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Luminosity Reduction Caused by the Full-Detuning LLRF Scheme on the HL-LHC Crab Cavities

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Luminosity Reduction Caused by the Full-Detuning LLRF Scheme on the HL-LHC Crab Cavities. / Yamakawa, Emi; Apsimon, Robert; Dexter, Amos et al.
IPAC 2018 Proceedings of the 9th International Particle Accelerator Conference. JACoW, 2018.

Research output: Contribution in Book/Report/Proceedings - With ISBN/ISSNConference contribution/Paperpeer-review

Harvard

Yamakawa, E, Apsimon, R, Dexter, A, Baudrenghien, P, Calaga, R, Galindo Guarch & Galindo Guarch, FJ 2018, Luminosity Reduction Caused by the Full-Detuning LLRF Scheme on the HL-LHC Crab Cavities. in IPAC 2018 Proceedings of the 9th International Particle Accelerator Conference. JACoW, IPAC'18 , Vancouver, Canada, 29/04/18. https://doi.org/10.18429/JACoW-IPAC2018-MOPMF022

APA

Yamakawa, E., Apsimon, R., Dexter, A., Baudrenghien, P., Calaga, R., Galindo Guarch, & Galindo Guarch, F. J. (2018). Luminosity Reduction Caused by the Full-Detuning LLRF Scheme on the HL-LHC Crab Cavities. In IPAC 2018 Proceedings of the 9th International Particle Accelerator Conference JACoW. https://doi.org/10.18429/JACoW-IPAC2018-MOPMF022

Vancouver

Yamakawa E, Apsimon R, Dexter A, Baudrenghien P, Calaga R, Galindo Guarch et al. Luminosity Reduction Caused by the Full-Detuning LLRF Scheme on the HL-LHC Crab Cavities. In IPAC 2018 Proceedings of the 9th International Particle Accelerator Conference. JACoW. 2018 doi: 10.18429/JACoW-IPAC2018-MOPMF022

Author

Yamakawa, Emi ; Apsimon, Robert ; Dexter, Amos et al. / Luminosity Reduction Caused by the Full-Detuning LLRF Scheme on the HL-LHC Crab Cavities. IPAC 2018 Proceedings of the 9th International Particle Accelerator Conference. JACoW, 2018.

Bibtex

@inproceedings{6f1abdfaef914e2c8f0fea86ef1d3f18,
title = "Luminosity Reduction Caused by the Full-Detuning LLRF Scheme on the HL-LHC Crab Cavities",
abstract = "The High-Lu­mi­nos­ity LHC (HL-LHC) crab cav­i­ties (CCs) will be in­stalled on both sides of IP1 (ATLAS) and IP5 (CMS) to com­pen­sate for the geo­met­ric lu­mi­nos­ity re­duc­tion due to the cross­ing angle. To cope with the in­creased beam cur­rent (0.55 A DC for LHC, 1.1 A for HL-LHC), the op­er­a­tion of the LLRF sys­tem has been changed: rather than fully com­pen­sat­ing the tran­sient beam load­ing, we allow the phase to vary along the turn (100 ps peak-peak with 1.1 A DC). This has been im­ple­mented at LHC since July 2017. The CCs have high loaded Q (5e5) and the avail­able RF power is in­suf­fi­cient to fol­low the bunch phase mod­u­la­tion. The crab­bing volt­age is not mod­u­lated, caus­ing a phase error w.r.t. the in­di­vid­ual bunch cen­troids, lead­ing to trans­verse kicks of the cen­troids and an asym­met­ric crab­bing of the bunch cores. We pre­sent an an­a­lyt­i­cal model for the re­sult­ing lu­mi­nos­ity re­duc­tion and val­i­date with par­ti­cle track­ing sim­u­la­tions. Due to the sym­me­try of the bunch fill­ing pat­terns for the counter-ro­tat­ing beams, the peak lu­mi­nos­ity is re­duced by only 2% for nom­i­nal HL-LHC pa­ra­me­ters at IPs 1 and 5, which is within tol­er­a­ble lim­its.",
author = "Emi Yamakawa and Robert Apsimon and Amos Dexter and Philippe Baudrenghien and Rama Calaga and {Galindo Guarch} and {Galindo Guarch}, {F. J.}",
year = "2018",
month = jun,
day = "1",
doi = "10.18429/JACoW-IPAC2018-MOPMF022",
language = "English",
booktitle = "IPAC 2018 Proceedings of the 9th International Particle Accelerator Conference",
publisher = "JACoW",
note = "IPAC'18 ; Conference date: 29-04-2018 Through 04-05-2018",
url = "https://ipac18.org/welcome",

