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TUPOST040 |
Automated Intensity Optimisation Using Reinforcement Learning at LEIR |
941 |
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- N. Madysa, R. Alemany-Fernández, N. Biancacci, B. Goddard, V. Kain, F.M. Velotti
CERN, Meyrin, Switzerland
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High intensities in the CERN Low Energy Ion Ring (LEIR) are achieved by stacking up to seven consecutive multi-turn injections from Linac3. Two inclined septa combined with a collapsing horizontal orbit bump allow a 6-D phase space painting via a linearly ramped mean momentum along the Linac3 pulse and injection at high dispersion. The beam is cooled and dragged longitudinally via electron cooling (e-cooling) into a stacking momentum. For optimal accumulation, the electron energy and trajectory need to match the ion energy and orbit at the e-cooler section. In this paper, a reinforcement learning (RL) agent is trained to adjust various e-cooler and Linac3 parameters to maximise the intensity at the end of the injection plateau. Variational Auto-Encoders (VAE) are used to compress longitudinal Schottky spectra into a compact representation as input for the RL agent. The RL agent is pre-trained on a surrogate model of the LEIR e-cooling dynamics, which in turn is learned from the data collected for the training of the VAE. The performance of the VAE, the surrogate model, and the RL agent is investigated in this paper. An overview of planned tests in the upcoming LEIR runs is given.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST040
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About • |
Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 10 July 2022 |
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TUPOST042 |
Towards the Automatic Setup of Longitudinal Emittance Blow-Up in the CERN SPS |
949 |
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- N. Bruchon, I. Karpov, N. Madysa, G. Papotti, D. Quartullo, C. Zisou
CERN, Meyrin, Switzerland
- C. Zisou
AUTH, Thessaloniki, Greece
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Controlled longitudinal emittance blow-up in the CERN SPS is necessary to stabilize high-intensity beams for the High-Luminosity LHC (HL-LHC) by increasing the synchrotron frequency spread. The process consists of injecting bandwidth-limited noise into the main RF phase loop to diffuse particles in the core of the bunch. The setting up of the noise parameters, such as frequency band and amplitude, is a non-trivial and time-consuming procedure that has been performed manually so far. In this preliminary study, several optimization methods are investigated to set up the noise parameters automatically. We apply the CERN Common Optimization Interfaces as a generic framework for the optimization algorithm. Single-bunch profiles generated with the BLonD simulation code have been used to investigate the optimization algorithms offline. Furthermore, analysis has been carried out on measured bunch profiles in the SPS to define the problem constraints and properly formulate the objective function.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST042
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About • |
Received ※ 31 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 17 June 2022 |
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WEIYGD1 |
Achievements and Performance Prospects of the Upgraded LHC Injectors |
1610 |
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- V. Kain, S.C.P. Albright, R. Alemany-Fernández, M.E. Angoletta, F. Antoniou, T. Argyropoulos, F. Asvesta, B. Balhan, M.J. Barnes, D. Barrientos, H. Bartosik, P. Baudrenghien, G. Bellodi, N. Biancacci, A. Boccardi, J.C.C.M. Borburgh, C. Bracco, E. Carlier, D.G. Cotte, J. Coupard, H. Damerau, G.P. Di Giovanni, A. Findlay, M.A. Fraser, A. Funken, B. Goddard, G. Hagmann, K. Hanke, A. Huschauer, M. Jaussi, I. Karpov, T. Koevener, D. Küchler, J.-B. Lallement, A. Lasheen, T.E. Levens, K.S.B. Li, A.M. Lombardi, N. Madysa, E. Mahner, M. Meddahi, L. Mether, B. Mikulec, J.C. Molendijk, E. Montesinos, D. Nisbet, F.-X. Nuiry, G. Papotti, K. Paraschou, F. Pedrosa, T. Prebibaj, S. Prodon, D. Quartullo, E. Renner, F. Roncarolo, G. Rumolo, B. Salvant, M. Schenk, R. Scrivens, E.N. Shaposhnikova, P.K. Skowroński, A. Spierer, F. Tecker, D. Valuch, F.M. Velotti, R. Wegner, C. Zannini
CERN, Meyrin, Switzerland
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To provide HL-LHC performance, the CERN LHC injector chain underwent a major upgrade during an almost 2-year-long shutdown. In the first half of 2021 the injectors were gradually re-started with the aim to reach at least pre-shutdown parameters for LHC as well as for fixed target beams. The strategy of the commissioning across the complex, a summary of the many challenges and finally the achievements will be presented. Several lessons were learned and have been integrated to define the strategy for the performance ramp-up over the coming years. Remaining limitations and prospects for LHC beam parameters at the exit of the LHC injector chain in the years to come will be discussed. Finally, the emerging need for improved operability of the CERN complex will be addressed, with a description of the first efforts to meet the availability and flexibility requirements of the HL-LHC era while at the same time maximizing fixed target physics output.
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Slides WEIYGD1 [5.905 MB]
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2022-WEIYGD1
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About • |
Received ※ 08 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 09 July 2022 |
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WEPOPT055 |
Linac3, LEIR and PS Performance with Ions in 2021 and Prospects for 2022 |
1983 |
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- N. Biancacci, S.C.P. Albright, R. Alemany-Fernández, D. Alves, M.E. Angoletta, D. Barrientos, H. Bartosik, G. Bellodi, S.B. Bertolo, D. Bodart, M. Bozzolan, H. Damerau, F.D.L. Di Lorenzo, A. Frassier, D. Gamba, A. Huschauer, S. Jensen, V. Kain, T. Koevener, G. Kotzian, D. Küchler, A. Lasheen, G. Le Godec, T.E. Levens, N. Madysa, E. Mahner, O. Marqversen, C.M. Mastrostefano, P.D. Meruga, C. Mutin, M. O’Neil, G. Piccinini, R. Scrivens, P.S. Solvang, D. Valuch, F.M. Velotti, R. Wegner, C. Wetton, M. Zampetakis
CERN, Meyrin, Switzerland
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CERN accelerators underwent a period of long shutdown from the end of 2018 to 2020. During this time frame, significant hardware and software upgrades have been put in place to increase the performance of both proton and ion accelerator chains in the High Luminosity LHC era. In the context of the CERN lead ion chain, 2021 has been mainly devoted to restore the injectors’ performance and to successfully prove the slip-stacking technique in SPS. In this paper we summarise the key milestones of the ion beam commissioning and the achieved beam performance for the Linac 3 (including the source), LEIR and PS accelerators, together with an outlook on 2022 operation.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT055
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About • |
Received ※ 03 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022 |
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