magistris 0.0 0.5 sim

17 AT/MT P. Sievers 0.3 0.3 design

18 EST M. Mayer 0.2 0.5 HW19 A. Bertarelli 0.2 0.5 HW20 R. Perret 0.3 0.9 HW21 L. Favre 0.1 0.5 HW

22 IHEP I. Baishev et al 0.2 0.7 sim23 I. Kouroutchkine 0.4 0.724 Igor 0.2 0.6

25 TIS/RP M. Brugger 0.8 0.5 design/sim26 S. Roesler 0.2 0.2 design/sim

27 TRIUMF D. Kaltchev 0.7 0.7 sim

Sum FTE 6.9 13.1Average FTE/person 0.3 0.5

Details manpower:

excluding ions

Page 31: LHC Ring Collimation – Overview – R. Assmann, AB/ABP for the LHC Collimation Project.

Dose rate for a carbon collimator - One day of coolingAll results are shown in mSv/h.

Collimator Pipe Shield

Tunnel without shield Tunnel with shieldM. Brugger, S. Roesler

1h40m intervention to change a carbon collimator (1 day cooling):1h40m intervention to change a carbon collimator (1 day cooling):

Primary collimator0.7 mSv (unshielded) 10 mSv (shielded)

Secondary coll. 0.07 mSv (unshielded) 1 mSv (shielded)

We do not want shielding at the collimators, if at all possible!We do not want shielding at the collimators, if at all possible!