Luminosity optimization near the beam-beam limit by increasing bunch length or crossing angle

Ruggiero, F.; Zimmermann, F.

doi:10.1103/physrevstab.5.061001

Cited by 37 publications

(30 citation statements)

References 6 publications

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“…Moreover, the horizontal tune shift x drops like 1= z . However, unlike [12,13], in the present crab-waist scheme the Piwinski angle is increased by decreasing the horizontal beam size and increasing the crossing angle. In this way we can gain in luminosity as well, and the horizontal tune shift decreases.…”

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confidence: 97%

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Test of “Crab-Waist” Collisions at theDAΦNEΦFactory

Zobov¹,

Alesini²,

Biagini³

et al. 2010

Phys. Rev. Lett.

129

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The electron-positron collider DAÈNE, the Italian È factory, has been recently upgraded in order to implement an innovative collision scheme based on large crossing angle, small beam sizes at the crossing point, and compensation of beam-beam interaction by means of sextupole pairs creating a ''crab-waist'' configuration in the interaction region. Experimental tests of the novel scheme exhibited an increase by a factor of 3 in the peak luminosity of the collider with respect to the performances reached before the upgrade. In this Letter we present the new collision scheme, discuss its advantages, describe the hardware modifications realized for the upgrade, and report the results of the experimental tests carried out during commissioning of the machine in the new configuration and standard operation for the users. DOI: 10.1103/PhysRevLett.104.174801 PACS numbers: 29.27.Bd, 29.20.db, 29.27.Eg Pushing the luminosity of storage-ring colliders to unprecedented levels opens up unique opportunities for precision measurements of rare decay modes and extremely small cross sections, which are sensitive to new physics beyond the standard model.In high luminosity colliders with conventional collision schemes the key requirements to increase the luminosity are: very small vertical beta function y at the interaction point (IP), high beam intensity and large horizontal emittance " x and beam size x . However, y cannot be much smaller than the longitudinal rms bunch size (bunch length) z without incurring the ''hour-glass'' effect. Unfortunately, it is very difficult to shorten the bunch in a high current ring without exciting collective instabilities. Even then, the large beam current may result in high power losses, beam instabilities and dramatic increase of the wallplug power. These problems can be overcome with the recently proposed crab-waist (CW) scheme of beambeam collisions [1,2] where a substantial luminosity increase can be achieved without bunch length reduction and with moderate beam currents.The CW scheme has been successfully tested at the electron-positron collider DAÈNE, the Italian È factory [3,4] operating at the energy of 1020 MeV in the center of mass. After an upgrade including the implementation of this novel collision scheme, the specific luminosity at low beam currents has been boosted by more than a factor of 4, while the present peak luminosity is a factor of 3 higher than the maximum value obtained with the original configuration based on the standard collision scheme.The successful test has provided the opportunity to continue the DAÈNE physics program. Moreover, the advantages of the crab-waist collision scheme have triggered several collider projects exploiting its potential. In particular, physics and accelerator communities are discussing new projects of a SuperB factory [5,6] and a SuperTau-Charm factory [7] with luminosities about 2 orders of magnitude beyond those achieved at the present B-[8] and Tau-charm factories [9].In this Letter we briefly introduce the CW concept, shortly discuss ...

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confidence: 97%

“…It has been also proposed for hadron colliders [12,13] to increase the bunch length and the crossing angle. In such a case, if it were possible to increase N proportionally to z , the vertical tune shift y would remain constant, while the luminosity would grow proportionally to z ; see (1).…”

mentioning

confidence: 99%

Test of “Crab-Waist” Collisions at theDAΦNEΦFactory

Zobov¹,

Alesini²,

Biagini³

et al. 2010

Phys. Rev. Lett.

129

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“…The crossing angle does not only reduce the geometric overlap of the colliding bunches, but it also reduces the beam-beam tune shift induced by the wanted central collision. For round beams with alternating planes of crossing in two IPs the reduction of the beam-beam tune shift is approximately given by the same factor R  as for the luminosity [39] (see above).…”

Section: Long-range Collisionsmentioning

confidence: 69%

Collider Beam Physics

Zimmermann

2014

Rev. Accl. Sci. Tech.

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“…[2] formulas are given for the incoherent tune shift due to the beam-beam interaction for particles in the beam center. In Fig.…”

Section: Beam-beam Tune Shiftsmentioning

confidence: 99%

“…He showed that an increase in the crossing angle reduces the beam-beam tune shift and allows a higher line density, which in turn leads to an increased luminosity. Recently, Ruggiero and Zimmermann extended this analysis to bunched beams [2]. They computed the incoherent beam-beam tune shift as a function of crossing angle and bunch length and showed how the luminosity increases at the beambeam limit with an increase in the crossing angle or bunch length.…”

Section: Introductionmentioning

confidence: 99%

Luminosity Increase at the Incoherent Beam-Beam Limit in RHIC

Fischer¹,

Blaskiewicz²

2003

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By colliding bunches of greater length under a larger angle, the tune spread caused by the beambeam interaction can be reduced. Assuming a constant limit for the beam-beam tune drift, the bunch intensity can then be increased. In this way, a luminosity increase is possible. We review this strategy for proton beams in RHIC with two collisions. We consider short bunches in the storage rf system, long bunches in the accelerating rf system, and superbunches that fill the whole circumference except for an abort gap. Resonances driven by the beam-beam interaction and coherent effects are neglected in this article.

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Luminosity optimization near the beam-beam limit by increasing bunch length or crossing angle

Cited by 37 publications

References 6 publications

Test of “Crab-Waist” Collisions at theDAΦNEΦFactory

Test of “Crab-Waist” Collisions at theDAΦNEΦFactory

Collider Beam Physics

Luminosity Increase at the Incoherent Beam-Beam Limit in RHIC

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