• J. A. Holmes, S. M. Cousineau, V. V. Danilov, S. Henderson, D.-O. Jeon, M. A. Plum, A. P. Shishlo, Y. Zhang
  ORNL, Oak Ridge, Tennessee
• D. A. Bartkoski
  UTK, Knoxville, Tennessee

The computational approach is providing essential guidance and analysis for the commissioning and operation of SNS. Computational models are becoming sufficiently realistic that it is now possible to study detailed beam dynamics issues quantitatively. Increasingly, we are seeing that the biggest challenge in performing successful analyses is that of knowing and describing the machine and beam state accurately. Even so, successful benchmarks with both theoretical predictions and experimental results are leading to increased confidence in the capability of these models. With this confidence, computer codes are being employed in a predictive manner to guide the machine operations. We will illustrate these points with various examples taken from the SNS linac and ring.

• A. P. Shishlo, S. M. Cousineau, V. V. Danilov, J. Galambos, S. Henderson, J. A. Holmes, M. A. Plum
  ORNL, Oak Ridge, Tennessee

The contents, structure, implementation, benchmarking, and applications of ORBIT as an accelerator simulation code are described. Physics approaches, algorithms, and limitations for space charge, impedances, and electron cloud effects are discussed. The ORBIT code is a parallel computer code, and the scalabilities of the implementations of parallel algorithms for different physics modules are shown. ORBIT has a long history of benchmarking with analytical exactly solvable problems and experimental data. The results of this benchmarking and the current usage of ORBIT are presented.

• J. A. Holmes, S. M. Cousineau, V. V. Danilov, J. Galambos, S. Henderson, M. A. Plum, A. P. Shishlo
  ORNL, Oak Ridge, Tennessee