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

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 (*) http://hbu.home.cern.ch/hbu/HTGEN.html A. Latina, ABP CWG 19/1/2017

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 FACET @SLAC, FERMI @ELETTRA, ATF2 @KEK A. Latina, ABP CWG 19/1/2017

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

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 6.6868 beta_y 2.7269 alpha_x -1.7211 alpha_y 0.7851} 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

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

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

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

Documentation, License, Sources PLACET Website (https://clicsw.web.cern.ch/clicsw) 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: andrea.latina@cern.ch PLACET is licensed with CERN License. A. Latina, ABP CWG 19/1/2017

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

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

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 24-36 hours per machine to simulate few hours of operation. Clusters like LXBATCH are well suited for PLACET. A. Latina, ABP CWG 19/1/2017