IPAC2015 - List of Authors (Liu, C.)

Paper	Title	Page
TUBD1	Optics Measurement and Correction during Acceleration with Beta-squeeze in RHIC	1380
	C. Liu, A. Marusic, M.G. Minty BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In the past, beam optics correction at RHIC has only taken place at injection and at final energy, with interpolation of corrections partially into the acceleration cycle. Recent measurements of the beam optics during acceleration and squeeze have evidenced significant beta-beats that, if corrected, could minimize undesirable emittance dilutions and maximize the spin polarization of polarized proton beams by avoiding the high-order multipole fields sampled by particles within the bunch. We recently demonstrated successfully beam optics corrections during acceleration at RHIC. We verified conclusively the superior control of the beam realized via these corrections. As a valuable by-product, these corrections have minimized the beta-beat at the profile monitors, so providing more precise measurements of the evolution of the beam emittances during acceleration.
	Slides TUBD1 [1.581 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUBD1
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TUPTY047	ERL with Non-Scaling Fixed Field Alternating Gradient Lattice for eRHIC	2120
	D. Trbojevic, J.S. Berg, S.J. Brooks, Y. Hao, V. Litvinenko, C. Liu, F. Méot, M.G. Minty, V. Ptitsyn, T. Roser, P. Thieberger, N. Tsoupas BNL, Upton, Long Island, New York, USA
	Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the US Department of Energy. The proposed eRHIC electron-hadron collider uses a "non-scaling FFAG" lattice to recirculate 16 turns of different energy through just two beamlines located in the RHIC tunnel. This paper presents lattices for these two FFAGs that are optimised for low magnet field and to minimise total synchrotron radiation across the energy range. The higher number of recirculations in the FFAG allows a shorter linac (1.322GeV) to be used, drastically reducing cost, while still achieving a 21.2GeV maximum energy to collide with one of the existing RHIC hadron rings at up to 250GeV. eRHIC uses many cost-saving measures in addition to the FFAG: the linac operates in energy recovery mode, so the beams also decelerate via the same FFAG loops and energy is recovered from the interacted beam. All magnets will constructed from NdFeB permanent magnet material, meaning chillers and large magnet power supplies are not needed. This paper also describes a smaller prototype ERL-FFAG accelerator that will test all of these technologies in combination to reduce technical risk for eRHIC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY047
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TUPWI050	Optics Correction for the Multi-pass FFAG ERL Machine eRHIC	2363
	C. Liu, S.J. Brooks, V. Litvinenko, M.G. Minty, V. Ptitsyn, D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Gradient errors in the multi-pass Fixed Field Alternating Gradient (FFAG) Energy Recovery Linac (ERL) machine, eRHIC, distort the beam orbit and therefore cause emittance increase. The localization and correction of gradient errors are essential for an effective orbit correction and emittance preservation. In this report, the methodology and simulation of optics correction for the multi-pass FFAG ERL machine eRHIC will be presented. The work was performed under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI050
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TUPWI051	Study of Orbit Correction for eRHIC FFAG Design	2366
	C. Liu, Y. Hao, V. Litvinenko, F. Méot, M.G. Minty, V. Ptitsyn, D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The chromaticities in the eRHIC linear non-scaling Fixed Field Alternating Gradient (FFAG) lattice are very large. Therefore, particles will decohere in phase space given the presence of lattice errors. The decoherence causes a deviation of the orbit response which is the basis for orbit corrections. In this report we will present a study of the linearity of the orbit response in a lattice with large chromaticity, a comparison of the results of orbit corrections for several cases together with a conclusion that correcting the average orbit with a measured orbit response works as good as an orbit correction for on-momentum particles. The work was performed under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI051
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TUPWI055	Chromatic Effects and Orbit Correction in eRHIC Arcs	2378
	F. Méot, C. Liu BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In the FFAG version of the electron energy recovery recirculator of the eRHIC electron-ion collider project, natural chromaticity is important and not corrected. Tracking simulations illustrate various aspects of its effects on 6-D bunch dynamics over the 16 turn recirculation from 1.3 to 21.2GeV collision energy, and back down to injection energy. These effects can be mitigated via orbit control, the methodology for that is described and its effectiveness illustrated via a series of ad hoc numerical simulations. Because polarization is paramount in the eRHIC NP program, its careful monitoring is part of the simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI055
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TUPWI060	RHIC Polarized Proton-Proton Operation at 100 GeV in Run 15	2384
	V. Schoefer, E.C. Aschenauer, G. Atoian, M. Blaskiewicz, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, Y. Dutheil, W. Fischer, C.J. Gardner, X. Gu, T. Hayes, H. Huang, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, P.H. Pile, A. Poblaguev, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, W.B. Schmidke, F. Severino, T.C. Shrey, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, S.M. White, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang BNL, Upton, Long Island, New York, USA
	The first part of RHIC Run 15 consisted of nine weeks of polarized proton on proton collisions at a beam energy of 100 GeV at two interaction points. In this paper we discuss several of the upgrades to the collider complex that allowed for improved performance this run. The largest effort consisted of commissioning of the electron lenses, one in each ring, which are designed to compensate one of the two beam-beam interactions experienced by the proton bunches. The e-lenses therefore raise the per bunch intensity at which luminosity becomes beam-beam limited. A new lattice was designed to create the phase advances necessary for a functioning e-lens which also has an improved off-momentum dynamic aperture relative to previous runs. In order to take advantage of the new, higher intensity limit without suffering intensity driven emittance deterioration, other features were commissioned including a continuous transverse bunch-by-bunch damper in RHIC and a double harmonic capture scheme in the Booster. Other high intensity protections include improvements to the abort system and the installation of masks to intercept beam lost due to abort kicker pre-fires.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI060
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Paper

Title

Page

Optics Measurement and Correction during Acceleration with Beta-squeeze in RHIC

1380

C. Liu, A. Marusic, M.G. Minty
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the past, beam optics correction at RHIC has only taken place at injection and at final energy, with interpolation of corrections partially into the acceleration cycle. Recent measurements of the beam optics during acceleration and squeeze have evidenced significant beta-beats that, if corrected, could minimize undesirable emittance dilutions and maximize the spin polarization of polarized proton beams by avoiding the high-order multipole fields sampled by particles within the bunch. We recently demonstrated successfully beam optics corrections during acceleration at RHIC. We verified conclusively the superior control of the beam realized via these corrections. As a valuable by-product, these corrections have minimized the beta-beat at the profile monitors, so providing more precise measurements of the evolution of the beam emittances during acceleration.

