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TOWARDS CONTINUOUS RUNNINIG WITH THE CRYSTAL IN THE TEVATRON BEAM

Fermilab. Accelerator Physics Center. TOWARDS CONTINUOUS RUNNINIG WITH THE CRYSTAL IN THE TEVATRON BEAM. T-980 Review Fermilab, Batavia, IL February 4, 2009. Nikolai Mokhov Fermilab. Crystal Collimation.

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TOWARDS CONTINUOUS RUNNINIG WITH THE CRYSTAL IN THE TEVATRON BEAM

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  1. Fermilab Accelerator Physics Center TOWARDS CONTINUOUS RUNNINIG WITH THE CRYSTAL IN THE TEVATRON BEAM T-980 Review Fermilab, Batavia, IL February 4, 2009 Nikolai Mokhov Fermilab

  2. Crystal Collimation Bent-crystal channeling is a technique with a potential to increase the beam-halo collimation efficiency at high-energy colliders. Theoretical studies in early 90s and measurements at the Tevatron in 2005 have shown that using a thin silicon crystal to deflect the proton beam halo onto a secondary collimator improves the system performance by reducing the machine impedance, beam losses in the collider detectors and irradiation of the superconducting magnets, all in agreement with simulations. Continuous Running with the Crystal - N.V. Mokhov

  3. End-of-Store Studies since September 2008 Blessed by this Committee on August 7, 2008, substantially improved goniometer, characterized crystal and enhanced beam diagnostics (T-980 experiment) have been installed last September in the E0 straight section of the Tevatron in order to test the feasibility of collimating the proton beam using the crystal. The outcome of several End-of-Store studies (EOS) since then is quite positive, Dean will highlight the main results of EOS in his talk. We are now confident that the crystal-based collimation at E0 behaves as it should. Therefore, we are proposing to start using this system in the Tevatron collider runs continuously. Continuous Running with the Crystal - N.V. Mokhov

  4. E0 Crystal Collimation Layout LE033 BLM 23.731 m Channeled beam At E03H 3.5 mm crystal channeled beam Flying Wire Pin Diode E03H Collimator 23.731 m 33.115 m Continuous Running with the Crystal - N.V. Mokhov

  5. Multi-Turn Simulations with 0.44-mrad O-shaped Crystal All collimators are in working positions Total losses on E03 and F172 via channeling, VR and MCS. Channeled beam loss on E03 Edge-scattered in E03 and F172, x 5 Loss at B0, x 140 Clearly seen in 2005 measurements. Reproducible, but not so clean signal in refined 2008 studies. Continuous Running with the Crystal - N.V. Mokhov

  6. Beam Loss Localization vs Crystal Angle Scan Theory Data Continuous Running with the Crystal - N.V. Mokhov

  7. Beam Loss Localization vs E03 Position Channeling improves localization! Other collimator positions need to be tuned for the crystal collimation! We desperately need a test at a Beginning-of-Store (BOS), with a better beam and the entire system tuned to the crystal mode Continuous Running with the Crystal - N.V. Mokhov

  8. Summary The purpose of Sep. 08 Review was to assess the overall risk of the T-980 installation and beam tests with respect to the impact on the Fermilab Collider program. EOS results – reproducibility, hardware/diagnostics tests, all main features of crystal collimation and a minimal impact on the Collider program – assure that we are ready for a BOS test. With your blessing, after a successful BOS, we can start routine use of the crystal in collider stores aiming at reproducible beam loss reduction in B0 and D0 as well as in the entire ring (in comparison with simulations). Continuous Running with the Crystal - N.V. Mokhov

  9. Continuous Running with the Crystal - N.V. Mokhov

  10. Impact on CDF/D0 • Benefit to CDF/D0: at least a factor of 2 reduction in beam loss (2005 data). Can be a more substantial reduction with new crystals and other hardware of (> June 2009). • Possibly another crystal at F49 to reduce pbar losses in CDF/D0. • Maximum possible luminosity loss in Phase I: 20 hrs, or 4.3 pb-1 out of 1300 pb-1/yr, or 0.33% (compared to 0.68% difference in CDF and D0 luminosities). • Nothing happens if the crystal doesn’t channel (Dec. 2007 results). • Minimal risk to the silicon: only the target at E0 is retracted, nothing else moves. • Effect or risk to CDF/D0 with crystal collimator for full store (BOS) (i) crystal works: losses reduced via efficient scraping; • (ii) crystal doesn’t work: re-insert tungsten target, loose small amount of luminosity at beginning of store (10 minutes), beam losses the same. Continuous Running with the Crystal - N.V. Mokhov

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