the larp collimation program 05 june 2007 larp doe review - fermilab tom markiewicz/slac bnl - fnal-...

The LARP Collimation Program

05 June 2007

LARP DOE Review - Fermilab

Tom Markiewicz/SLAC

BNL - FNAL- LBNL - SLAC

US LHC Accelerator Research Program

LARP DOE Review - 05 June 2007 Collimation Tasks - T. MarkiewiczSlide n° 2 / 55

Four LARP Collimation Program Tasks:Address Efficiency, Reliability and Design of Phase I &

Prototype a possible solution for Phase II

Use RHIC data to benchmark the code used to predict the cleaning efficiency of the LHC collimation system and develop and test algorithms for setting collimator gaps that can be applied at the LHC

Responsible: Angelika Drees, BNL TASK ENDS FY07

Understand and improve the design of the tertiary collimation system that protects the LHC final focusing magnets and experiments

Responsible: Nikolai Mokhov, FNAL TASK ENDS FY07

Study, design, prototype and test collimators that can be dropped into 32 reserved lattice locations as a part of the “Phase II Collimation Upgrade” required if the LHC is to reach its nominal 1E34 luminosity

Responsible: Tom Markiewicz, SLAC

Use the facilities and expertise available at BNL to irradiate and then measure the properties of the materials that will be used for phase 1 and phase 2 collimator jaws

Responsible: Nick Simos, BNL TASK ENDS FY07


Task: Use RHIC Data to Benchmark LHC Tracking Codes

Scope: – Install SixTrackwColl particle tracking code at BNL and configure it to

simulate RHIC performance for both ions and protons.– Take systematic proton and ion data and compare observed beam

loss with predictions– Test (and perhaps help to develop) algorithms proposed for the

automatic set up of a large number of collimators

Status: Guillaume Robert-Demolaize (ex-CERN) hired January 2007 BNL• The tracking tools developed at CERN are now up and runningup and running for RHIC

proton beam simulations.• Even though the tracking code itself is portable and can be used for any

machine, the aperture model is specific to each machine studied=> had to generate one for the RHIC lattice !=> had to generate one for the RHIC lattice !

• While still in its early stages, it is already fully compatible fully compatible with the established tools; some effort is still dedicated in refining it (transition regions, local aperture restrictions…).

• The events selected so far contained enough data for the first enough data for the first preliminary studiespreliminary studies that allowed for debugging of the new functions of the codes


Task 2: Progress Since June 2005 DOE Review

Simulating a horizontal jaw movement

(1)(2)

(1)

(2)

Effect on BLM signal


Task: Model tertiary collimators at the LHC experimental insertions

• Study of betatron collimation and beam-gas debris cleanup by tertiary collimators in IP1 & IP5 complete– Peak energy deposition in IRQ is more than two orders of

magnitude below the quench limits at normal operation and nominal parameters. • Tungsten is noticeably better than copper (1 meter). • Betatron cleaning contribution dominates over beam-gas, esp. for 0.22-

hr beam life time.

– Tertiary collimators noticeably reduce machine backgrounds at small radii (pixels, tracker) and protect these components at beam accidents. • Backgrounds and radiation levels in the CMS and ATLAS detectors are

dominated – at nominal luminosity - by pp-collisions. • Tungsten is better. • There is only a minor effect of TCTs at radii > 1 m.

• .Momentum cleaning and an impact of a single bunch loss on TCT still need to be addressed (need someone to help!).


Neutron (bgas & pp) and Muon Fluxes (bgas) in CMS

With tertiary collimators in

LARP Rotatable Collimators for LHC Phase II Collimation

Representing Gene Anzalone, Eric Doyle, Lew Keller & Steve Lundgren

BNL - FNAL- LBNL - SLAC

US LHC Accelerator Research Program


CERN Collimation Plan & Schedule

0) Assume SLAC LARP develops Rotatable Collimator1) Develop TWO other complementary designs2) Develop a test stand for the three designs3) Fabricate 30 Phase II collimators of chosen design & 6 spares

The target schedule for phase 2 of LHC collimation:2005 Start of phase 2 collimator R&D at SLAC (LARP) with CERN support.2006/7 Start of phase 2 collimator R&D at CERN.2009 Completion of three full phase 2 collimator prototypes at CERN and SLAC.

