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ERDs for the CT extraction in the PS Proposal for a new correction scheme

ERDs for the CT extraction in the PS Proposal for a new correction scheme. Andrea Franchi. G. Arduini, O. E. Berrig, S. Gilardoni, M. Giovannozzi, M. Martini. APC 30 March 2007. Outline. 1. Overview and motivations 2. Present correction scheme

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ERDs for the CT extraction in the PS Proposal for a new correction scheme

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  1. ERDs for the CT extraction in the PS Proposal for a new correction scheme Andrea Franchi G. Arduini, O. E. Berrig, S. Gilardoni, M. Giovannozzi, M. Martini APC 30 March 2007

  2. Outline 1. Overview and motivations 2. Present correction scheme 3. Principle of the new correction scheme (proposal) 4. Application manual 5. Summary & conclusion

  3. Overview:the CT extraction Fixed-target experiments CNGS

  4. Overview:the CT extraction Qx =6.25 => 90º rot./turn The el. septum in SS31 shave hor.the beam Each slice enters in the ma. septum in SS16 & is ejected

  5. Overview:the CT extraction [MTE extr ~ CT extr.] Qx =6.25 => 90º rot./turn The el. septum in SS31 shave hor.the beam Each slice enters in the ma. septum in SS16 & is ejected

  6. Overview:the CT extraction The centroids in (X,PX) of the ejected islands are not the same!!! 3 skew quads in TT10 exchange the transv. emittances Result: the beamlets are injected in the SPS with a vertical offset Result: vertical emittance blow up∝∆y 2 Qx =6.25 => 90º rot. The el. septum in SS31 shave hor.the beam Each slice enters in the ma. septum in SS16 & is ejected

  7. Present correction scheme The orbit averaged over the 5 turns is corrected with 3 BHZs

  8. Present correction scheme The orbit averaged over the 5 turns is corrected with 3 BHZs The 2 ERDs (1 pedestal + 1 staircase=turn by turn) can correct the orbit of each beamlet

  9. Present correction scheme Constraints The 2 kickers are next to each other => only the angle PX can be corrected (vertical arrows in the picture) The kicker voltage can be only positive => beamlets with positive angle PX @ the entrance of the ERDs cannot be corrected

  10. Present correction scheme Constraints The 2 kickers are next to each other => only the angle PX can be corrected (vertical arrows in the picture) The kicker voltage can be only positive => beamlets with positive angle PX @ the entrance of the ERDs cannot be corrected

  11. New correction scheme (principle) The 2nd kicker (ERD2) has been moved ~ 20 m downstream the ERD1 (~70° phase advance) => correction in angle & position 70° phase advance is a trade off between the best “angle & position” correction (90°) and aperture constraints

  12. New correction scheme (principle) The 2nd kicker (ERD2) has been moved ~ 20 m downstream the ERD1 (~70° phase advance) => correction in angle & position To overcome the V>0 limit, the beam is displaced with the BHZs => the largest angle @ ERD1 is ~ zero ERD1

  13. New correction scheme (principle) The 2nd kicker (ERD2) has been moved ~ 20 m downstream the ERD1 (~70° phase advance) => correction in momentum & position To overcome the V>0 limit, the beam is displaced with the BHZs => the largest momentum offset @ ERD1 is ~ zero The ERD2 impart a turn-by-turn variable kick and reduce the “spread”

  14. New correction scheme (principle) The 2nd kicker (ERD2) has been moved ~ 20 m downstream the ERD1 (~70° phase advance) => correction in angle & position To overcome the V>0 limit, the beam is displaced with the BHZs => the largest angle @ ERD1 is ~ zero The ERD2 impart a turn-by-turn variable kick and reduce the “spread” 3 Bending magnets (BHZ377 & MAL1001s) downstream the ERDs are used to correct the “average” trajectory

  15. New correction scheme (principle) The 2nd kicker (ERD2) has been moved ~ 20 m downstream the ERD1 (~70° phase advance) => correction in angle & position To overcome the V>0 limit, the beam is displaced with the BHZs => the largest angle @ ERD1 is ~ zero The ERD2 impart a turn-by-turn variable kick and reduce the “spread” 3 Bending magnets (BHZ377 & MAL1001s) downstream the ERDs are used to correct the “average” trajectory

  16. Application manual 1. Measure the vertical beamlet positions in the SPS right after the injection (First-Turn option)

  17. Application manual 2. Infer the initial conditions (X,X’) at the beginning of TT2 that best reproduce the measured SPS values

