1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
10 * copies and that both the copyright notice and this permission notice *
11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
21 #include <TObjArray.h>
22 #include <TParticle.h>
27 #include "AliITSmodule.h"
28 #include "AliITSMapA2.h"
29 #include "AliITSpList.h"
30 #include "AliITSresponseSSD.h"
31 #include "AliITSsegmentationSSD.h"
32 #include "AliITSdcsSSD.h"
34 #include "AliITShit.h"
36 #include "AliITSgeom.h"
37 #include "AliITSsimulationSSD.h"
38 #include "AliITSTableSSD.h"
40 ClassImp(AliITSsimulationSSD);
41 ////////////////////////////////////////////////////////////////////////
43 // Written by Enrico Fragiacomo
46 // AliITSsimulationSSD is the simulation of SSDs.
48 //----------------------------------------------------------------------
49 AliITSsimulationSSD::AliITSsimulationSSD(){
53 fDifConst[0] = fDifConst[1] = 0.0;
54 fDriftVel[0] = fDriftVel[1] = 0.0;
58 //----------------------------------------------------------------------
59 AliITSsimulationSSD::AliITSsimulationSSD(AliITSsegmentation *seg,
60 AliITSresponse *resp){
63 // AliITSsegmentationSSD *seg Pointer to the SSD segmentation to be used
64 // AliITSresponseSSD *resp Pointer to the SSD responce class to be used
71 fDifConst[0] = fDifConst[1] = 0.0;
72 fDriftVel[0] = fDriftVel[1] = 0.0;
75 Init((AliITSsegmentationSSD*)seg,(AliITSresponseSSD*)resp);
77 //----------------------------------------------------------------------
78 void AliITSsimulationSSD::Init(AliITSsegmentationSSD *seg,
79 AliITSresponseSSD *resp){
80 // Inilizer, Inilizes all of the variable as needed in a standard place.
82 // AliITSsegmentationSSD *seg Pointer to the SSD segmentation to be used
83 // AliITSresponseSSD *resp Pointer to the SSD responce class to be used
91 Float_t noise[2] = {0.,0.};
92 fResponse->GetNoiseParam(noise[0],noise[1]); // retrieves noise parameters
93 fDCS = new AliITSdcsSSD(seg,resp);
95 SetDriftVelocity(); // use default values in .h file
96 SetIonizeE(); // use default values in .h file
97 SetDiffConst(); // use default values in .h file
98 fpList = new AliITSpList(2,GetNStrips());
99 fMapA2 = new AliITSMapA2(fSegmentation);
101 //______________________________________________________________________
102 AliITSsimulationSSD& AliITSsimulationSSD::operator=(
103 const AliITSsimulationSSD &s){
106 if(this==&s) return *this;
108 this->fDCS = new AliITSdcsSSD(*(s.fDCS));
109 this->fMapA2 = s.fMapA2;
110 this->fIonE = s.fIonE;
111 this->fDifConst[0] = s.fDifConst[0];
112 this->fDifConst[1] = s.fDifConst[1];
113 this->fDriftVel[0] = s.fDriftVel[0];
114 this->fDriftVel[1] = s.fDriftVel[1];
117 //______________________________________________________________________
118 AliITSsimulationSSD::AliITSsimulationSSD(const AliITSsimulationSSD &source){
123 //______________________________________________________________________
124 AliITSsimulationSSD::~AliITSsimulationSSD() {
129 //______________________________________________________________________
130 void AliITSsimulationSSD::InitSimulationModule(Int_t module,Int_t event){
131 // Creates maps to build the list of tracks for each sumable digit
133 // Int_t module // Module number to be simulated
134 // Int_t event // Event number to be simulated
145 //______________________________________________________________________
146 void AliITSsimulationSSD::FinishSDigitiseModule(){
147 // Does the Sdigits to Digits work
155 FillMapFrompList(fpList); // need to check if needed here or not????
156 SDigitToDigit(fModule,fpList);
160 //______________________________________________________________________
161 void AliITSsimulationSSD::DigitiseModule(AliITSmodule *mod,
162 Int_t dummy0,Int_t dummy1) {
163 // Digitizes hits for one SSD module
164 Int_t module = mod->GetIndex();
166 HitsToAnalogDigits(mod,fpList);
167 SDigitToDigit(module,fpList);
172 //______________________________________________________________________
173 void AliITSsimulationSSD::SDigitiseModule(AliITSmodule *mod,Int_t dummy0,
175 // Produces Summable/Analog digits and writes them to the SDigit tree.
