1. EIC Monte Carlo and the Question of Jets Joseph Seele University of Colorado at Boulder seele@down.colorado.edu Second Electron-Ion Collider Workshop - March 16, 2004 Jefferson Lab

2. Outline Monte Carlo –History of Development –Basic Structure –Current State Question of Jets –Events Displays of e - p from MC at 10 GeV on 50 GeV 10 GeV on 150 GeV 10 GeV on 250 GeV –Hadronic Angular Distributions of Event Samples Joseph Seele Second Electron-Ion Collider Workshop

3. History of the Monte Carlo Joseph Seele Second Electron-Ion Collider Workshop EIC Naomi Makins (UIUC) Antje Bruell (JLab) Joseph Seele (Colo.) The physics monte carlo was primarily derived from the HERMES monte carlo

4. Joseph Seele Second Electron-Ion Collider Workshop History of the Monte Carlo Bernd Surrow (MIT) An elementary detector simulation was built in ELECTRA, a GEANT based system poof!

5. Structure of the Monte Carlo Joseph Seele Second Electron-Ion Collider Workshop The physics monte carlo consists of a framework called GMC (Generator Monte Carlo) inside which a simulation, based on either external or internal calculations, is built. physics calculations GMC data

6. Structure of the Monte Carlo Joseph Seele Second Electron-Ion Collider Workshop There are three current simulations based on separate packages disNG – (deep inelastic scattering Next Generation) This is an internal code built originally for HERMES, but then adapted to a colliding beam experiment setup for EIC. pepsi4 – (polarized electron-proton scattering interactions) A standard external package for polarized electron proton scattering. aroma – An external package to simulate the production of heavy quarks in electron proton scattering through boson-gluon fusion. (insert your generator here)

7. Current State of Development Joseph Seele Second Electron-Ion Collider Workshop aroma pepsi4 disNG pythia6 Current Team Next to Corral dev. proceeding then on to RAPGAP ep scattering ho! here I come EIC! heavy quarks don’t stand a chance

8. Question of Jets The possibility of jets in EIC was explored in the MC using disNG at 3 collision energies with unpolarized species. –10 GeV on 50 GeV –10 GeV on 150 GeV –10 GeV on 250 GeV W 2 > 4.0 and Q 2 > 0.5 were used in the analysis. Joseph Seele Second Electron-Ion Collider Workshop

9. Joseph Seele Second Electron-Ion Collider Workshop Most events look like this one 10 GeV on 50 GeV Event Displays

10. Joseph Seele Second Electron-Ion Collider Workshop

11. Joseph Seele Second Electron-Ion Collider Workshop 10 GeV on 50 GeV Event Displays

12. Joseph Seele Second Electron-Ion Collider Workshop 10 GeV on 50 GeV Event Displays

13. Joseph Seele Second Electron-Ion Collider Workshop 10 GeV on 150 GeV Event Displays Again most events look like this one

14. Joseph Seele Second Electron-Ion Collider Workshop 10 GeV on 150 GeV Event Displays

15. Joseph Seele Second Electron-Ion Collider Workshop 10 GeV on 150 GeV Event Displays

16. Joseph Seele Second Electron-Ion Collider Workshop 10 GeV on 150 GeV Event Displays

17. 10 GeV on 250 GeV Event Displays Joseph Seele Second Electron-Ion Collider Workshop Again most events look like this one

18. 10 GeV on 250 GeV Event Displays Joseph Seele Second Electron-Ion Collider Workshop

19. 10 GeV on 250 GeV Event Displays Joseph Seele Second Electron-Ion Collider Workshop

20. 10 GeV on 250 GeV Event Displays Joseph Seele Second Electron-Ion Collider Workshop

21. Theta Distributions Definition of Theta z x y incident electron incident proton (beam) (target) scattered electron Essentially q is the angle that the hadrons’ momentum vectors make with the momentum vector of the incident electron. q Second Electron-Ion Collider Workshop Joseph Seele hadrons

22. Theta Distribution at 10 GeV on 50 GeV Joseph Seele Second Electron-Ion Collider Workshop =2.643 RMS=.7623 The red lines indicate a 3 o acceptance on either side of the detector

23. Joseph Seele Second Electron-Ion Collider Workshop =2.751 RMS=.6971 Theta Distribution at 10 GeV on 150 GeV The red lines indicate a 3 o acceptance on either side of the detector

24. Joseph Seele Second Electron-Ion Collider Workshop =2.801 RMS=.6520 Theta Distribution at 10 GeV on 250 GeV The red lines indicate a 3 o acceptance on either side of the detector

25. Conclusions Monte Carlo –Development is proceeding with Pythia6. –Development then to shift to RAPGAP. –The MC and all its documentation can be found at http://www.npl.uiuc.edu/~eic for anyone interested in performing simulations. http://www.npl.uiuc.edu/~eic –If you are interested in helping with development please contact myself (seele@down.colorado.edu), Naomi Makins (makins@uiuc.edu) or Antje Bruell (abr@lns.mit.edu)seele@down.colorado.edumakins@uiuc.eduabr@lns.mit.edu Question of Jets –The uncertainty about whether we can speak of jets or not depends on the definition that we wish to use for a jet. –The issue is not completely closed though. I would like to see a more quantitative assessment (and plan on performing one). Joseph Seele Second Electron-Ion Collider Workshop