Prototype qualification in a 450 GeV beam test stand at CERN.2010 Installation of prototypes into the LHC and tests with LHC beam at 7 TeV.

Decision on phase 2 design and production at end of year2011 Production of 36 phase 2 collimators.2012 Installation of 30 phase 2 collimators during the 2010/11 shutdown.

Commissioning of the phase 2 collimation system.LHC ready for nominal and higher intensities.

RED One year slip from recent white paper, “Second Phase LHC Collimators”


June 2006 DOE ReviewIntroduce new jaw-hub-shaft design which

eliminates central stop & flexible springs

x5 improvement in thermal deformation1260 um 236 um (60kW/jaw, 12min) 426 um 84 um (12kW/jaw, t=60min)


Restrain each tube on centerline of bearing

960mm

136mm dia

June 2006 DOE ReviewIntroduce new reverse-bend winding concept for the

cooling coil which eliminates the 3 end loops, permitting longer jaws and freeing up valuable space for jaw supports, rotation mechanism and RF-features

EXTERNAL COIL PERMITS 1 REV OF JAW

Sheet Metal formed RF transition

4-1/2 Turns without failure


Main accomplishments in the last year

• Hundreds of 3-D concept & 2-D manufacturing drawings made

• Rotation & support mechanism fully designed and manufactured

• Many test pieces manufactured and examined, tooling developed, and, especially, brazing protocols worked out

• All parts for first full length jaw assembly manufactured & in-house

• Test lab fully wired, plumbed and equipped


Model showing 42.5 winds of coil on Mandrel with 80mm wide space for U-Bend at downstream end


Comparison of Hollow Moly shaft and Solid Copper Shaft to same FLUKA secondaries: Improved deflections

Solid Cu, 75cm tapered jaw, asymmetric hub

Tubular Moly, 95 cm straight jaw, symmetric hub

Steady State=1 hour

= 12 min for 10 sec

Steady State=1 hour

= 12 min for 10 sec

Gravity sag 200 um 67.5 um

Power absorbed 11.7 kW 58.5 kW 12.9 kW 64.5 kW

Peak Temp. 66.3 °C 197 °C 66 °C 198 °C

Midjaw x 100 um 339 um 83.6 um 236 um

Effective Length 51 cm 25 cm 74 cm 39 cm

Sagitta 221 um 881 um 197 um 781 um


Current Upstream end with actuator and cooling lines


Introduce new Internally actuated drive for rotating after beam abort damages surface

New rotation drive with “Geneva

Mechanism”

NLC Jaw Ratchet MechanismUniversal Joint Drive Axle

Assembly

•Thermal expansion

•Gravity sag

•Differential transverse displacement


Upstream end vertical section

Jaw

Geneva Mechanism

Support Bearings

Worm GearShaft

Water CoolingChannel

U-Joint Axle

Lundgren

1-2mm Gap

Diaphragm


RF Shielding: ONLY PART THAT REMAINS TO BE DESIGNED

Baseline ConceptTie-Rods with Fingers Connect Jaws & Tank

Issues:– At a few 10s of grams per finger (.1 mΩ/contact) force causes

excessive deflection of the tie-rod holding fingers– Cooling required

Discussions with CERN and PeP-II experts in progress

Tie-Rods


Revised RF Spring configuration under consideration

Double Wedge Adapters mountacross Tank ceiling & floor

2 RF springs mount to each Adapter

Jaw facet RF springs mount on Tank ceiling & floor

Shorter length springs also mount to

Tank ceiling & floor

Note: Jaw facet springs are wide enough for line contact thru full transverse travel range


RF Contact Springs for Investigation


BrazeTest #1(shown June 2006)

