Simulation Codes in Accelerator Physics the n source example

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Simulation Codes in Accelerator Physics (the n
source example)
V. Daniel Elvira Fermilab
October 19th, 2000
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Outline

• The neutrino source/muon collider studies
• Technical computing challenges
• Software simulation packages
• Computational resources
• Conclusions

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Physics Motivation
Muon Collider/Higgs Factory (0.1-4 TeV)
n source (based on m storage ring (50 GeV)

• High intensity n beam ( 2x1020 per year)
• Both ne and nm produced

• Radiative E loss 1/m4
• shiggs(l anti-l) ml2

Higgs, W and Top pair production Supersymmetric
particles
n-mass hierarchy Mixing matrix driving flavor
oscillations
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The FNAL 2000 design for a Neutrino factory
Proton driver
RLA2
Induction Linac
Target
Buncher
Cooler
3 GeV Linac
Storage Ring (m decay in straight sections)
RLA1
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Technical Challenges

• High intensity n beam 1.2-4 MW proton beam
  onto target
• Small final beam emittance cool large
  initial beam emittance
  EN (sxspxsyspysctsE)/mm
  3
• large angles (sin q q) non-linearities
• need solenoids x-Py correlations
• Cooling Channel RF cavities (longitudinal
  acceleration), solenoids, dipoles, absorbers

Beam equations difficult to solve
Ionization cooling dE/dx physics processes,
straggling,
multiple scattering
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Computing Challenges
Software Tools design and detailed
simulation of
accelerator elements

• Private code (conceptual design)
• Standard beam physics programs (detailed
  simulation of different elements)
• MARS (FERMILAB) target, pion production
• COSY (MSU)-MAD (CERN) linacs, muon storage ring
  (lattice design)
• MAFIA (DESY) RF cavity design (electromagnetic
  fields)

• Larger HEP style packages GEANT(CERN),
  ICOOL (BNL)

Full tracking, propagation of particles in e.m
fields, through vacuum or materials
(used in n-souce cooling channel simulations)
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ICOOL DPGeant3
Author popular CERN HEP detector simulator.
Upgraded by P.Lebrun (Fermilab) electric
fields and double precision tracking Language
Fortran77 Extensive physics library mantained by
CERN
Author R.Fernow (BNL) Specifically written to
simulate ionization cooling Language Fortran77
Well targeted physics library mantained by n/m
collaboration
Specific beam line elements dipole, solenoid,
r.f. cavity. limited modeling
User defined beam line elements field maps and
basic shapes modeling flexibility
2D geometry (long and transverse to the beam)
3D geometry
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ICOOL DPGeant3
Physics processes dE/dx, delta rays, multiple
scattering Diagnostics emittance calculation
Speed about the same for ICOOL and DPGeant3
Platforms LINUX, DEC, SUN, SGI Primitive
Graphics available
Platforms LINUX, PC (windows), SGI, Suns,
Cray No Graphics available
Popular among particle physicists contributing to
beam physics research
Popular among beam physicists
Users 15 physicists at 3 labs and several
universities
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Hardware Resources

• Conceptual designs (desktop/laptop machines
  adequate)
• Thousands of particles minutes/hours
• Optimization (multi-parameter space) Small
  farm required hours
• Space Charge Studies
• more will be needed (farms of tightly coupled
  systems)

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Visualization in DPGEANT3

• Example of a Cooling Channel based on a Lithium
  Lense
• Li lense is a solid Lithium cylinder with
  surface current so that
• Matching solenoid with acceleration

tracks
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Why GEANT4 ?

• GEANT4 is the OO/C version the CERN detector
  simulation tool kit GEANT3 ( Large collaboration
  100 physicists ) http//wwwinfo.cern.ch/asd/gean
  t4/geant4.html
• GEOMETRY More basic shapes
  New
  shapes can be added
  CAD interface
• TRACKING Double precision built-in
  Better
  tracking in EM fields
• PHYSICS More complete set of EM processes
  Better hadronic physics
  New
  physics processes

With no changes in tracking code
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Migration to GEANT4

• Students do not write in Fortran anymore, and
  computing professionals reject projects
  involving ancient language
• Future Accelerators long term projects
  unfortunatelly
• Users 3 physicists at FNAL (PAT/CD), some
  interest expressed at BNL

PAT group developing interface tools to make
GEANT4 user friendly for accelerator
simulations Classes like Current Sheet,
Solenoid, Dipole, RF Cavity, LINAC defined to
construct objects from data cards or ascii files
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Example Geometry of a Helical Channel
Achieve emittance cooling all 6D (x,y,ct,px,py,E)
Solenoid Rotating Dipole
0.9 m
x
0.9 m
Z
RF cavity
y
Absorber
Solenoid Rotating Dipole
Unit Cell ( 1.8 m )
GEANT4 visualization (Open Inventor) (the purple
disks are idealized RF cavities)
z
x
40 cells long
y
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Visualization drivers available for a number of
packages like DAWN, OpenInventor (developed at
PAT/CD FNAL), ..many in preparation
Light directioning, interactive rotation, zoom,
wire frame/solid options
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A Wedge in GEANT4

• G4Trap wedge
• new G4Trap("wedge",200mm,0.0,0.0,200mm,
  53.333mm,0.1mm,0.0deg,200mm,53.333mm,0.1mm,0
  .0deg)
• G4LogicalVolume wedge_log
• new G4LogicalVolume(wedge,LithiumHydride,
  "wedge_log",0,0,0)
• G4RotationMatrix rm new G4RotationMatrix
• rm-gtrotateZ(90deg)
• rm-gtrotateY(-90deg)
• G4VPhysicalVolume wedge_phys
• new G4PVPlacement(rm, G4ThreeVector(wedgex,wedgey
  ,wedgez),wedge_log,"wedge",exphall_log,false,0)

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A Solenoid in GEANT4 (developed at PAT/CD FNAL)

Sheet current1(CartesianCoord(0.0, 0.0, zsheet),
idsheet, typesheet, thicksheet, radsheet,
lensheet, cursheet)) Solenoid
magnet1(CartesianCoord(solx, soly, solz),
minrxy, maxrxy, numptrxy, minz, maxz, numptz,
vsheets)
Same thing we can do with dipoles, quadrupoles,
RF Cavities, LINACS, and any other beam physics
related class
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Conclusions

• Future accelerators complex technological
  problems
• Demand for HEP style multidisciplinary packages
  (beam, particle, plasma physics)
• In PAT/CD FERMILAB we are moving toward OO/C
  options (like GEANT4) and developing beam physics
  related classes to help the user