IBS benchmarking for Xsuite

A series of examples including IBS with the aim of integrating IBS effects in Xsuite:

• IBS MADX code: modified version on March 2023 wrapped in cpymad. Original code from: S. Papadopoulou and F. Antoniou in https://github.com/stpapado/calculateIBS_MADX.git
• IBS Python code: IBS library by M. Zampetakis in https://github.com/MichZampetakis/IBS_for_Xsuite. No local copies of these libraries in the current project.
• Xsuite by G. Iadarola et al in https://github.com/xsuite

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IBS background

Intra-beam scattering (IBS) is together with space charge an incoherent type of collective effect, that can strongly degrade beam quality and lead to uncontrolled emittance growth - particularly in the low-energy regime with beams of higher charge states and bunch brightness. In particular, the CERN Ion Injector Chain is strongly affected, where IBS and space charge create intensity bottlenecks in the Proton Synchrotron (PS) and the Super Proton Synchrotron (SPS). A literature review of space charge and IBS can be found here.

File structure

1. 000_sequences_and_XSlines: save sequences and create Xsuite lines. Examples for LHC protons and ions, SPS protons and ions, injection and top energy. Parameters might not exactly correspond to operational scenario. For the LHC, 000_pymask.py and optics_specific_tools.py can be found on the lhcmask repo. Step-by-step benchmarking of PS and SPS sequences for Xsuite vs PTC and MADX can be found in this repo

2. 001_PythonIBS_vs_MadxIBS: benchmarking of analytical approaches with MADX IBS and PyIBS. Formulas for bunch length and energy deviation are valid only for small amplitude oscillations.

   • master: contains ibs_madx.py and ibs_python.py which are the template scripts to use. ibs_python.py is based on the example of https://github.com/MichZampetakis/IBS_for_Xsuite/blob/main/CLIC_DRs_IBS_allmodels.py
   • examples: A series of examples that benchmarks the analytical approach of MADX-IBS and PyIBS. Input parameters are passed through config.yaml and sequences are read from 000_sequences_and_XSlines.

3. 001.5_LongitudinalLimitRect_Tests: checks the effect of adding xtrack.LongitudinalLimitRect(..) aperture element to the line, i.e. killing all particles outside of the RF bucket (so-called unbunched beam). If this element is not installed, particles that drift into other buckets will contribute to unrealistically long bunch lengths.

4. 002_PyIBS_Xsuite: PyIBS with Xsuite example for SPS ions. Based on CLIC example of https://github.com/MichZampetakis/IBS_for_Xsuite/blob/main/CLIC_DRs_IBS_allmodels.py

5. 003_PyIBS_Xsuite_treemaker: scripts to submit to htcondor with tree_maker