Accelerator physics codes

A charged particle accelerator is a complex machine that takes elementary charged particles and accelerates them to very high energies. Accelerator physics is a field of physics encompassing all the aspects required to design and operate the equipment and to understand the resulting dynamics of the charged particles. There are software packages associated with each such domain. There are a large number of such codes. The 1990 edition of the Los Alamos Accelerator Code Group's compendium provides summaries of more than 200 codes. Certain of those codes are still in use today although many are obsolete. Another index of existing and historical accelerator simulation codes is located at

Single particle dynamics codes

For many applications it is sufficient to track a single particle through the relevant electric and magnetic fields. Old unmaintained codes include: BETA, AGS, ALIGN, COMFORT, DESIGN, DIMAD, GUINEA-PIG, HARMON, LEGO, LIAR, MAGIC, MARYLIE, PATRICIA, PETROS, RACETRACK, SYNCH, TRANSPORT, TURTLE, and UAL. Maintained codes include:

	Single Particle Dynamics	Spin Tracking	Taylor Maps	Collective Effects	Synchrotron Radiation Tracking	Wakefields	Extensible	Notes
Accelerator Toolbox (AT),	Yes	Yes	No	Yes	No	No	Yes
ASTRA	Yes	No	No	Yes	No	Yes	No	For space-charge effects evaluation
BDSIM	Yes	No	No	No	No	No	Yes	For particle-matter interaction studies.
Bmad (contains PTC)	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Reproduces PTC's unique beam line structures. Also simulates X-rays.
COSY INFINITY	Yes	Yes	Yes	No	No	No	Yes
Elegant	Yes	No	No	Yes	No	Yes	No
MAD8 and MAD-X (includes PTC)	Yes	No	Yes	No	Yes	No	No
MAD-NG	Yes	No	Yes	No	Yes	No	Yes	Very extensible, embeds LuaJIT
MERLIN++	Yes	Yes	No	No	No	Yes	Yes	Other: beam-matter interactions, sliced-macroparticle tracking
OCELOT	Yes	No	No	Yes	Yes	Yes	Yes
OPA	Yes	No	No	No	No	No	No
OPAL	Yes	No	Yes	Yes	No	Yes	Yes	Open source, runs on the laptop and on x 10k cores.
PLACET	Yes	No	No	Yes	Yes	Yes	Yes	Simulates a LINAC including wakefields.
Propaga	Yes	No	No	No	No	No	Yes
PTC	Yes	Yes	Yes	No	No	No	Yes
SAD	Yes	No	No	No	Yes	Yes	No
SAMM	Yes	Yes	No	No	No	No	No
SixTrack	Yes	No	Yes	No	No	No	No	Can run on BOINC
Zgoubi	Yes	Yes	No	No	Yes	No	Yes	Open source.

Columns

Spin Tracking

Tracking of a particle's spin.

Taylor Maps

Construction of Taylor series maps to high order that can be used for simulating particle motion and also can be used for such things as extracting single particle resonance strengths.

Collective effects

The interactions between the particles in the beam can have important effects on the behavior, control and dynamics. Collective effects take different forms from Intrabeam Scattering (IBS) which is a direct particle-particle interaction to wakefields which are mediated by the vacuum chamber wall of the machine the particles are traveling in. In general, the effect of direct particle-particle interactions is less with higher energy particle beams. At very low energies, space charge has a large effect on a particle beam and thus becomes hard to calculate. The above simulation codes do not handle low energy space charge effects. See below for a list of programs that can handle low energy space charge forces.

Synchrotron radiation tracking

Ability to track the synchrotron radiation (mainly X-rays) produced by the acceleration of charged particles.

Wakefields

The electro-magnetic interaction between the beam and the vacuum chamber wall enclosing the beam are known as wakefields. Wakefields produce forces that affect the trajectory of the particles of the beam and can potentially destabilize the trajectories.

Extensible

Object oriented coding to make it relatively easy to extend the capabilities.

Space Charge Codes

The self interaction (e.g. space charge) of the charged particle beam can cause growth of the beam, such as with bunch lengthening, or intrabeam scattering. Additionally, space charge effects may cause instabilities and associated beam loss. Typically, at relatively low energies (roughly for energies where the relativistic gamma factor is less than 10 or so), the Poisson equation is solved at intervals during the tracking using Particle-in-cell algorithms. Space charge effects lessen at higher energies so at higher energies the space charge effects may be modeled using simpler algorithms that are computationally much faster than the algorithms used at lower energies. Codes that handle low energy space charge effects include:

• ASTRA
• Bmad
• CST Studio Suite
• GPT
• IMPACT
• mbtrack
• ORBIT, PyORBIT
• OPAL
• PyHEADTAIL
• Synergia
• TraceWin
• Tranft
• VSim
• Warp

At higher energies, space charge effects include Touschek scattering and coherent synchrotron radiation (CSR). Codes that handle higher energy space charge include:

• Bmad
• ELEGANT
• MaryLie
• SAD

Beam-beam effects codes

When two beams collide, the electro-magnetic field of one beam will then have strong effects on the other one, called beam-beam effects. Codes for this computation include

• GUINEA-PIG

Impedance computation codes

An important class of collective effects may be summarized in terms of the beams response to an "impedance". An important job is thus the computation of this impedance for the machine. Codes for this computation include

• ABCI
• ACE3P
• CST Studio Suite
• GdfidL
• TBCI
• VSim

Step-wise ray-tracing codes; ability to ray-trace in electrostatic and/or magnetic field maps

• Zgoubi

Magnet and other hardware-modeling codes

To control the charged particle beam, appropriate electric and magnetic fields must be created. There are software packages to help in the design and understanding of the magnets, RF cavities, and other elements that create these fields. Codes include

• ACE3P
• COMSOL Multiphysics
• CST Studio Suite
• OPERA
• VSim
• Zgoubi. Creates electric and magnetic fields from built-in analytical models. Ability to deliver 1D, 2D & 3D field maps from these models.

Lattice file format and data interchange issues

Given the variety of modelling tasks, there is not one common data format that has developed. For describing the layout of an accelerator and the corresponding elements, one uses a so-called "lattice file". There have been numerous attempts at unifying the lattice file formats used in different codes. One unification attempt is the Accelerator Markup Language, and the Universal Accelerator Parser. Another attempt at a unified approach to accelerator codes is the UAL or Universal Accelerator Library.

The file formats used in MAD may be the most common, with translation routines available to convert to an input form needed for a different code. Associated with the Elegant code is a data format called SDDS, with an associated suite of tools. If one uses a Matlab-based code, such as Accelerator Toolbox, one has available all the tools within Matlab.

Codes in applications of particle accelerators

There are many applications of particle accelerators. For example, two important applications are elementary particle physics and synchrotron radiation production. When performing a modeling task for any accelerator operation, the results of charged particle beam dynamics simulations must feed into the associated application. Thus, for a full simulation, one must include the codes in associated applications. For particle physics, the simulation may be continued in a detector with a code such as Geant4.

For a synchrotron radiation facility, for example, the electron beam produces an x-ray beam that then travels down a beamline before reaching the experiment. Thus, the electron beam modeling software must interface with the x-ray optics modelling software such as SRW, Shadow, McXTrace, or Spectra. Bmad can model both X-rays and charged particle beams. The x-rays are used in an experiment which may be modeled and analyzed with various software, such as the DAWN science platform. OCELOT also includes both synchrotron radiation calculation and x-ray propagation models.

See also

• CARE-HHH Codes Repository
• List of codes from UCLA Particle Beam Physics Laboratory