Beam Delivery Simulation Development &
BDS / MDI ApplicationsL. Nevay, S. Boogert, H. Garcia-Morales,
S. Gibson, J. Snuverink, L. Deacon
Royal Holloway, University of London13th May 2014
http://twiki.ph.rhul.ac.uk/twiki/bin/view/PP/JAI/[email protected]
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OutlineBDSIM structure & overview
Previous studies using BDSIM
Prospects for Linear Collider Studies
High Luminosity LHC studies
Current developments
On going simulations
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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
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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
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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 12 081001 2009
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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
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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
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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
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The LHC Model• 27 km Geant4 model• ~1s / particle revolution• Converted from MADX twiss output• Under development• Symplectic tracking routines to be added
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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 impactATF2 lattice
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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
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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
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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, 112801 (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
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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
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Current Development• BDSIM is under active development• 5 active developers
• Open source!• Contributions and collaborators welcome• Git repository
https://bitbucket.org/stewartboogert/bdsim
• Can not only ‘checkout’ latest version but also ‘fork’ and develop yourself
• Can then merge into BDSIM
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Conclusions• 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
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Thank you
http://twiki.ph.rhul.ac.uk/twiki/bin/view/PP/JAI/BdSim
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