# Presentation: 050132

## Simulation Codes in Accelerator Physics (the  source example)

- V. Daniel Elvira Fermilab

- October 19th, 2000

- V. Daniel Elvira

- October 19th, 2000

## Outline

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

- V. Daniel Elvira

- October 19th, 2000

## Physics Motivation

- _Muon Collider/Higgs Factory (0.1-4 TeV)_

- ___ __source (based on ____ storage ring (50 GeV)_

-  Radiative E loss ~ 1/m4
-  higgs(l anti-l) ~ ml2

- Higgs, W and Top pair production
- Supersymmetric particles

- High intensity **** beam ( 2x1020 per year)
-  Both ****e and **** produced

****-mass hierarchy
- Mixing matrix driving flavor oscillations

- V. Daniel Elvira

- October 19th, 2000

## The FNAL 2000 design for a Neutrino factory

- _The FNAL 2000 design for a Neutrino factory_

- Proton driver

- Target

- Induction Linac

- Buncher

- Cooler

- 3 GeV Linac

- RLA1

- RLA2

- Storage Ring (**** decay in straight sections)

- V. Daniel Elvira

- October 19th, 2000

## Technical Challenges

- High intensity **** beam     1.2-4 MW proton beam onto target
- Small final beam emittance       cool large initial beam emittance                                                     E**N** ~ (******x********px********y********py********ct********E**)/m****3
- large angles (sin****)     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

- V. Daniel Elvira

- October 19th, 2000

## Computing Challenges

- 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)

- Software Tools         design and detailed simulation of                                    accelerator elements

-  Larger HEP style packages :  GEANT(CERN),   ICOOL (BNL)

- Full tracking, propagation of particles in e.m fields, through vacuum or materials

- (used in ****-souce cooling channel simulations)

- V. Daniel Elvira

- October 19th, 2000

##  ICOOL              &           DPGeant3 

- _Author:_ R.Fernow (BNL) Specifically written to simulate ionization cooling
- _Language:_ Fortran77     Well targeted physics library mantained by ****/**** collaboration

- _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

- _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_

- V. Daniel Elvira

- October 19th, 2000

##  ICOOL              &           DPGeant3 

- _Platforms:_ LINUX, PC (windows), SGI, Suns, Cray...
- _No Graphics_ available

- _Platforms:_ LINUX, DEC, SUN, SGI...
- _Primitive Graphics_ available

- _Physics processes:_ dE/dx, delta rays, multiple scattering Diagnostics: emittance calculation

- Popular among particle physicists contributing to beam physics research

- Popular among beam physicists

- Users: 15 physicists at 3 labs and several universities

- _Speed:_ about the same for ICOOL and DPGeant3

- V. Daniel Elvira

- October 19th, 2000

## 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)

- V. Daniel Elvira

- October 19th, 2000

## 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

- V. Daniel Elvira

- October 19th, 2000

## Why GEANT4 ?

** **_**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

**Why GEANT4 ?**

- With no changes in tracking code

- V. Daniel Elvira

- October 19th, 2000

## 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

- V. Daniel Elvira

- October 19th, 2000

## Example: Geometry of a Helical Channel

**Z**

**Solenoid + Rotating Dipole**

**Solenoid + Rotating Dipole**

**RF cavity**

**Absorber**

**0.9 m**

**0.9 m**

**Unit Cell ( 1.8 m )**

**GEANT4 visualization (Open Inventor)**
**(the purple disks are idealized RF cavities)**

- z

**x**

**y**

**x**

**y**

**40 cells long**

- Achieve emittance cooling all 6D (x,y,ct,px,py,E)

- V. Daniel Elvira

- October 19th, 2000

## Visualization drivers available for a number of packages like DAWN, OpenInventor (developed at PAT/CD FNAL), ........many in preparation

**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

- V. Daniel Elvira

- October 19th, 2000

## A Wedge in GEANT4

-  G4Trap* wedge
-     = new G4Trap("wedge",200*mm,0.0,0.0,200*mm, 53.333*mm,0.1*mm,0.0*deg,200*mm,53.333*mm,0.1*mm,0.0*deg);
-  G4LogicalVolume* wedge_log
-     = new G4LogicalVolume(wedge,LithiumHydride, "wedge_log",0,0,0);
-  G4RotationMatrix *rm = new G4RotationMatrix;
-   rm->rotateZ(90*deg);
-   rm->rotateY(-90*deg);
- G4VPhysicalVolume* wedge_phys =
- 	new G4PVPlacement(rm, G4ThreeVector(wedgex,wedgey,wedgez),wedge_log,"wedge",exphall_log,false,0);

- V. Daniel Elvira

- October 19th, 2000

## 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

- V. Daniel Elvira

- October 19th, 2000

## 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

- V. Daniel Elvira

- October 19th, 2000