1. APEX Report March 3, 2010 Fulvia Pilat Time Meeting, March 9, 2010

3. 10 Hz Global Orbit Feedback System First Beam Results R. Michnoff, P. Cerniglia, L. DeSanto, C. Folz, C. Ho, R. Hulsart, A. Jain, Y. Luo, W. MacKay, G. Mahler, W. Meng, K. Mernick, M. Minty, P. Popken, V. Ptitsyn, J. Ritter, P. Thieberger, A. Weston, P. Ziminski

4. Purpose of the System  To provide global orbit correction of the beam perturbations around 10 Hz.  36 BPM measurements and 12 dedicated corrector magnets will be used for each ring Configuration for the first APEX test  Magnets:  3 new steel-laminated core magnets installed in the blue ring on the Q3 vacuum tees at 5, 6, and 7 o’clock  1 air core magnet in the blue ring near the 8 o’clock Q3  1 air core magnet in the blue ring near the 7 o’clock Q3 (used for inducing 10 Hz on beam)  BPM’s:  bi5-bh3, bi5-bh1, bo6-bh1, bo6-bh3, bo7-bh3, bo7-bh1, bi8-bh1, bi8-bh3

5. Typical New Steel Laminated Core Magnet Installed in Ring

6. First Tests: BPM’s  BPM measurements were monitored via GPM using the new BPM data distribution network and ML-510 Xilinx processor hardware  RESULT: all 8 BPM’s displayed expected data micron s 1000 samples at approx 5 ms interval; approx 5 sec period Data read from ML-510 ADOs for: bi5-bh3, bi5-bh1, bo6-bh1, bo6-bh3, bo7-bh3, bo7-bh1, bi8-bh1, bi8-bh3 while exciting beam with 7 o’clock air-core magnet at 10 Hz, +/- 6 Amps

7. First Tests: Magnets  Excited each magnet with 10 Hz, +/- 6 amps, and monitored result with ML-510 BPM data.  RESULT: all magnets modulated beam as expected. microns 1000 samples at approx 5 ms interval; approx 5 sec period 6 o’clock steel magnet turned ON at 10 Hz, +/-6 amps

8. First Tests: feedback  Excited blue beam with 7 o’clock air-core magnet (10 Hz, +/-6 amps), and attempted to close feedback loop.  RESULTS  Clear 10 Hz damping noted when looped closed with 7 o’clock steel magnet only.  Damping not apparent when all 4 corrector magnets were ON. microns Feedback turned ON using 7 o’clock steel magnet only. 1000 samples at approx 5 ms interval; approx 5 sec period 7 o’clock air-core magnet driving beam for full duration of this period (10 Hz, +/- 6 Amps)

9. BBA APEX Todd Satogata, Jordan Ziegler  Objective was to take beam-based alignment measurements of all yellow low-beta Q1/Q3 BPM’ s, sharing beam at injection with 10Hz orbit feedback personnel by splitting WFG managers  Some crosstalk tests from 10Hz orbit feedback slowed us down, but we were still able to debug and get a full data set in yellow  Method: Measure orbit feed-down from quadrupole variation with -6,-4,- 2,0,2,4,6 mm bumps in quad/bpm  One objective is speed: we can get BBA data for each BPM in under 5 minutes, so all 16 IR6/8 planes can be done in 90 minutes  Jordan is working on automated analysis; done by hand now  Request: ~60 minutes at injection in blue to complete blue IR BPMs

10. Mar 5 2010 RHIC BBA APEX10 Some Feb 3 results: bo7-bh1  From Jordan: Consistent with bo7-bh1 BBA offset of about -200 um

11. APEX: Chromaticity Feedback 03/03/10 01/08/10 Marusic, Minty, Tepikian blue ring, ramp chromaticity measurement yellow ring, ramp chromaticity measurement xx yy xx yy QxQx QyQy QxQx QyQy previously: verified data integrity in the both rings (including absence of instrumental sign flips): since then: more chromaticity algorithm improvements code modifications for - interaction with persistent-current compensation - RTDL 23-bit limit APEX 03/03/10: successful demonstration of simultaneous tune, coupling, and chromaticity feedback (at injection energy) xx yy setpoint

12. Effect of yellow tails on blue (E-lens) Montag, Drees Injection: collisions found in STAR but not Phenix Start scraping In yellow Start scraping In yellow Collimators At ~1.7 sigma Collimators At ~1.7 sigma Collimators At ~3 sigma Collimators At ~3 sigma Blue beam decay improves after retracting the collimators That is not great news for the E-lens if confirmed. Need to repeat study at store Blue beam decay improves after retracting the collimators That is not great news for the E-lens if confirmed. Need to repeat study at store

13. 3 rd integer Bai, Marr, Marusic, Minty, Schoefer 11836: 6x6 Chromaticity measurement 11837: 12x12 Chrom changes based on previous. 11838: 23x23 Swing away from resonance 10 seconds early, more chrom changes 11839: 23x56 Blue transition limited, blue transition chrom changes, a few early yellow chrom changes. 11840: 111x111 Lost at t280, blue losses shoot up. 11841: 56x56 Back away blue 0.001, Lost slightly later at t300, same symptoms, just delayed Conclusion: relax beta* on the ramp (will test ramp tomorrow) If viable the final beta* can be squeezed at store.