Slides TUBD1 [1.581 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUBD1

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TUPTY047

ERL with Non-Scaling Fixed Field Alternating Gradient Lattice for eRHIC

2120

D. Trbojevic, J.S. Berg, S.J. Brooks, Y. Hao, V. Litvinenko, C. Liu, F. Méot, M.G. Minty, V. Ptitsyn, T. Roser, P. Thieberger, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the US Department of Energy.
The proposed eRHIC electron-hadron collider uses a "non-scaling FFAG" lattice to recirculate 16 turns of different energy through just two beamlines located in the RHIC tunnel. This paper presents lattices for these two FFAGs that are optimised for low magnet field and to minimise total synchrotron radiation across the energy range. The higher number of recirculations in the FFAG allows a shorter linac (1.322GeV) to be used, drastically reducing cost, while still achieving a 21.2GeV maximum energy to collide with one of the existing RHIC hadron rings at up to 250GeV. eRHIC uses many cost-saving measures in addition to the FFAG: the linac operates in energy recovery mode, so the beams also decelerate via the same FFAG loops and energy is recovered from the interacted beam. All magnets will constructed from NdFeB permanent magnet material, meaning chillers and large magnet power supplies are not needed. This paper also describes a smaller prototype ERL-FFAG accelerator that will test all of these technologies in combination to reduce technical risk for eRHIC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY047

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TUPWI050

Optics Correction for the Multi-pass FFAG ERL Machine eRHIC

2363

C. Liu, S.J. Brooks, V. Litvinenko, M.G. Minty, V. Ptitsyn, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Gradient errors in the multi-pass Fixed Field Alternating Gradient (FFAG) Energy Recovery Linac (ERL) machine, eRHIC, distort the beam orbit and therefore cause emittance increase. The localization and correction of gradient errors are essential for an effective orbit correction and emittance preservation. In this report, the methodology and simulation of optics correction for the multi-pass FFAG ERL machine eRHIC will be presented.
The work was performed under Contract No. DE-AC02-98CH10886
with the U.S. Department of Energy.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI050

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

TUPWI051

Study of Orbit Correction for eRHIC FFAG Design

2366

C. Liu, Y. Hao, V. Litvinenko, F. Méot, M.G. Minty, V. Ptitsyn, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The chromaticities in the eRHIC linear non-scaling Fixed Field Alternating Gradient (FFAG) lattice are very large. Therefore, particles will decohere in phase space given the presence of lattice errors. The decoherence causes a deviation of the orbit response which is the basis for orbit corrections. In this report we will present a study of the linearity of the orbit response in a lattice with large chromaticity, a comparison of the results of orbit corrections for several cases together with a conclusion that correcting the average orbit with a measured orbit response works as good as an orbit correction for on-momentum particles.
The work was performed under Contract No. DE-AC02-98CH10886
with the U.S. Department of Energy.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI051

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TUPWI055

Chromatic Effects and Orbit Correction in eRHIC Arcs

2378

F. Méot, C. Liu
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the FFAG version of the electron energy recovery recirculator of the eRHIC electron-ion collider project, natural chromaticity is important and not corrected. Tracking simulations illustrate various aspects of its effects on 6-D bunch dynamics over the 16 turn recirculation from 1.3 to 21.2GeV collision energy, and back down to injection energy. These effects can be mitigated via orbit control, the methodology for that is described and its effectiveness illustrated via a series of ad hoc numerical simulations. Because polarization is paramount in the eRHIC NP program, its careful monitoring is part of the simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI055

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TUPWI060

RHIC Polarized Proton-Proton Operation at 100 GeV in Run 15

2384

V. Schoefer, E.C. Aschenauer, G. Atoian, M. Blaskiewicz, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, Y. Dutheil, W. Fischer, C.J. Gardner, X. Gu, T. Hayes, H. Huang, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, P.H. Pile, A. Poblaguev, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, W.B. Schmidke, F. Severino, T.C. Shrey, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, S.M. White, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
BNL, Upton, Long Island, New York, USA

The first part of RHIC Run 15 consisted of nine weeks of polarized proton on proton collisions at a beam energy of 100 GeV at two interaction points. In this paper we discuss several of the upgrades to the collider complex that allowed for improved performance this run. The largest effort consisted of commissioning of the electron lenses, one in each ring, which are designed to compensate one of the two beam-beam interactions experienced by the proton bunches. The e-lenses therefore raise the per bunch intensity at which luminosity becomes beam-beam limited. A new lattice was designed to create the phase advances necessary for a functioning e-lens which also has an improved off-momentum dynamic aperture relative to previous runs. In order to take advantage of the new, higher intensity limit without suffering intensity driven emittance deterioration, other features were commissioned including a continuous transverse bunch-by-bunch damper in RHIC and a double harmonic capture scheme in the Booster. Other high intensity protections include improvements to the abort system and the installation of masks to intercept beam lost due to abort kicker pre-fires.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI060

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