Cooling Tube

Jaw Center Mandrel

~100 mm

~70 mmdia

~100 mm dia


Aluminum Mandrel for Coil Winding Test and to test 3-axis CNC Mill before cutting 200mm and

950mm Copper Mandrels

200mm

Cooling Tube aligner


Development of Winding Tooling

Vise-Type Roller-Type

Aluminum Mandrel with Coil Wound

Test Winding the 200mm Copper Mandrel


Fabrication of Quarter Jaws for 2nd Braze Test


Final Wind of 200mm Copper Mandrel


First 200mm PrototypeBefore-After Brazing Coil to Mandrel

4 braze cycles were required before part deemed good enough to do jaw braze

Learned a lot about required tolerances of cooling coil and mandrel grooves

Pre-Coil-Braze


More Winding Tooling Developed

1m winding tooling Mill vise as precision bender


1mm raised shoulder (Hub) at center

Full Length Molybdenum Shaft


Braze Test#2 Delivered 19 Dec 2006


Vacuum Bake Test Results: 4/1/07~3x over LHC Spec

1st Jaw Braze Test Assembly has been vacuum baked at 300 degrees C for 32 hours.

•LHC Requirement = 1E-7 Pa = 7.5E-10 Torr•Baseline pressure of Vacuum Test Chamber:

4.3E-7 Pa (3.2E-9 Torr)•Pressure w/ 200mm Jaw Assy. in Test Chamber: 4.9E-7 Pa (3.7E-9 Torr)•Presumed pressure of 200mm lg. Jaw Assy.:

6.0E-8 Pa (4.5E-10 Torr)•Note: above readings were from gauges in the foreline, closer to the pump than to the Test Chamber. Pressures at the part could be higher.

SLAC vacuum group has suggested longitudinal grooves be incorporated into the inner length of jaws; incorporated into next prototype

Next steps: •Use in Moly-Hub cold press fitSectioning & examine braze quality


Aluminum Test Mandrel with 80mm Gap for Downstream U-Bend (11/17/06)


Braze Test #3: 200mm Cu mandrel with U-Bend

Upstream end of mandrelTubing Wound and Tack Welded

to Mandrel at the U-Bend

Note stub ends of cooling tube


Braze Test #3: Coil-mandrel brazed & 8 ¼-round jaws prepped

Next steps: -Braze jaws by mid-June

NB: experience is indicating 20cm long full round jaws may be feasible -Vacuum test? -Section & examine braze quality

After 2 braze cycles, OD & braze wire grooves machined


Fear of Copper-Moly Braze Joint Leads to Mini Devoted R&D Cycle

#1 - Mandrel Dummy#2 - Mo Shaft Dummy#3 - Mo Backing Ring#4 - Cu Hub with braze wire grooves

#2#1

#3

#4

Initial plan to braze one long Mo shaft with raised hub to inner radius of Cu mandrel deemed unworkable

Brazing HALF-LENGTH shafts to a COPPER hub piece and THEN brazing the Cu hub to the Cu mandrel deemed possible

First test if Mo “backing ring” sufficient to keep Mo and Cu in good enough contact for a strong braze joint


Cu-Mo Hub Braze Test Assembly after 3 additional heat cycles (to mimic full assembly procedure) then sectioned. Moly-Cu Joint Declared “Good” by SLAC

Braze Shop Experts, but…..

Small holes held braze wire

•Grain boundary issues?•Possible fracturing?

Samples sliced & polished and sent to Physical Electronics lab for analysis:Fractures evident

Cu-Mo joints we care about

1mm expansion gap


Details of Shaft attachment to the CollimatorInterference Fit versus Improved Braze

Braze Hub improvement includes aflexible Molybdenum end that preventsthe copper Hub stub from pulling awayfrom the Mo.

Copper Jaw is constrained on the outside diameter with Carbon and when heated to ~ 900 degrees C is forced to yield so that upon cooling to ~ 500 degrees C the inner diameter begins to shrink onto the Mo Shaft resulting a substantial interference fit.