177 HitsToAnalogDigits(mod,fpList);
179 WriteSDigits(fpList);
184 //______________________________________________________________________
185 void AliITSsimulationSSD::SDigitToDigit(Int_t module,AliITSpList *pList){
186 // Takes the pList and finishes the digitization.
188 // FillMapFrompList(pList); //commented out to avoid double counting of the
191 ApplyNoise(pList,module);
192 ApplyCoupling(pList,module);
194 ChargeToSignal(pList);
196 //______________________________________________________________________
197 void AliITSsimulationSSD::HitsToAnalogDigits(AliITSmodule *mod,
199 // Loops over all hits to produce Analog/floating point digits. This
200 // is also the first task in producing standard digits.
201 Int_t lasttrack = -2;
203 Double_t x0=0.0, y0=0.0, z0=0.0;
204 Double_t x1=0.0, y1=0.0, z1=0.0;
206 Int_t module = mod->GetIndex();
208 TObjArray *hits = mod->GetHits();
209 Int_t nhits = hits->GetEntriesFast();
210 if (nhits<=0) return;
211 AliITSTableSSD * tav = new AliITSTableSSD(GetNStrips());
212 module = mod->GetIndex();
213 if ( mod->GetLayer() == 6 ) GetSegmentation()->SetLayer(6);
214 if ( mod->GetLayer() == 5 ) GetSegmentation()->SetLayer(5);
215 for(Int_t i=0; i<nhits; i++) {
216 // LineSegmentL returns 0 if the hit is entering
217 // If hits is exiting returns positions of entering and exiting hits
218 // Returns also energy loss
220 // cout << mod->GetHit(i)->GetXL() << " "<<mod->GetHit(i)->GetYL();
221 // cout << " " << mod->GetHit(i)->GetZL();
223 if (mod->LineSegmentL(i, x0, x1, y0, y1, z0, z1, de, idtrack)) {
224 HitToDigit(module, x0, y0, z0, x1, y1, z1, de,tav);
225 if (lasttrack != idtrack || i==(nhits-1)) {
226 GetList(idtrack,i,module,pList,tav);
230 } // end loop over hits
234 //----------------------------------------------------------------------
235 void AliITSsimulationSSD::HitToDigit(Int_t module, Double_t x0, Double_t y0,
236 Double_t z0, Double_t x1, Double_t y1,
237 Double_t z1, Double_t de,
238 AliITSTableSSD *tav) {
239 // Turns hits in SSD module into one or more digits.
240 Float_t tang[2] = {0.0,0.0};
241 GetSegmentation()->Angles(tang[0], tang[1]);//stereo<<->tan(stereo)~=stereo
243 Double_t dex=0.0, dey=0.0, dez=0.0;
244 Double_t pairs; // pair generation energy per step.
245 Double_t sigma[2] = {0.,0.};// standard deviation of the diffusion gaussian
246 Double_t tdrift[2] = {0.,0.}; // time of drift
248 Double_t inf[2], sup[2], par0[2];
250 // Steps in the module are determined "manually" (i.e. No Geant)
251 // NumOfSteps divide path between entering and exiting hits in steps
252 Int_t numOfSteps = NumOfSteps(x1, y1, z1, dex, dey, dez);
253 // Enery loss is equally distributed among steps
255 pairs = de/GetIonizeE(); // e-h pairs generated
256 for(Int_t j=0; j<numOfSteps; j++) { // stepping
257 x = x0 + (j+0.5)*dex;
258 y = y0 + (j+0.5)*dey;
259 if ( y > (GetSegmentation()->Dy()/2+10)*1.0E-4 ) {
260 // check if particle is within the detector
261 Warning("HitToDigit","hit out of detector y0=%e,y=%e,dey=%e,j =%e",
265 z = z0 + (j+0.5)*dez;
266 // cout <<"HitToDigit "<<x<<" "<<y<<" "<<z<< " "<<dex<<" "<<dey<<" "<<dez<<endl;
267 // calculate drift time
268 // y is the minimum path
269 tdrift[0] = (y+(GetSegmentation()->Dy()*1.0E-4)/2)/GetDriftVelocity(0);
270 tdrift[1] = ((GetSegmentation()->Dy()*1.0E-4)/2-y)/GetDriftVelocity(1);
272 for(Int_t k=0; k<2; k++) { // both sides remember: 0=Pside 1=Nside
274 tang[k]=TMath::Tan(tang[k]);
276 // w is the coord. perpendicular to the strips
278 w = (x+(GetSegmentation()->Dx()*1.0E-4)/2) -
279 (z+(GetSegmentation()->Dz()*1.0E-4)/2)*tang[k];
281 w = (x+(GetSegmentation()->Dx()*1.0E-4)/2) +
282 (z-(GetSegmentation()->Dz()*1.0E-4)/2)*tang[k];
284 w /= (GetStripPitch()*1.0E-4); // w is converted in units of pitch
286 if((w<(-0.5)) || (w>(GetNStrips()-0.5))) {
287 // this check rejects hits in regions not covered by strips
288 // 0.5 takes into account boundaries
289 return; // There are dead region on the SSD sensitive volume.
