Record low<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>β</mml:mi></mml:math>beating in the LHC

Tomás, Rogelio; Bach, Thomas; Calaga, R.; Langner, Andy; Levinsen, Yngve; Maclean, Ewen; Persson, Tobias; Skowroński, Piotr; Strzelczyk, M; Vanbavinckhove, G; Miyamoto, Ryoichi

doi:10.1103/physrevstab.15.091001

Cited by 50 publications

(48 citation statements)

References 9 publications

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“…For the extreme Ã values of 5-10 cm under consideration, the chromatic correction is sensitive to variations of the order of 0.5-1 degrees (2-3 Â 10 À3 in tune units) for the left and right phase advances of the low-insertions. This requirement is challenging, but actually not far from what has been already demonstrated in the LHC where the -beating correction is actually based on the measurement of the betatron phase advances and on the minimization of their deviation with respect to the model [32].…”

Section: The Telescopic Collision Opticsmentioning

confidence: 95%

Achromatic telescopic squeezing scheme and application to the LHC and its luminosity upgrade

Fartoukh

2013

Phys. Rev. ST Accel. Beams

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A novel optics concept, the achromatic telescopic squeezing (ATS) scheme has been invented in the context of the Large Hadron Collider (LHC) upgrade studies, and chosen as the baseline scheme for the optics and layout of the recently approved high luminosity LHC project (HL-LHC). This scheme offers an extremely powerful and flexible machinery in order to strongly reduce Ã in a symmetric or asymmetric way (i.e. without necessarily imposing the same Ã in both planes), while perfectly controlling the chromatic aberrations induced, namely the linear and nonlinear chromaticities, the off-momentum beating, and the spurious dispersion from the large crossing angle which is required at small Ã in the particular case of the (HL)-LHC. The initial motivations of the scheme will be reviewed, followed by a detailed description of its fundamental theoretical foundations. An effective construction of ATS optics will be given and its main features illustrated in the case of the LHC and HL-LHC.

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Section: The Telescopic Collision Opticsmentioning

confidence: 95%

Achromatic telescopic squeezing scheme and application to the LHC and its luminosity upgrade

Fartoukh

2013

Phys. Rev. ST Accel. Beams

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“…Luminosity imbalance between different detectors is another important consideration for circular colliders operating with more than one experiment (LEP, LHC). In 2012, the LHC luminosity imbalance between the ATLAS and CMS experiments was reduced to less than 3% thanks to the applied optics corrections [73]. Overall, the LHC optics control has set an impressive new record for hadron colliders.…”

Section: Luminosity Tuningmentioning

confidence: 99%

“…One important exception is the LHC, whose optics has proven remarkably stable and reproducible, even from one year to the next, without requiring any further correction in the following year. During the LHC commissioning, a segment-by-segment local IR optics correction has been applied together with global corrections, and IP parameter scans are found not to be necessary [73]. Luminosity imbalance between different detectors is another important consideration for circular colliders operating with more than one experiment (LEP, LHC).…”

Section: Luminosity Tuningmentioning

confidence: 99%

Collider Beam Physics

Zimmermann

2014

Rev. Accl. Sci. Tech.

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“…This is done using an analysis package developed for the LHC. A description can be found in [3,9]. The action is derived from the measured functions and represents the average of all BPMs in the ring.…”

Section: Data Processing and Analysismentioning

confidence: 99%

Direct amplitude detuning measurement with ac dipole

White

Maclean

Tomás

2013

Phys. Rev. ST Accel. Beams

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In circular machines, nonlinear dynamics can impact parameters such as beam lifetime and could result in limitations on the performance reach of the accelerator. Assessing and understanding these effects in experiments is essential to confirm the accuracy of the magnetic model and improve the machine performance. A direct measurement of the machine nonlinearities can be obtained by characterizing the dependency of the tune as a function of the amplitude of oscillations (usually defined as amplitude detuning). The conventional technique is to excite the beam to large amplitudes with a single kick and derive the tune from turn-by-turn data acquired with beam position monitors. Although this provides a very precise tune measurement it has the significant disadvantage of being destructive. An alternative, nondestructive way of exciting large amplitude oscillations is to use an ac dipole. The perturbation Hamiltonian in the presence of an ac dipole excitation shows a distinct behavior compared to the free oscillations which should be correctly taken into account in the interpretation of experimental data. The use of an ac dipole for direct amplitude detuning measurement requires careful data processing allowing one to observe the natural tune of the machine; the feasibility of such a measurement is demonstrated using experimental data from the Large Hadron Collider. An experimental proof of the theoretical derivations based on measurements performed at injection energy is provided as well as an application of this technique at top energy using a large number of excitations on the same beam.

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Record lowβbeating in the LHC

Cited by 50 publications

References 9 publications

Achromatic telescopic squeezing scheme and application to the LHC and its luminosity upgrade

Achromatic telescopic squeezing scheme and application to the LHC and its luminosity upgrade

Collider Beam Physics

Direct amplitude detuning measurement with ac dipole

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