Collider Beam Physics

Zimmermann, F.

doi:10.1142/s1793626814300096

Cited by 3 publications

(2 citation statements)

References 52 publications

(64 reference statements)

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“…The two components of Acol could be disentangled via two measurements, one with the nominal bunches, the other with the pilot bunches. The intensities of the e − and e + pilot bunches are taken to be equal, and the bunch length scales as the square root of this intensity [18]. The left panel of Fig.…”

Section: Using Pilot Bunchesmentioning

confidence: 99%

Beam-beam effects on the luminosity measurement at FCC-ee

Voutsinas

Pérez

Dam

et al. 2019

J. High Energ. Phys.

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The first part of the physics programme of the integrated FCC (Future Circular Colliders) proposal includes measurements of Standard Model processes in e + e − collisions (FCCee) with an unprecedented precision. In particular, the potential precision of the Z lineshape determination calls for a very precise measurement of the absolute luminosity, at the level of 10 −4 , and the precision on the relative luminosity between energy scan points around the Z pole should be an order of magnitude better. The luminosity is principally determined from the rate of low-angle Bhabha interactions, e + e − → e + e − , where the final state electrons and positrons are detected in dedicated calorimeters covering small angles from the outgoing beam directions. Electromagnetic effects caused by the very large charge density of the beam bunches affect the effective acceptance of these luminometers in a nontrivial way. If not corrected for, these effects would lead, at the Z pole, to a systematic bias of the measured luminosity that is more than one order of magnitude larger than the desired precision. In this note, these effects are studied in detail, and methods to measure and correct for them are proposed.

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Section: Using Pilot Bunchesmentioning

confidence: 99%

Beam-beam effects on the luminosity measurement at FCC-ee

Voutsinas

Pérez

Dam

et al. 2019

J. High Energ. Phys.

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“…The luminosity reduction is a combination of a purely geometric component (quantified by the so-called geometric reduction factor) and the impact of beam-beam effects. The geometric reduction factor depends on the crossing angle and the bunch aspect ratio in the plane of crossing, as the crossing angle increases the effective bunch size in the transverse dimension of the plane of crossing [2]. The aspect ratio for the proton and electron bunches of eRHIC is 569 and 47, respectively [1].…”

Section: Introductionmentioning

confidence: 99%

Luminosity geometric reduction factor from colliding bunches with different lengths

Verdú-Andrés

2017

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In the interaction point of the future electron-Ion collider eRHIC, the electron beam bunches are at least one order of magnitude shorter than the proton beam bunches. With the introduction of a crossing angle, the actual number of collisions resulting from the bunch collision gets reduced. Here we derive the expression for the luminosity geometric reduction factor when the bunches of the two incoming beams are not equal.

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