LARP Collimator Tasks

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LARP Collimator Tasks
US LHC Accelerator Research Program
BNL - FNAL- LBNL - SLAC

• 6 October 2005
• LARP Collaboration Meeting-St. Charles, IL
• Tom MarkiewiczSLAC

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Four LARP Collimation Program TasksAddress
Efficiency, Reliability and Design of Phase I
Propose a possible solution for Phase II Conundrum

• 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 2
• Understand and improve the design of the tertiary
  collimation system that protects the LHC final
  focusing magnets and experiments
• Responsible Nikolai Mokhov, FNAL Task 3
• 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 Task 1
• Use the facilities and expertise available at BNL
  and FNAL to irradiate and then measure the
  properties of the materials that will be used for
  phase 1 and phase 2 collimator jaws proposed new
  work package
• Responsable Nick Simos, BNL Task 4

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2005-06-01 DOE Review of Collimation Program A

• "The activity in collimation is impressive, with
  the work being approached in a very professional
  manner. It is a critical problem, and solving it
  will have great impact on the ability of the LHC
  to reach design luminosity. Even the task sheets
  for this project were done very professionally,
  lending confidence in a well-managed and
  well-focused activity. (The synergy with the ILC
  is clearly evident here.)"

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Task 2 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
• Resources Required
• 50 postdoc/student supervision travel
• Timescale
• Now until LHC beam commissioning
• Comments
• Preliminary data taken comparison programs being
  improved
• Postdoc search ongoing

5
Task 2 Progress Since Pt. Jeff Meeting

• Guillaume Robert-Demolaize from CERN visited BNL
  for 3 weeks after PAC.
• Special' loss proton data (1 h beam time, 2
  times) taken at 100 GeV and in one ring only
  loss maps with single collimators obtained.
• The newest version of the SixTrack ("colltrack")
  code was copied over from CERN and compiles
  modifications were made to implement the RHIC
  style collimators (dual plane, single sided).
• A first pass on some simulations was made with a
  few hundred turns and a varying number of
  particles (up to a few thousands) and loss maps
  produced which were then compared with the data.
  However quantitative comparison was hindered by
  the necessary debugging required with the new
  code implementation.
• Robert-Demolaize plans to continue to debug the
  RHIC simulation code at CERN and to produce
  simulated loss maps which will then be compared
  with the datasets. It is thought that these
  comparisons may begin in August or September
  after his other CERN responsibilities are
  addressed.

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Tertiary Collimators in IP1/IP5
LARP Collaboration
Fermilab
Nikolai Mokhov, Fermilab

• LARP Collaboration Meeting
• Pheasant Run, St. Charles, IL
• October 5-6, 2005

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TERTIARY COLLIMATORS

• Tertiary collimators at 8.4s around IR1/5 protect
  SC triplets from tertiary halo coming from
  particles leaking from 7s secondary collimators,
  upstream beam-gas and inefficiency of MPS if
  unsynchronized beam abort.
• These TCTs must not induce peak energy deposition
  in the triplets above the quench limit (1.6mW/gm)
  with a safety margin of 3 nor induce detector
  backgrounds at level above IP produced
  backgrounds
• 80 x 25 x 1000mm Cu jaws at .4s 145m from IP
  added to MARS15 Halo gt 8.4s assumed to go as
  1/r operational beam loss rate at TCTV/H assumed
  to be 1E6 p/s

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TERTIARY BEAM HALO LOSS IN IP5
Without TCTs
With Cu TCTH, TCTV
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MARS15 RESULTS FOR COPPER TCTs
Peak power density is 0.35 mW/g in Q3. Particle
fluxes on CMS similar to those from earlier
studied accelerator backgrounds. Conclusion
keep TCT scraping rates below 2x106 p/s.
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TERTIARY COLLIMATORS PROGRESS PLANS

• MARS runs with without TCTs MARS runs with CU
  W TCTs
• File of TCT induced background rays sent to CMS
• File of Beam1 loss in TCT region calculated by
  CERN 7 received 2005-09
• Need similar file for Beam2
• Need similar files for momentum cleaning
  insertion IR3
• Plan to begin updating results using these files
  beginning mid-October

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The LARP Collimation Program
US LHC Accelerator Research Program
BNL - FNAL- LBNL - SLAC

