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APEX 2010 – Dynamic Beta* Squeeze

APEX 2010 – Dynamic Beta* Squeeze. G. Robert-Demolaize , M. Bai, , A. Marusic, S. Tepikian. Previous Experiments. The goal is to have an application similar to the one used for orbit correction at store: β * as a function of time should follow the change in emittance as “controlled” by SC.

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APEX 2010 – Dynamic Beta* Squeeze

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  1. APEX 2010–Dynamic Beta* Squeeze G. Robert-Demolaize, M. Bai, , A. Marusic, S. Tepikian

  2. Previous Experiments • The goal is to have an application similar to the one used for orbit correction at store: β* as a function of time should follow the change in emittance as “controlled” by SC. K. Mernick, RHIC Retreat, 7/1/2010

  3. APEX’09 Results • APEX time during Run10 was used to measure the effect of the Beta* squeeze algorithm when used with regular beam. This was done in parallel with M. Bai’s APEX on machine optics measurement. • For practical purposes, it was decided to perform our tests by only squeezing Beta* in one insertion (IR6 in the following). • New Beta* settings would be noticed by changes in ZDC rates, background signal, and ultimately in M. Bai’s measurements. • Strength of algorithm and limitations in online model calculations and activations had to be tested before actual application with an operating stochastic cooling system.

  4. First attempts at new Beta* • Working with the Au104 physics ramp, initial Beta* values are 0.7m at both IP6 and IP8 => try to squeeze to 0.65

  5. First attempts at new Beta* • Working with the Au104 physics ramp, initial Beta* values are 0.7m at both IP6 and IP8 => try to squeeze to 0.65

  6. First attempts at new Beta* • Working with the Au104 physics ramp, initial Beta* values are 0.7m at both IP6 and IP8 => try to squeeze to 0.65m => try 0.675m

  7. First attempts at new Beta* • Working with the Au104 physics ramp, initial Beta* values are 0.7m at both IP6 and IP8 => try to squeeze to 0.65m => try 0.675m

  8. What we learned… • Power supply limit can actually be bypassed by manually changing the ones at fault via Stepstone Editor; need to collect name from error message!!

  9. What we learned… • Power supply limit can actually be bypassed by manually changing the ones at fault via Stepstone Editor; need to collect name from error message!! • Noticeable impact on experimental background and ZDC rates:

  10. Plans for Run11 • Test the online model further to assess: • time constraints depending on squeezing steps; • robustness of script when PS limits are reached. • Main goal: use the effect of SC on emittance changes along a store to increase luminosity by dynamically reducing β* (i.e. keep the ratio ε/β* constant). • This can be done in stages: first a step function, then a fitted exponential (once SC is fully commissioned).

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