292 // sigma is the standard deviation of the diffusion gaussian
293 if(tdrift[k]<0) return;
294 sigma[k] = TMath::Sqrt(2*GetDiffConst(k)*tdrift[k]);
295 sigma[k] /= (GetStripPitch()*1.0E-4); //units of Pitch
297 Error("HitToDigit"," sigma[%d]=0",k);
302 // we integrate the diffusion gaussian from -3sigma to 3sigma
303 inf[k] = w - 3*sigma[k]; // 3 sigma from the gaussian average
304 sup[k] = w + 3*sigma[k]; // 3 sigma from the gaussian average
305 // IntegrateGaussian does the actual
306 // integration of diffusion gaussian
307 IntegrateGaussian(k, par0[k], w, sigma[k], inf[k], sup[k],tav);
308 } // end for loop over side (0=Pside, 1=Nside)
311 //______________________________________________________________________
312 void AliITSsimulationSSD::ApplyNoise(AliITSpList *pList,Int_t module){
315 Double_t signal,noise;
316 Double_t noiseP[2] = {0.,0.};
319 fResponse->GetNoiseParam(a,b); // retrieves noise parameters
320 noiseP[0] = (Double_t) a; noiseP[1] = (Double_t) b;
321 for(k=0;k<2;k++){ // both sides (0=Pside, 1=Nside)
322 for(ix=0;ix<GetNStrips();ix++){ // loop over strips
323 noise = gRandom->Gaus(0,noiseP[k]);// get noise to signal
324 signal = noise + fMapA2->GetSignal(k,ix);//get signal from map
325 if(signal<0.) signal=0.0; // in case noise is negative...
326 fMapA2->SetHit(k,ix,signal); // give back signal to map
327 if(signal>0.0) pList->AddNoise(k,ix,module,noise);
329 } // loop over k (P or N side)
331 //______________________________________________________________________
332 void AliITSsimulationSSD::ApplyCoupling(AliITSpList *pList,Int_t module) {
333 // Apply the effect of electronic coupling between channels
335 Double_t signalLeft=0, signalRight=0,signal=0;
337 for(ix=0;ix<GetNStrips();ix++){
339 if(ix>0.)signalLeft = fMapA2->GetSignal(0,ix-1)*fDCS->GetCouplingPL();
340 else signalLeft = 0.0;
341 if(ix<(GetNStrips()-1)) signalRight = fMapA2->GetSignal(0,ix+1)*
342 fDCS->GetCouplingPR();
343 else signalRight = 0.0;
344 signal = signalLeft + signalRight;
345 fMapA2->AddSignal(0,ix,signal);
346 if(signal>0.0) pList->AddNoise(0,ix,module,signal);
348 signalLeft = signalRight = signal = 0.0;
350 if(ix>0.) signalLeft = fMapA2->GetSignal(1,ix-1)*fDCS->GetCouplingNL();
351 else signalLeft = 0.0;
352 if(ix<(GetNStrips()-1)) signalRight = fMapA2->GetSignal(1,ix+1)*
353 fDCS->GetCouplingNR();
354 else signalRight = 0.0;
355 signal = signalLeft + signalRight;
356 fMapA2->AddSignal(1,ix,signal);
357 if(signal>0.0) pList->AddNoise(1,ix,module,signal);
358 } // loop over strips
360 //______________________________________________________________________
361 Float_t AliITSsimulationSSD::F(Float_t av, Float_t x, Float_t s) {
362 // Computes the integral of a gaussian using Error Function
363 Float_t sqrt2 = TMath::Sqrt(2.0);
364 Float_t sigm2 = sqrt2*s;
367 integral = 0.5 * TMath::Erf( (x - av) / sigm2);
370 //______________________________________________________________________
371 void AliITSsimulationSSD::IntegrateGaussian(Int_t k,Double_t par, Double_t w,
373 Double_t inf, Double_t sup,
374 AliITSTableSSD *tav) {
375 // integrate the diffusion gaussian
376 // remind: inf and sup are w-3sigma and w+3sigma
377 // we could define them here instead of passing them
378 // this way we are free to introduce asimmetry
380 Double_t a=0.0, b=0.0;
381 Double_t dXCharge1 = 0.0, dXCharge2 = 0.0;
382 // dXCharge1 and 2 are the charge to two neighbouring strips
383 // Watch that we only involve at least two strips
384 // Numbers greater than 2 of strips in a cluster depend on
385 // geometry of the track and delta rays, not charge diffusion!
