AGS Cold Snake Status and Plans 10 05

AGS Cold Snake: Status and Plans 10 -05 -05 Haixin Huang

Operation Plan Start with cold snake at 15% and warm snake at 5%. Polarized source starts operation before Nov. 14. LINAC operation starts on Nov. 14. Source polarization tuning starts around Nov. 20. Booster and AGS beam tuning starts Nov. 21. No operation on Thanksgiving Day. AGS polarization setup starts on Nov. 25. Polarized beam available for RHIC on Dec. 12. Drawback solution: run cold snake only. The second drawback solution: warm snake + AC dipole.

Status of hardware Cold snake cryo: the 3 rd relieve valve was added. The burst disk was moved outside the ring, so a ring access is not needed if a quench happens during operation. Cooling down of the cold snake has started Monday with Nitrogen. It is estimated that it will take three weeks before we can switch to Helium (then it is a matter of days to reach operation temperature). The cold snake correction quads remain to be four, the same as the end of last run, but the inner two quads will have opposite signs. Horizontal sextupoles is ready for higher current to push horizontal chromaticity to zero. Quad P/S fixed to reach 700 A, required to achieve higher vertical tunes at high energies. AC dipole : use revolution frequency instead of a “fixed” frequency.

Quads for Warm Snake We did not have any correction quad for the warm snake last run. We plan to add four quads. Two inner ones are new thin quads and the two outer ones are backleg winding on the existing quads. We need new power supplies, new cables, and new controls. – Cable pulling is expected to be done before Oct. 25. – Start P/S work in the middle of October. – Control group is working on the new application. – New magnets are scheduled to be installed by Nov. 18. P/S test will follow. – The P/S for the outer two quads at warm snake may start without filters.

Simulation and Modeling Build AGS online model to deal with the complicated optical control of AGS after insertion of snakes. (Kevin) Spin tracking of the effect of horizontal resonances. There is already simple model to calculate the horizontal resonance effect. Simulations with more realistic model (with two snakes, synchrotron motion considered) is underway. (Fanglei) Spin tracking of the early part of the energy ramp (with vertical tune ramping the same time). Ideally, the correction strength should scale with 1/p^2. The quad strengths can be optimized for each eneriges, but some strengths are not scaled as expected. Work continues. (Nick, Alfredo, Ernest).

AGS Injection Lattice

AGS CNI Polarimeter Add horizontal target to provide vertical polarization profile. The work will finish later this month. (Alan, Tony) Plan to add 45 degree Si detectors. (Tony, Sandro) All electronics are out for modification and expected to be back in two weeks. (Tony, Sandro) Automatic target scan has been tested succesfully before the hardware is dissembled. (Seth) Upgrade the DAQ to fast readout. (Kin, Jeff, Yuke, Igor [remotely]). – A new PC has been used for the test. – It is a copy of RHIC fast readout but some code change is necessary (AGS uses external clock). – WFD memory test with external clock is a critical test.