Guidance for electron cooling

Guidance for Electron Cooling

Updated 05/01/08

Acnet pages that will be needed:

a) R117 Operation subpage 1

b) E48 ECooling sequencer

The current nominal D1 save file is file #884.

For any questions/problems, consult the On-call person.

Addendum to the Electron Cooling Procedure (to be used if there are Pelletron temperature problems), by L. Prost, July 5, 2006.

For the more experienced Operator (more detailed description below):

1. Note in Recycler Logbook that you have begun cooling for the shot.

2. Start Recycler beam and cooling plot (saved under Utilities window, FTP, Electron Cooling file #22).

3. Open E48 Sequencer.

a) Look at R117 Operations subpage 1. If ECool beam is not running (R:DCCT=0), run the aggregate “Turn beam on for ecooling”.

b) If ECool beam is running (R:DCCT=-0.1), run the aggregate “Shift Beam in Cooling Section” with a desired final position of at least +3.0 (3mm) to begin cooling. As more cooling is needed, re-run this aggregate moving the beam in closer each iteration. Minimum position is 0.

4. For shots to the Recycler:

For a stash size of 200-300 e10:

· Transverse Cooling

o Keep transverse signal suppression values from 2.5-3.5 dB until emittances reach 6-7 pi, then reduce attenuation to maintain achieved level.

· Longitudinal Cooling

o Beam is no longer being fully expanded after transfers. What is important is that the Dp(sig) remain between 3.9 - 4.5 MeV/c; if after the Pbar transfer the Dp(sig) is greater than 5 MeV/c, expand the beam such that the Dp(sig) falls within the nominal level. Keep longitudinal signal suppression values at nominals mentioned in section 2, Signal Suppression setup; also maintain a longitudinal emittance of 100-150 eV-sec.

· Taking additional transfers

o Approximately 1 hour before taking additional transfers, use e-cool to help cool so we can compress the beam to 4.1-4.2 usec. The electron beam should be moved in to +2 mm level initially; if deeper cooling is needed, move the beam in 0.5 mm steps. Lifetime may suffer during this phase (i.e < 200 hours). Once transfers are complete the electron beam can be kept at the 2 mm level to aid in cooling.

For a Stash Size 300-400 e10

· Transverse Cooling

o Keep transverse signal suppression values from 2.5-3.5 dB until emittances reach 6-7 pi, then reduce attenuation to maintain achieved level.

· Longitudinal Cooling

Taking additional transfers

o Approximately 1 hour before taking additional transfers, use e-cool to help cool so we can compress the beam to 4.1-4.2 usec. The electron beam should be moved in to +1 mm level initially; if deeper cooling is needed, move the beam in 0.5 mm steps. Lifetime may suffer during this phase (i.e < 200 hours). Once transfers are complete the electron beam can be kept at the 1 mm level to aid in cooling.

For Stash Size 400 e10 and up

· Transverse Cooling

o Keep transverse signal suppression values from 2.5-3.5 dB until emittances reach 6-7 pi, then reduce attenuation to maintain achieved level.

· Longitudinal Cooling

· Taking additional transfers

o Approximately 1 hour before taking additional transfers, use e-cool to help cool so we can compress the beam to 4.1-4.2 usec. The electron beam should be moved in to .5 - 1 mm level initially; if deeper cooling is needed, move the beam in 0.25 mm steps. Lifetime may suffer during this phase (i.e < 200 hours). Once transfers are complete the electron beam can be kept at the .75 mm level to aid in cooling.

For shots to the Tevatron:

Below are a set of cooling guidelines for Tevatron shots for all Pbar intensities as displayed on R:BEAM or R:ACBEAM:

· During shot setup to the Tevatron, keep all stochastic cooling systems ON until just prior to mining.

· Prior to mining:

o Longitudinal emittance as measured by R:LEMITA should be between 60 and 70 eV-sec.

o Average transverse Schottky emittance as measured by R:AVEMIT should be below 5.0 π-mm-mrad.

o Average beam density as measured by R:AVDNST should never exceed 2.0.

Adjust the Electron beam position while keeping the stochastic cooling systems optimized to achieve the above criteria.

· For Pbar intensities above 300 e10 as displayed on R:BEAM or R:ACBEAM, if the above criteria cannot be met:

Longitudinal emittance up to 75 eV-sec is allowed while keeping the rest of the criteria as above.

5. a) When ECool beam is not needed for two or more hours, run the aggregate “Pelletron OFF short access”.

b) If ECool beam will be used sometime in the next two hours, run the aggregate “Regulate ebeam current” and set the current to 0. When beam is needed, re-run this aggregate and set the current to 0.1a.

c) If an access is to be made into MI-31, run the aggregate “Pelletron OFF short access”. When access is complete, run the aggregate “Turn on from short access”.

6. Plots to put in logbook after shots:

a) D44 cooling history plot (saved under data source: ECOOL, recall cool.histor plot).

For the not-so-experienced Operator, a detailed version of the above steps:

Note in Recycler logbook that you have begun cooling for the shot.

If it is needed, restore D1 save file #806. NEVER RESTORE NMR_PS LIST!!

