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T-980 Meeting Dec 3, 2008 Dean Still
Dec 3, 2008 Meeting Agenda n News (Nikolai) n Overview of IHEP goniometer - (Rob) n Simulation for best location of proposed Ver Goniometer. (Sasha) n Results of last EOS studies - (Dean , Valentina) n Plans for next study period (Dean) n PAC paper - author list and subject/abstract (All)
Crystal 2008 Study Plans T-980 has requested 12 -20 hours of EOS to reach the following goals: n Measure channeled, volume-reflected and scattered beams as well as beam losses (radiation levels) downstream of the crystal setup in comparison with simulations n n n n n Measure channeled Measured V. R. region Reliable/ repeatable angles Collimated channeled beam – Similar results to 2005 data. Did not attempt to collimate V. R. beam Compare to simulation –> missing predicted bend angle. Compare to old data - >width of channel is increased & V. R. Efficiencies down 40%. ? ? No understanding of downstream losses ~ 0. Need better instrument at crystal – new pin (maybe gated or new paddles Rick & Todd have ideas) No profile seen (I think or not yet reported) on Flying wire.
Crystal 2008 Study Plans (2) What's happening in the abort gap? (From Rick) How are the rates of channeled beam (E 1 LABT) affected by turning off the T. E. L. A. Instantaneous (rates immediately after turning off) B. After beam accumulates to steady state (~20 min after T. E. L. is off). What happens to the rates (E 1 LABT) when the duty factor of the T. E. L. is increased/decreased? What happens to bunched beam loss rates (E 1 LBNC) when the T. E. L is used to compensate for beam-beam effects? (T. E. L. used during bunches)
Crystal 2008 Study Plans (3) n Demonstrate reproducible beam loss reduction in the B 0 and D 0 in comparison with simulations, aiming at a routine use of the crystal based collimation in the Tevatron stores. n n n Collimated channeled beam. . But No efficiencies at CDF or D 0. Need some more understanding of normal 2 stage efficiencies to compare store to store. Need better understanding of channeling abort gap beam or how to get and detect channeled bunched beam. Effects of TEL are not fully explored. Software is written for automated crystal motion with feedback just need beam testing time. n GOAL SHOULD BE TO GET TO A POINT TO USE CRYSTAL AT BOS - At what point do we consider ready to attempt BOS?
NEXT EOS PLAN n Next EOS should include the following: n Estimate of D 49 to Crystal efficiencies at CDF and D 0. Find optimal setting points for BOS. n Effects of TEL On/Off – but I need someone to give me some projections on TEL and time. n Flying Wire Scans in Abort Gap. n If some conclusion about settings can be made request BOS (sometime in Nov). n Need approval for BOS –when do we get this.
Plan for Nov 20 to be continued to next EOS n Determine if max displacement and max intensity of channeled particles occur at same angle. Probably not because of mis-cut. n Find equal point for E 0 CH and E 03 HCP. n Confirmed feedback for E 0 CH insertion works. n Find equal point for E 0 CH and F 172 HCP. n Collimator using E 03 & F 172 V. R, VCAP, scattered, channeled beam from crystal. n D 49 target vs Crystal. n Flying Wire data in abort gap. n Effect of TEL on the channeled beam.
Normal Collimation Efficiencies Moved E 03 H and D 49 Almost equal E 1 LABT E 03 H 1. 5 mm Ahead of D 49 E 1 LABT E 0 LABT
Effect on Proton Halo Reduction ? ?
Proposed Abstract for PAC 09 n Title: Crystal Collimation Studies at the Tevatron (T-980) n Presenter: A. I. Drozhdin or D. A. Still (whoever going to PAC 09) n Authors: G. E. Annala, A. Apyan, R. A. Carrigan, A. I. Drozhdin, T. R. Johnson, A. Legan, N. V. Mokhov, V. Previtali, R. E. Reilly, V. D. Shiltsev, S. Shiraishi, D. A. Still, R. Tesarek, I. Yazynin, J. Zagel n Abstract Bent-crystal channeling is a technique with a potential to increase the beam-halo collimation efficiency at high-energy colliders. First measurements at the Tevatron in 2005 have shown that using a 5 mm 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. Recent results, obtained with substantially improved goniometer and enhanced beam diagnostics, are reported showing channeling collimation of the ~1 -Te. V circulating proton beam halo at the Tevatron collider. Comprehensive results of computer modeling are presented which allow further developments of the T-980 experiment towards a robust system compatible with requirements to high-efficient collimation at the Tevatron and LHC hadron colliders.