FY 2017 AGS Polarized Proton Run Plan

December 6, 2016

Haixin Huang

 

 

Overview

        Two months before RHIC cool down starts.

o   December 12: Polarized proton beam setup in Booster and AGS. No weekend work, and with Dec. 22-Jan.2 machine shutdown.

o   January 3: Continue polarized proton setup in the AGS.

o   Feb. 8: Finish major work on AGS pp setup.

 

 

Booster Job List

        Setup with dual harmonic RF (h=2 and h=1)as the default setup in the Booster. (Keith)

        With shorter pulse width, move the injection time around at the porch and measure BtA emittance. (Keith)

        Scrape beam at LEBT(35keV) or 750keV(horizontal scraper) so that we still can have 2.5-3E11 intensity at AGS flattop. Check emittance at BtA006 without Booster scraping. (Keith)

        Test matching at LtB with higher current in the last two quads. (Keith)

        Measure BtA emittance as function of source pulse width. (Keith)

        Measure BtA emittance as function of source Rb temperature (with fixed pulse width). (Keith)

AGS Job List

        Setup AGS without cold snake. (Keith)

        Setup AGS with cold snake on the nominal user. (Keith)

        Measure IPM emittance with RF off at flattop as function of source pulse width in both snake and snake-less user. The two user should have similar vertical tune path. First do it with low tune then do it with high tune. (Keith,Vincent, Haixin)

        Set up eIPM at D5 and D15 first at injection, then on the ramp(Roger, Steve) 2 shifts.

        Take ramp polarization measurement with JQ off for JQ timing derivation. This requires probably two nights data taking. (Kin, Andrei, Haixin)

        Horizontal tune jump quads setup. (Vincent, Haixin)

        Injection match study (in conjunction with turn-by-turn eIPM measurement) 1-2 shifts (Vincent,Steve, Roger, Haixin)

        Take ORM data with snake off and on (at injection and flattop). 2-3 seperated shifts (Vincent)

        Measure emittance as function bias HV (down to 5kV). Measure emittance with steps of RF voltages at flattop (to gauge space charge effect). 1-2 shifts

        Measure polarization profiles (JQ on and off), emittance (RF on/off) and beta function at IPM with several flattops at Ggamma=40.5, 31.5, 22.5, 13.5, 7.5.We will start from Ggamma=22.5 one (Caitlin, Vincent, Haixin)

        Take beta function measurement at C5 (and E15 if time allowed) IPM 2-3 shifts(Vincent, Haixin, Caitlin)

        Take beta function measurement at D5 and D15 eIPM (Roger, Steve, Caitlin, Haixin)

        With h=2 in the Booster, scrape AGS late intensity down to 2-2.5*10^11. Compare polarization with h=1 case. (Haixin, Keith)

        With h=1 in the Booster, test injection-on-the-fly on a different AGS user. Measure emittance and polarization at flattop. (Haixin, Freddy, Keith)

        With h=2 in the Booster, scrape AGS late intensity down to 1-1.3*10^11. Merge two bunches at AGS injection on a different AGS user. Measure emittance and polarization at flattop. (Haixin, Kip, Freddy, Keith)

        Check polarization at AGS flattop with different Booster RF setups. 1-2 shifts

        Model comparison data taking. (Francois, Nick)

        AGS BBQ tune meter preliminary study (Matt Paniccia)

        Measure polarization with low intensity but two very different emittances (by mis-steering at injection). The key is to have low intensity so that no beam loss on the ramp. (Haixin)

        Polarization profile (both horizontal and vertical) measurements at Ggamma=45.5 (JQ on/off). 

        Polarization ramp measurement with flattop at Ggamma=45.5. 2-3 shifts ( Kin, Andrei) 

        Calibration of JQ timing (Need to get accurate measurements of frequency and radius. 2-3 shifts (Vincent, Leif) 

        Maintain same high bunch intensity(2.5-3*10^11), scan Booster input intensity and measure emittance and polarization in the AGS. 4-6 shifts  

New Things for This Run

        The preamp boards of D15 eIPM have been replaced.

        A Booster survey has been done in the summer 2015. The booster harmonic corrector settings for optimized polarization transfer may have changed.

        Full sextupole corrector set are installed.

        BBQ system is in the AGS for commissioning.

 

 

Beam Setup Plans

        Machine parameters:

o   ν_x=8.80, ν_y~8.90 at injection.

o   RF parameter: Start with Booster h=1 and h=2 on Booster user4, AGS h=6 on user4.

o   Warm snake current=2670A.(6.7% at injection, 5.9% at extraction).

o   Cold snake helix current=238A and solenoid current=81.2A.

o   AGS rep rate is 6 sec in December and 4 sec next year.

o   The injection and extraction energies: = 4.5 and = 45.5, respectively.


