EicRoot and Calorimeter Code Development Overview by A. Kiselev

1. EicRoot status report and calorimeter code development A. Kiselev BNL, 06/20/2013

2. Contents • SVN repository • Interface to EIC smearing generator • Tracking detector “designer” tools • Overall status • Update on track resolution studies • Calorimeter code development & studies A.Kiselev

3. EIC in FairRoot framework • FairRoot is officially maintained by GSI; dedicated developers • O(10) active experiments; O(100) users CbmRoot • ROOT • VMC • VGM • “Boost” library • … R3BRoot FairRoot external package bundle FairBase C++ classes … PandaRoot • Interface to GEANT • Magnetic fields • Parameter database • MC stack handling • … EicRoot eic-smear -> Make best use of FairRoot development -> Utilize efficiently existing codes developed by EIC taskforce A.Kiselev

4. Overall status

5. EicRoot availability & usage • SVN -> http://svn.racf.bnl.gov/svn/eic/eicroot • eic000* cluster -> /eic/data/FairRoot • README & installation hints • Few basic usage examples -> MC points End user point of view: simulation digitization reconstruction “PID” Pass -> Hits -> “Short” tracks -> Clusters -> “Combined” tracks -> Vertices @ IP • ROOT files for analysis available after each step • C++ class structure is (well?) defined at each I/O stage A.Kiselev

6. Interface to eic-smear • directly uses eic-smear library calls to import ASCII event files after MC generators … • … as well as “unified” ROOT format event files • EicRoot input • EicRoot output • is available in eic-smear format with charged particle momentum variables “smeared” by Kalman Filter fit after track reconstruction … • … while other variables modified by smearing generator according to its recipes A.Kiselev

7. Detector view (June’2013) FEMC CEMC SOLENOID BEMC • EMC and tracking detectors ~implemented so far A.Kiselev

8. Update on track resolution studies

9. Tracking elements vertex silicon tracker: • 6 MAPS layers at up to of 160mm radius; STAR ladder design • digitization: discrete ~20x20mm2 pixels forward/backward silicon trackers: • 2x7 disks with up to 280 mm radius; MAPS pixels assumed • N sectors per disk; 200mm silicon-equivalent thickness • digitization: same as for vertex tracker TPC: • ~2m long; gas volume radius [300..800] mm • 1.2% X0 IFC, 4.0% X0 OFC; 15.0% X0 aluminum endcaps • digitization: idealized, assume 1x5 mm GEM pads GEM trackers: • 3 disks behind the TPC endcap; STAR FGT design • digitization: 100mm resolution in X&Y; gaussian smearing A.Kiselev

10. Tracker view (June’2013) FGT FST VST BST TPC BGT A.Kiselev

11. Tracking scheme • So-called ideal PandaRoot track “finding”: • PandaRoot track fitting code: • Monte-Carlo hits are digitized on a per-track basis • Effectively NO track finder MRS-B1 solenoid design used • Kalman filter • Steering in magnetic field • Precise on-the-fly accounting of material effects A.Kiselev

12. Example plots from tracking code 1 GeV/c p+ tracks at h=0.5: <ndf> = 206 32 GeV/c p+ tracks at h=3.0: <ndf> = 9 -> look very reasonable from statistical point of view A.Kiselev

13. Momentum resolution plot#1 p+ track momentum resolution vs. pseudo-rapidity -> expect 2% or better momentum resolution in the whole kinematic range A.Kiselev

14. Momentum resolution plot#2 p+ track momentum resolution at h = 3.0 vs. Silicon thickness -> ~flat over inspected momentum range because of very small Si pixel size A.Kiselev

15. Momentum resolution plot#3 p+ track momentum resolution at h = 3.0 vs. Silicon pixel size -> 20 micron pixel size is essential to maintain good momentum resolution A.Kiselev

