1. The D0 Monte Carlo Challenge Gregory E. Graham University of Maryland (for the D0 Collaboration) February 8, 2000 CHEP 2000

2. February 8, 2000Greg Graham - CHEP 20002 D0 Monte Carlo Challenge Goals Testing the D0 GEANT Monte Carlo Program (D0GSTAR) –Performance : CPU time, event size, memory –Accuracy of detector simulation Testing the D0 Reconstruction Program (D0RECO) –Performance : CPU time, event size, memory –Efficiency and rejection power of reconstruction algorithms

3. February 8, 2000Greg Graham - CHEP 20003 D0 Monte Carlo Challenge Goals Testing the infrastructure for running D0GSTAR and D0RECO –remote site Monte Carlo generation –storage testing (Sequential Access Method - SAM) (C241 - these proceedings) –farm processing (E60 - these proceedings) Testing the integration of these systems with large numbers of events –Stress testing

4. February 8, 2000Greg Graham - CHEP 20004 D0 Monte Carlo Challenge Goals Evaluating the Physics Potential of the D0 Detector in Fermilab Tevatron Run II –detailed studies of different physics processes –trigger studies –algorithm performance –background rejection / signal efficiency –discovery potential

5. February 8, 2000Greg Graham - CHEP 20005 The D0GSTAR Program Based on GEANT 3.21 (Fortran) with C++ wrapper –Linux and IRIX Platforms Input is ISAJET, PYTHIA (with QQ libraries and TAUOLA ) Output are Hits and Digi information Typical event size : 1.0 - 1.5 MB Typical detector simulation time : 5 - 7 minutes –Shown for SGI R12000 processor at 300 MHz

6. February 8, 2000Greg Graham - CHEP 20006 D0 Monte Carlo Challenge Objectives Phase I : Initial Stage (Summer 1999) –Generate 100,000 events –Test and develop D0GSTAR, D0RECO Phase II : Intermediate Stage (Winter 2000) –Generate 300,000 - 500,000 events –Use remote sites for MC generation –Further testing and development of D0GSTAR, D0RECO –Integration of Systems –Initial Physics and Trigger studies

7. February 8, 2000Greg Graham - CHEP 20007 D0 Monte Carlo Challenge Objectives Phase III : Final Stage (Fall 2000) –Further develop remote MC generation sites –Further testing of software systems integration –Trigger studies –Physics Studies –Double Blind tests

8. February 8, 2000Greg Graham - CHEP 20008 D0 Monte Carlo Challenge Phase II How do we efficiently generate 500,000 D0GSTAR MC events ? –This corresponds to about 55,000 CPU hours (on a 300 MHz/CPU) How do we store 500,000 MC events ? –This corresponds to about 0.6 TB of data How do we further improve our capacity for MC generation while ensuring homogeneity of generated samples at remote sites ?

9. February 8, 2000Greg Graham - CHEP 20009 MCC Event Generation and Storage Use many remote computing facilities to generate Monte Carlo –MC generation must be homogenized –Tools to collect statistics on MC generation Use SAM / ENSTORE system at FNAL to store event files –Currently configured to use a tape robot using Mammoth-I tapes (18 GB/tape)

10. February 8, 2000Greg Graham - CHEP 200010 MCC Remote Processing Sites

11. February 8, 2000Greg Graham - CHEP 200011 MCC Remote Processing Sites FNAL (Batavia, IL) –17 processors on 48 processor SGI R12000 –300 MHz, memory 250 MB/processor Lyon (IN2P3,France) –15 dual Pentium II/III PC Farm –450/500 MHz, memory 250 MB/processor Amsterdam ( NIKHEF, Netherlands ) –6/128 processors on 128 processor SGI R10000 (now 32/128 - Thanks, Kors!) –250 MHz, memory 450 MB/processor

12. February 8, 2000Greg Graham - CHEP 200012 MCC Remote Processing Sites Prague (Czech Rep. Acad. Sciences) –3 Pentium III based PCs – 450/500 MHz, memory 128/256 MB/processor University of Texas at Arlington –7 dual Pentium III PCs –500 MHz, memory 250 MB/processor Further Sites in the Planning Stage –Lancaster (UK), Nijmegen, and others –Hardware upgrades are also being planned

13. February 8, 2000Greg Graham - CHEP 200013 MC Homogeneity Event Generation is by isajet or pythia –these are D0 standard tools (cvs package) –supplemented by QQ and tauola D0GSTAR is also standard –D0GSTAR based on 3 cvs packages –Linux and Irix platforms Python based tools for MC generation –Standardized input files –Random number seeds updated automatically –Built in scripting tool for multi-job generation No D0 environment necessary –Distributed as executables + libraries + input files + tools

14. February 8, 2000Greg Graham - CHEP 200014 Collecting the MC Data After generation, MC data is imported into SAM –Directly into SAM via sam store commands (possible at FNAL site) –Via ftp connection to SAM import site –Via Mammoth-I tapes (plus suitcase and airplane ticket) Statistics for generation are now collected locally at the remote sites and compiled by hand at the central site

15. February 8, 2000Greg Graham - CHEP 200015 Results on Generated Events QCD DIJET events in each of 7 different Et thresholds.... 50K tt events..........................................50K b  J/  (  ee or  ).............................. 50K Z  ee, ,  each.............................. 10K Z  bb...........................................5K W  e  each)............................. 1K  jets........................................... 1K  ee.......................................... 1K Other Signal Events.................................10K Total Generated................................... 500K And we still continue to generate events ! Snapshot January, 2000

16. February 8, 2000Greg Graham - CHEP 200016 Results on Generated Events MCC production by site FNAL..................... 240K Lyon...................... 210K NIKHEF................... 30K Prague..................... 20K UTA....................(just starting) Total...................... 500K Snapshot January, 2000

17. February 8, 2000Greg Graham - CHEP 200017 MCC Event Generation Capacity Generation Capacity –Phase II has achieved a capacity of about 5,000 events per day at all existing remote sites –Can expand to at least 25,000 events per day with further hardware upgrades and new centers Storage Capacity –Network bandwidth less than desirable (ftp), but not a bottleneck –0.6 TB stored so far in SAM, also not a bottleneck

18. February 8, 2000Greg Graham - CHEP 200018 MCC - Debugging D0 Integration issues are being addressed –SAM was exercised extensively. Problems were uncovered and debugged in the software. Debugging D0RECO –Six pass minor releases in current production release Development of tools –micro-DST, Analyze tools Problems were uncovered and fixed in the MC generation tools at remote sites Beginning to look at D0TRIGSIM, uDSTs, etc

19. February 8, 2000Greg Graham - CHEP 200019 What Did We Learn Every remote site is different –porting and verifying released code was easy –porting the MC generation tools was hard Python/Tk UNIX shells Customization Compiling statistics by hand is hard –we need a tool to do this

20. February 8, 2000Greg Graham - CHEP 200020 Future Plans for MCC Phase III Develop tools to better control remote production –Presently, remote production is controlled locally –Software is being developed to control MC generation over the network from a central server Develop tools to collect MC generation statistics –Software is being developed to automate collection of MC generation statistics

21. February 8, 2000Greg Graham - CHEP 200021 Conclusions Integration of D0 MC production, storage, and access was extensively tested (and debugged!) –500 K Events generated for D0 Experiment –55,000 distributed CPU hours logged since 10/1/99 at 5 remote sites –0.6 TB of data successfully stored on SAM Certification of the D0RECO program is currently underway using the MCC samples Other projects (eg- trigger simulation) are ramping up