• TASK 4 Summary
• Material Irradiation Studies
• Nick Simos
• Nikolai Mokhov

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Task 4 Irradiation Damage Assessment of LHC
collimator materials

• 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 (117 200 MeV protons)
• FNAL120 GeV protons behind pbar target planned
• Measure material properties thermal expansion,
  mechanical properties, thermal conductivity/diffus
  ivity and thermal shock
• BNL Hot Cell Sample Measurement Facility
• Resources Required
• Irradiation hot cell use fees
• Sample prep, measurement apparatus improvement
• Fraction of postdoc fraction of physicist
  travel
• Timescale
• 2005,2006 proton runs analysis into FY2007
• Status
• Phase I Carbon-Carbon irradiation completed
• Sample activation measurements completed
• Thermal Expansion of specimens started
• PLANNING of FY06 Post-Irradiation and Follow-up
  Irradiation Studies

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C-C samples arrive from CERN supplier and are
assembled and pre-tested before irradiation
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LHC Phase I 2D carbon-carbon samples Irradiated
at BNL, Disassembled, Inspected Dose/sample
measured
Beam Spot during the short 200 MeV Irradiation
at the end of the cycle
Integrated 2D carbon Exposure micro-Amp Hours gt
100,000
Preliminary Assessment 2D CC specimens normal to
the planes of reinforcing fibers and close to the
center of the beam (receiving high dose)
experienced degradation. Less degradation was
seen in the specimens along the
reinforcement. NOTE Total dose received MUCH
HIGHER than what LHC collimator jaws will see.
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LHC Phase I and Phase II Planned Activities

• Irradiation Damage Assessment of 2D Carbon of
  Phase I
• Using the nickel foils of the irradiation
  assembly and deduce exact beam position and
  profile through
• radiographic analysis. These results, combined
  with the exposure record will provide the number
  of
• protons seen by the different specimens.
• USE results for irradiation damage (dpa)
  estimation.
• Refine model for dpa estimation (based on MCNPX
  code and damage cross-sections)
• Isotope generation
• The isotopes generated in the composite will be
  fully assessed.
• Preliminary results show that the predominant is
  Be-7. Such result is important for collimator
  servicing.
• CTE set-up for 250 C thermal Cycling
• Thermal expansion measurements with cyclic
  temperature profile between room temperature
• and 250 degrees C (as requested by LHC collimator
  group.
• Measure effects of irradiation on the coefficient
  of thermal expansion (CTE).
• Upgrade Apparatus to Measure Irradiation Effects
  on
• Thermal Condutivity/Diffusivity
• Electrical Resistivity

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Irradiation Tests at FNAL Pbar Target Area
PRELIMINARY Layout for FNAL Pbar Target
Irradiation
Proposed Target Stack
Beam time free but need to hire/pay for
technician
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Task1 Studies of a Rotatable Metallic
Collimator for Possible Use in LHC Phase II
Collimation System

• If we ALLOW (rare) ASYNCH. BEAM ABORTS to DAMAGE
  METAL JAWS, is it possible to build a ROTATING
  COLLIMATOR
• that we can cool to lt10kW, keeping TltTFRACTURE
  and PH2Olt1 atm.
• that has reasonable collimation system efficiency
• that satisfies mechanical space 25um accuracy
  requirements

• Scope
• Tracking studies to understand efficiency and
  loss maps of any proposed configuration
  (SixTrack)
• Energy deposition studies to understand heat load
  under defined normal conditions damage extent
  in accident (FLUKA MARS)
• Engineering studies for cooling deformation
• Construct 2 prototypes with eventual beam test at
  LHC in 2008
• After technical choice by CERN, engineering
  support
• Commissioning support after installation by CERN

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Status of Phase II Collimator Conceptual
Designat 2005-06-01 DOE Review

• Adequate software in place and MANY studies have
  been done but
• We do NOT yet have a conceptual design for the
  1st of the 11 collimators needed (per beam) in
  IR7
• 28 of 30 Phase II collimators will not have a
  heating problem
• No magic design or material which could
  simultaneously provide good efficiency with
  combination of energy absorption, thermal
  conductivity, thermal expansion to maintain 25
  um flatness tolerance over length of jaw during
  1hr/12min (90/450kW) beam lifetime transients for
  nominal jaw length (1m) and gap setting (7s)
• Focus on
• 150mm O.D. 25mm wall Cu jaws with helical cooling
  tubes
• 150mm O.D. solid Cu jaws cooled with axial flow
  over 36 of arc

