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"
35 #include "AliITSgeom.h"
36 #include "AliITSsimulationSSD.h"
37 #include "AliITSTableSSD.h"
39 ClassImp(AliITSsimulationSSD);
40 ////////////////////////////////////////////////////////////////////////
42 // Written by Enrico Fragiacomo
45 // AliITSsimulationSSD is the simulation of SSDs.
47 //----------------------------------------------------------------------
48 AliITSsimulationSSD::AliITSsimulationSSD(){
52 fDifConst[0] = fDifConst[1] = 0.0;
53 fDriftVel[0] = fDriftVel[1] = 0.0;
56 //----------------------------------------------------------------------
57 AliITSsimulationSSD::AliITSsimulationSSD(AliITSsegmentation *seg,
58 AliITSresponse *resp){
62 fDifConst[0] = fDifConst[1] = 0.0;
63 fDriftVel[0] = fDriftVel[1] = 0.0;
65 Init((AliITSsegmentationSSD*)seg,(AliITSresponseSSD*)resp);
67 //----------------------------------------------------------------------
68 void AliITSsimulationSSD::Init(AliITSsegmentationSSD *seg,
69 AliITSresponseSSD *resp){
74 Float_t noise[2] = {0.,0.};
75 fResponse->GetNoiseParam(noise[0],noise[1]); // retrieves noise parameters
76 fDCS = new AliITSdcsSSD(seg,resp);
78 SetDriftVelocity(); // use default values in .h file
79 SetIonizeE(); // use default values in .h file
80 SetDiffConst(); // use default values in .h file
81 fMapA2 = new AliITSMapA2(fSegmentation);
84 //______________________________________________________________________
85 AliITSsimulationSSD& AliITSsimulationSSD::operator=(
86 const AliITSsimulationSSD &s){
89 if(this==&s) return *this;
91 this->fDCS = new AliITSdcsSSD(*(s.fDCS));
92 this->fMapA2 = s.fMapA2;
93 this->fIonE = s.fIonE;
94 this->fDifConst[0] = s.fDifConst[0];
95 this->fDifConst[1] = s.fDifConst[1];
96 this->fDriftVel[0] = s.fDriftVel[0];
97 this->fDriftVel[1] = s.fDriftVel[1];
100 //______________________________________________________________________
101 AliITSsimulationSSD::AliITSsimulationSSD(const AliITSsimulationSSD &source){
106 //______________________________________________________________________
107 AliITSsimulationSSD::~AliITSsimulationSSD() {
112 //______________________________________________________________________
113 void AliITSsimulationSSD::DigitiseModule(AliITSmodule *mod,
114 Int_t dummy0,Int_t dummy1) {
115 // Digitizes hits for one SSD module
116 Int_t module = mod->GetIndex();
117 AliITSpList *pList = new AliITSpList(2,GetNStrips());
119 HitsToAnalogDigits(mod,pList);
120 SDigitToDigit(module,pList);
125 //______________________________________________________________________
126 void AliITSsimulationSSD::SDigitiseModule(AliITSmodule *mod,Int_t dummy0,
128 // Produces Summable/Analog digits and writes them to the SDigit tree.
129 AliITSpList *pList = new AliITSpList(2,GetNStrips());
131 HitsToAnalogDigits(mod,pList);
138 //______________________________________________________________________
139 void AliITSsimulationSSD::SDigitToDigit(Int_t module,AliITSpList *pList){
140 // Takes the pList and finishes the digitization.
142 // FillMapFrompList(pList); //commented out to avoid double counting of the
145 ApplyNoise(pList,module);
146 ApplyCoupling(pList,module);
148 ChargeToSignal(pList);
150 //______________________________________________________________________
151 void AliITSsimulationSSD::HitsToAnalogDigits(AliITSmodule *mod,
153 // Loops over all hits to produce Analog/floating point digits. This
154 // is also the first task in producing standard digits.
155 Int_t lasttrack = -2;
157 Double_t x0=0.0, y0=0.0, z0=0.0;
158 Double_t x1=0.0, y1=0.0, z1=0.0;
160 Int_t module = mod->GetIndex();
162 TObjArray *hits = mod->GetHits();
163 Int_t nhits = hits->GetEntriesFast();
164 if (nhits<=0) return;
165 AliITSTableSSD * tav = new AliITSTableSSD(GetNStrips());
166 module = mod->GetIndex();
167 if ( mod->GetLayer() == 6 ) GetSegmentation()->SetLayer(6);
168 if ( mod->GetLayer() == 5 ) GetSegmentation()->SetLayer(5);
169 for(Int_t i=0; i<nhits; i++) {
170 // LineSegmentL returns 0 if the hit is entering
171 // If hits is exiting returns positions of entering and exiting hits
172 // Returns also energy loss
174 if (mod->LineSegmentL(i, x0, x1, y0, y1, z0, z1, de, idtrack)) {
175 HitToDigit(module, x0, y0, z0, x1, y1, z1, de,tav);
177 if (lasttrack != idtrack || i==(nhits-1)) {
178 GetList(idtrack,i,module,pList,tav);
182 } // end loop over hits
186 //----------------------------------------------------------------------
187 void AliITSsimulationSSD::HitToDigit(Int_t module, Double_t x0, Double_t y0,
188 Double_t z0, Double_t x1, Double_t y1,
189 Double_t z1, Double_t de,
190 AliITSTableSSD *tav) {
191 // Turns hits in SSD module into one or more digits.
