1. Silicon Tracker Digitization in MARLIN/DigiSim Framework (status)
S. Shulga
LPP JINR, Dubna, Russia
Francisk Skarina Gomel State University, Belarus
ILC Summer Software Mini Workshop
June 27/28, 2005

2. Contents Introductory words: why I use DigiSim
My proposition: directory tree in DigiSim
BRAHMS lcio-events as input
Processors for analysis
Fixed/free parameters for tracker digitization
Hit multimap processor
Detector geometry parameters in user steering file
Processor for digitization
Si Pixel/Strip geometry parameters in user steering file
Si Tracker digitization in “Zero” approximation
Plans

3. Introductory words: LCIO is a manager of collection and events
SimCalorimeterHit
RawCalorimeterHit
CalorimeterHit
SimTrackerHit
TrackerRawData
TrackerPulse
TrackerData
TrackerHit …
Event = set of collections is main object of LCIO. LCIO has a list of predefined types of collection: common stages of processing and subdetectors.
ecal
hcal
tpc
vxd
sit
ftd
fch
List of collections is created in run-time with unique name defined by user.
LCIO, as a manager, can create
event ~ map[name collection]

4. Introductory words: MARLIN is a manager of processors
Processor of event is main object of MARLIN. MARLIN creates a list of types of processors.
LCIOOutputProcessor
AIDAProcessor
CalDigiSimProcessor
TraDigiSimProcessor
CalHitMapProcessor
TraHitMapProcessor
ProcessorROOTTree
ProcessorROOTGeom
OutputProcessor
CalHitMapProcessor
EMDigiSimProcessor
HADDigiSimProcessor
TraHitMapProcessor
vxdDigiSimProcessor
sitDigiSimProcessor
List of processors is
created in run-time with unique name
defined by user.
MARLIN, as a manager, creates map of processors
map[name processor]

5. Introductory words: DigiSim is a manager of hit modifiers
Hit modifier is a main object of DigiSim (G.Lima, Sim.Mini Workshop Dec, 2004) DigiSim creates a list of dedicated types of modifiers collection and common physics digi-processes.
SmearedLinear
GainDiscrimination
CrossTalkModifier FunctionModifier TraSmearedLinear
TraFunctionModifier
List of modifiers is created in run-time with unique name
defined by user.
HADFixedGain
HADThreshOnly
HADGaussianGain
HADDigiIdentity
EMFixedGain
EMThreshOnly
EMGaussianGain
EMDigiIdentity
TraDigiIdentity
DigiSim, as a manager,
creates a map of modifiers
map[name processor]

6. My first step: complicated directory tree in DigiSim
My first step: complicated directory tree in DigiSim. Aim: convenience of developer in case of number of files will be significantly increased
ana – source codes for analysis processors * ProcessorROOTTree * ProcessorROOTGeom bin – object and executable files doc – documentation include – header files (for external usage) lib – library of package (for external usage) mak – command files, input/output/steer files src – source codes for digitization processors * Calorimeter * Globals * Tracker

7. Branches of directory tree in DigiSim (Calorimeter, G.Lima)
* Calorimeter – CalHitMapProcessor + CalHitMapMgr – CalDigiSimProcessor + CalHitModifier ~TempCalHit ~GainDiscrimination ~SmearedLinear ~FunctionModifier ~CrossTalkModifier * Globals * Tracker

8. Branches of directory tree in DigiSim (Tracker, current status)
* Tracker – TraHitMapProcessor + TraHitMapMgr ~TraDetectorGEOM – TraDigiSimProcessor + TraHitModifier ~TempTraHit ~TraSmearedLinear ~TraFunctionModifier

9. Brahms LCIO-events as input
New conditions to study detector with BRAHMS: – Separation of “simulation” and “reconstruction” – lcio-output in Brahms. Collection names of Brahms lcio-events : ecal, hcal, tpc, vxd, sit, ftd, fch, and subdetector names ECAL, HCAL, TPC, VXD, SIT, FTD, FCH

10. DigiSim: detector geometry
Detector geometry and Brahms event (sim.hits) obtained by DigiSim/ana/ProcessorROOTGeom
VXD
DigiSim: detector geometry
TPC
FCH
FCH
FTD
SIT

11. The same event in 3d-view (ROOT interactive 3d-graphycs)

12. My second step: including processors for analysis in DigiSim: ProcessorROOTTree and ProcessorROOTGeom
To create the pictures, shown above, it is necessary to do two steps: – switch on (make active) ProcessorROOTTree and then run job to create Root Tree; – switch on ProcessorROOTGeom and run job to pass to interactive Root session with picture, created by using Root Tree.
Graphics part of “DigiSim/ana” codes uses ROOT classes: TShape, TSPHE, TTUBE, TNode

13. Si Tracker and Si FCH in DigiSim: fixed/free parameters
Fixed parameters number of subdetectors (4) and types of subdetectors – VXD (cylinder), SIT (cylinder), FTD (plane), FCH (plane) Free parameters (set in user steer.file) – names of subdetectors, layers, collections – number of layers – Si layer technology – pixels, strips – pixel/strip geometry parameters – layer geometry parameters

14. My third step: Hit map processor
Purposes:
* to create convenient input for next (digi) processor
* to read detector geometry information
*Calorimeter: processor CalHitMapProcessor creates hit map [cellID, hit] (G.Lima, LC Simulation Mini Workshop, Dec 2004)
* Si Tracker : processor TraHitMapProcessor creates hit multimap [layer_name, hits] Layer names: VXD1,…, SIT1,…, FTD1,…,FCH1,… .

