Update on simulation and sensor procurement Mathieu Benoit

Introduction The AllPix framework, the Timepix digitizer and its integration in ILCSoft Summary of SmallPix disscusion Counter depth influence on tracking resolution, using Allpix TCAD simulation with Magnetic field

The Allpix framework A generic pixel detector simulation framework Based on GEANT4 Usable without (or a little) knowledge of C++ Input Pixel Geometry Pitch # of pixel GR area Digitizer parameters Test Structure Support structure Human body Cabling etc Simulation scenario Nature of the particles Geometric distribution Energy distribution Number of trials AllPix World construction Sensitive volume Appliance Scoring Radiation transport EM and Nuclear interaction Low EM interaction Generate Edep in sensitive volumes Digitization Transform energy depositiion in signal and digital data following a user provided model Output MC Truth information Frames Scoring results

The Timepix digitizer The Allpix framework contains a generic Timepix-style digitizer that aims at reproducing the behavior – Based on drift-diffusion model – Radiation damage Effect can be included – Accept any E Field as an input – Velocity saturation effects included

The AllPix Timepix digitizer The Allpix framework contains a generic Timepix-style digitizer that aims at reproducing the behavior – Based on drift-diffusion model – Radiation damage Effect can be included – Velocity saturation effects included Full Electric Field Simulation – E field fed to digitizer in f(x,y,z) form – 5th order variable timestep integration of trajectories + Hecht equation for multiple traps Accurate but fast – Ramo Potential calculation of CCE (TH2D form, as Electric Field) or ballistic model – Tilted angles Separation of tracks in multiple charge elements – Thin vs Thick effects taken into account using this method M.I.P Pixel

Front-End Simulation The pulse shape is determined by a set of parameters that mimics a timepix chip time Amplitude Threshold Gain (V/Q) Rise Time (ns/Q) Fall Time (ns/V) Clock

Front-End Simulation Each parameter can be assigned to each pixel differently – Following an input file – Following gaussian dispersion using user provided parameters – Pixel can also be masked – Counter Depth can be modified – A saturation Energy for Gain can also be provided What Parameter should be used there (to be quantitative ) ? – Dependence of Rise Time on E ? – Dependence of Gain on E (Saturation, non-monotonic behavior ?) – Dispertion on values ? How can we match realistically these parameters to DAC values?

The MAFALDA analysis tool Input (Allpix, pixelman output) MC Truth information Frames Scoring results Clustering residuals Converter Long Track analysis Beam dispersion analysis User algorithm Output User plots Residuals TOT distribution Charge sharing etc EUDET Telescope format data LHCb Telescope format data Output User plots Residuals TOT distribution Charge sharing etc EUDET Telescope format data LHCb Telescope format data Mafalda MAFALDA is used to process in an intelligible way the output of AllPix, Clustering and Conversion to various format included in the software. Each user can easily write his analysis or aconverter to his desired format. MAFALDA also support data from pixelman

Integrating AllPix and Mafalda in ILCSoft ILCSoft pixel digitizer are in java/C++ – Energy deposition from GEANT not used, internal distribution used. – We can use the internal energy deposition process and useTimepix Digitizer algorithm to generate cluster in ILCSoft data flow Timepix digitizer is written following the Digitizer abstraction provided by GEANT4 – Possible to simply wrap this code in another object that make translation between two format AllPix + Mafalda are used by many other group also contribution to the code – Official GEANT4 simulation for EUDET telescope – Used by LHCb telescope team to train their reconstruction – Mid-Sweden University are planning to use it for imagery – Used by NASA for medipix-based Dosimetry – Used in ATLAS (LAL-Orsay) for testbeam analysis – Used in CEA for micromega analysis – We should avoid linking it to other ILC/CLIC specific code to keep a large user (and debugger) base – Could be installed as a denpendencie (As is ROOT, GEANT4 CLHEP etc...)