387 Double_t strip = TMath::Floor(w); // closest strip on the left
389 if ( TMath::Abs((strip - w)) < 0.5) {
390 // gaussian mean is closer to strip on the left
391 a = inf; // integration starting point
392 if((strip+0.5)<=sup) {
393 // this means that the tail of the gaussian goes beyond
394 // the middle point between strips ---> part of the signal
395 // is given to the strip on the right
396 b = strip + 0.5; // integration stopping point
397 dXCharge1 = F( w, b, sigma) - F(w, a, sigma);
398 dXCharge2 = F( w, sup, sigma) - F(w ,b, sigma);
400 // this means that all the charge is given to the strip on the left
402 dXCharge1 = 0.9973; // gaussian integral at 3 sigmas
405 dXCharge1 = par * dXCharge1;// normalize by mean of number of carriers
406 dXCharge2 = par * dXCharge2;
408 // for the time being, signal is the charge
409 // in ChargeToSignal signal is converted in ADC channel
410 fMapA2->AddSignal(k,(Int_t)strip,dXCharge1);
411 tav->Add(k,(Int_t)strip);
412 if(((Int_t) strip) < (GetNStrips()-1)) {
413 // strip doesn't have to be the last (remind: last=GetNStrips()-1)
414 // otherwise part of the charge is lost
415 fMapA2->AddSignal(k,((Int_t)strip+1),dXCharge2);
416 tav->Add(k,((Int_t)(strip+1)));
419 // gaussian mean is closer to strip on the right
420 strip++; // move to strip on the rigth
421 b = sup; // now you know where to stop integrating
422 if((strip-0.5)>=inf) {
423 // tail of diffusion gaussian on the left goes left of
424 // middle point between strips
425 a = strip - 0.5; // integration starting point
426 dXCharge1 = F(w, b, sigma) - F(w, a, sigma);
427 dXCharge2 = F(w, a, sigma) - F(w, inf, sigma);
430 dXCharge1 = 0.9973; // gaussian integral at 3 sigmas
433 dXCharge1 = par * dXCharge1; // normalize by means of carriers
434 dXCharge2 = par * dXCharge2;
435 // for the time being, signal is the charge
436 // in ChargeToSignal signal is converted in ADC channel
437 fMapA2->AddSignal(k,(Int_t)strip,dXCharge1);
438 tav->Add(k,(Int_t)strip);
439 if(((Int_t) strip) > 0) {
440 // strip doesn't have to be the first
441 // otherwise part of the charge is lost
442 fMapA2->AddSignal(k,((Int_t)strip-1),dXCharge2);
443 tav->Add(k,((Int_t)(strip-1)));
447 //______________________________________________________________________
448 Int_t AliITSsimulationSSD::NumOfSteps(Double_t x, Double_t y, Double_t z,
449 Double_t & dex,Double_t & dey,Double_t & dez){
451 // it also returns steps for each coord
452 //AliITSsegmentationSSD *seg = new AliITSsegmentationSSD();
454 Double_t step = 25E-4;
455 //step = (Double_t) seg->GetStepSize(); // step size (cm)
456 Int_t numOfSteps = (Int_t) (TMath::Sqrt(x*x+y*y+z*z)/step);
458 if (numOfSteps < 1) numOfSteps = 1; // one step, at least
460 // we could condition the stepping depending on the incident angle
468 //----------------------------------------------------------------------
469 void AliITSsimulationSSD::GetList(Int_t label,Int_t hit,Int_t mod,
470 AliITSpList *pList,AliITSTableSSD *tav) {
471 // loop over nonzero digits
475 for(Int_t k=0; k<2; k++) {
478 signal = fMapA2->GetSignal(k,ix);
482 } // end if signal==0.0
483 // check the signal magnitude
484 for(i=0;i<pList->GetNSignals(k,ix);i++){
485 signal -= pList->GetTSignal(k,ix,i);
487 // compare the new signal with already existing list