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Helical and axial cooling channels
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ANSYS thermal and structural results for full ID
cooling and limited cooling arc showing 64 less
distortion with limited cooling

360 cooling of I.D.
36 cooling arc
Note transverse gradient causes bending
Note axial gradient
61C
89C
Note more swelling than bending
support
dx221 mm Spec 25mm
dx79 mm
64 less distortion
support
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Material evaluations
Material Reasons for rejection in favor of Copper
BeCu Beryllium is forbidden by CERN management, low cleaning efficiency due to few particles absorbed
Super Invar Poor thermal conductivity gt high temperature (866C), exceeding (by 4x) temperature at which the material loses its low thermal expansion coefficient
Inconel 718 Poor thermal conductivity gt high temperature very high deflection (1039 um)
Titanium Poor thermal conductivity gt deflection 2.7 x Cu
2219 Aluminum Relatively poor cleaning efficiency, water channel fabrication difficulty
Tungsten High temperature on water side (207C - 18bar to suppress boiling) high power density - can't transfer without boiling
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Directions under investigation negotiation at
time of 2005-06-01 DOE Review

• Redefine secondary hybrid system to treat 1st
  collimator as special
• Break 1st secondary into two (unequal?) lengths
  of perhaps different materials
• Grooved expansion slots to limit deformation
• Adjust gaps of the first carbon metal secondary
  to reduce heat load while maintaining efficiency
  with remainder of secondary system
• Keep 1st C-C secondary collimators jaws at 7s
  and leave out 1st metal secondary collimator
• Relax deformation tolerance relaxed to if jaws
  expand AWAY from beam
• Begin to deal with LHC infrastructure
  operational constraints
• 45mm jaw gap at injection incompatible with NLC
  inspired circumferentially mounted gap adjustor
• Look into adopting Phase I adjustment mechanism
• Spatial constraints of LHC beam pipes tunnel a
  challenge
• Jaw dimensions, tank dimension

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IR7 Collimator Layout
Primary Collimators
Beam Direction
Hard Hit Secondary Collimators
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Possible Path to Immediate RC1 Prototype Leave
TCS1 Carbon-Carbon, Remainder Cu
Inefficiency   1C-10Cu All Cu
Horizontal 2.84x10-4  3.72x10-4 
Vertical 3.63x10-4   4.36x10-4 
Skew   4.57x10-4     3.85x10-4 
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Mechanical Model 2005-06-01 Used NLC Concept of
Central Strongback with mid-collimator jaw gap
adjuster
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June 15-17 CERN/SLAC Collaboration Meeting

• Attendees
• CERN Ralph Assmann (Project Leader, Tracking),
  Allesandro Bertarelli (Mechanical Eng.), Markus
  Brugger (Radiation Issues), Mario Santana (FLUKA)
  
• SLAC Tom Markiewicz, Eric Doyle (ME), Lew Keller
  (FLUKA), Yunhai Cai (Tracking), Tor Raubenheimer
• Radiation Physics Group Alberto Fasso, Heinz
  Vincke
• Results
• Agreement on basic design of RC1 (1st rotatable
  prototype)
• Transfer of many of CERN mechanical CAD files
• Lists of
• Further studies required
• Outstanding Engineering Issues requiring more
  design work
• Project Milestone List Action Items List
• Test Installation of New FLUKA

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Conceptual Design of RC1 (1 of 2)

• Mechanics must fit within CERN Phase I C-C
  envelope
• 224mm center-to-center with 88mm OD beampipes
• 1480mm longitudinal flange-to-flange
• 25mm adjustment/jaw (22.5mm relative to beam
  w/5mm allowed beam center motion
• and use Phase I alignment and adjustment scheme
• Two 75cm Cu cylindrical jaws with 10cm tapered
  ends, 95cm overall length with axes connected to
  vertical mover shafts
• 136mm OD with 9mm taper
• Each jaw end independently moved in 10um steps
• Vacuum vessel sized to provide 8mm clearance to
  adjacent beam and allow gross/fine 0, 45, 90
  positions
• Relaxed mechanical deformation specifications
• lt25 um INTO beam guaranteed by adjustable
  mechanical stop(s)
• Ride on groove deep enough to not be damaged in
  accident case
• Adjustable between 5 and 15 sigma (2-6mm)
  centered on beam
• lt325 um (750um) AWAY FROM beam _at_ 0.8E1p/s loss
  (4E11p/s)
• Flexible support on adjustment

