The electron lens test bench for the relativistic heavy ion collider at Brookhaven National Laboratory

Gu, X.; Altinbas, F.Z.; Beebe, E.; Fischer, W.; Frak, B.; Gassner, D.; Hamdi, K.; Hock, J.; Hoff, L.; Kankiya, Prerana; Lambiase, R.; Luo, Y.; Mapes, M.; Mi, J.; Miller, Toby; Montag, C.; Nemesure, S.; Okamura, M.; Olsen, R.; Pikin, A.; Raparia, D.; Rosas, P.; Sandberg, J.; Tan, Y.; Theisen, C.; Tuozzolo, J.; Zhang, W.

doi:10.1016/j.nima.2013.11.102

Cited by 10 publications

(26 citation statements)

References 21 publications

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“…2 shows that with an electron beam of 1.2 A current and 5 keV energy, the space charge potential (absolute value) is very close to the beam energy. If it becomes greater than its initial energy, the electron beam will stop and become a virtual cathode, which was observed on the test bench for the RHIC electron lens [24]. With higher beam energy, this effect is reduced.…”

Section: Changes In the Profile Of The Transverse Beam Due To The Lonmentioning

confidence: 91%

“…For measuring the profile of the electron beam, there are two insertion devices, viz., a YAG screen and a pinhole detector [24]. When the electron lens runs with a high-current (e.g.…”

Section: Introduction To the Rhic Electron Lensmentioning

confidence: 99%

“…During the commissioning of the electron lenses in 2013 and 2014, the transverse profile of the electron beam was measured via both the YAG screen and pinhole scanner [24] systems. Both methods show that the electron beam still has a Gaussian transverse distribution.…”

Section: Introduction To the Rhic Electron Lensmentioning

confidence: 99%

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Transverse profile of the electron beam for the RHIC electron lenses

Altinbas

Costanzo

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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a b s t r a c tThe transverse profile of the electron beam plays a very important role in assuring the success of the electron lens beam-beam compensation, as well as its application in space charge compensation. To compensate for the beam-beam effect in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory, we recently installed and commissioned two electron lenses. In this paper, we describe, via theory and simulations using the code Parmela, the evolution of the density of the electron beam with space charge within an electron lens from the gun to the main solenoid. Our theoretical analysis shows that the change in the beam transverse density is dominated by the effects of the space charge induced longitudinal velocity reduction, not by those of transverse Coulomb collisions. We detail the transverse profile of RHIC electron-lens beam, measured via the YAG screen and pinhole detector, and also describe its profile that we assessed from the signal of the electron-backscatter detector (eBSD) via scanning the electron beam with respect to the RHIC beam. We verified, in simulations and experiments, that the distribution of the transverse electron beam is Gaussian throughout its propagation in the RHIC electron lens.& 2015 Elsevier B.V. All rights reserved. MotivationDuring the 2013 255 GeV proton run of the Relativistic Heavy Ion Collider, we found that the threshold of the intensity of the proton bunch in RHIC was about 2 Â 10 11 [1], as was predicted by the beam-beam simulations [2]. To further increase the bunch intensity, and therefore, its luminosity via compensating for the large beam-beam tune spread from the proton-proton interactions at IP6 and IP8, we installed two electron lenses in the electronproton interaction region IR10 [3] and commissioned them during the RHIC 2013 and 2014 runs. For long-range compensation of beam-beam tune shifts [4], electron lenses had been installed and operated in the Fermilab Tevatron collider [5][6][7]. They were also used for head-on beam-beam compensation [8], to remove uncaptured particles in the abort gap [9], and as well as to demonstrate halo scraping with hollow electron beams [10].In an earlier paper [2], we specified the requirements of the electron beam in the RHIC electron lens, such as its current, shape, and the distribution of the profile of the transverse beam in the interaction region. For optimum head-on beam-beam compensation, according to theory and simulation, the electron beam in the RHIC electron lens should have the same transverse distribution as does the proton beam, i.e., it should be a Gaussian beam [11].According to theoretical modeling [12, p. 169] of the electron beam, if the effects of space charge dominate the physics of the beam, or if the Debye length is much smaller than the beam radius, then, in a state of thermal equilibrium, the beam tends to be uniform with a sharp radius. If we ignore the space charge, or if the Debye length is much greater than beam radius, then the external focusing field will dominate the p...

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Section: Changes In the Profile Of The Transverse Beam Due To The Lonmentioning

confidence: 91%

“…For measuring the profile of the electron beam, there are two insertion devices, viz., a YAG screen and a pinhole detector [24]. When the electron lens runs with a high-current (e.g.…”

Section: Introduction To the Rhic Electron Lensmentioning

confidence: 99%

See 1 more Smart Citation

Transverse profile of the electron beam for the RHIC electron lenses

Altinbas

Costanzo

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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“…IrCe offers a comfortable combination of a high-emission current density and a long lifetime. A LaB 6 (monocrystalline lanthanum hexaboride) cathode was also tested on the RHIC electron lens test bench [24]. These cathodes were manufactured by the Budker Institute of Nuclear Physics and have an expected lifetime of more than 20 000 h under nominal operating conditions [25,26].…”

Section: A Cathode Size and Materialsmentioning

confidence: 99%

Electron lenses for head-on beam-beam compensation in RHIC

Gu¹,

Fischer²,

Altinbas³

et al. 2017

Phys. Rev. Accel. Beams

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Two electron lenses (e-lenses) have been in operation during the 2015 RHIC physics run as part of a head-on beam-beam compensation scheme. While the RHIC lattice was chosen to reduce the beam-beaminduced resonance-driving terms, the electron lenses reduced the beam-beam-induced tune spread. This has been demonstrated for the first time. The beam-beam compensation scheme allows for higher beam-beam parameters and therefore higher intensities and luminosity. In this paper, we detail the design considerations and verification of the electron beam parameters of the RHIC e-lenses. Longitudinal and transverse alignments with ion beams and the transverse beam transfer function measurement with head-on electronproton beam are presented.

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“…The main parameters of the RHIC electron lenses (Fig. 2) [9,18] are shown in Table I. A major design consideration was the creation of a low-noise (DC) electron beam with a Gaussian transverse profile [18]. The electron beam is fully magnetized, i.e.…”

mentioning

confidence: 99%