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LHC Momentum in 2008

LHC Momentum in 2008. J. Wenninger December 2008. Injection Test No. 1. SPS momentum set to P nom,SPS = 450 GeV which corresponds to 449.16 GeV (calibrated with ions in 2002). Synchronization test 8-11 August: Sector 23 offset : -33 units with SPS @ P nom,SPS = 450 GeV

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LHC Momentum in 2008

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  1. LHC Momentum in 2008 J. Wenninger December 2008

  2. Injection Test No. 1 • SPS momentum set to Pnom,SPS = 450 GeV which corresponds to 449.16 GeV (calibrated with ions in 2002). • Synchronization test 8-11 August: • Sector 23 offset : -33 units with SPS @ Pnom,SPS = 450 GeV • Sector 23 offset : -7.3 units with SPS @ Pnom,SPS = 451 GeV • >> Obtained a difference of 0.26%, expected 0.22% • >> PSPS = 450.31 GeV @ Pnom,SPS = 451 GeV • LHC : fRF,LHC = 400'788'790 Hz • SPS : fRF,SPS = fRF,LHC /2 = 200'394'395 Hz • SPS central frequency (2002) fc,SPS = 200'394'215 Hz (+- 70 Hz) • >> fRF,SPS – fc,SPS = 144 Hz >> Delta E = -0.039% = -3.9 units • >> ES23 = 449.2 x 1.0033 (S23 traj) x 0.9994 (central f SPS) = 450.5 +- 0.2 GeV

  3. 10th September first turn offsets • LHC fRF,LHC = 400'788‘790 Hz ?? • Average offsets b1-b2 differ only by ~ 0.01% = 1 units. • Statistically consistent…

  4. 12th September closed orbit • LHC fRF,cap,LHC = 400'788'963 Hz • LHC theoretical fRF,nom-LHC = 400'788‘734 Hz • Average energy offset of CO : -0.094% = 9.4 units. • Ft offset consistent with CO within 0.01-0.02%. • >> Why did it change with respect to 10th ?

  5. FT and CO • b1 & b2 FTdp/p offsets on Sept 10th are consistent / show no significant difference. • dp/p = -4 units • fRF,LHC = 400'788'790 Hz (??) • b2CO dp/p offsets on Sept 12th : • dp/p = -9.4 units • FT seems well centered on CO, i.e. similar shift as CO within 1 unit. • fRF,LHC = 400'788‘963 Hz • >> The RF frequency difference of 173 Hz (wrt 10th) can explain a shift of the FT of -2.2 units due to the energy change in the SPS. Is the remaining shift of -2 to -3 units due to LHC ? • >> A shift of -119 Hz is required to center b2 on the CO: • fRF,LHC = 400'788‘884 Hz • >> The SPS field must be increased by 8 units to re-center FT. Beam2 data

  6. Central orbits – b2 • To center the beam2 closed orbit and compensate for the radial offset (-9.4 units): • The b2 central frequency (central = ~ centered in the BPMs) : • LHC fRF,c,b2 = 400'788‘884 Hz • >> 150 Hz higher than design : Ring 2 radius is 1.6 mm smaller than nominal. • >>Note that the SPS radius is 1 cm larger than nominal. • The corresponding SPS extraction frequency is: • SPS fRF,ext = LHC fRF,c,b2 /2 = 200‘394’442 Hz • To be compared with the SPS central frequency (central ~ centered in sextupoles, 2002-2004): • SPS fRF,c = 200’394’239 +- 70 Hz • >> SPS fRF,ext- fRF,c = 203 +- 70 Hz • >> Offset of -0.5 permill • >> SPS radial position shifted inwards by -2 mm - OK

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