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Conceptual Design of RC1 (2 of 2)

• Assumed worst case heat load (FLUKA)
• 11.3 kW/jaw steady state, 56.5kW/jaw transient
  (10 sec)
• Cooling boundary conditions
• 200 C maximum temperature of Cu
• 27 C input H2O temperature
• 42 C maximum allowed return H2O temperature
• Two Cooling Schemes under consideration
• Helical tube more secure H2O-vacuum interface
• Axial channels w/ diverter superior thermal
  mechanical performance
• Sufficient pressure (3 atm.) to prevent local
  boiling in transient
• Flexible supply lines to provide 360 rotation
• Other
• Vacuum lt1E-7 Pa (1.3E-5 torr)
• RF shielding scheme has been proposed

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Proposed layout 136mm diameter x 950mm long
jaws, vacuum tank, jaw support mechanism and
support base derived from CERN Phase I
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Vacuum tank enlarged to accommodate jaw motion.
Relative location of opposing beam pipe near
interference in skew orientations 10 deviation
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Helical cooling passages fabrication concept
Based on CERNs design no weld or braze between
water vacuum

• Tube formed as helix, slightly smaller O.D. than
  jaw I.D.
• O.D. of helix wrapped with braze metal shim
• Helix inserted into bore, two ends twisted wrt
  each other to expand, ensure contact
• Fixture (not shown) holds twist during heat cycle

• Variations
• Pitch may vary with length to concentrate cooling
• Two parallel helixes to double flow
• Spacer between coils adds thermal mass, strength
• Electroform jaw body onto coil

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Adjustable central gap-defining stop

• Stop prevents gap closing as jaw bows inward due
  to heat
• Jaw ends spring-loaded to the table assemby
  move outward in response to bowing
• May use two stops to control tilt
• Slot deep enough to avoid damage in accident
• Stop far enough from beam to never be damaged
  is out of way at injection

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Flexible end supports used in conjunction with
central gap-defining mechanism
Adjustable central jaw stops (not shown) define
gap Flexible bearing supports allow jaw thermal
distortion away from beam
Self aligning bearing
Leaf springs allow jaw end motion up to 1mm away
from beam
CERNs jaw support/positioning mechanism. Vacuum
tank, bellows, steppers not shown.
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RF Contact Overview
35
Jaw Support Concept unresolved issues
interferences with RF parts
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Flex cooling supply tube concept
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Detail of flex cooling supply tube
Stub-shaft (bearing not shown)
Contiguous with helical tube inside jaw. Formed
after assembly-brazing of jaw and installation of
bearing on stub-shaft Exits through support shaft
per CERN design Material CuNi10Fe1, 10mm O.D.,
8mm I.D.
Relaxed (as shown) coils 4
Relaxed (as shown) O.D. 111mm (4.4in)
full 360 rotation coils 5
full 360 rotation O.D. 91mm (3.6in)
full 360 rotation torque 9.1N-m (81in-lb)
Support shaft
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Final Expected Performance of RC1 Design
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Outstanding RC1 Unresolved Issues

• Jaw positioning
• Acceptance of estimated deflection by
  CERN281/869um
• Design concept for central stop gap adjust, 5
  central position float,..
• Bearings springs attaching jaws to vertical
  movers
• Load capacity of steppers
• Jaw alignment perpendicular to collimation
  direction
• Jaw rotation
• Specification of mechanism on crowded jaw
• Force required to rotate jaws against cooling
  coil
• Misc
• Spring arrangement for H, V, S orientations
• Springs to ensure that device fails open
• Motors, cables, temperature sensors, position
  probes,
• Cooling
• Possible local boiling in transient condition
  need for P3 atm. H2O system
• More flexible yet vacuum safe water supply for
  helical cooling
• Vacuum safe water connection/diverter for axial
  cooling scheme