16. Tracker “designer” tools • Allow to easily add “simple” tracking detector templates to the “official” geometry • Require next to zero coding effort Which momentum resolution for 10 GeV/c pions will I get with 10 MAPS layers at h=3? -> see tutorials/designer/tracking directory for details A.Kiselev

17. Tracker “designer” tools -> workflow sequence: • Create geometry file (few dozens of lines ROOT C script) • Include few lines in “standard” sim/digi/reco scripts: • Analyze output ROOT file A.Kiselev

18. Calorimeters in EicRoot

19. General • Code written from scratch • Unified interface (geometry definition, digitization, clustering) for all EIC calorimeter types • Rather detailed digitization implemented: • configurable light yield • exponential decay time; light collection in a time window • attenuation length; possible light reflection on one “cell” end • SiPM dark counting rate; APD gain, ENF, ENC • configurable thresholds A.Kiselev

20. Backward EM Calorimeter (BEMC) • PWO-II, layout a la CMS & PANDA • -2500mm from the IP • both projective and non-projective geometry implemented • digitization based on PANDA R&D 10 GeV/c electron hitting one of the four BEMC quadrants Same event (details of shower development) A.Kiselev

21. BEMC energy resolution plot#1 electrons at h = 2.0 -> projective geometry may lag behind in terms of resolution? A.Kiselev

22. BEMC energy resolution plot#2 non-projective geometry; h = 2.0 • “Realistic” digitization: light yield 17pe/MeV; APD gain 50, ENF 2.0, ENC 4.2k; 10 MeV single cell threshold; -> would be interesting to check sensitivity to all settings in detail A.Kiselev

23. Forward EM Calorimeter (FEMC) tower (and fiber) geometry described precisely • tungsten powder scintillating fiber sampling calorimeter technology • +2500mm from the IP; non-projective geometry • sampling fraction for e/m showers ~2.6% • “medium speed” simulation (up to energy deposit in fiber cores) • reasonably detailed digitization; “ideal” clustering code A.Kiselev

24. FEMC energy resolution study 3 degree track-to-tower-axis incident angle • “Realistic” digitization: 40MHz SiPM noise in 50ns gate; 4m attenuation length; 5 pixel single tower threshold; 70% light reflection on upstream fiber end; -> good agreement with original MC studies and measured data A.Kiselev

25. FEMC tower “optimization” original mesh -> optimized mesh design can probably decrease “constant term” in energy resolution optimized mesh A.Kiselev

26. Barrel EM Calorimeter (CEMC) -> barrel calorimeter collects less light, but response (at a fixed 3o angle) is perfectly linear • same tungsten powder + fibers technology as FEMC, … • … but towers are tapered • non-projective; radial distance from beam line [815 .. 980]mm A.Kiselev

27. CEMC energy resolution plot#1 3 degree track-to-tower-axis incident angle -> simulation does not show any noticeable difference in energy resolution between straight and tapered tower calorimeters A.Kiselev

28. CEMC energy resolution plot#2 8 GeV/c electrons -> energy response goes down with polar angle because of effectively decreasing sampling fraction; quite reasonable A.Kiselev

29. CEMC energy resolution plot#3 8 GeV/c electrons -> energy resolution degrades with polar angle because of effectively decreasing sampling frequency (?) A.Kiselev

30. Calorimeter “designer” tools • Allow to easily add “simple” calorimeter detector templates to the “official” geometry • Require next to zero coding effort Which energy resolution for 1 GeV/c electrons will I get with a “basic” PWO calorimeter? A.Kiselev

31. Calorimeter “designer” tools • your dream calorimeter is a logical 2D matrix … • … composed of “long cells” as elementary units, • all the game is based on (known) light output per energy deposit, • energy resolution after “ideal” digitization suffices as a result • As long as the following is true: • … one can with a moderate effort (99% of which is writing a ROOT C macro with geometry and mapping description) build custom EicRoot-friendly calorimeter which can be used for both standalone resolution studies and/or as an optional EIC device (and internal cell structure does not matter) -> see tutorials/designer/calorimetry directory for details A.Kiselev