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Channeling collimation discussion issues

Channeling collimation discussion issues. Dick Carrigan Fermilab 9th LARP Collaboration Meeting October 17 - 19, 2007 Stanford Linear Accelerator Center. Tevatron channeling projects. E853 – parasitic extraction done in mid nineties – originally in connection with SSC

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Channeling collimation discussion issues

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  1. Channeling collimation discussion issues Dick Carrigan Fermilab 9th LARP Collaboration Meeting October 17 - 19, 2007Stanford Linear Accelerator Center

  2. Tevatron channeling projects • E853 – parasitic extraction done in mid nineties – • originally in connection with SSC • most successful, maybe only successful SSC activity • Politics and operational challenges: • funding, schedule, demise of SSC • tunnel access • Technical challenges: • alignment/goniometer • how to drive parasitic extraction – Peggs, … • stability of loss monitors Channeling collimation 2005 – presentations by Mokhov, Still directed toward LHC important successes – confirms RHIC, shows collimation Operational challenge: running time Technical challenges; alignment/goniometer stability of loss monitors D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

  3. E853 Crystal Extraction at the Tevatron see Carrigan, Mokhov, et al., Phys. Rev. ST Accel. Beams AB 1, 022801 (1998) http://prstab.aps.org/abstract/PRSTAB/v1/i2/e022801 Carrigan, Mokhov, et al., Phys. Rev. ST. Accel. Beams, AB 5, 043501 (2002) http://prst-ab.aps.org/abstract/PRSTAB/v5/i4/e043501 (see these for collaborators) D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

  4. E853 history and goals History – In early 1990s, proposal for an SSC fixed target B flavor experiment. Crystal proposed for extraction. E853 given $100K to test at Tevatron. Used existing C0 dump – not needed at 900 GeV. A location with more dispersion would have helped longitudinal noise excitation • Goals • Extract 106 protons/s with 1012 circulating • Study extraction efficiency • Show luminosity lifetime not affected • Investigate background at CDF and D0 D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

  5. E853 Successes • Extracted significant beams from the Tevatron • parasitic, kicked and RF stimulated • First ever luminosity-driven extraction • Highest energy channeling ever (until recent • Tevatron collimation studies) • Useful collimation studies • Extensive information on • time-dependent behavior • Very robust D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

  6. First crystal extraction at the Tevatron C0 straight section June 6, 1995 (kick mode) D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

  7. E853 Experience Bad: • Interaction counters very sensitive to beam motion <background?> • “Extracted” beams in the 108 - 109 regime need special instrumentation • Beam halo behavior is often non-linear • Lattice location important (RHIC – difficult, Tevatron extraction, collimation better but imperfect) Good: • Crystal extraction works well, robust • Extraction in diffusion modes means crystal collimation can work • Multiple pass works, can take bigger goniometer steps Neutral: • Large variety of time dependent behavior D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

  8. Channeling collimation studies at the Fermilab Tevatron Dean Still, Jerry Anala, Todd Johnson, Robert Reilly, Dwayne Plant, Dick Carrigan, Sasha Drozhdin, Ray Fliller, Nikolai Mokhov, and Vladimir Shiltzev Fermilab D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

  9. Collimator scans for different crystal angles-Mokhov • Channeled beam produces a shoulder 7 + 0.8 mm from the core • The channeled beam should have been ~10.5 mm from the core. • First data set suggested the channeled beam was hitting an aperture. • But on 1/10/2006, after moving the crystal 10mm, new data proved there was no aperture limit. Measured deflection ~ 325 μrad, not 440 μrad. Scatter Channel Reflections Beam probe w/out crystal

  10. E03 data fitted and differentiated Channeling peak is > 50% of deflected beam. Remainder dechanneling? Sigma is twice critical angle, some due to beam divergence. D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

  11. Comments for the discussion paper • Instrumentation • Studies/Experiment • Simulation/theory needs Radiation damage for some other time D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

  12. Instrumentation • What does single particle instrumentation mean? • Need for Roman pots • Reducing “background” in the BLMs. What is “background?” • Reducing fluctuations • Goniometer – need for redundancy, linearity, angular range, …, D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

  13. Studies/Experiment • What is experiment plan (see draft of “Discussion Document”) O shaped vs strip crystal • Strengthening the collimation results • Speeding up measurements, particularly alignment • Should experiment also mirror LHC needs? • Fundamental aligned crystal questions for example - demonstrate that whole arc processes (volume reflection) kicks in opposite direction from channeled D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

  14. Simulation/theory needs • What simulation is needed of alignment curves with crystal bend, length • Simulation of collimator withdrawal curves • Simple parameterization of bend, crystal length D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

  15. Comments? D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

  16. For more accelerator channeling information see: Fermilab - Dean Still’s site: http://www-bdnew.fnal.gov/tevatron/projects/crystal_collimator/index.htm Fermilab channeling home: http://home.fnal.gov/~carrigan/Channeling/Channeling_master.htm Fermilab - Channeling Formulary: http://home.fnal.gov/~carrigan/Channeling/Channeling_formulary.htm Other sites CERN: http://www.fe.infn.it/%7Efiorini/ Serpukhov: http://crystalbeam.narod.ru/ D. Carrigan LARP CM9 Oct. 17-19,2007 SLAC

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