Full length Mandrel: In-House & Inspected

– Most groove widths meet specification except for a few at each end.– Positioning of distorted areas could indicate damage was done by

excessive forces imparted by hold down fixturing during machining.– Future Mandrel drawings will include a note warning about potential

damage caused by excessive clamping forces.

out of specification grooves


Exploded view of CAD model of Flex Mount

Triple CogGeneva DriveWheel required for 512 clicks per facet

U-Joint Flexes forShaft “sag” and “Slewing”

Water Cooling Inlet and outlet


Up Beam Flex Mount Assembly showing Ratchet and Actuator


Test Lab Preparation ~Finished

Clean space with gantry access Basic equipment: Granite table, racks,

hand tools Power supplies to drive heaters Chiller & plumbed LCW to cool jaw 480V wiring for heater power supplies

• required engineering review, safety review, and multiple bids (?!)

Acquire Heaters• 5kW resistive heaters from OMEGA

PC & Labview Rudimentary software tests only

National Instruments DAQ with ADCs• Data Acquisition and Control Module• 32-Channel Isothermal Terminal Block• 32-Channel Amplifier

Thermocouples Capacitive Sensors– Vacuum or Nitrogen (?)– Safety Authorization (!!!)

Adjacent 16.5 kW Chiller

Heater Power Supplies staged for installation in rack


CONCERN #1: Still have not brazed nor thermally tested a full length jaw assembly

Main Steps Still Needed• After 200mm Jaw tests Completed Satisfactorily Freeze brazing protocol• Jaw 1/4 sections (16 needed of 24 now at SLAC) require slight

modifications for braze gap requirements. • Moly shaft (at SLAC) will perhaps need to be cut in two pieces and brazed

to copper hub or interference fit made• Drill Cu mandrel for Moly Shaft• Wind coil using in-house SLAC Copper,

– Need to order more (Finland 20 week delivery) OFE 10mm x 10mm or use CERN order of Ni-Cu alloy, anneal & wind mandrel

• Several braze Cycles• Drill jaw to accept resistive heater

– Understand (ANSYS) any change to expected performance


Concern#2: Still do not have a complete mechanical (=“RC1”) prototype

• Successful thermal performance of first full length jaw• Complete the design of RC1 RF features• Fit-up and initial tests of support/rotation mechanism on 1st full length jaw• Complete fabrication of second and third jaws (Glidcop?, Moly??) with

full support assembly on the four corners• Acquisition of Phase I support & mover assemblies

– CERCA/AREVA REFUSES to supply SLAC– Recent (18 APR 07) proposal to sell SLAC a non-functional CERN

TCS collimator with damaged tank & bellows• Remodeling of CERN parts for interface to US parts

– An enlarged vacuum tank has been modeled and some CERN support stand modifications have been identified• No fabrication drawings have been done as yet

• Acquire motors, sensors,.. Not part of CERN TCS purchase


Vacuum tank, jaw positioning mechanism and support base derived from CERN Phase I

beam

beam


Inter-Lab Collaboration

Good will & cooperation limited only by busy work loads– Regular ~monthly video meetings – Many technical exchanges via email– CERN FLUKA team modeling Rotatable Collimator– CERN Engineering team looking at SLAC solid-model of RC and

independently doing ANSYS calculations of thermal shock– CERN physicists

• investigating effects of Cu jaws at various settings on collimation efficiency

• Participating in discussion of RF shielding design

– SLAC Participation in upcoming CERN Phase II brainstorming meeting

– Ralph Assmann to visit SLAC in summer 2007


Examples of CERN Collaboration on SLAC Phase II Design

Luisella Lari

Elias Metral Addressing RF Concerns

Collaboration on ANSYS


Collaboration on Tracking Efficiency StudiesChiara Bracco - CERN

• Phase II collimators should provide x 2.5 improvement in global inefficiency• Beam intensity limitations are due to losses in the dispersion suppressor above the

quench limit. These losses are not improved by metallic secondary collimators• Solutions must be found to improve performance of primary collimators


