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/BdSimlaurie.nevay@rhul.ac.uk

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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

laurie.nevay@rhul.ac.uk