Setup with Both Snakes Off

        Establish beam in the Booster(h=1 and 2) and then the AGS with both snakes off on the nominal user (user4). [1-2 shifts]

        Setup RF to establish beam at flattop. [1-2 shifts]

        Copy the snake off machine to a separate user (user3). [1-2 shifts]

        REV-TICK and Tunemeter setup. The tunemeter is critical to check tunes when snakes are on. As soon as it is done, we should move forward to snake on machine. [0-1 shift]

        CNI polarimeter setup. The setup can start as soon as beam survives at extraction energy. It may take more than two shifts allocated here, but it can be stopped and continue after snake on. Prior to this work, the orbits (both horizontal and vertical) at top energy in C15 section should be set as flat (both in time and angle) as possible. Since the polarimeter setup involves different crew, it can be done in parallel with other activities. [1-2 shifts]

 

Setup with Both Snakes On

        Establish beam in the AGS (injection at =4.5, extraction at = 45.5 with snake on. Start with on-demand mode and intensity of a few E10. Turn on cold snake (helical 238A, solenoid 81.2A,trim1 0A, trim2 7A) and E20 warm snake (2670A). Turn on correction quads and bumps for both snakes. While tuning the injection beam survival(first with rf off, then rf on), the beam dump bump (J10) should be on at injection porch. After reaching a few times 10^10 beam survives, remove the dump bump and tune for beam survival along the ramp. It may be efficient to load archives from last run and get beam circulating first with that setting. [1-2 shifts]

        Commissioning instrumentation if not finished before: AGS tune-meter; IPM. [0-1 shift]

        CNI polarimeter commissioning if not finished yet before. Since the polarimeter setup involves different crew, it can be done in parallel with other activities. [2 shifts].

        Ramp development:

o   Tune the AGS injection to maximize beam survive at injection. Minimize emittances at AGS extraction (judged by IPM with rf off).

o   Correct both horizontal and vertical orbits with iterations.

o   Tune the 8th and 9th harmonics along the ramp.

o   Start with vertical tune around 8.8 along the ramp.

o   Raise vertical tunes along the ramp while tuning the orbit. The vertical tune should be chosen to avoid the higher order snake resonances, especially at 36+ν. The proposed vertical tune values are: 0+ν (~8.98 or higher), 12+ν (~8.97) , 36-ν(8.985) and 36+ν(8.99).

o   Measure polarization at extraction.
[1-2 shifts]

 

        Measure polarization at extraction as function of B field. The field scan should cover = 44.5 to 46. [1-2 shifts]

        Increase intensity from source gradually to the desired intensity. Measure polarization as intensity goes up. [2 shifts]

        Measure polarization at extraction as function of various quantities. There are several potential causes for polarization loss and they need to be scanned. The purpose of these scans are to find the optimum working point, so there is no need to make wide range scan. [2 shifts]

o   Vertical tune not high enough before 0+ν.

o   Vertical tune not high enough at 0+ν (high order snake resonance).

o   Vertical tune not high enough at 36+ν (high order snake resonance).

 

        Harmonics corrections in Booster for both =3 and 4, sine and cosine. This had better to be done at injection for accuracy (step size of 4A). [1-2 shifts]

 

Tune Jump Quads

Measure betatron tune along the ramp with each of the two jump quads on and off. Setup the tune jump quads strength based on the tune measurements. Setup the precise tune jump timing based on the tune measurements and polarization ramp measurement. Center vertical orbit by the feedforward method. [3 shifts] (Vincent, Haixin)

Repeated polarization measurements at =45.5 with jump quads on and off at beam center. [1 shift]

 

AGS pp Operation System Experts


Booster scraping: Keith
BtA lattice: Keith, Nick, Kevin
AGS/Booster optics control application: Kip, Kevin
AGS injection tuning: Keith
AGS RF: Keith, Freddy
AGS tune-meter: Dave Maffie
AGS IPM:Kevin
AGS orbit control and display: Vincent, Keith, Shawn
AGS Jump Quad System: Vincent, Wenge
AGS Ggamma_meter: Vincent
Krisch sheet: Seth
AGS snake operation: Haixin
Snake bumps and corrections: Nick
AGS CNI polarimeter: Kin,Andrei, Haixin
AGS extraction: Vincent, Greg, Nick
AGS lattice matching: Vincent, Francois, Nick