Resource Loaded Schedule Showing June 2008 for Full RC1


LARP Collimator Delivery Schedule

Done Braze test #1 (short piece) & coil winding procedures/hardware

Prep heaters, chillers, measurement sensors & fixtures, DAQ & lab

Section Braze test #2 (200mm Cu) and examine –apply lessons

Braze test #3 (200mm Cu) – apply lessons learned

Fab/braze 930mm shaft, mandrel, coil & jaw pieces

2007-09-01 1st full length jaw ready for thermal tests

Fab 4 shaft supports with bearings & rotation mechanism

Fab 2nd 930mm jaw as above with final materials (Glidcop) and equip with rf features, cooling features, motors, etc.

Modify 1st jaw or fab a 3rd jaw identical to 2nd jaw, as above

Mount 2 jaws in vacuum vessel with external alignment features

2008-07-01 2 full length jaws with full motion control in vacuum tank available for mechanical & vacuum tests in all orientations (“RC1”)

Modify RC1 as required to meet requirements

2009-01-01 Final prototype (“RC2”) fully operational with final materials, LHC control system-compatible, prototype shipped to CERN to beam test


Phase II Task Summary

There has been continued progress in design and excellent but slow progress on the necessary small scale projects to finalize procedures.

Time estimates for thermal test of first jaw and construction of first 2 jaw prototype (RC1) are expanding. In June 2006 DOE was told

“Expect thermal tests and completely tested RC1 device by end of FY06 and mid-FY07, respectively”

Now need to say:

“Expect thermal tests to begin and completely tested RC1 device by end of FY07 and end-FY08, respectively”

Jeff Smith (Ph.D., Cornell) joins SLAC Collimation team ~July 23, 2007– 25% ILC, 75% LARP


Task #4: Irradiation Damage Assessment of LHC collimator materials: N. Simos

Scope: Irradiate 2-D weave carbon-carbon and exact graphite used in Phase I jaws

plus materials considered viable for Phase II jaws• BNL AGS/BLIP (70 A of 117 & 200 MeV protons)

Measure material properties: thermal expansion, mechanical properties, thermal conductivity/diffusivity and thermal shock

• BNL “Hot Cell” Sample Measurement Facility

Status2005-06: Irradiate 2D-weaved CC composite & measure CTE – DONE 2006-07: Irradiate Cu & Glidcop & measure CTE - DONETo Do: Measurements of Thermal Conductivity & Mechanical Properties

NB1: 2006 exposure included graphite, super-invar, gum metal, Ti Alloy (6Al-4V), Tungsten Tantalum, AlBeMet, Graphite bonded to Cu & Ti

In Progress: neutron exposure of 2006 Phase II collimator materials

Plan: Finish “To Do” & analyze neutron irradiated samples to correlate results with proton irradiated data. In principle will allow for the use of the wealth of radiation data generated from reactor operations

NB2: Nick (not LARP) considers ALL these materials as LHC relevant


CTE Measurements of Irradiated 3D C-C

fluence ~ 1020 protons/cm2

Irradiation Damage Self Anneals through thermal cycling as seen in 2-D C-C


CTE Measurements of Irradiated Copper



CTE Measurements of Irradiated GlidCop



Carbon Composite & Graphite Damage


3-D carbon

2-D carbon

Graphite


Conclusions-Platitudes

The four LARP Collimation program tasks– Provide R&D results to a key LHC subsystem that will need to

perform well from the beginning• Strong support for all tasks from LHC Collimation group

– Play to the unique strengths of the US Labs• RHIC as a testbed

• BNL irradiation test facilities

• Fermilab’s simulation strength

• SLAC’s Linear Collider collimator engineering program


Conclusions-Pessimistic

• No real work has happened at BNL to understand RHIC data until recently. Progress may be made soon, but will analysis of existing RHIC data really add anything to LHC design at this point?

• FNAL Tertiary collimator simulations too little, too late: Main choice (W vs. Cu) made, collimators fabricated & installed. These studies will never be truly over. Is that so bad?

