1. 23 April 2012 Tom Markiewicz/SLAC
US LHC Accelerator Research Program
BNL - FNAL- LBNL - SLAC
SLAC RC Introduction for HiRadMat Planning (Material Originally Presented 20 May 2010 to HiRadMat Group)
23 April 2012
Tom Markiewicz/SLAC

2. What is RC?
Two jaw collimator made of Glidcop; same dimensions as Phase I collimator; rotate jaw if beam accident occurs
Each jaw is a cylinder with an embedded brazed cooling coil
No vacuum-water braze
Maximum radius cylinder possible given beam pipe separation
Advantages:
Not exotic material
High Z for efficiency
Low resistance for impedance
Elemental for high radiation resistance
Disadvantages:
Glidcop WILL be damaged in asynchronous beam abort
20 2cm facets provided for 20 presumed rare beam abort accidents
HiRadMat Project Mtg May 2010
RC Intro - T. Markiewicz

3. Jaw Design
HiRadMat Project Mtg May 2010
RC Intro - T. Markiewicz

4. RC Prototype with Apertures Designed for Testing in SPS
beam
HiRadMat Project Mtg May 2010
RC Intro - T. Markiewicz

5. SLAC design details RC-1 Jaw (Glidcop)
RF foils carry image current and shields Rot. Mech.
Tank geometry allows a 60mm
facet-to-facet gap in fully retracted
Jaw position
BPM assemblies at each end are fiducialized to Collimator
RC-0 Jaw (copper)
Ratchet Gear Drive
LHC IR7
Style BPM Buttons
4 per end
Base Plate
Flex Support
Drive Mechanism
Ferrite could
mount to Base
Plate facing Jaw
facet
HiRadMat Project Mtg May 2010
RC Intro - T. Markiewicz

6. Short Status
Collimator mechanism and vacuum/BPM system completed April 2011 Final tests of assembled device revealed that each cooling tune had a vacuum leak After much agonizing. Testing, diagnostics decision made to rebuild the jaws & reuse the vacuum system This work is in progress Finally suite of tests that will be done at CERN will be decided by mutual agreement after the collimator arrives finally at the CERN site
HiRadMat Project Mtg May 2010
RC Intro - T. Markiewicz

7. PRELIMINARY HiRadMat Test Goals
Measure the full extent of the GlidCop collimator jaw that melts and vaporizes as a function of deposited energy
Determine the extent of the molten and vaporized spray released from the surface, how far it travels and how it congeals to the hit surfaces.
Verify that the water cooling circuit survives a beam impact with no water to vacuum leak.
Verify the rotation mechanism will continue to operate after beam impact
Determine if nearby facets will get deposited with molten material from a hit facet.
Measure permanent deformation from beam impact
HiRadMat Project Mtg May 2010
RC Intro - T. Markiewicz

8. Diagnostics SPS RC Prototype has/will have 15 view ports for
visual or camera viewing
Laser micrometers to measure deformation
Eventually plan to open vacuum tank and make metrology measurements on jaws
HiRadMat Project Mtg May 2010
RC Intro - T. Markiewicz

9. One Idea for a Beam Plan
Assume that vacuum vessel cover is sealed adequately for low quality vacuum and that the tank can be easily removed to expose the two Glidcop jaws
O-ring or indium seal and clamps or equivalent?
After jaw alignment with pilot bunches, inflict multiple beam strikes of differing total beam energy on 20 facets spanning damage threshold
Hit Jaw AC with 10 weakest beam strikes 0-1 Megajoule
Rotate AC 2 facets after each strike
Rotate BD 2 facets after each strike
BD is 7 sigma – 3mm from AC
BD face is witness for damage for beam strike on AC
Hit Jaw BD with 10 most intense beam strikes 1-2 Megajoule
Use unused facets on each jaw
Now AC unused facets are witness facets for the BD beam strikes
Test water pipes while under pressure and rotation drive survivability
Jaws will have twisted 2x 360° under suggested test program
After beam test and radiation cool-down
Remove vacuum tank cover
Visual inspection and quantification of damage pattern on each struck facet and on each corresponding facet on the adjacent jaw
HiRadMat Project Mtg May 2010
RC Intro - T. Markiewicz