IPAC2019 - List of Authors (Timko, H.)

Paper	Title	Page
MOPGW091	Capture and Flat-Bottom Losses in the CERN SPS	327
	M. Schwarz, A. Lasheen, G. Papotti, J. Repond, E.N. Shaposhnikova, H. Timko CERN, Meyrin, Switzerland
	Particle losses on the flat bottom of the SPS, the last accelerator in the injector chain of the LHC at CERN, are a strong limitation for reaching the high intensities required by the high luminosity upgrade of the LHC. Two contributions to these losses are investigated in this paper. The first losses occur during the PS-to-SPS bunch-to-bucket transfer, since the bunch rotation in the PS creates halo particles and the bunch does not completely fit into the SPS RF-bucket. The effect of longitudinal shaving in the PS on the beam transmission was recently tested. At high intensities, further capture losses are caused by beam loading in the traveling wave RF system of the SPS, which is partially compensated by the LLRF system, in particular by one-turn delay feedback. While the feedforward system reduces the capture losses, it also increases the losses along the flat bottom due to the RF noise.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW091
About •	paper received ※ 09 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
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MOPRB055	First Partially Stripped Ions in the LHC (208Pb⁸¹⁺)	689
	M. Schaumann, R. Alemany-Fernández, H. Bartosik, T. Bohl, R. Bruce, G.H. Hemelsoet, S. Hirlaender, J.M. Jowett, V. Kain, M.W. Krasny, J. Molson, G. Papotti, M. Solfaroli Camillocci, H. Timko, J. Wenninger CERN, Geneva, Switzerland
	The Gamma Factory initiative proposes to use partially stripped ion (PSI) beams as drivers of a new type of high intensity photon source. As part of the ongoing Physics Beyond Collider studies, initial beam tests with PSI beams have been executed at CERN. On 25 July 2018 lead ions with one remaining electron (208Pb⁸¹⁺) were injected and accelerated in the LHC for the first time. After establishing the injection and circulation of a few 208Pb⁸¹⁺ bunches, beam lifetimes of about 50 hours could be established at 6.5 TeV proton equivalent energy. This paper describes the setup of the beam tests and observations made.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB055
About •	paper received ※ 29 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEYYPLM2	The 2018 Heavy-Ion Run of the LHC	2258
	J.M. Jowett, C. Bahamonde Castro, W. Bartmann, C. Bracco, R. Bruce, J.M. Coello de Portugal, J. Dilly, S.D. Fartoukh, E. Fol, N. Fuster-Martínez, A. Garcia-Tabares, M. Hofer, E.B. Holzer, M.A. Jebramcik, J. Keintzel, A. Lechner, E.H. Maclean, L. Malina, T. Medvedeva, A. Mereghetti, T.H.B. Persson, B.Aa. Petersen, S. Redaelli, B. Salvachua, M. Schaumann, C. Schwick, M. Solfaroli, M.L. Spitznagel, H. Timko, R. Tomás, A. Wegscheider, J. Wenninger, D. Wollmann CERN, Meyrin, Switzerland D. Mirarchi The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
	The fourth one-month Pb-Pb collision run brought LHC Run 2 to an end in December 2018. Following the tendency to reduce dependence on the configuration of the preceding proton run, a completely new optics cycle with the strongest ever focussing at the ALICE and LHCb experiments was designed and rapidly implemented, demonstrating the maturity of the collider’s operating modes. Beam-loss monitor thresholds were carefully adjusted to provide optimal protection from the multiple loss mechanisms in heavy-ion operation. A switch from a basic bunch-spacing of 100 ns to 75 ns was made as the beam became available from the injector chain. A new record luminosity, 6 times the original design and close to the operating value proposed for HL-LHC, provided validation of the strategy for mitigating quenches due to bound-free pair production (BFPP) at the interaction points of the ATLAS and CMS experiments. Most of the beam parameters of the HL-LHC Pb-Pb upgrade were attained during this run and the integrated luminosity goals for the first 10 years of LHC operation were substantially exceeded.
	Slides WEYYPLM2 [10.884 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM2
About •	paper received ※ 08 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPTS049	Flat-Bottom Instabilities in the CERN SPS	3224
	M. Schwarz, K. Iliakis, A. Lasheen, G. Papotti, J. Repond, E.N. Shaposhnikova, H. Timko CERN, Meyrin, Switzerland
	At beam intensities of 2.6·10¹¹ protons per bunch, required at SPS injection for the High Luminosity LHC beam, longitudinal instabilities can degrade the beam quality delivered by the SPS, the LHC injector at CERN. In this paper, we concentrate on beam instability at flat bottom. The dependence of the instability threshold on longitudinal emittance and LLRF system settings was measured, to help identify the impedance driving this instability. While reducing the longitudinal emittance reduces the losses at injection, it can drive the beam unstable. The LLRF system of the SPS (partially) compensates beam loading, but also affects the instability. The effect of the different LLRF systems (feedback, feedforward, phase loop and longitudinal damper) and fourth harmonic RF system on the instability was investigated. The measurements are compared with simulations performed with the longitudinal tracking code BLonD.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS049
About •	paper received ※ 10 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Capture and Flat-Bottom Losses in the CERN SPS