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Other Studies Planned

• Tracking Studies Hit maps for each of 11 IR7
  collimators/beam and efficiency with 60cm C-C
  primaries and Cylindrical 75cm jaws which
  includes effect of tertiary collimators and
  absorbers
• FLUKA energy deposition with 60cm primaries
  cylindrical 75 cm jaws Complete self consistent
  package of tracking, FLUKA ANSYS results to
  support design choices unambiguously
• Better definition of RC1 thermal tests
• Remnant Prompt Dose Rate calculations
• Engineer damage assessment mechanism into design
• Thermal shock studies
• Studies/experiments to verify
• assumed extent of damage in accident assume 1mm
  for now
• Where metal slag will wind up
• acceptable peak temperature of jaw assume 200 C
  for now

41
FY2005 Deliverables
RC1 CDR Draft 9/30/05 32 pages figures
Collimator Assembly Test Area (SLAC-ESB)
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FY2006 Work PlanNon-beam Mechanical Thermal
Performance of RC1

• Single jaw thermal test one jaw with internal
  helical cooling channels to be thermally loaded
  for testing the cooling effectiveness and
  measuring thermal deformations.
• Heating by commercial electric resistance heaters
  coupled to the jaw with thermal grease
• Operated in a tank purged with inert gas to
  protect the copper jaw from oxidation.
• Flexible cooling supply that wont be intended to
  allow rotation of the jaw.
• A FE model of the test jaw will be used as a
  benchmark to evaluate the response of the test
  jaw to the test conditions.
• Full RC1 prototype a working prototype for bench
  top testing of the jaw positioning mechanism,
  supported to simulate operation in all necessary
  orientations, but not intended for mounting on
  actual beamline supports with actual beamline,
  cooling, control and instrumentation connections.
  
• Lidded vacuum tank for easy access.
• Cooling water feed-throughs and flexible
  connections as realistic as possible.
• A reasonable effort will be made to test RC1
  under heat loading but this will probably prove
  to be impractical.

43
FY 2006 Deliverables

• Final version of RC1 CDR
• Nov. 1, 2005 ?
• External review of RC1 CDR
• Nov. 14-18, 2005 ?
• Dec 12-17, 2005 ?
• Performance report on RC1
• Sept.30, 2006

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Inter-Lab Collaboration

• Excellent good will cooperation limited only by
  busy work loads on other systems
• Exchange of mechanical drawing files
• Installation of latest FLUKA at SLAC
• Transfer of latest mod to SixTrack
• Latest hit maps with 60cm primaries
• Invaluable 3 day visit by 4 CERN staff
• Monthly video meetings mostly killed
  April-present due to visit, other meetings,
  summer,
• Next video meeting Oct 11, 2005
• CERN review of SLAC draft CDR
• CERN participation in RC1 CDR review
• Exchange of detailed technical information will
  be crucial to delivering prototypes on time
• Drawing of support structures for H, V Skew
• Ideally, CERN would send old prototype parts
  (i.e. everything support structure with
  steppers, motors, bellows, LVDTs, except for
  the tank cylinder jaws) rather than have SLAC
  re-fab from drawings or from transcriptions of
  drawings

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Task 1 Conclusions

• To meet the Jan.1, 2008 RC2 ship date requirement
  SLAC and CERN collaborators have agreed on an
  initial set of specifications for the first
  mechanical prototype RC1
• based on extensive but incomplete studies done to
  date
• consistent with CERN beam mechanical
  constraints which uses Phase I design to
  maximum extent
• RC1 Prototype Conceptual Design, while not 100
  complete, has been written up and serves as a
  start point for construction.
• report to be finalized reviewed in FY2006
• Fabrication of RC1 in two main steps in FY2006,
  with appropriate thermal mechanical tests, should
  validate most of the design issues
• Design extension to RC2, a beam-test-capable
  prototype, will occur in parallel
• Good (but of course could always be better)
  communication and exchange of information marks
  collaboration between labs
• 100 devoted manpower required to ensure success

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Action Items from Session

• Tertiary Collimators
• Prepare a better defined schedule of required
  inputs from CERN and delivered results from MARS
  team
• Radiation Studies
• Specify when results of first irradiation cycle
  will be ready
• Understand financial requirements of both
  continued BNL program and expansion of effort to
  Fermilab 120 GeV area
• Crystal Collimation
• Develop a proposal LARP sponsored RD required to
  incorporate crystal collimation into LHC where,
  when, etc.
• Rotatable Secondary Collimator Prototypes
• Continue work on lists shown at session