The DOE program of scientific discovery relies heavily on particle accelerators, which comprise 14 of the 28 facilities in the DOE twenty-year outlook on Facilities for the Future of Science. The Community Petascale for Accelerator Science and Simulation (COMPASS) project, funded by the Offices of High Energy Physics (HEP), Nuclear Physics (NP), Basic Energy Sciences (BES) and the Office of Advanced Scientific Computing Research (ASCR), will develop a comprehensive computational infrastructure for accelerator modeling and optimization. This project will advance accelerator computational capabilities from the terascale to the petascale to support DOE priorities for the next decade and beyond.
The Accelerator Science & Technology (AST) SciDAC1 project, the predecessor project to COMPASS, a partnership of accelerator computationalists, applied mathematicians, and computer scientists, generated a suite of parallel accelerator simulation tools. These were applied to important accelerator projects of the DOE.
Under SciDAC2, these tools will be enhanced to contain new capabilities as needed by HEP projects, such as the ILC, the LHC, the Tevatron, and PEP-II, and for Advanced Acceleration research; NP projects, such as CEBAF and RHIC, the CEBAF and RHIC upgrades, RIA, and an NP electron collider, including ELIC and eRHIC; and BES projects, such as LCLS, NSLS-II, SNS, and upgrades to the APS.
This simulation suite will contain a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and advanced accelerator modeling. Beam dynamics studies will include developing an understanding of the lifetime limits from beam collisions in colliders. Electromagnetics modeling will be used to optimize cavity shapes for increased accelerating gradient and beam current. Electron cooling computations will determine the configuration of cooling systems needed for mitigating beam-beam effects. Advanced accelerator modeling is needed to develop concepts for HEP accelerators beyond the ILC and to develop tabletop electron accelerators for BES and NP projects.
Configuration space visualization of a simulated beam slice of the Fermilab Booster during the injection phase of the machine cycle. Details about the model can be found here.
Visualization of electrons and generated wake fields in a Tesla cavity. The electric field lines are shown as red lines, while the magnetic field lines are circular, and shown in yellow and green. The particle bunch is larger than actual for visualization purposes. More details can be found here.
A 3D isosurface contour of the plasma density created behind an intense electron beam that self-ionizes a gas and creates a plasma wakefield. The drive beam shown in orange is moving from left to right. More details about the simulation can be found here.
In each of these areas, the modeling tools require petascale supercomputers and advanced software for making effective use of these large, parallel platforms. Computational infrastructure in the areas of shape determination and optimization; advanced adaptive meshing; dynamic load balancing; embedded boundaries; component methodologies; performance measurement, assessment and improvement; linear and nonlinear solvers; and visualization will be used and advanced. Consequently, critical to this effort will be the embedded collaborations with the applied mathematics and computer science communities. In the end, high-quality computational tools developed with the best computational physics, applied mathematics, and computer science will be made available to the US particle accelerator community through installation at government laboratories, universities, and industry.