1.  Advanced Accelerator Simulation Panagiotis Spentzouris Fermilab Computing Division (member of the SciDAC AST project)

2.  Accelerators are essential for the advance of science. In DOE’s “Facilities for the Future of Science” 13 of the 28 facilities are accelerators!

3.  SciDAC AST project (Accelerator Science & Technology) UC Davis Visualization, multi- resolution techniques FNAL Software Integration, Lie methods, space charge in rings, Booster simulation& experiment UCLA Parallel PIC Frameworks SLAC Ellectromagnetic component modeling LBNL Beam-beam modeling, space charge in linacs & rings, parallel Poisson solvers, collisions U. Maryland Lie Methods in Accelerator Physics, MaryLie LANL High order optics, beam expts, collisions, multi-language support, statistical methods M=e :f 2 : e :f 3 : e :f 4 : … N=A -1 M A BNL Wakefield effects, Space charge in rings, BNL Booster simulation

4.  SciDAC AST project goals  Develop and apply an advanced, comprehensive, high-performance simulation environment to solve challenging problems and to enable new discoveries in accelerator science & technology.  maximize performance of existing and optimize design of future accelerators

5. Synergia Multi-language, extensible, parallel PIC framework Incorporates multi-physics; state-of-the-art numerical libraries, solvers, physics modules Humane user interface and job creation/monitoring tools

6.  Multi-bunch capability  Multiple Poisson solvers  FFT, multigrid (PETSc)  Multi-turn injection  Ramping rf and magnet modeling  Active feedback modeling From test suite: comparison w/ analytical result (J. Comp. Phys, 211,1, 2005) Synergia used in international space charge benchmark effort lead by I.Hofmann (PAC'05) Unique capabilities for synchrotrons, boosters, and storage rings Longitudinal phase space shows halo & space-charge “drag” during bunch merge

7.  Synergia performance ● Utilized NERSC SP3 and Linux clusters Millions of macro- particles on hundredths of processors

8.  Fermilab’s accelerator complex Main Injector Booster Tevatron

9.  The Fermilab Booster The Booster is a rapid cycling machine (15Hz) accelerating protons from 400 MeV to 8 GeV The success of the quest to understand the nature and properties of neutrino masses at Fermilab depends on the Booster. Multi-particle dynamics effects, such as space charge are responsible for machine losses which limit performance

10.  High intensity proton driver modeling ● Problem: optimize accelerator performance ● Problem size (FNAL Booster example):  6 × 10 12 protons circulating for 20,000 turns  ~100 electromagnetic elements in accelerator ● Need to model the beam's self-interaction ● Need to understand observed beam characteristics and losses ➔ simulation requires 10 6 to 10 7 macro-particles

11.  Booster simulation details ● Self-consistent 3D space-charge ● High order magnetic optics ● 33x33x257 grid, ~5M particles ● boundary conditions  longitudinal periodic  transverse closed ● Realistic model  multi-turn injection  machine ramping with position feedback Multi-bunch modelling in 3D ➔ follow 5 200 MHz Linac micro-bunches in a 37.8 MHz PhS slice.

12.  ● Synergia to study and optimize beam quality on normal operating conditions  compare to turn-by-turn beam profiles ● 3D model enables study of phase space correlations

13.  Space charge effects on resonances Synergia simulation Data, machine running on resonance Less charge more charge

14.  Beam evolution on resonance: how close to a resonance can we operate?

15.  Requirements for end to end Booster simulation ● Computational effort: ~ N turns × N bunches × N kicks × {parameters}  for 20,000 turns → 20 days  for multi-bunch simulation with smoothing, effective N bunches ~10  need ~100× current capability and improved scalability  continuing R&D for solvers with better performance and scalability

16.  As the beams pass through each other, each beam’s charge affects the other beam, reducing performance. We need to study and understand these “Beam-Beam” effects to maximize Tevatron luminosity. The Tevatron is the highest energy particle accelerator in the world; it accelerates protons and antiprotons up to 1 TeV (trillion electron volt). The two beams circulate together and collide at the detector locations. BeamBeam3D: a 3D, self consistent code Can model multiple bunches!

17.  But first verify model: beam-beam force couples transverse and longitudinal dynamics, so effect can be tested by comparing to FFT of the bunch motion in dedicated experiments. VEP-II accelerator, dedicated to beam measurements