| Paper | Title | Page |
|---|---|---|
| MOAM5P50 | LHC Run 2: Results and Challenges | 14 |
|
||
| The first proton run of the LHC was very successful and resulted in important physics discoveries. It was followed by a two-year shutdown where a large number of improvements were carried out. In 2015, the LHC was restarted and this second run aims at further exploring the physics of the standard model and beyond at an increased beam energy. This article gives a review of the performance achieved so far and the limitations encountered, as well as the future challenges for the CERN accelerators to maximize the data delivered to the LHC experiments in Run 2. Furthermore, the status of the 2016 LHC run and commissioning is discussed. | ||
|
Slides MOAM5P50 [9.283 MB] | |
| Export • | reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| TUAM4X01 | Electron Cloud in the CERN Accelerator Complex | 266 |
|
||
| Operation with closely spaced bunched beams causes the build up of an Electron Cloud (EC) in both the LHC and the two last synchrotrons of its injector chain (PS and SPS). Pressure rise and beam instabilities are observed at the PS during the last stage of preparation of the LHC beams. The SPS was affected by coherent and incoherent emittance growth along the LHC bunch train over many years, before scrubbing has finally suppressed the EC in a large fraction of the machine. When the LHC started regular operation with 50 ns beams in 2011, EC phenomena appeared in the arcs during the early phases, and in the interaction regions with two beams all along the run. Operation with 25 ns beams (late 2012 and 2015), which is nominal for LHC, has been hampered by EC induced high heat load in the cold arcs, bunch dependent emittance growth and degraded beam lifetime. Dedicated and parasitic machine scrubbing is presently the weapon used at the LHC to combat EC in this mode of operation. This talk summarises the EC experience in the CERN machines (PS, SPS, LHC) and highlight the dangers for future operation with more intense beams as well as the strategies to mitigate or suppress the effect. | ||
|
|
Slides TUAM4X01 [9.785 MB] | |
| Export • | reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| TUAM5X01 | Space Charge Driven Beam Loss for Cooled Beams and Mitigation Measures in the CERN Low Energy Ion Ring | 272 |
|
||
| The performance of the CERN Low Energy Ion Ring (LEIR) with electron cooled lead ion beams is presently limited by losses, which occur during RF capture and the first part of acceleration. Extensive experimental studies performed in 2015 indicate that the losses are caused by the interplay of betatron resonances and the direct space charge detuning, which is significantly enhanced during bunching. Mitigation measures have already been identified and successfully tested, such as reducing the peak line charge density after RF capture, i.e. increasing the rms longitudinal emittance, and compensating third order resonances using existing harmonic sextupole correctors. New record intensities at extraction have been achieved. This talk describes the main experimental results from the 2015 measurement campaign including already implemented mitigation measures and the proposed strategy for even further increasing the LEIR intensity reach in the future. | ||
|
|
Slides TUAM5X01 [8.803 MB] | |
| Export • | reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| WEAM1X01 | Code Bench-Marking for Long-Term Tracking and Adaptive Algorithms | 357 |
|
||
|
At CERN we have ramped up a program to investigate space charge effects in the LHC pre-injectors with high brightness beams and long storage times. This in view of the LIU upgrade project for these accelerators. These studies require massive simulation over large number of turns. To this end we have been looking at all available codes and started collaborations on code development with several laboratories: pyORBIT from SNS, SYNERGIA from Fermilab, MICROMAP from GSI and our in-house MAD-X code with an space charge upgrade. We have agreed with our collaborators to bench-mark all these codes in the framework of the GSI bench-marking suite, in particular the main types of frozen space charge and PIC codes are being tested. We also include a study on the subclass of purely frozen and the adaptive frozen modes both part of MAD-X in comparison with the purely frozen MICROMAP code. Last, we will report on CERN's code development effort to understand and eventually overcome the noise issue in PIC codes.
J. Coupard et al., ‘‘LHC Injectors Upgrade, Technical Design Report, Vol. I: Protons'', LIU Technical Design Report (TDR), CERN-ACC-2014-0337. |
||
|
|
Slides WEAM1X01 [2.348 MB] | |
| Export • | reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| WEAM3X01 | Code Development for Collective Effects | 362 |
|
||
| The presentation will cover approaches and strategies of modeling and implementing collective effects in modern simulation codes. We will review some of the general approaches to numerically model collective beam dynamics in circular accelerators. We will then look into modern ways of implementing collective effects with a focus on plainness, modularity and flexibility, using the example of the PyHEADTAIL framework, and highlight some of the advantages and drawbacks emerging from this method. To ameliorate one of the main drawbacks, namely a potential loss of performance compared to the classical fully compiled codes, several options for speed improvements will be mentioned and discussed. Finally some examples and application will be shown together with future plans and perspectives. | ||
|
|
Slides WEAM3X01 [65.643 MB] | |
| Export • | reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |