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

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

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: 1007.393 MeV Sigma – fit: 60.70 Rel. resolution: 5.96% phot2E: 0.765697 Radius = x2 + y2 Distance along the module [cm]

New ECAL look-up tables 1.5 inch EMI 3 inch Hamamatsu Mean – fit: 999.99 MeV Sigma – fit: 58.47 Rel. resolution: 5.85% phot2E: 0.891507 Mean – fit: 1001.66 MeV Sigma – fit: 54.45 Rel. resolution: 5.44% phot2E: 0.3828485 Radius = x2 + y2 Radius = x2 + y2 Distance along the module [cm] Distance along the module [cm]

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: 1.5inch PMT 2: 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

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

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

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

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

Comparison of cosmic muon measurements and simulations fotka setupu v Řeži

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??

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...

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)

ECAL cosmic muons - simulation x 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).

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

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!

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

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

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!

Backup

1 inch Hamamatsu PMT look-up table Mean – fit: 999.864 MeV Sigma – fit: 69.4003 Rel. resolution: 6.94% phot2E: 1.555533 Radius = x2 + y2 Distance along the module [cm]