  18. Application manual 3. Launch a routine that, given the TT2-TT10 setting and the initial conditions of the 5 beamlets/slice, find the best corrector setting (BHZs,ERDs,MAL1001) # BEST CORRECTOR SETTING: SUMMARY INITIAL (X,PX) SLICE 1 : 0.1050E-02 0.8550E-05 INITIAL (X,PX) SLICE 2 : -0.8210E-03 -0.1080E-03 INITIAL (X,PX) SLICE 3 : -0.2800E-03 -0.4850E-04 INITIAL (X,PX) SLICE 4 : 0.7260E-03 -0.5510E-04 INITIAL (X,PX) SLICE 5 : -0.2890E-02 -0.4980E-03 INITIAL SPREAD [Cour-Sny] : 0.4800E-03 OFFSET [Cour-Sny] : 0.5304E-03 ******************* STEERERS ************************* BEST BHZ117 correction [A,mrad] : 0.7567593 0.1000E-03 BEST BHZ147 correction [A,mrad] : 0.7567593 0.1000E-03 BEST BHZ167 correction [A,mrad] : 0.9586615 0.1000E-03 BEST BHZ377 correction [A,mrad] : -0.8695056 -0.5000E-04 BEST MAL100103 correction [mrad] : -0.1600E-03 ********************* ERD ************************** BEST DFA242 setting [kV,mrad] : 12.56443 0.1400E-03 START FROM SLICE # 5 BEST DFA243-1 setting [kV,mrad] : 9.444498 0.1200E-03 BEST DFA243-2 setting [kV,mrad] : 9.444498 0.1200E-03 BEST DFA243-3 setting [kV,mrad] : 9.444498 0.1200E-03 BEST DFA243-4 setting [kV,mrad] : 15.74083 0.2000E-03 BEST DFA243-5 setting [kV,mrad] : 15.74083 0.2000E-03 ****************************************************** FINAL (X,PX) SLICE 1 @MAL100113 : -0.6812E-03 -0.9433E-04 FINAL (X,PX) SLICE 2 @MAL100113 : 0.2235E-03 0.4916E-04 FINAL (X,PX) SLICE 3 @MAL100113 : 0.6074E-03 0.5734E-04 FINAL (X,PX) SLICE 4 @MAl100113 : 0.2614E-03 0.1268E-04 FINAL (X,PX) SLICE 5 @MAL100113 : -0.8176E-03 -0.3587E-04 FINAL SPREAD [Cour-Sny] : 0.1051E-03 OFFSET [Cour-Sny] : 0.2506E-04

  19. Application manual 4. Run MADX with the same initial conditions of before and the new setting, and check the vertical offset } ∆y ~ 6mm } ∆y ~ 2mm Emittance blow up reduced by a factor ~(2/6)2=1/9 [in absence of TFB]

  20. New correction scheme The correction, even on the paper, cannot be perfect! 1. ERD1 will remain pedestal (constant Vs time) until 2009. } ∆y ~ 6mm } ∆y ~ 2mm Emittance blow up reduced by a factor ~(2/6)2=1/9 [in absence of TFB]

  21. New correction scheme The correction, even on the paper, cannot be perfect! 1. ERD1 will remain pedestal (constant Vs time) until 2009 2. ERDs staircase: turn by turn the voltage can be either increased or left at the same value (± 10%). 4th & 5th turns must have the same voltage (to avoid mismatch of the rise time with the PS kickers)

  22. New correction scheme The correction, even on the paper, cannot be perfect! 1. ERD1 will remain pedestal (constant Vs time) until 2009 2. ERDs staircase: turn by turn the voltage can be either increased or left at the same value (± 10%). 4th & 5th turns must have the same voltage 3. The max. offset that the BHZs may create upstream the ERDs is limited by the pipe aperture & by the maximum kicker voltage (30 kV)

  23. New correction scheme Horizontal clearance The correction, even on the paper, cannot be perfect! 1. ERD1 will remain pedestal (constant Vs time) until 2009 2. ERDs staircase: turn by turn the voltage can be either increased or left at the same value (± 10%) 3. The Pipe aperture and the max kicker voltage (30 kV) limit the maximum offset that the BHZs can create upstream th ERDs εx(RMS,unorm)=0.5 μm [CNGS,h.i.] In this example, the displacement upstream the ERDs leads to a clearance reduction of ~1σ

  24. New correction scheme The correction, even on the paper, cannot be perfect! 1. ERD1 will remain pedestal (constant Vs time) until 2009 2. ERDs staircase: turn by turn the voltage can be either increased or left at the same value (± 10%) 3. The max. offset that the BHZs may create upstream the ERDs is limited by the pipe aperture & by the maximum kicker voltage (30 kV) 4. The routine is model dependent => a by-hand trimming in CCC would be necessary.

  25. New correction scheme OUTLOOK 1. The scheme would be applicable to the MTE too 2. From 2009 the ERD1 will also be staircase => more flexibility.

  26. Summary & conclusion The slice/beamlets extracted with the CT (& MTE) enter in TT2 with a slice-dependent horizontal offset, that leads to a vertical emittance blow up in the SPS if not corrected. The BHZs are used to correct the global trajectory, while two ERD kickers (1 pedestal & 1 staircase) are used to steer the beamlets individually => vertical offset in the SPS ~ 6 mm (measur. 2006) A new correction scheme has been proposed => vertical offset in the SPS ~ 2 mm (simulations), emittance blow up reduced of a factor ~9. This scheme shall be tested during the 2007 run, to check its effectiveness.

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