Estimation of Radiation Effects in the Front-End Electronics of an ILC

Electromagnetic Calorimeter

V. Bartsch, M. Postranecky, M. Warren, M. Wing

University College London

very frontend electronics (VFE) based on ASICs

frontend electronics (FE) based on FPGAs,1 FPGA/slab

HCAL

ECAL, 30 slabs stacked on top each other, in z direction 25 slabs next to each other extends to |eta|=1.1

magnet

Geometry

Single Event Upsets (SEUs)

sensitive volume(can be guessed by irradiating with different ions with a different linear energy transfer, plus guessing the dephts of the device => Weibull fit which gives the cross sectional area of the sensitive region per node)

critical energy( depend on angle and entry point of the incident particle and its energy at each point

of the volume)

look for particles which deposit much charge in small area p, , n

Physics processes

Process no of events / hour

generated events

QCD (7-9)x106 1987

events

(machine background)

4.1x107 2301

• other physics processes like ttbar, WW and Bhabhar scattering also studied but small in terms of SEUs• pair production as another machine background studied but focussed on the very forward region

Event generation

Process Event generator

QCD PYTHIA

gg events

(machine background)

• GUINEAPIG to generate • PYTHIA as a collider with a variable energy

• device simulation in both cases done with MOKKA using the TESLA geometry model

energy spectrum at the FPGAs

• only n, p, deposit enough energy for SEUs• not every event causes a SEU

some FPGAs’ SEU cross sections

D. Gingrich et al., IEEE Transactions on Nuclear Science, Vol. 50, No. 2, 2003

type of FPGA SEU SEUs in ECAL/h

Virtex II X-2V100 8x10-9 0.55

Altera Stratix 10-7 4.20

Xilinx XC4036XLA 3x10-9 0.09

• cross sections for SEU to occur vary for each FPGA• values can be found in literature• SEU rate in ECAL FPGAs small, but needs to be considered in choice of FPGA

additional studies

• studies are based on the generated MC samples for the SEU study, for the further studies all generated particles have been used• occupancy for the barrel ECAL: 0.002

needs to be considered in the DAQ for the ECAL combined with occupancy resulting from noise

• ECAL radiation damage studies: • expected fluence: 2x106 (1 MeV n eq.)/(cm2*year)• expected radiation: 0.13 Rad/year fluence and radiation dose small enough not to cause damage to the FPGAs

conclusion

• machine background and QCD physics background main contributor to protons, pions and neutrons crossing the ECAL

• Single Event Upset rate small for the ECAL FPGAs at the Linear Collider

• needs to be considered though for the final choice of the FPGA type