• BNL irradiation studies support 2-D C-C for Phase I (after the fact) and Cu/GLIDCOP for Phase II (after the fact). Not all measurements of relevant physical properties made yet. Part of an ongoing study of encompassing many materials of general academic but not necessarily LHC-relevant interest.

• SLAC team working hard but:– Thermal mechanical tests > 1 year late: what will happen if they do not

deliver performance– Need to start construction of “RC1” at beginning of FY08– Need CERN mover assembly as there is no way we can re-manufacture

so many parts – Need other improvements (to primaries?) to improve quench limit– CERN to provide 2 Phase II secondary collimator designs. What then?

Bonus Slides


Specification Changes Relative to April 2006 Design

RC1 Report 12/12/05 Current spec value value jaw Length 95cm including 10cm end tapers 93cm with 1cm end

tapers Diameter 136mm 20 facets, tangent to

136mm Material Copper Glidcop AL-15 cooling Embedded helical channel Reduced helix depth,

Helix pitch reversal Special features Circumferential slots to reduce

thermal-induced bending, if no RF problems

eliminated

deformation <25um toward beam; <325mm away in steady state; <750um away in 10 sec transient

Inward: 84um SS, 236um Trans – 1st coll to be set at 8.5 for clearance

Range of motion 25mm per jaw, including +/- 5mm beam location drift

27.5 mm per jaw including +/- 5mm

Aperture stop Range of motion Controls aperture from 5-15 sigma (2-6mm full aperture), must float +/- 5mm as jaws are moved to follow beam drift

eliminated

Heat load Steady state 11.3 kW 12.9kW Transient 56.5 kW 64.5kW RF contacts configuration Sheet metal parts subject to

CERN approval New geometry


Heat deposited in major components (W/m^3) in 1 hr beam lifetime operation

Component Units Upbeam Downbeam Stub shaft, aluminum W/m^3 6.5e3 52e3 Bearing, Si3N4 W/m^3 8.3e3 66.4e3 Image current bridge, aluminum W/m^3 150e3 400e3 Mo shaft (~const in z, concentrated in =120o) W 520 Jaw, Glidcop AL-15 (heat highly variable in z and ) kW 12.8


Major jaw dimensions and calculated cooling performance

Component dimension units Jaw OD tangent to 20-faceted surface 136 mm Jaw OD to facet vertices 137.7 mm Jaw ID 66 mm Jaw length, including 10mm (in z) x 15o taper on each end 930 mm Mo Shaft OD 64 mm Mo Shaft ID 44 mm Hub length (centered) 150 mm Cooling tube OD x ID (square x square) 10 x 7 mm Embedded helix – center radius 80 mm Helix – number of turns ~47 - Cooling tube length – helix + entry + exit from vac tank ~16 m Flow per jaw 9 l/min Velocity 3 m/s Water temperature rise (SS 12.8 kW per jaw) 20.3 C Pressure drop 2.4 bar


One Year Later…

At June 2006 DOE Review we introduced• New jaw-hub-shaft design which eliminates central stop & flexible springs• New reverse-bend winding concept for the cooling coil which eliminates

the 3 end loops, permitting longer jaws and freeing up valuable space for jaw supports, rotation mechanism and RF-features

• Internally actuated drive for rotating after beam abort damages surfaceMain accomplishments in the last year• Many test pieces manufactured and examined, tooling developed, and,

especially, brazing protocols worked out• Hundreds of 3-D concept & 2-D manufacturing drawings made • Rotation & support mechanism fully designed and manufactured• All parts for first full length jaw assembly manufactured & in-house• Test lab fully wired, plumbed and equippedBUT…

– Still have not brazed nor thermally tested a full length jaw assembly– Still do not have a complete mechanical (=“RC1”) prototype


Summary of New Baseline Configuration

Jaw consists of a tubular jaw with embedded cooling tubes, a concentric inner shaft joined by a hub located at mid-jaw

– Major thermal jaw deformation away from beam– No centrally located aperture-defining stop– No spring-mounted jaw end supports

