Beam Delivery Simulation Development & BDS / MDI Applications L. Nevay, S. Boogert, H. Garcia-Morales, S. Gibson, J. Snuverink, L. Deacon Royal Holloway, University of London 13 th May

2Outline BDSIM structure & overview Previous studies using BDSIM Prospects for Linear Collider Studies High Luminosity LHC studies Current developments On going simulations

3 Beam Delivery SIMulation Beam Delivery Simulation is a Geant4 based tool for tracking and energy deposition studies in linear colliders Started by G. Blair at Royal Holloway Geant4 simulation with fast in-vacuum tracking routines L. Deacon TUPC005 EPAC 08

4 Using Geant4 Geant4 - a C++ Monte-Carlo framework ― Tracking of particles through matter ― Access to electromagnetic, hadronic & optical processes ― Powerful geometry description framework ― Many visualisation tools ― No main() function or complete program ― Must write your own C++ simulation BDSIM uses ASCII input files with MAD-like syntax Builds accelerator beamline as Geant4 model Utilises its own fast tracking routines for typical magnets Standalone program – no compilation

5 CLIC Beam Delivery System BDSIM used to accurately simulate beam losses for CLIC Losses due to secondaries and showers are important Phys. Rev. S.T. Accel. & Beams

6 BDSIM for Linear Colliders Current developments are towards circular colliders… however… BDSIM is already suitable for linear colliders! Current developments improving efficiency and usability Significantly increased efficiency ~40x faster Input from MADX and MAD8 improved Can convert MAD scripts or use twiss output in TFS file Support for GDML added and being improved

7 Input Sources Machines are typically designed in some other software ― MADX, MAD8 etc Geometry descriptions in other formats ― GDML, LCDD, Mokka Improvements on easily importing input sources Can convert MAD scripts directly to GMAD (bdsim) syntax Or use new python suite to convert input formats ― pybdsim – included with BDSIM ― TFS files for both MAD8 and MADX accepted Can programmatically vary input files using python ― adjust collimator settings for different runs ― adjust magnet strengths

8 LHC and HiLumi LHC BDSIM being developed for rings CERN uses SixTrack for tracking studies ― applies aperture definition after tracking complete ― digital loss maps ― custom physics routines for collimator scattering Use FLUKA for energy deposition near IPs Aim to use BDSIM for accurate loss maps around ring Detailed energy deposition due to primaries and secondaries

9 The LHC Model 27 km Geant4 model ~1s / particle revolution Converted from MADX twiss output Under development Symplectic tracking routines to be added

10 ATF2 Simulations Practice lattice for larger linear collider Conversion of large linear lattice straightforward Readily applicable to ILC / CLIC Large lattice conversion from LHC S.T. Boogert et al. WEPC46 IBIC 2013 particle impact ATF2 lattice

11 Generic Geometry Library Currently basic cylinders of material ― if not specifying geometry ― can detail size and material easily Library of different magnet types being added ― conventional normal conducting 2n-pole magnets ― basic LHC quadrupole & dipole Easily extendable for generic types Improves the accuracy of particle / radiation transport ILC cryo-modules already exist as separate geometry

12 The Beam Delivery System The BDS has many features that require simulation Diagnostics Compton systems (laserwires / polarimeters) ― laserwires as main emittance measurement during operation Betatron and energy collimation IPBSM / tune up station Dumps Possible SC magnets Dosimetry All require accurate beam loss predictions

13 Laserwire Simulations Royal Holloway have extensive experience with laserwires ― laser used to scan across electron / positron beam for emittance measurement ― Compton-scattered photon flux measured Compton cross-section is low – requires high power laser ― GW peak powers Low number of scattered photons (~1 – 1000) Requires high precision for accurate emittance measurement ― Agapov et al. Phys. Rev. ST Accel. Beams 10, (2007) Not a problem at few Hz bunch train frequency Much better to perform intra-train scanning Fibre lasers suitable for this and being developed ― Up to several MW peak powers demonstrated for intra-train scanning Laser requirements depend on background levels and location

14 Laserwire Simulations Simulations underway at Royal Holloway Determine background levels and location Develop more definite requirements for laserwire Affects: ― scan precision ― laser requirements ― choice of laser technology ― scanning methodology ― detector design & placement L. Deacon TUPC005 EPAC 08

15 Current Development BDSIM is under active development 5 active developers Open source! Contributions and collaborators welcome Git repository Can not only ‘checkout’ latest version but also ‘fork’ and develop yourself Can then merge into BDSIM

16Conclusions BDSIM is a mature beam line simulation tool Under active development Being developed for circular colliders Open source and easily extendable! Readily useable for linear collider studies

17 Thank you