Allpix and TB activities I wrote a converter that produce frames in LHCb telescope format – LHCb now using the produced data to tune their reconstruction algorithm The simulation use the Timepix Digitizer – Daniel Hynds sent me data taken with the telescope in various angles, we will use these to start tuning free parameters of the digitizer with 300um thickess – Calibrated data for 150um sensor also on the way

Smallpix disscusion Smallpix Disscussion revolved around the choice of pixel size vs couter depth – The chip will work in ToA + TOT mode – Rafa made estimate that fix possible pixel size (in 130nm) From 31 -> 38um ~+1um per 2 bits of ToT +ToA The medipix community seems to favor a 16bit TOT 16 bit ToA option with 40um pixels, 512x512 matrix

Smallpix disscusion Our point of view – Time of Arrival : 312 BX over 156 ns Clock assumed at 100MHz -> 10ns bins We only need 16 bins (eventually 32) of ToA -> 4-5bits of ToA – Time over Threshold Smaller pixel means larger clusters -> We can use ToT to increase resolution but … Preamplifier must be adapted to our forseen dynamic range -> Energy deposition 5-50 keV ( e) Large ToT counter are only useful if we use the full counter depth We would like the chip to stop « detecting » when Train is finished (10ns per clock cycle) ToT DepthMax « detection» time 4160ns us us

Smallpix disscusion Even without simulation, it is clear we aim at ToA=4-5bits and ToT <=8 bits – But that kind of chip is useless for medipix community I am preparing a study to be presented next smallpix meeting with an allpix simulation of the smallpix possible geometry and TOT counter depth – Pixel pitch um – ToT of 4, 8, 16 bits

Smallpix disscusion (20 um pixel low gain)

Smallpix disscusion (40 um pixel low gain)

Smallpix disscusion (20um pixel High gain)

Smallpix disscusion (40um pixel High gain)

Smallpix disscusion It seems deep TOT counter is not so beneficial to resolution for smaller pixels, but is for larger ones (40 um +) Eta Correction could change much to the results I am implementing an Eta Correction algorithm in Mafalda, result for Smallpix meeting will include Eta corrected residuals

Lorentz angle Lorentz angle depends on mobility which depends on Electric field and eventually on dopant concentration In a 50um 10kOhmcm p-type wafer, 10V bias, E≈[1600,2700]V/cm – Vary with resistivity, bias voltage In a planar sensor, E is proportional to V applied – V applied is proportional to thickness 2 (Full depletion voltage) – For thin sensor, at full depletion voltage, Electric field is very low – To be investigated : How much over Full depletion can we apply voltage 15/03/12 mini workshop on engineering aspects of the CLIC vertex detectors 19

Lorentz angle It is a usual practice in vertex design to tilt modules with regard to the particle direction to account for Lorentz angle and minimize cluster size B= 5T Holes Electrons Drift E Reco hit 15/03/12 mini workshop on engineering aspects of the CLIC vertex detectors 20

Lorentz angle B= 5T Holes Electrons Drift E Reco hit 15/03/12 mini workshop on engineering aspects of the CLIC vertex detectors 21

Lorentz angle 10V 80V (?) 15/03/12 mini workshop on engineering aspects of the CLIC vertex detectors 22

Lorentz angle 10V 80V (?) 15/03/12 mini workshop on engineering aspects of the CLIC vertex detectors 23

TCAD simulation : B Field Animation (sanity check)

TCAD simulation : B Field

Conclusion AllPix can be integrated as a stand-alone dependency to ILCSoft – A wrapper for ILD and SiD digitizer can be made to bring AllPix digitizer to the simulation software (as as been done in ATLAS ) – Keeping the product stand-alone favorize use by other institute Good pool of debuggers, developpers Some preliminary simulation on ToT counter depth influence on resolution have been performed – Need to implement Eta correction – Need input from electronician on possible digitization parameters B Field Transient in TCAD is possible, an example has been show – Next step is to produce pulses for various angles and Bias voltage and evaluate B field influence on Cluster Size in n-in-p, p-in-n sensors – This should be used for adding this effect to timepix digitizer

AllPix SVN : – SSH Adresssvn+ssh://svn.cern.ch/reps/allpixsvn.cern.ch/reps/allpix – HTTPS Adresshttps://svn.cern.ch/reps/allpixhttps://svn.cern.ch/reps/allpix – Public Adresshttp://svnweb.cern.ch/guest/allpixhttp://svnweb.cern.ch/guest/allpix Twiki – Need to ask authors for commiting rights : – –

Mafalda Svn : – – (should move to CERN soon) Twiki : – ationEUDET ationEUDET – (should move to CERN soon, change name)