1. LHCf Collaboration Meeting, Catania, 4-6 July 2009 MC comparison: Fluka vs Epics Oscar Adriani

2. Oscar Adriani Catania 2009 Main Idea 2 Independent simulations of detectors –Japan based (Epics) –Italian based (Fluka) Originally developed in 2004/2005 for the TDR No precise modeling of detectors Better control and check of systematics

3. Oscar Adriani Catania 2009 How to proceed Work done in strict collaboration with Menjo (Many Thanks!!!!) Transportation from I.P to TANs I.P 140m 20cm 7TeV-7TeV collision 5 models are available now. 5 models are available now. DPMJET3 、 QGSJET1,2 SIBYLL 、 EPOS Detector Simulation Our Detector Gencol Double Arm End2End

4. Oscar Adriani Catania 2009 What are we doing For the moment only Arm2 has been studied The output of the DoubleArm code is the input for Fluka simulation We try to compare the output of my Fluka simulation with the output of the Epics End2End simulation Event by event comparison!!!! Important tool to understand how similar are the simulatin code and how much we can trust them

5. Oscar Adriani Catania 2009 Statistic and machine time The most important problem that we found is the statistic and machine time: –1500 events in Fluka: > 24 hours of CPU –Very long time to have high statistic sample –The analysis I will show is based on 60.000 events

6. Oscar Adriani Catania 2009 Event selection I select ‘clean’ events: –E<10 GeV (at generator level) particles are neglected –Particles not hitting the towers are neglected ‘Pure e.m.’ events: only 1 e.m. particle hitting the towers ‘Pure hadronic’ events: only 1 had particle hitting the towers

7. Oscar Adriani Catania 2009 Variables for the comparison Global energy and topological energy release variables –Total energy in scintillators –Longitudinal development of the shower Mean value of longitudinal energy deposit: Z med –  (z i *E i )/  (E i ) over all the 16 layers RMS: Z rms –Total energy in silicon –Transverse shower profile in silicon Mean value of transverse energy deposit –  (x i *E i )/  (E i ) over all the 384 strips of one sensor RMS

8. Oscar Adriani Catania 2009 Total e.m. Energy Nice correlation, as we can expect

9. Oscar Adriani Catania 2009 Total e.m. Energy Conversion factors are calibrated to give in average the same energy measured

10. Oscar Adriani Catania 2009 Total e.m. Energy

11. Oscar Adriani Catania 2009 Total e.m. Energy 5% difference

12. Oscar Adriani Catania 2009 Total had Energy Some discrepancy?!

13. Oscar Adriani Catania 2009 Total had Energy Very bad correlation, as we can expect, since only few hadrons interact in the calo

14. Oscar Adriani Catania 2009 Z med in e.m. events Ooopssss…. I forgot to add the beam pipe in the geometry….

15. Oscar Adriani Catania 2009 Z med in e.m. events The peak is in different positions, but the sigma is similar

16. Oscar Adriani Catania 2009 Z med in had. events Also here we see the beam pipe effect

17. Oscar Adriani Catania 2009 Z rms in e.m. events Epics RMS is broader and with longer tails?!

18. Oscar Adriani Catania 2009 Z rms in had. events

19. Oscar Adriani Catania 2009 e.m. energy in silicon (1^ plane) Here the missing beam pipe effect is very important! All the difference is there or not?

20. Oscar Adriani Catania 2009 e.m. shower position in silicon (1^ plane)

21. Oscar Adriani Catania 2009 e.m. shower rms in silicon (1^ plane) Why the EPICS rms is smaller? Beam pipe missing should go in the other way?

22. Oscar Adriani Catania 2009 Conclusion EPICS and Fluka detailed comparison for pure e.m. and hadronic events Fluka geometry should be modified to insert the beam pipe….. Nice agreement for e.m. energy Some discrepancy in had. energy Silicon response still to be understood