SBS Monte Carlo Simulation Update Andrew Puckett SBS

SBS Monte Carlo Simulation Update Andrew Puckett SBS Weekly Meeting June 3, 2015

Outline • • Recent geometry additions to g 4 sbs Recent code improvements Highlights of recent g 4 sbs simulation results/analysis Ongoing projects/status: • • • Missing/incomplete geometries Simulation capabilities wish-list Simulation studies wish-list Status of user documentation Status of code • Outlook 6/3/2015 SBS Weekly Meeting June 3, 2015 2

Recent geometry additions: • HCAL (Freddy Obrecht, code from Vahe Mamyan) • Big. Bite shower/preshower calorimeters (Freddy Obrecht, geometry from S. Riordan thesis) • ECAL (Freddy Obrecht, transparency model from S. Abrahamyan & Bogdan W. ) • RICH geometry finalized (“full” details from CAD drawings, A. Puckett) 6/3/2015 SBS Weekly Meeting June 3, 2015 3

GRINCH Implementation To-do: • update PMT quantum efficiency (currently based on RICH PMTs) • Detailed description of containment volume • Understand mitigate sources of background • GEANT 4 model developed by H. Yao (W&M) imported to g 4 sbs framework 6/3/2015 SBS Weekly Meeting June 3, 2015 4

RICH update • Virtually complete description of RICH aluminum box and steel shielding for PMTs from CAD drawings • New acceptance, PID performance and background studies under way 6/3/2015 SBS Weekly Meeting June 3, 2015 5

HCAL Implementation HCAL GEANT 4 code from V. Mamyan imported to g 4 sbs by R. F. Obrecht (code version up-to-date as of ~Oct. 2014, doesn’t include more recent developments by CMU) 6/3/2015 SBS Weekly Meeting June 3, 2015 6

Big. Bite Calorimeter implementation in g 4 sbs Big. Bite preshower and shower calorimeters implemented by R. F. Obrecht Note—optical properties taken from GEP ECAL simulation; need to update for different type of lead-glass; should be reasonable approximation already 6/3/2015 SBS Weekly Meeting June 3, 2015 7

Highlights of g 4 sbs simulation results/analysis 6/3/2015 SBS Weekly Meeting June 3, 2015 8

Checkout of HCAL in g 4 sbs—coordinate resolution Preliminary HCAL coordinate resolution in g 4 sbs ~2. 8 cm (based on cluster center of gravity calculation with linear energy weighting) consistent with CDR 6/3/2015 SBS Weekly Meeting June 3, 2015 9

Checkout of HCAL in g 4 sbs—Energy resolution Preliminary σE/E ~ 23% @7 Ge. V ~ 60%/sqrt(E) (consistent with CDR number) 6/3/2015 SBS Weekly Meeting June 3, 2015 10

Notes on preliminary HCAL performance study • Code is the same as that used by CMU group; studies done to validate implementation in g 4 sbs program—consistency with previous results suggests implementation is correct. • Studies made extensive use of new code features in uconn_dev branch: • “detector maps” which provide cell coordinate info needed for clustering of hits • FT/FPP 1/FPP 2 track information utilized 6/3/2015 SBS Weekly Meeting June 3, 2015 11

FPP simulated angular distributions (unpolarized) • Scattering angle distribution for all tracks in FPP 1 relative to elastically scattered proton track in FT • Qualitatively similar to real data from e. g. , Hall C FPP 6/3/2015 SBS Weekly Meeting June 3, 2015 12

FPP simulated distance of closest approach • FPP 1 • FPP 2 6/3/2015 SBS Weekly Meeting June 3, 2015 13

FPP simulated “zclose” vs. theta • Left: theta vs. zclose for FPP 1 relative to FT • Right: theta vs. zclose for FPP 2 relative to FPP 1 6/3/2015 SBS Weekly Meeting June 3, 2015 14

Notes on preliminary FPP studies • Unpolarized angular distributions look qualitatively similar to real data from e. g. , Hall C • So far, track reconstruction “cheats” using MC “truth” information to group hits into tracks • Cuts applied on track momentum, chi 2, etc. • No polarization info included yet. • Knowledge of MC “truth” info enables detailed study of FPP efficiency and particle energy distributions, particle IDs and multiplicities as a function of scattering angle— could inform polarization analysis 6/3/2015 SBS Weekly Meeting June 3, 2015 15

ECAL MC studies (R. F. Obrecht) Presented at APS April 2015 Meeting in Baltimore 6/3/2015 SBS Weekly Meeting June 3, 2015 16

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Recent code improvements 6/3/2015 SBS Weekly Meeting June 3, 2015 22

Segregation of g 4 sbs commands into pre/post-initialization • Added optional segregation of configuration commands into “pre-init” and “post-init” execution: • Motivation: g 4 sbs user needs the option to turn off computationally expensive optical photon production without recompiling the code. • Need to work around (apparently long-standing) GEANT 4 bug that crashes g 4 sbs when attempting to disable scintillation using “/process/inactivate Scintillation” • Solution: added commands “/g 4 sbs/useckov” and “/g 4 sbs/usescint” to toggle Cerenkov/Scintillation processes on/off in G 4 SBSPhysics. List • Commands only have an effect if invoked in the pre-initialization phase • How it works: program interprets “. /g 4 sbs file 1. mac file 2. mac” to mean: • Execute the commands in file 1. mac before Run. Manager: : Initialize() • Execute the commands in file 2. mac after Run. Manager: : Initialize() • If only one macro file is given on the command line, will execute after initialization (this was default behavior previously) • For most existing g 4 sbs commands, GEANT 4 doesn’t care whether they are invoked pre-init or post-init. Known exceptions: • /g 4 sbs/useckov and /g 4 sbs/usescint must be pre-init • /g 4 sbs/run must be invoked post-initialization. • Elimination of existing GEANT 4 bug could eliminate the need for this feature, but: • Potentially useful for other purposes such as user configuration of geometry/materials and other parameters defined pre-initialization. 6/3/2015 SBS Weekly Meeting June 3, 2015 23

