Update on Ecal simulation Dr. Mauro Raggi Sapienza Universita’ di Roma PADME ECal meeting LNF, 17 January 2017

Simulating effect of crystals gap In order to understand the constraints on the mechanical assembly of the PADME Ecal it is very important to study the effect of dead spaces. PADME MC has been modified to include TiO2 based paint and a paint surface of 100um surrounding each crystal. M. Raggi PADME Ecal 09/05/2019

Simulation of the gap in PADMEMC New MC configuration with: Crystals 21x21x230mm3 Reflective paint 100mm Vacuum gap (50mm) To study the effect on the Ecal performance due to the gap the size of the gap has been changed from 50mm to 500mm No changes of the paint thickness A 30K photon of different energies (25 -1000) MeV have been fired on the Ecal to study the energy containment and the energy resolution. PAMDE MC crystals gaps Crystal TiO2 paint 100um M. Raggi PADME Ecal 09/05/2019

Effect of the angle Due to the non pointing geometry of the PADME ecal the energy leakage and energy resolution depend on the azimuthal angle Each simulation generates a spot of 5cm diameter centered at at a precise position Two different central positions where used X=0, Y=12 X=12 , Y=12 M. Raggi PADME Ecal 09/05/2019

Position of the spots Due to the non pointing geometry of the PADME ecal the energy leakage and energy resolution depend on the azimuthal angle Each simulation generates a spot of 5cm diameter centered at user defined position Two different central positions where used X=0, Y=17 X=12 , Y=12 1 2 M. Raggi PADME Ecal 09/05/2019

E coll. and E resolution spot1 M. Raggi PADME Ecal 09/05/2019

E coll. and E resolution spot2 The lower azimuthal angle gives a worst energy collection and resolution with larger gaps The total dead region is given by: 200mm paint + gap M. Raggi PADME Ecal 09/05/2019

Ecal and SAC radiation dose We tried to simulate the total dose of radiation accumulated by Ecal and SAC exposed to 1013 550 MeV pot (e+ on target) The integrated energy in each of the Ecal crystals was simulated and the result converted into radiation dose. 400M e+ on target fully simulated and energy deposit scaled to 1E13 e+ Energy converted from MeV to Joule (*1E6*1.6E-19) To convert in Gy we used the average weight of a single crystal 0.7Kg so just divide by 0.7 (not properly true most of the energy is released in the first 1-2 cm) M. Raggi PADME Ecal 09/05/2019

Dose in Gy in the SAC 1E13 e+ In the central crystal the accumulated dose is ~1Gy The dose scales by ~ one order of magnitude per column M. Raggi PADME Ecal 09/05/2019

X vs Z energy profile Energy fraction deposit in the X vs Z profile M. Raggi PADME Ecal 09/05/2019

Ecal accumulated dose In the Ecal central crystals the accumulated dose is ~10-4 Gy per 1013 e+ There is a visible effect of the synchrotron radiation on the left side of the Ecal M. Raggi PADME Ecal 09/05/2019

Conclusion on dose rate On all the padme detector the dose rate accumulated during 1 year of run ~1E13 pot is modest Order 1Gy is the maximum dose on the SAC crystals Dose rate on the Calorimeter in below 1E-3 Gy in one year of data taking The simulation does not include for the moment the beam dump Non negligible radiation dose may come from back-splash from beam dump Need to define beam dump geometry before repeating the simulation M. Raggi PADME Ecal 09/05/2019

Simulating shower development To better understand the test beam data is necessary to study the distribution of the energy deposit in the 5x5 crystals prototype After measuring the threshold induced by the pedestal during the data taking the amount of crystals to be included in the cluster can be extracted for different positron energy 4 different energy have been simulated using M. Raggi PADME Ecal 09/05/2019

Fraction of energy in each crystal 500MeV 250MeV 10MeV 100MeV M. Raggi PADME Ecal 09/05/2019

Energy deposit in each crystal 500MeV 250MeV 100MeV 50MeV 10MeV M. Raggi PADME Ecal 09/05/2019

Conclusions on shower development Given a minimum energy threshold of 1-1.5 MeV all the crystals except the inner 9 have an average signal below or near the threshold. There is no need to use a cluster including 25 crystals In general we may expect worst resolution in data wrt 9 crystals For energies below 50 MeV is most probably better to use the seed crystal only. The calorimeter performance may benefit more from a lower thr (higer gain) wrt to extended linearity range. M. Raggi PADME Ecal 09/05/2019