1. PLACET Overview for CWG Program for Linear Accelerator Correction and Efficiency Tests
Speaker: Andrea Latina
Developers and contributors: D. Schulte, A. Latina, N. Leros, P. Eliasson, E. D’Amico, G. Rumolo, E. Adli, B. Dalena, J. Snuverink, Y. Levinsen, J. Esberg

2. What effects are included and what are not?
PLACET is a tracking code originally developed by Daniel Schulte to evaluate the performance of future high-energy linear colliders under the effects of imperfections
It performs 4D and 6D tracking of one or many bunches, using two beam models:
Sliced beam: each bunch is sliced longitudinally, each slice contains a number of 2nd-order macro particles (e.g. 15 slices x 21 macro-particles per slice)
Single-particle beam: each bunch is composed of many macro particles (e.g. 100’000)
PLACET implements the following element types: accelerator structures, drifts, sector bends, quadrupoles, multipoles, collimators, corrector kickers, beam position monitors, custom elements, and…
It implements the Power Extraction and Transfer Structures (PETS), key elements of CLIC, including beam loading
Collective effects:
Resistive-wall wakefields in collimators
Short-range (single-bunch) wakefields: optimized implementation in accelerator structures and collimators; wakefields can be attached to any elements using splines
Long-range (multi-bunch) wakefields in accelerator structures, time-domain, frequency-domain models
Incoherent synchrotron radiation in any magnets and in kickers
Coherent synchrotron radiation (w/ and w/o shielding) in sector bends
It can simulate dynamics effects, such as vibrations, ground motion (ATL law or measured on site), magnetic stray fields
It can compute Twiss and optics functions
If compiled with HTGEN (*), it can simulate the Halo and Tail generation and transport (*)
A. Latina, ABP CWG 19/1/2017

3. What is used for at CERN CLIC:
Design optimization, non-linear matching, performance optimization, static and dynamic imperfections, beam-based correction techniques for:
CLIC:
Main Linac : RTML + ML + Beam Delivery and Final Focus Systems
Drive Beam : decelerators, arcs, transfer lines and injectors
Together with GUINEA-PIG: two-armed start-to-end simulations with ground motion and dynamic effects + luminosity measurement
ILC:
RTML + ML + Beam Delivery and Final Focus System
FACET, ATF2, X-band based FEL
It has been used as a Flight-Simulator during our campaign of measurements at
A. Latina, ABP CWG 19/1/2017

4. Programming languages, style
PLACET is about 140K lines of code
C/C++
Tcl/Tk interface
Octave and Python extensions
If uses GSL (GNU Scientific Library) and fftw (Fast Fourier Transform)
It uses SWIG and PERL to generate the Octave and the Python interfaces (SWIG and PERL are not needed at compile time)
PLACET uses Tcl/Tk as backbone. After a quick initialization, it hands the control to Tcl/Tk which can be used either interactively or to parse a Tcl simulation script.
It is fully programmable, new elements (or new effects) can be added through the Tcl, Octave, and Python interfaces. Each element can trigger a Tcl script during tracking: e.g. to launch programs, monitor the beam, interactively modify the beamline, etc.
Standard Linux compilation: ./configure && make && make install
It runs on Linux, MacOS, cygwin.
Internal Parallelism:
OpenMP: each element can transport particles in a parallel manner (including those emitting synchrotron radiation)
MPI: there exist an (experimental) external module capable or performing tracking with MPI
A. Latina, ABP CWG 19/1/2017

5. Example of basic script
set script_dir . source $script_dir/clic_basic_single.tcl source $script_dir/clic_beam.tcl BeamlineNew source $script_dir/clic_linac.tcl BeamlineSet -name linac array set match {beta_x beta_y alpha_x alpha_y } set n_slice 15 set n 21 make_beam_slice beam0 $n_slice $n TwissPlot -beam beam0 -file twiss.dat GroundMotionInit -file $script_dir/data/GM/harm.B.300 -t_step 0.02 proc survey { GroundMotion –beamline linac } Octave { [emitt,beam] = placet_test_no_correction(”linac", "beam0", ”survey”); save -text beamEmitt.out emitt plot(beam(:,2), beam(:,5), '.'); xlabel("x [um]"); ylabel("x' [um]");
A. Latina, ABP CWG 19/1/2017

6. Example of simulation: stabilization of the ML quads
Luminosity achieved/lost [%]
B10
No stab.
53%/68%
Current stab.
108%/13%
Future stab.
118%/3%
PLACET
Close to/better
than target
Machine model
Beam-based feedback
A. Latina, ABP CWG 19/1/2017

7. Example of simulation: stabilization of the ML quads
Courtesy of J. Pfingstner
A. Latina, ABP CWG 19/1/2017

8. Benchmark of PLACET ILC Main Linac
FACET response matrix (simulated vs measured)
A. Latina, ABP CWG 19/1/2017

9. Documentation, License, Sources
PLACET Website ( guides through the installation
Access to code: svn+ssh://svn.cern.ch/reps/clicsw/trunk/placet SVN repository for PLACET and code browser.
Bug Tracker though JIRA
Documentation:
User manual: stable but new version in (slow) progress
Contacts:
PLACET is licensed with CERN License.
A. Latina, ABP CWG 19/1/2017

10. Future Plans Continue the development and support of the main code:
Adding whatever new needs come for the CLIC study
General clean-up and improvement in the documentation (maximize maintainability)
Help the migration of the physics code to PLACET2
A. Latina, ABP CWG 19/1/2017

11. Resources
Present resources for PLACET working on the code: 30% FTE of CERN staff Resources are sufficient to fix bugs and implement new features.
A. Latina, ABP CWG 19/1/2017

12. PLACET Hardware
PLACET runs on normal PCs Linux and Mac systems, however some studies are not practical on single machines. Several CPUs (100) can be used for running Monte Carlo simulations of different random seeds. For example: CLIC Beam Delivery System alignment simulations, which require the use of GUINEA-PIG, for the beam-beam effects and the evaluation of the luminosity, might take up to hours per machine to simulate few hours of operation. Clusters like LXBATCH are well suited for PLACET.
A. Latina, ABP CWG 19/1/2017