Encapsulation of calorimeters for optional “fast” simulation • Enclose all heavy showering detectors (ECAL/HCAL/BBCAL) in mother volumes that can be optionally made “total absorbers” with “calorimeter sensitivity” using “/g 4 sbs/steplimit” command • When enabled, all particles entering the mother volume enclosing a calorimeter are killed and recorded without simulating any details of the shower development. • Speeds up simulation when calorimeter info not wanted for e. g. , rate estimates and acceptance calculations 6/3/2015 SBS Weekly Meeting June 3, 2015 24

Ongoing Projects/Status • HCAL performance checkout (UConn): • GRINCH backgrounds (JLab, Dasuni A. ) • nearly done, update code • FPP efficiency and to latest version from polarimetry (UConn) CMU • RICH performance • ECAL (UConn): (UConn) • Done, but need final geometry • Documentation and user support (UConn) • CDet (SMU) 6/3/2015 SBS Weekly Meeting June 3, 2015 25

Simulation capabilities wish-list: • Particle spin-tracking (relevant mainly to GEP and new GEN recoil proposal) • “Smart” retention of more limited subset of “particle history” info for heavy showering detectors—current approach is “all” (complete history) or “nothing” (hit info only; e. g. nphe, total edep, etc) • Fast, parametrized detector response for optical photon/shower detectors • Fast, parametrized “full digitization” to generate ADC/TDC pseudo-data • More detailed GEM response simulation including strips, clustering, etc. (need to parametrize response from real test data, not planning to simulate ionization/amplification process) • Interface to “minimum-bias” event generators such as PYTHIA and others • Investigating use of ROOT-PYTHIA 6 interface (“TPythia 6”) 6/3/2015 SBS Weekly Meeting June 3, 2015 26

Simulation studies wish-list • SBS spin precession with GEANT 4 spin-tracking and realistic magnetic field map—ray-tracing AND fitting • SBS and Big. Bite optics and resolution (already done, but needs to be re-done for all experiments with realistic field maps) • Optimize layout of the SIDIS experiment • Update background rates for all detectors in all experiments • Develop reconstruction for all detectors with realistic background conditions 6/3/2015 SBS Weekly Meeting June 3, 2015 27

Status of User Documentation • Draft documentation of new tree structure in “uconn_dev” written by R. F. Obrecht • End-user and API documentation coming soon • Encourage use of “uconn_dev” branch; contact Andrew Puckett/Freddy Obrecht with specific questions • “Standard” scripts for all experiment configurations coming soon. • Documentation of g 4 sbs commands coming soon 6/3/2015 SBS Weekly Meeting June 3, 2015 28

Status of Code • Major changes represented by “uconn_dev” branch largely tested, debugged. • Need to update default/standard simulation scripts for all experiment configurations • Different tree structure depending on detectors in use need standard “TTree: : Make. Class()” files (skeleton ROOT analysis macros) for each experiment configuration. • Near future—merge stable version of “uconn_dev” into “master” branch 6/3/2015 SBS Weekly Meeting June 3, 2015 29

Outlook • Major improvements to g 4 sbs largely tested/debugged • New capabilities already bearing fruit in analysis of simulation results • Current development priorities: • Clean-up of simulation scripts and ROOT macros to make compatible with new tree structure and code: need to work “out-ofthe-box” • “Official release” of new g 4 sbs version, merge of “uconn_dev” into master branch of g 4 sbs, integration of parallel efforts • User and developer documentation: • How to run simulations • How to analyze data—documentation of tree structure • How to add new detectors/geometries • Opportunities for collaboration—many geometries still missing/incomplete 6/3/2015 SBS Weekly Meeting June 3, 2015 30

SIDIS Cherenkov Background Rates GRINCH: 3. 8 MHz/PMT average (3. 8% occupancy for 10 ns window) RICH: 700 k. Hz/PMT average (0. 7% occupancy for 10 ns window) • PRELIMINARY RICH (left) and GRINCH (right) counting rates for SIDIS configuration • Caveats: results obtained with “bare-bones” He-3 target in air—target is only ~1/3 of material along beamline • More effective shielding and collimation of target can reduce rates • Investigation of background sources for Cherenkov counters ongoing using (new) detailed particle histories 6/3/2015 SBS Weekly Meeting June 3, 2015 31

SIDIS GEM Backgrounds SBS GEM tracker for SIDIS average hit rate at first plane ~ 35 k. Hz/cm 2 (10 X below GEP case) 6/3/2015 SBS Weekly Meeting June 3, 2015 32

ECAL position resolution from GEANT 4 6/3/2015 SBS Weekly Meeting June 3, 2015 33