327

M. Schwarz, A. Lasheen, G. Papotti, J. Repond, E.N. Shaposhnikova, H. Timko
CERN, Meyrin, Switzerland

Particle losses on the flat bottom of the SPS, the last accelerator in the injector chain of the LHC at CERN, are a strong limitation for reaching the high intensities required by the high luminosity upgrade of the LHC. Two contributions to these losses are investigated in this paper. The first losses occur during the PS-to-SPS bunch-to-bucket transfer, since the bunch rotation in the PS creates halo particles and the bunch does not completely fit into the SPS RF-bucket. The effect of longitudinal shaving in the PS on the beam transmission was recently tested. At high intensities, further capture losses are caused by beam loading in the traveling wave RF system of the SPS, which is partially compensated by the LLRF system, in particular by one-turn delay feedback. While the feedforward system reduces the capture losses, it also increases the losses along the flat bottom due to the RF noise.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW091

About •

paper received ※ 09 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPRB055

First Partially Stripped Ions in the LHC (208Pb⁸¹⁺)

689

M. Schaumann, R. Alemany-Fernández, H. Bartosik, T. Bohl, R. Bruce, G.H. Hemelsoet, S. Hirlaender, J.M. Jowett, V. Kain, M.W. Krasny, J. Molson, G. Papotti, M. Solfaroli Camillocci, H. Timko, J. Wenninger
CERN, Geneva, Switzerland

The Gamma Factory initiative proposes to use partially stripped ion (PSI) beams as drivers of a new type of high intensity photon source. As part of the ongoing Physics Beyond Collider studies, initial beam tests with PSI beams have been executed at CERN. On 25 July 2018 lead ions with one remaining electron (208Pb⁸¹⁺) were injected and accelerated in the LHC for the first time. After establishing the injection and circulation of a few 208Pb⁸¹⁺ bunches, beam lifetimes of about 50 hours could be established at 6.5 TeV proton equivalent energy. This paper describes the setup of the beam tests and observations made.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB055

About •

paper received ※ 29 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEYYPLM2

The 2018 Heavy-Ion Run of the LHC

2258

J.M. Jowett, C. Bahamonde Castro, W. Bartmann, C. Bracco, R. Bruce, J.M. Coello de Portugal, J. Dilly, S.D. Fartoukh, E. Fol, N. Fuster-Martínez, A. Garcia-Tabares, M. Hofer, E.B. Holzer, M.A. Jebramcik, J. Keintzel, A. Lechner, E.H. Maclean, L. Malina, T. Medvedeva, A. Mereghetti, T.H.B. Persson, B.Aa. Petersen, S. Redaelli, B. Salvachua, M. Schaumann, C. Schwick, M. Solfaroli, M.L. Spitznagel, H. Timko, R. Tomás, A. Wegscheider, J. Wenninger, D. Wollmann
CERN, Meyrin, Switzerland
D. Mirarchi
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom

The fourth one-month Pb-Pb collision run brought LHC Run 2 to an end in December 2018. Following the tendency to reduce dependence on the configuration of the preceding proton run, a completely new optics cycle with the strongest ever focussing at the ALICE and LHCb experiments was designed and rapidly implemented, demonstrating the maturity of the collider’s operating modes. Beam-loss monitor thresholds were carefully adjusted to provide optimal protection from the multiple loss mechanisms in heavy-ion operation. A switch from a basic bunch-spacing of 100 ns to 75 ns was made as the beam became available from the injector chain. A new record luminosity, 6 times the original design and close to the operating value proposed for HL-LHC, provided validation of the strategy for mitigating quenches due to bound-free pair production (BFPP) at the interaction points of the ATLAS and CMS experiments. Most of the beam parameters of the HL-LHC Pb-Pb upgrade were attained during this run and the integrated luminosity goals for the first 10 years of LHC operation were substantially exceeded.

Slides WEYYPLM2 [10.884 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM2

About •

paper received ※ 08 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTS049

Flat-Bottom Instabilities in the CERN SPS

3224

M. Schwarz, K. Iliakis, A. Lasheen, G. Papotti, J. Repond, E.N. Shaposhnikova, H. Timko
CERN, Meyrin, Switzerland

At beam intensities of 2.6·10¹¹ protons per bunch, required at SPS injection for the High Luminosity LHC beam, longitudinal instabilities can degrade the beam quality delivered by the SPS, the LHC injector at CERN. In this paper, we concentrate on beam instability at flat bottom. The dependence of the instability threshold on longitudinal emittance and LLRF system settings was measured, to help identify the impedance driving this instability. While reducing the longitudinal emittance reduces the losses at injection, it can drive the beam unstable. The LLRF system of the SPS (partially) compensates beam loading, but also affects the instability. The effect of the different LLRF systems (feedback, feedforward, phase loop and longitudinal damper) and fourth harmonic RF system on the instability was investigated. The measurements are compared with simulations performed with the longitudinal tracking code BLonD.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS049

About •

paper received ※ 10 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)