Jaw is a 930mm long faceted, 20 sided polygon of GlidcopShorter end taper: 10mm L at 15o (effective length 910mm)Cooling tube is square 10mm Cu w/ 7mm square aperture at depth = 24.5 mmJaw is supported in holder

– jaw rotate-able within holder– jaw/holder is plug-in replacement for Phase I jaw

Nominal aperture setting of FIRST COLLIMATOR as low as 8.5 – Results in minimum aperture > 7 in transient 12 min beam lifetime event

(interactions with first carbon primary TCPV)– Absorbed power relatively insensitive to aperture: for 950mm long jaw

p=12.7kW (7), p=12.4kW (8.23)Auto-retraction not available for some jaw orientationsJaw rotation by means of worm gear/ratchet mechanism “Geneva Mechanism”


Cu-Mo Hub Braze Test parts

#1 - Mandrel Dummy (not shown)#2 - Mo Shaft Dummy#3 - Mo Backing Ring#4 - Cu Hub with braze wire grooves

#2

#3 #4


Up Beam Flex Mount – Rotation Assembly Complete

Design features that may not be apparent in the photos include:– Integral water cooling channel.– Flexibility for length increase of the Collimator Shaft (proton

load). – Compensation for Shaft (in-plane) end angle rotation (sag).– Flexibility for the +/- 1.5mm offsets required during “slewing”.– Does not require an extra drive and control (uses existing

systems).– 2.5mm motions advance the ratchet 1 “click”. – 512 “clicks” advance the Collimator to the next facet.– Facet advancing is ~5% of the lifting load for Vertical

Collimator


PLASTIC DEFORMATION of ENTIRE JAW after a BEAM ABORT ACCIDENT?

PRELIMINARY RESULT:– 0.27 MJ dumped in 200 ns into ANSYS model– Quasi steady state temperature dependent stress-strain

• bilinear isotropic hardening

– Result: • plastic deformation of 208 um after cooling, sagitta ~130um

– Jaw ends deflect toward beam

• Jaw surfaces at 90 to beam impact useable, flat within 5 um

Doyle

54 umBeam side

Far side Melted material removed


Rotatable Collimator Activation & Handling

Need dose rate at ~1m; Mokhov et al


BNL Irradiation (BLIP) and Post-Irradiation Testing Facilities and Set-Up

Layout of multi-material irradiation matrix at BNL BLIP

Test Specimen Assembly

Remotely-operated tensile testing

system in Hot Cell #2

Dilatometer Set-up

In Hot Cell #1


Task #4 Status

Completed:• Phase I Carbon-Carbon irradiation• Sample activation measurements (mCi, dpa)• Thermal Expansion of C-C specimens• Preparation of Phase II material samples

Specimens highly degraded under dose>> LHC collimator jaws will see.


CTE Measurements of Irradiated 2D C-C

Strong (fiber plane) direction

Irradiation Damage Self Anneals through thermal cycling in both strong and weak directions

7.50 mCi

Weak (┴fiber plane) direction

LHC collimator operating temperature regime


Irradiation damage assessment – to date

• While all carbon composites tested (2005-2007) exhibit stability in their thermal expansion coefficient in the temperature range they are expected to operate normally, they experience a dramatic change in their CTE with increased radiation. However they are able to fully reverse the “damage” with thermal annealing

• Carbon composites also showed that with increased proton fluence (> 0.2 10^21 p/cm2) they experience serious structural degradation. This finding was confirmed for the family of such composites and not only for the 2-D composite used in the LHC.

• It was also experimentally shown that under similar conditions, graphite also suffers structurally the same way as the carbon composites

• Proton radiation was shown to not effect the thermal expansion of Copper and Glidcop that are considered for Phase II

• Encouraging results were obtained for super-Invar, Ti-6Al-4V alloy and AlBeMet

In Progress:• Set up of existing tensile test apparatus & test of irradiated C-C• Set up of new thermal conductivity apparatus

the larp collimation program 05 june 2007 larp doe review - fermilab tom markiewicz/slac bnl - fnal-...

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