Main Injector Collimation

1. Main Injector Collimation Bruce C. Brown DOE Tevatron Operations Review March 27, 2007

2. Main Injector Collimation - Outline • Beam Loss Measurements • Residual Radiation • Power Loss Calculation – BEL • Loss Monitors • Collimation of Beam from Booster • Collimator Design and Capability • Collimator Commissioning • Collimation of Main Injector Beam • Simulation of Slip Stacking and Losses • Kicker Gap Losses • Out of Bucket Losses • Loss Distribution without Collimation • Collimation Design • Slip Stacking Loss distribution with Collimation • Radiation Effect Considerations • Collimator Design and Schedule 2007 DOE Tevatron Operations Review – Bruce C. Brown

3. Main Injector Radiation Monitoring (June 04 – Oct 05) Monitor Residual Radiation at Beam Pipe with Log Survey Meter Found locations which increased from 50 mR/hr => 2000 mR/hr Identified vertical aperture limitations due to beam pipe sag Developed plan for monitoring. (Oct 05 to present) Bar-Coded 125 locations (emphasizing Lambertson Magnets) Purchased dual-detector survey meter with memory/barcode Use periodic surveys to identify issues, keep levels from rising Added Beam Loss Energy (BEL) monitoring (loss X energy) New Beam Loss Monitor electronics/software for real time measurements. Expect to cross reference to Residual Rad. 2007 DOE Tevatron Operations Review – Bruce C. Brown

4. Collimation Plan for Booster Beam Halo of Beam from Booster create losses (residual radiation) at many Main Injector Locations. Modest collimation of this halo can reduce the number of locations with significant losses (simplify diagnostics of more serious problems). Installed collimator pair at 836 and 838 locations in MI8 line (from Booster to Main Injector). 5 Ton collimators with 2”x2” aperture and precise motion control permits each collimator to define a horizontal and a vertical edge. Pairs are separated by about 90o phase advance. Collimation capacity limited for each pair to 1% of 10 Hz at 5E12 protons per pulse by activation of materials outside of the tunnel. Residual radiation in tunnel shielded by marble shell outside steel absorber. Installed in Spring 2006 shutdown. Commissioning ongoing. Collimating about 0.5% of beam with current settings. 2007 DOE Tevatron Operations Review – Bruce C. Brown

5. MI836 Collimator System 2007 DOE Tevatron Operations Review – Bruce C. Brown

6. MI8 Collimation Effects Study of MI8 Collimation Set collimator positions to scrape ½% of beam at each edge of each collimator (4%nominal = 3.5% observed) • Vertical aperture scan at V301 found 2 mm => 6 mm free • Loss monitors for 30 ms early in cycle. Greatly reduced loss at Lambertson Magnets Beam Loss Monitors All Locations around Ring Black = No Red = Horiz. Blue = Both 2007 DOE Tevatron Operations Review – Bruce C. Brown

7. Main Injector Collimation Efforts High Intensity Operation implies Collimation in Main Injector With best available Booster Beam, Slip-stacking will only accelerate 95% of injected beam because of longitudinal losses. Few percent loss from other mechanisms. Only location with longitudinal space for collimators and radial aperture is MI300 straight – where dispersion is zero. To capture losses of wrong momentum must start with primary collimator (0.25 mm W) in arc and place secondary collimators in MI300 Straight Section. Electron Cooling Straight is nearby – must protect it. Strategy – fill available transverse space – 20 Tons of Steel Simulation Effort: Tracking with STRUCT code to simulate slip-stacking Energy Loss and radiation effects using MARS 2007 DOE Tevatron Operations Review – Bruce C. Brown

8. Collimator Efficiency from STRUCT Loss Simulation: • STRUCT tracking code • Model Slip-stack process • Higher Harmonics using random draw from measured distribution • Orbits observe limits due to MI to RR Transfers Loss Simulation Results: Loss dominated by uncaptured beam (1%dp/p) Localized in MI300 Straight (at right) Pr S1 S2 ECOOL S3 S4 230 301 303 307 309 2007 DOE Tevatron Operations Review – Bruce C. Brown

9. MI300 Collimation Plan Typical Tunnel Cross Section 230 301 303 ECOOL 307 309 2007 DOE Tevatron Operations Review – Bruce C. Brown

10. Main Injector Secondary Collimator Length: 61.5” Width: 48” Stainless Steel Vacuum Liner Steel Absorber Marble Cover 20 Ton Main Injector Secondary Collimator 2007 DOE Tevatron Operations Review – Bruce C. Brown

11. Main Injector Collimation Objectives Beam loss from slip-stacking due to bucket area limitations. Some beam outside of bucket will drift to injection kicker gap. Balance of out-of-bucket beam lost at momentum aperture If not intercepted by primary collimator, will strike Lambertson apertures or experience resonances due to chromatic effects. With collimation, will intercept Primary collimator at 1.7 m dispersion point (MI230) after about 1% acceleration of captured beam. Of particles which strike Primary, >99% simulated to be lost within 250 m collimation region, most into Secondary Coll. Secondary Collimators should contain radiation so that 5% loss can be accepted limited by surface (sump) water concerns. 2007 DOE Tevatron Operations Review – Bruce C. Brown

12. MARS Calculations for the Absorbed Dose in the Collimation Region (Preliminary) 2007 DOE Tevatron Operations Review – Bruce C. Brown

13. MARS Calculation for the Residual Dose in The MI Collimation Region (Preliminary) 2007 DOE Tevatron Operations Review – Bruce C. Brown

14. Status and Schedule STRUCT simulation of losses complete MARS simulation of Secondary demonstrates capability Residual Radiation <100 mr/hr in work areas Surface water (sump) limits observed Other radiation concerns less restrictive MARS simulation of entire region underway to minimize radiation damage to components minimize radiation in ECOOL region Most Parts on order for Secondary collimators Installation planned for Summer 2007 Facility Shutdown 2007 DOE Tevatron Operations Review – Bruce C. Brown

15. MI Collimators – Summary • Residual Radiation Monitoring Ongoing • Incorporating Beam Loss Monitor Upgrade into Operations • Abort on excessive beam loss • MI8 Collimation System in operation • Collimating at 836 and 838 about 0.5% each (1% total) • Loss limit aborts implemented to limit poor Booster beam • Studies at 4% total loss and 10% loss have easily demonstrated benefits to Main Injector Losses • Need more experience with new BLM software to document benefits to Main Injector from current operational settings. • Main Injector System Simulation and Design being finalized. • Main Injector System Simulation and Design being finalized. • Loss Simulation Complete • Preliminary Radiation Assessment for Secondary Complete • MARS simulation for collimation region underway • Secondary Collimator designed, reviewed, parts ordered 2007 DOE Tevatron Operations Review – Bruce C. Brown