The 2003 Polarized Run - the AGS Story

1. The 2003 Polarized Run - the AGS Story • Team: (Mei, Haixin, Christoph, and Vadim)(also RHIC) +( Kevin, Kip, Nick)(also NSRL), • + ( Leif , Woody, and Steve) +(Operations, rf, …) • First beam (mode switching against Au-d) in late January.  • Then mid February till the end of March mode switching behind RHIC Au-d filling. • Then continue behind P^ in RHIC, with simpler context switch in AGS, but using all four AGS Users. • 40% polarization at G = 46.5 (RHIC injection energy) was achieved “easily” - little polarization-based tuning required – only for Booster G = 4 imperfection.

3. We have a fine source: (Anatoli) 5e11 protons with 75% polarization available from the Linac at 200 MeV for each Booster Batch ( = RHIC fill) This gives us enough beam to allow shaving vigorously in all planes (longitudinal, vertical and horizontal)– to meet RHIC specs and beyond. With this and Zeno’s semi-empirical Booster injection tuning and scraping strategies we typically worked with 6 95% normalized emittance vertically beam in AGS. And also small (12) horizontally.

4. IPM Profiles IPM Profiles

5. IPM Processed Data

6. We have a fine new AGS polarimeter the AGS CNI polarimeter (and a fine older one “E880” for checking):  With the CNI, one measurement at 46.5 takes about 6 minutes for 2.5% error in polarization. That error is fine to learn that systems are working – which is wonderful. However this error is not small enough to do “tuning”. We need at least a factor of 2, but not by taking 4x the time. (however at the retreat Osamu promised x 20 next time if I understood – with a little help.) Pics of some outputs at ggam 46.5 and 18.5

8. We have a model for polarization survival in AGS:  (pic: Haixin’s plot of pol vs energy)

9. We even can imagine filling in the steps:

10. Osamu’s pic from Tuesday (retreat) (Jeff Woods data analysis) “ Up-the-Ramp” measurement. To make this more useful quantitatively we need model of cni polarimeter analyzing power “up the ramp”. To this end we measured at several lower energies during this run, with simultaneous measurements using E880.

12. A significant part of the predicted losses come from resonances made strong by the solenoidal partial snake. The plan is to add a helical warm snake this summer to get rid of this source of coupling. We do have problems – perhaps small perhaps large: Systematic improvement beyond 40% did not occur – we predicted better than 50%. Polarization variation cycle-to-cycle(?) (run #1977 again). More statistics will help. Also data correlation tools. The CNI polarimeter is only partially integrated into the controls system.

13. And there is possibly some intensity dependence to the polarization … which we do not expect

14. So what else to do next? Is the ac dipole strong enough? Ongoing discussion – some interesting data. Something was going sour over the last couple of days of the run. What? (ongoing search). The diagnostics appear to work. We need easier methods for data collection to see. More automated systems for collecting Gauss clock, rf frequency, emittance, ac dipole coherence, … measurements. Transverse emittance was excellent, but can be even better. Measurements of the effect of staying on the injection foil for the long pulse length showed emittance growth (using multiwires in BtA). The foil is optimized for efficiency when we are running high intensity. A thinner foil will be added for polarized running (Depak Raparia , Kip, Keith (Zeno)). The equilibrium orbit tools and the magnet positions in AGS are a bit rusty. Work for the summer – vertical survey and repositioning, bpm survey and data reduction to improve the information coming from this system. Possible AGS sextupole problem (Woody’s measurements). About this we will soon learn.

15. A well-behaved ac dipole pulse (at 0+)