488 if(signal>0)pList->AddSignal(k,ix,label,hit,mod,signal);
490 } // end of loop on strips
491 } // end of loop on P/N side
494 //----------------------------------------------------------------------
495 void AliITSsimulationSSD::ChargeToSignal(AliITSpList *pList) {
497 static AliITS *aliITS = (AliITS*)gAlice->GetModule("ITS");
498 Float_t threshold = 0.;
499 Int_t digits[3], tracks[3],hits[3],j1;
500 Float_t charges[3] = {0.0,0.0,0.0};
502 Float_t noise[2] = {0.,0.};
504 ((AliITSresponseSSD*)fResponse)->GetNoiseParam(noise[0],noise[1]);
506 for(Int_t k=0;k<2;k++){ // both sides (0=Pside, 1=Nside)
507 // Threshold for zero-suppression
508 // It can be defined in AliITSresponseSSD
509 // threshold = (Float_t)fResponse->MinVal(k);
510 // I prefer to think adjusting the threshold "manually", looking
511 // at the scope, and considering noise standard deviation
512 threshold = 4.0*noise[k]; // 4 times noise is a choice
513 for(Int_t ix=0;ix<GetNStrips();ix++){ // loop over strips
514 if(fMapA2->GetSignal(k,ix) <= threshold)continue;
515 // convert to ADC signal
516 signal = ((AliITSresponseSSD*)fResponse)->DEvToADC(
517 fMapA2->GetSignal(k,ix));
518 if(signal>1024.) signal = 1024.;//if exceeding, accumulate last one
521 digits[2] = (Int_t) signal;
522 for(j1=0;j1<3;j1++){ // only three in digit.
523 tracks[j1] = pList->GetTrack(k,ix,j1);
524 hits[j1] = pList->GetHit(k,ix,j1);
527 aliITS->AddSimDigit(2,0,digits,tracks,hits,charges);
531 //______________________________________________________________________
532 void AliITSsimulationSSD::WriteSDigits(AliITSpList *pList){
533 // Fills the Summable digits Tree
535 static AliITS *aliITS = (AliITS*)gAlice->GetModule("ITS");
537 pList->GetMaxMapIndex(ni,nj);
538 for(i=0;i<ni;i++)for(j=0;j<nj;j++){
539 if(pList->GetSignalOnly(i,j)>0.0){
540 aliITS->AddSumDigit(*(pList->GetpListItem(i,j)));
541 // cout << "pListSSD: " << *(pList->GetpListItem(i,j)) << endl;
546 //______________________________________________________________________
547 void AliITSsimulationSSD::FillMapFrompList(AliITSpList *pList){
548 // Fills fMap2A from the pList of Summable digits
551 for(k=0;k<2;k++)for(ix=0;ix<GetNStrips();ix++)
552 fMapA2->AddSignal(k,ix,pList->GetSignal(k,ix));
555 //______________________________________________________________________
556 void AliITSsimulationSSD::Print(ostream *os){
557 //Standard output format for this class
559 //AliITSsimulation::Print(os);
561 *os << fDifConst[0] <<","<< fDifConst[1] <<",";
562 *os << fDriftVel[0] <<","<< fDriftVel[1];
563 //*os <<","; fDCS->Print(os);
564 //*os <<","; fMapA2->Print(os);
566 //______________________________________________________________________
567 void AliITSsimulationSSD::Read(istream *is){
568 // Standard output streaming function.
570 //AliITSsimulation::Read(is);
572 *is >> fDifConst[0] >> fDifConst[1];
573 *is >> fDriftVel[0] >> fDriftVel[1];
577 //______________________________________________________________________
578 ostream &operator<<(ostream &os,AliITSsimulationSSD &source){
579 // Standard output streaming function.
584 //______________________________________________________________________
585 istream &operator>>(istream &os,AliITSsimulationSSD &source){
586 // Standard output streaming function.
591 //______________________________________________________________________