1. Status of MERLIN and Recent Developments
Haroon Rafique
On behalf of the MERLIN group:
R. B. Appleby, R. Barlow, S. C. Tygier
In Collaboration with CERN:
R. Bruce, A. Santamaría, S. Redaelli, J. F. Wagner

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Contents
MERLIN LHC Collimation using MERLIN HEL process CC Failure process What next?
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3. MERLIN

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MERLIN
C++ Accelerator Physics Library (N. DESY, storage ring functionality added by A. Wolksi)
User writes their own simulation containing:
Beam -> Bunch
Accelerator Model (MAD .tfs table)
Tracker (different integrators available)
Physics Processes (user defined / pre existing)
Modular – easier to use
Extensible – if you have the physics, adding a process is trivial
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Merge
Consolidation of processes:
Collimation (scattering, binning, etc)
Hollow Electron Lens (HEL)
Crab Cavity Failure
Clean up
Optimisation
Test suite
Cmake
Git history + =
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Former Developers
Thanks to all:
James Molson [Manchester]
Maurizio Serluca [Manchester]
Adina Toader [Manchester]
Adriana Bungau [Manchester]
Andy Wolski [Liverpool]
Others …?
Dirk Krücker [DESY]
Nick Walker [DESY]
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7. Collimation using merlin

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Typical User Code
LatticeFunctionTable
BeamData
ProtonBunch
AcceleratorModel
MADInterface
CollimatorDatabase
ApertureConfiguration
AcceleratorModelConstructor
ParticleTracker
CollimateProtonProcess
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Apertures
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HL LHC Optics
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Integrator
MERLIN includes 3 standard integrator sets:
TRANSPORT
SYMPLECTIC
THIN_LENS
myParticleTracker->SetIntegratorSet (new ParticleTracking::SYMPLECTIC::StdISet());
myParticleTracker->SetIntegratorSet (new ParticleTracking::TRANSPORT::StdISet());
Legend:
Class
User object
Function
Variable
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12. TRANPSORT vs SYMPLECTIC
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Synchrotron Motion
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14. Collimation Process CollimateParticleProcess Collimator Material
CollimateProtonProcess
ppDiffractiveScatter
ScatteringModel
CrossSections
ppElasticScatter
PathLength()
EnergyLoss()
Configure()
ScatteringProcess
Straggle()
Scatter()
ParticleScatter()
Dustbin
DeathReport()
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Scattering Processes
Merlin
Rutherford
Elastic pn
Elastic pN SD
Inelastic
SixTrack & ST + Ad. Ionisation
ST Rutherford
ST Elastic pn
ST Elastic pN
ST SD
Inelastic
SixTrack+K2 – like & MERLIN scattering for:
Rutherford
Elastic pn
Elastic pN SD
Inelastic
ST + Ad. Elastic
ST Rutherford
Elastic pn
Elastic pN
ST SD
Inelastic
ST + Ad. SD
ST Rutherford
ST Elastic pn
ST Elastic pN SD
Inelastic
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Scattering
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17. Hollow electron lens process
HR & Joschka CERN

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Poincaré Sections
s = m (40m downstream of IP4) in LHC lattice (RB46)
104 – 105 turns in the LHC
Nominal v6.503, HL v1.2
Output particle position every turn
Plot xx’ phase space to see effect
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19. SixTrack vs MERLIN: DC SixTrack MERLIN Identical SixTrack bunch
Parameter
Value
LHC lattice
Nominal
HEL
hardware
Tevatron
Mode DC
I [A]
1.2
Ee [KeV] 5
L [m] 2
Rmin [σx] 4
Rmax [σx]
6.8
Distn
SixTrack
1-10 σx
SixTrack
MERLIN
NO inteferance when r < Rmin
Resonances, dependent on position
4σx ≈ 1.17 mm
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20. SixTrack vs MERLIN: DC 4σx ≈ 1.17 mm
Different initial bunch for clarity
Parameter
Value
LHC lattice
Nominal
HEL
hardware
Tevatron
Mode DC
I [A]
1.2
Ee [KeV] 5
L [m] 2
Rmin [σx] 4
Rmax [σx]
6.8
Distn
SixTrack (Left)
MERLIN (Right)
1-10 σx
SixTrack (using SixTrack bunch)
MERLIN (using MERLIN bunch)
Resonances depend on initial distn – no change for r < Rmin
4σx ≈ 1.17 mm
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21. Nominal vs HL LHC: DC Identical MERLIN bunch MERLIN nominal MERLIN HL
Parameter
Value
LHC lattice
Nominal
(left) HL
(right)
HEL
hardware
LHC
Mode DC
I [A] 5
Ee [KeV] 10
L [m] 3
Rmin [σx] 4
Rmax [σx] 8
Distn
MERLIN
1-10 σx
Identical MERLIN bunch
MERLIN nominal
MERLIN HL
Size and position of resonances dependent on lattice
Nominal round beams – HL not round beams
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22. HL LHC: AC vs Diffusive Identical MERLIN bunch AC Diffusive Parameter
Value
LHC lattice HL
HEL
hardware
LHC
Mode
AC (left)
Diffusive (right)
I [A] 5
Ee [KeV] 10
L [m] 3
Rmin [σx] 4
Rmax [σx] 8
Distn
MERLIN
1-10 σx
Identical MERLIN bunch AC
Diffusive
Size and position of resonances dependent on lattice
Nominal round beams – HL not round beams
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23. Cleaning: nominal vs HL LHC
Nominal LHC
High Luminosity LHC
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24. Crab cavity failure process
HR & Andrea Santamaria CERN

25. Simple Kick Model Andrea Santamaría García 30.10.15
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Thin CC Kick
Vertical IP1 (ATLAS)
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Closed Bump
Bunch at TCP after a full ‘CC’ turn ‘Pre tracked’ IP1 -> First ATLAS CC ‘Tracked + CCF Process’ First ATLAS CC -> 1 turn ‘Post tracked’ First ATLAS CC -> IP1 Holds for many turns
Y [m]
ct [m]
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28. 4 CC 90° Phase Failure A. Santamaría (Wednesday) MERLIN (Thursday)
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29. future

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Documentation
Sourceforge (not up to date)
GitHub (in near future)
Current git repository is private
HR merlin site:
HR HEL site:
HR thesis – early 2016
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Future Work
Run side-by-side with SixTrack for HL LHC (J.
Use of CC failure model (A. CERN)
HEL integration study (A. CERN)?
Support of MERLIN CERN (A. Valloni + many more)
CC failure + HEL + Loss Maps?
S. Tygier – HL squeeze loss study
Always welcome new users / new applications
H. Rafique PhD Thesis (Early 2016)
All of the above + MERLIN manual
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Future HEL Work
MERLIN vs SixTrack for identical bunches, various operation modes (Poincare Sections)
Investigation of optimal AC mode parameters in HL v1.2
Investigation of optimal HEL position in HL v1.2
Cleaning enhancement with more realistic TCP setting (use 6.2 sigma now, possibly 6 or 5.7 sigma in future) for all modes
Cleaning enhancement with scattering (for all modes) - currently use TCP as a black absorber
Cleaning enhancement with a full collimation scheme (for all modes)
Cleaning enhancement for all above with a more realistic bunch (for all modes)
Crab Cavity failure model
Loss map with CC failure
Loss map with HEL and CC  failure (with HEL halo depletion post, pre, and both post & pre CC failure)
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Acknowledgements
J. Molson & M. Serluca – MERLIN development R. Bruce & S. Redaelli – Collimation A. Santamaría – CC failure D. Mirarchi & J. Wagner – HEL A. Valloni – Sanity check
Questions?
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