15. Detector Geometry in user steering file – - parameters of TraHitMapProcessor
.begin TraHitMapProcessor # name of processor
ProcessorType TraHitMapProcessor # type of processor
# Par Detector NSubDets SubDet names …
DETECTOR TESLA VXD SIT FTD FCH
# Par SubDet Collection NLayers Layer names …
VXD VXD vxd VXD1 VXD2 VXD3 VXD4 VXD5
SIT SIT sit SIT1 SIT2
FTD FTD ftd FTD1 FTD2 FTD3 FTD4 FTD5 FTD6 FTD7 … FTD14
FCH FCH fch FCH1 FCH2 FCH3 FCH4 FCH5 FCH6 … FCH10
# Par Name Layer parameters [cm] …
VXD1 VXD
VXD2 VXD
SIT SIT
SIT SIT
FTD1 FTD
FTD2 FTD …
FTD7 FTD
FCHX FCHX
.end

16. TraHitMapMgr: additional functions
to check of initial events : every hit must be in one of the layers !
to create hit multimap and detector geometry member in global scope to be used in the following steps

17. My fourth step: DigiSim processor for digitization
Purpose:
transformation sim. hits to readout signals
Calorimeter: processor CalDigiSimProcessor (G.Lima, LC Simulation Mini Workshop, Dec 2004)
Si Tracker : processor TraDigiSimProcessor

18. Si pixel geometry in user steering file - - parameters of TraDigiSimProcessor
.begin sitDigSimProcessor
# Par Type of processor
ProcessorType TraDigiSimProcessor
# Par Collection SubDet
InputCollection sit SIT
OutputCollection sitraw
Raw2SimLinksCollection sitraw2sim
# Par for coding/decoding hit pixels
# Coding rule: cellID0=A1* Readout + column, cellID1=A2*K + row, K=A3*NSubDet + Layer
# Par collection Subdet NSubDet A A A3
PixelCodParameters sit SIT
PixRowColumnInReadout
# Par Pixel size [micrometer]
PixelRowColumnSize
# Par Modifier names …
ModifierNames TraDigiIdentity1 TraDigiIdentity2
# Par=Modifier name Modifier type Modifier parameters (floats)
TraDigiIdentity TraSmearedLinear
TraDigiIdentity TraSmearedLinear
.end

19. Digitization in “Zero” approximation (Si Pixel)
Temporary hit map [cellID hit]
represents digitization in “0” approximation
cellID = pair[cellID0, cellID1]
cellID0 = A1* Readout + column
cellID1 = A2*K row
K = A3*SubDet + layer
A1, A2, A3 – coding parameters
LCIO v01-05, collection:
class TrackerRawDataImpl{ …
int _cellID0;
int _cellID1;
int _channelID;
ShortVect _adc; }

20. Full list of the digitization physics processes (Si pixel) to be done
Landau fluctuations in thin material layers
Drift of charge
Diffusion of charge
Lorenz drift in magnetic field
Noise in hit pixel and noise pixels
Inefficiencies
Readout threshold

21. Plans Tracker digitization in “0-approximation” will be ready soon;
Simple digitization physics effects will be added;
First step of reconstruction - clustering;
Study dependences:
resolution parameters vs.
- subdetector geometry,
- Si pixel/strip size and shape,
- readout inefficiency, occupancy, trigger rate
Using MOKKA lcio-events as input;
Using common geometry access.
More realistic digitization physics processes;

22. BACKUP

23. Branches of directory tree in DigiSim (detailed)
“make_release” : gmake –directory=../bin – makefile=../mak/GNUMakefile creates obj-files and exe-file in separated “bin” directory using GNUMakefile placed in “mak”
“run” : ../bin/DigiSim.exe digi.steer placed in “mak” directory and runs exe-file from “bin” directory, using in/out and steer files placed in “mak”
“GNUMakefile” contain full directory tree for compilation relative to directory “../bin”

24. TraHitMapProcessor and TraHitMapMgr (more detailed)
Constructor TraHitMapProcessor reads user steer.info and creates _mgr which is a “singleton” (static element) of class TraHitMapMgr.
TraHitMapProcessor::Init() * transforms user information * send it to _mgr which ~ creates and fills Detector Geometry member _DG
TraHitMapProcessor::processEvent( event ): * set event to _mgr * creates multimap [layer_name, hits] using geometry information and hit position

25. TraDigiSimProcessor (more detailed)
Constructor TraDigiSimProcessor reads user steer.info * names of input/output/relation LCIO-collections * Si pixel/strip user information (next slide)
TraDigiSimProcessor::Init() * transforms user pixel information in a convenient form * fills pixel/strip geometry, using TraHitMapMgr * creates a map of hit modifiers
TraDigiSimProcessor::processEvent( event )

26. TraDigiSimProcessor::processEvent( event )
Creates reference to the global scope hit multimap [layer_name hits]
Creates pixel/strip/sublayer/redout geometrical map in global (static) detector geometry member TraHitMapMgr::DG
Creates temporary hit map [cellID hit]
Call processHits method for each modifier from map of modifiers
to transform input temp. hit map output temp. hit map
Creates output collection and add it to the event