It is recommended to run a fast time plot (saved under FTP Electron Cooling file #22) with parameters R:BEAM (~ 2-5% window) to monitor the beam lifetime, R:LEMITA (goal parameter), R:EMITVA (0-8) to trace the transverse heating, and R:COLLI to be sure that the electron beam is there. It may also be beneficial to have the parameter R:EMVANM on one of the plots to monitor possible ‘fast’ changes of the emittance. The Mode Controller can also be run at the console to allow a quick analysis of possible recirculation interruptions, but this is not necessary for operation. Ask the on-call person if you have any questions about this.

Open E48 sequencer and run the aggregate ‘Turn beam on for ecooling’. This will set up what is needed and start beam running at 100ma. You need to input a desired position offset of 3 (+3mm vertically.) It will also start the Crash recovery finite state machine to keep the beam running, and the Autotune programs.

You can start the BPM plot to see the trajectory, but this is not required for operation. Use R39, Select EcoolRR line, select electron beam, select Fast/LoRes data, use a 3 plot, horz. scale 3mm, vert. scale 6mm, click on Snapshot, enable_SA with refreshing plot (obviously, choose an open slot).

To cool the Pbars in Recycler, run the aggregate ‘Shift Beam in Cooling Section’. You usually start to see cooling at +3mm, so use a desired position of 3. As you need more cooling, move the beam in closer, with 0 being the final position. When finished cooling the Pbars, move the beam to a desired position of 5.

The minimum meaningful step is 0.5 mm. Fast cooling sometimes results in a poor pbar lifetime, so try to keep the beam just close enough to the axis so it is enough to cool down to the target longitudinal emittance (R:LEMITA).

For shots to the Recycler:

For a stash size of 200-300 e10:

· Transverse Cooling

o Keep transverse signal suppression values from 2.5-3.5 dB until emittances reach 6-7 pi, then reduce attenuation to maintain achieved level.

· Longitudinal Cooling

· Taking additional transfers

For a Stash Size 300-400 e10

· Transverse Cooling

o Keep transverse signal suppression values from 2.5-3.5 dB until emittances reach 6-7 pi, then reduce attenuation to maintain achieved level.

· Longitudinal Cooling

Taking additional transfers

For Stash Size 400 e10 and up

· Transverse Cooling

o Keep transverse signal suppression values from 2.5-3.5 dB until emittances reach 6-7 pi, then reduce attenuation to maintain achieved level.

· Longitudinal Cooling

· Taking additional transfers

For shots to the Tevatron:

Below are a set of cooling guidelines for Tevatron shots for all Pbar intensities as displayed on R:BEAM or R:ACBEAM:

· During shot setup to the Tevatron, keep all stochastic cooling systems ON until just prior to mining.

· Prior to mining:

o Longitudinal emittance as measured by R:LEMITA should be between 60 and 70 eV-sec.

o Average transverse Schottky emittance as measured by R:AVEMIT should be below 5.0 π-mm-mrad.

o Average beam density as measured by R:AVDNST should never exceed 2.0.

Adjust the Electron beam position while keeping the stochastic cooling systems optimized to achieve the above criteria.

· For Pbar intensities above 300 e10 as displayed on R:BEAM or R:ACBEAM, if the above criteria cannot be met:

Longitudinal emittance up to 75 eV-sec is allowed while keeping the rest of the criteria as above.

a) When ECool beam is not needed for two or more hours, run the aggregate “Pelletron OFF Short Access”.

c) If an access is to be made into MI-31, run the aggregate “Pelletron OFF short access”. When access is complete, run the aggregate “Turn on from short access”.

Make from D44 a “cooling history” plot, showing R:BEAM, R:LEMITA, R:EMITVA, R:BYC00S, R:DCCT, R:DPSIGA, and R:CBKTLN. This plot can be recalled from D44: Data source ECOOL, cool.histor. and put it in the Recycler logbook.

Addendum to the Electron Cooling Procedure, by L. Prost, July 5, 2006

Since issues with the Pelletron tank getting hot were acknowledged in the ‘temporary procedure’ passed on to the Operations Department on June 20^th, 2006, the Pelletron tank temperature has been under scrutiny. As a result of our recent observations, we have decided to make the following changes:

1. The temperature (R:TNKT4) at which the Pelletron will shut itself off has been raised to 34˚C.

2 The tank temperature (R:TNKT4) will go into alarm at 33.5˚C. This alarm is acknowledgeable. On hot days (>85˚F), it will take approximately 2 hours for the alarm temperature to reach 34˚C once the device is into alarm.

a. If cooling is underway and close to a time at which electron cooling will not be needed (at least for some time), continue on.

b. If cooling is not needed or could be interrupted for some time (30-45 minutes) without a major impact on operation of the complex, turn the Pelletron off.

Meanwhile, actions (i.e. addition of an AC unit for now) are being taken to maintain the maximum Pelletron temperature below these levels.

Nevertheless, to prevent the deterioration of the Pelletron mechanical parts (chain, motors, bearings,…), the Pelletron should be turned off when it is not needed (cooling or study) for more than 4 hours (e.g.: after a shot to the Tev).