1. An update on ECAL simulations
Arun Prakash
for the ECAL group
HADES collaboration meeting XXX, October 7 – 10, 2015, Lisbon

2. Outlook simulation – new stuff since last meeting new lookup tables
renumbering of modules
diffusion tuning
cosmics – relative energy resolution check
cosmics – using for calibration at final setup
plans for (near) future
photon analysis -> π0 diphoton analysis
including of ECAL data to track info for charged particles

3. Old 1.5 inch PMT look-up table
wrong PMT active area (1.8 cm instead of 1.6 cm as stated in EMI datasheet)
relative energy resolution 6% instead of 5.8% (measured at MAMI experiment)
1GeV photons
Mean – fit: MeV
Sigma – fit: 60.70
Rel. resolution: 5.96%
phot2E:
Radius = x2 + y2
Distance along the module [cm]

4. New ECAL look-up tables
1.5 inch EMI
3 inch Hamamatsu
Mean – fit: MeV
Sigma – fit: 58.47
Rel. resolution: 5.85%
phot2E:
Mean – fit: MeV
Sigma – fit: 54.45
Rel. resolution: 5.44%
phot2E:
Radius = x2 + y2
Radius = x2 + y2
Distance along the module [cm]
Distance along the module [cm]

5. Adaptation of Hydra to accommodate two PMT types
done by Ilse König (many thanks!) in June 2015
propagated in hydra2-4.9e version
needed changes:
new container EmcSimulPar
- contains lookup table for the photomultiplier types
(0: no PMT : 1.5inch PMT : 3inch PMT)
- lookup table contains numbers for all 1530 possible cell indexes
(6 sector * 15 rows * 17 columns)
parameter phot2E and sigmaEReal changed to TArrayF with array size 3
Changes in Hydra2:
base/runtimedb/hemcsimulpar.h
base/runtimedb/hemcsimulpar.cc
base/runtimedb/hbasecontfact.cc
base/runtimedb/RuntimeDbLinkDef.h
base/Makefile
Changes in HGeant2/gemc
emctuple.inc
emcinit.F
profastinit.h
profastinit.cc
emcstep.F
profast.cc

6. Renumbering of ECAL modules
done in May 2015 in order to match with HADES conventions (it was vice versa before)
new numbering starts now in the right lower corner of the EMC module in sector 1 (negative x- and y-lab coordinate
validated in Oracle for simulation project ECAL13SIM (all older simulations cannot be read anymore) y x
GMOM
Rows
Columns

7. Diffusion tuning to increase muon response
based on the measurements in Mainz 2014, cosmic muons seems to have a twice large response in comparison to what we see in simulations
aim is to enlarge the response on muons and keep the response for photons. Muons and photons (or pions and electrons) have different interaction and secondary particle generation in the ECAL lead glass module
idea was to change the diffusion coefficient in order to change the ratio of registered Cherenkov photons from muons and photons (recommended also by Kirill).
diffusion - spreading the light evenly X reflection – reflecting the light under defined angle
Muon – 4GeV
Gamma – 1213MeV
GEANT3
secondary particles
x:y:z hit coordinates

8. Probability to detect a photon with respect to its angle and diffusion coefficient (lookup table)
diffusion factor: 0.
diffusion factor: 0.3
no diffusion
angle of generated photons ()
diffusion factor: 0.64
(original one) 
diffusion factor: 0.78
diffusion factor: 1.
full diffusion

9. histogram shows a mean number of registered Cherenkov photons (those, which fit the active surface of 1.5 inch PMT) for different values of diffusion coefficient in lighttransport/optics.cc
total „deposited“ energy in simulation can be tuned by changing the phot2E factor
(number of Cherenkov photons * phot2E = Energy [MeV].
no value of diffusion factor (even the non-physical ones like 0. or 1.) changes the ratio twice as we need...can be used only for minor tuning.
Kirill‘s value 0.64

10. Comparison of cosmic muon measurements and simulations
fotka setupu v Řeži

11. ECAL cosmic muons – standard measurement
sum of measurements
Relative energy resolution worse than in beam tests (MAMI Mainz, CERN)...can it be caused by various muon energies in cosmic radiation??

12. ECAL cosmic muons – simulation – various energies
Various energies of muons – hGeant sim
Cutting low energy cosmic muons by additional lead shielding (15cm) failed...no change in measured spectra...

13. central position gives smaller amplitudes..!
ECAL cosmic muons – horz. measurement m- m- m-
1st measurement
central position gives smaller amplitudes..!
2nd measurement
ratio to standard cosmics ~ 0.12
measured at different binning and oscilloscope setting, trigger PMTs in vertical position (more vertical tracks only)

14. ECAL cosmic muons - simulationx m- m- m- x x
PMT side
PMT side
PMT side z z z x
PMT side
ratio ~ 0.13 z
Simulation in good agreement with measurement (ratio 0.12 vs 0.13).

15. ECAL cosmic muons – measurement– various angles
Direction of created Cherenkov photons seems to be more important than their absolute number (for similar events).

16. Note: direction of muon has bigger influence than its path length!
ECAL cosmic muons – simulation – various angles
30°
PMT side
PMT side
45°
PMT side
60°
PMT side
Note: direction of muon has bigger influence than its path length!

17. will be used for calibration at full ECAL using cosmic muons
ECAL cosmic muons – simulation – various angles
-30°
30°
PMT side
PMT side
-45°
45°
PMT side
PMT side
-60°
60°
PMT side
PMT side
will be used for calibration at full ECAL using cosmic muons

18. Summary
new lookup tables for 1.5“ and 3“ (1“) PMTs, including results from MAMI Mainz (real relative energy resolution)
renumbering of modules to comply with HADES customs
diffusion tuning to check relation between muon and electron response
cosmics – relative energy resolution check and its comparison with simulation
---> good agreement!
– studies of various geometries of incoming muons to understand effects playing role in future cosmic muons calibration at final ECAL setup

19. Plans for (near) future
What is still missing or can be improved on simulation side of the ECAL?
HGEANT:
● question of muon response (how to make it 2x higher)
possibility to use particle dependent response in digitizer
HYDRA:
● reuse existing hit finders & clustering for correct energy measurement (diphoton analysis)
● MetaMatching to EMC
● propagation of Runge-Kutta to EMC modules
● adding to HParticleCand of needed data
We need help of an HGEANT/Hydra expert(s) to start the tasks!

20. Backup

21. 1 inch Hamamatsu PMT look-up table
Mean – fit: MeV
Sigma – fit:
Rel. resolution: 6.94%
phot2E:
Radius = x2 + y2
Distance along the module [cm]