Testbeam comparisons ar Xiv 1704 01461 Jet measurements
Testbeam comparisons ar. Xiv: 1704. 01461
Jet measurements: Electromagnetic and Hadronic calorimetry Upsilon Spectroscopy: Excellent momentum resolution tracking in high occupancy heavy ion events b-jets: Secondary vertices
Testbeam Setup @ Fermilab Beam s. PHENIX side view Midrapidity Configuration (emcal modules + hcal tiles) Readout Si PMs Yes – sampling fraction changes with depth which makes the analysis somewhat tricky
EMCal 8 Ge. V electron shower, only particles with E>7. 8 Me. V shown Tungsten epoxy with embedded scintillating fiber (Spacal) Projective in phi (+eta forward/backward eta, next test beam) Two Towers in one block
HCals 32 Ge. V p. Midrapidity tiles (steel is identical for high eta) Babar cryostat mocked up by 3 aluminum plates with X 0=1. 4 4 Scintillating tiles/row Measurements with and without EMCal in front
In the real world and everything needs to be light tight and supported Sadly no particle gun available at FTBF
GEANT steps GEANT propagates particles one step at a time. The step size is determined by the physics processes associated with the current particle or when a boundary between volumes is crossed After each step the user stepping method is called with a pointer to the current volume which has access to the full information (energy loss, particle momentum at beginning and end of step, …)
Our G 4 Hits In our stepping method we add the energy loss in each volume and store the entry and exit coordinates (and for tracking detectors the momentum at the entry and exit) G 4 Hit We also keep the ancestry for G 4 Hits so any hit can be traced back to a primary particle. To reduce size we do not store particles which do not leave G 4 Hits and are not in the ancestry of a particle which created a G 4 Hit
No difference when it comes to em showers (okay - no big surprise all lists use the same em physics processes)
Major differences when it comes to hadronic showers
Simulation setup • • • G 4 version 10. 02 P 01 QGSP_BERT_HP Default Birks constant (0. 0794 mm/Me. V) Timing window 0 -60 ns (our electronics) Light attenuation in scintillator Si. PM pixels added to simulate ADC Pedestal (measured from cosmics)
EMCal Energy resolution well reproduced (beam momentum spread folded in)
EMCal Hadron Rejection Hadron (mostly p-, < 1%K-) rejection as function on energy cut in 5 x 5 towers. Should be sensitive to shower sizes
HCal Energy deposition well described (inner+outer hcal), peak at low energy in data due to muons which were not simulated 4 Ge. V muon mip peak overlaps with hadron peak
Hcal e/h 4 Ge. V contaminated by muons, best description by 0. 2 mm/Me. V Birks constant
Summary • The resolution seems to be very well reproduced by G 4 • No real sensitivity on physics lists here • Probably mainly geometry driven • Hadron rejection in emcal shows sensitivity to physics lists (shower size? ) • Hcal e/h sensitive to Birks constant
- Slides: 18