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Phase Module calibration with beam and Longitudinal impedance measurements at 4 TeV

Phase Module calibration with beam and Longitudinal impedance measurements at 4 TeV. T. Argyropoulos , P. Baudrenghien , N. Biancacci , T . Bohl , J. F. Esteban M üller , G. Papotti , T. Mastoridis , N. Mounet , B. Salvant , E. Shaposhnikova , H. Timko , +…. Introduction.

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Phase Module calibration with beam and Longitudinal impedance measurements at 4 TeV

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  1. Phase Module calibration with beam and Longitudinal impedance measurements at 4 TeV T. Argyropoulos, P. Baudrenghien , N. Biancacci, T. Bohl,J. F. Esteban Müller, G. Papotti, T. Mastoridis, N. Mounet, B. Salvant, E. Shaposhnikova, H. Timko, +…

  2. Introduction • Different results from previous MD for Beam 1 and Beam 2 and also between different modules, even after some corrections • Calibration needed • Only measurements at FB • Measurements at 4 TeV needed • MD summary: • 2 fills for phase module calibration at 450 GeV • 8 bunches of low intensity (1 - 6 x 1010p) • 1 fill with ramp for impedance measurements at 4 TeV • 3 bunches of high intensity (0.5 - 1.6 x 1011 p) • Measurements done: • Synchronous phase • Peak Detected Schottky • Transverse tune shift • Beam profiles Beam 1 Fill #1 TDI IN Fill #1 TDI OUT Fill #2 TDI IN Fill #2 TDI OUT Fill #3 TDI IN Fill #3 TDI OUT Beam 2 LSWG

  3. Phase Module Calibration • 8 bunches low intensity (1 - 6 x 1010 p) • Signal amplitude was increased to the level of high intensity used in previous measurements • Voltage changed from 3.5 MV to 6 MV to disentangle the impedance contribution and the phase module effect • Two fills at injection energy: • Similar intensities (3 - 5 x 1010 p) and different bunch lengths (1-1.8 ns) • Similar bunch lengths (1.5 -1.7 ns) and different intensities (1 - 6 x 1010 p) • No simple (linear) dependence could be extracted so far MD Fill 1 MD Fill 2 LSWG

  4. Longitudinal Impedance at 4 TeV • Only 3 bunches due to limited time • Intensities in the range 0.5 - 1.6 x 1011p • Similar bunch lengths ~0.8 when arrived at 4 TeV • Longitudinal impedance from synchronous phase shift not possible • More bunches and phase module calibration is needed • Loss of Landau damping was observed when the phase loop was switched off for bunches with 1x1011 p and 0.8 ns bunch length PL ON PL ON PL ON PL OFF PL OFF PL ON PL OFF PL OFF RAMP 4 TeV 4 TeV 450 GeV 450 GeV RAMP LSWG

  5. Peak Detected Schottky • Estimated quadrupole line frequency shift at 4 TeV for ImZ/n=0.1 and 0.9 ns bunch length (V=12 MV) is <1 Hz/1011 • Measurement precision is around 0.2 Hz • Very limited time  Only measurements for two bunches with different Peak Detected modules • Analysis on-going LSWG

  6. Transverse Tune Shift • Measurements with the ADT pickups: • Injection oscillations • Kicks at 4 TeV • Tune vs. intensity  To be analysed LSWG

  7. Conclusions • Synchronous phase measurements: • We observed a systematic error of ~ 0.2 deg in the measurements range • Modules behave different (opposite for Beam 1 and Beam 2) • If the impedance model is correct, the required precision is ~0.1 degrees or less • Relative measurements (TDI) and for larger phase shift (electron cloud) are correct • We will try calibrate the module and extract the best from the data LSWG

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