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

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 - 20 May 2010 RC Intro - T. Markiewicz

Jaw Design HiRadMat Project Mtg - 20 May 2010 RC Intro - T. Markiewicz

RC Prototype with Apertures Designed for Testing in SPS beam HiRadMat Project Mtg - 20 May 2010 RC Intro - T. Markiewicz

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 - 20 May 2010 RC Intro - T. Markiewicz

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 2011-03-16 HiRadMat Project Mtg - 20 May 2010 RC Intro - T. Markiewicz

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 - 20 May 2010 RC Intro - T. Markiewicz

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 - 20 May 2010 RC Intro - T. Markiewicz

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 - 20 May 2010 RC Intro - T. Markiewicz