}

RIS

TY - GEN

T1 - Luminosity Reduction Caused by the Full-Detuning LLRF Scheme on the HL-LHC Crab Cavities

AU - Yamakawa, Emi

AU - Apsimon, Robert

AU - Dexter, Amos

AU - Baudrenghien, Philippe

AU - Calaga, Rama

AU - Galindo Guarch,

AU - Galindo Guarch, F. J.

PY - 2018/6/1

Y1 - 2018/6/1

N2 - The High-Lu­mi­nos­ity LHC (HL-LHC) crab cav­i­ties (CCs) will be in­stalled on both sides of IP1 (ATLAS) and IP5 (CMS) to com­pen­sate for the geo­met­ric lu­mi­nos­ity re­duc­tion due to the cross­ing angle. To cope with the in­creased beam cur­rent (0.55 A DC for LHC, 1.1 A for HL-LHC), the op­er­a­tion of the LLRF sys­tem has been changed: rather than fully com­pen­sat­ing the tran­sient beam load­ing, we allow the phase to vary along the turn (100 ps peak-peak with 1.1 A DC). This has been im­ple­mented at LHC since July 2017. The CCs have high loaded Q (5e5) and the avail­able RF power is in­suf­fi­cient to fol­low the bunch phase mod­u­la­tion. The crab­bing volt­age is not mod­u­lated, caus­ing a phase error w.r.t. the in­di­vid­ual bunch cen­troids, lead­ing to trans­verse kicks of the cen­troids and an asym­met­ric crab­bing of the bunch cores. We pre­sent an an­a­lyt­i­cal model for the re­sult­ing lu­mi­nos­ity re­duc­tion and val­i­date with par­ti­cle track­ing sim­u­la­tions. Due to the sym­me­try of the bunch fill­ing pat­terns for the counter-ro­tat­ing beams, the peak lu­mi­nos­ity is re­duced by only 2% for nom­i­nal HL-LHC pa­ra­me­ters at IPs 1 and 5, which is within tol­er­a­ble lim­its.

AB - The High-Lu­mi­nos­ity LHC (HL-LHC) crab cav­i­ties (CCs) will be in­stalled on both sides of IP1 (ATLAS) and IP5 (CMS) to com­pen­sate for the geo­met­ric lu­mi­nos­ity re­duc­tion due to the cross­ing angle. To cope with the in­creased beam cur­rent (0.55 A DC for LHC, 1.1 A for HL-LHC), the op­er­a­tion of the LLRF sys­tem has been changed: rather than fully com­pen­sat­ing the tran­sient beam load­ing, we allow the phase to vary along the turn (100 ps peak-peak with 1.1 A DC). This has been im­ple­mented at LHC since July 2017. The CCs have high loaded Q (5e5) and the avail­able RF power is in­suf­fi­cient to fol­low the bunch phase mod­u­la­tion. The crab­bing volt­age is not mod­u­lated, caus­ing a phase error w.r.t. the in­di­vid­ual bunch cen­troids, lead­ing to trans­verse kicks of the cen­troids and an asym­met­ric crab­bing of the bunch cores. We pre­sent an an­a­lyt­i­cal model for the re­sult­ing lu­mi­nos­ity re­duc­tion and val­i­date with par­ti­cle track­ing sim­u­la­tions. Due to the sym­me­try of the bunch fill­ing pat­terns for the counter-ro­tat­ing beams, the peak lu­mi­nos­ity is re­duced by only 2% for nom­i­nal HL-LHC pa­ra­me­ters at IPs 1 and 5, which is within tol­er­a­ble lim­its.

U2 - 10.18429/JACoW-IPAC2018-MOPMF022

DO - 10.18429/JACoW-IPAC2018-MOPMF022

M3 - Conference contribution/Paper

BT - IPAC 2018 Proceedings of the 9th International Particle Accelerator Conference

PB - JACoW

T2 - IPAC'18

Y2 - 29 April 2018 through 4 May 2018

ER -