193 Float_t tang[2] = {0.0,0.0};
194 GetSegmentation()->Angles(tang[0], tang[1]);//stereo<<->tan(stereo)~=stereo
196 Double_t dex=0.0, dey=0.0, dez=0.0;
197 Double_t pairs; // pair generation energy per step.
198 Double_t sigma[2] = {0.,0.};// standard deviation of the diffusion gaussian
199 Double_t tdrift[2] = {0.,0.}; // time of drift
201 Double_t inf[2], sup[2], par0[2];
203 // Steps in the module are determined "manually" (i.e. No Geant)
204 // NumOfSteps divide path between entering and exiting hits in steps
205 Int_t numOfSteps = NumOfSteps(x1, y1, z1, dex, dey, dez);
206 // Enery loss is equally distributed among steps
208 pairs = de/GetIonizeE(); // e-h pairs generated
209 for(Int_t j=0; j<numOfSteps; j++) { // stepping
210 x = x0 + (j+0.5)*dex;
211 y = y0 + (j+0.5)*dey;
212 if ( y > (GetSegmentation()->Dy()/2+10)*1.0E-4 ) {
213 // check if particle is within the detector
214 Warning("HitToDigit","hit out of detector y0=%e,y=%e,dey=%e,j =%e",
218 z = z0 + (j+0.5)*dez;
220 // calculate drift time
221 // y is the minimum path
222 tdrift[0] = (y+(GetSegmentation()->Dy()*1.0E-4)/2)/GetDriftVelocity(0);
223 tdrift[1] = ((GetSegmentation()->Dy()*1.0E-4)/2-y)/GetDriftVelocity(1);
225 for(Int_t k=0; k<2; k++) { // both sides remember: 0=Pside 1=Nside
227 tang[k]=TMath::Tan(tang[k]);
229 // w is the coord. perpendicular to the strips
231 w = (x+(GetSegmentation()->Dx()*1.0E-4)/2) -
232 (z+(GetSegmentation()->Dz()*1.0E-4)/2)*tang[k];
234 w = (x+(GetSegmentation()->Dx()*1.0E-4)/2) +
235 (z-(GetSegmentation()->Dz()*1.0E-4)/2)*tang[k];
237 w /= (GetStripPitch()*1.0E-4); // w is converted in units of pitch
239 if((w<(-0.5)) || (w>(GetNStrips()-0.5))) {
240 // this check rejects hits in regions not covered by strips
241 // 0.5 takes into account boundaries
242 return; // There are dead region on the SSD sensitive volume.
244 if(k==0) Warning("HitToDigit",
245 "no strip in this region of P side");
246 else Warning"HitToDigit","no strip in this region of N side");
251 // sigma is the standard deviation of the diffusion gaussian
252 if(tdrift[k]<0) return;
253 sigma[k] = TMath::Sqrt(2*GetDiffConst(k)*tdrift[k]);
254 sigma[k] /= (GetStripPitch()*1.0E-4); //units of Pitch
256 Error("HitToDigit"," sigma[%d]=0",k);
261 // we integrate the diffusion gaussian from -3sigma to 3sigma
262 inf[k] = w - 3*sigma[k]; // 3 sigma from the gaussian average
263 sup[k] = w + 3*sigma[k]; // 3 sigma from the gaussian average
264 // IntegrateGaussian does the actual
265 // integration of diffusion gaussian
266 IntegrateGaussian(k, par0[k], w, sigma[k], inf[k], sup[k],tav);
267 } // end for loop over side (0=Pside, 1=Nside)
271 //______________________________________________________________________
272 void AliITSsimulationSSD::ApplyNoise(AliITSpList *pList,Int_t module){
275 Double_t signal,noise;
276 Double_t noiseP[2] = {0.,0.};
279 fResponse->GetNoiseParam(a,b); // retrieves noise parameters
280 noiseP[0] = (Double_t) a; noiseP[1] = (Double_t) b;
281 for(k=0;k<2;k++){ // both sides (0=Pside, 1=Nside)
282 for(ix=0;ix<GetNStrips();ix++){ // loop over strips
283 noise = gRandom->Gaus(0,noiseP[k]);// get noise to signal
284 signal = noise + fMapA2->GetSignal(k,ix);//get signal from map
285 if(signal<0.) signal=0.0; // in case noise is negative...
286 fMapA2->SetHit(k,ix,signal); // give back signal to map
287 if(signal>0.0) pList->AddNoise(k,ix,module,noise);
289 } // loop over k (P or N side)
291 //______________________________________________________________________
292 void AliITSsimulationSSD::ApplyCoupling(AliITSpList *pList,Int_t module) {
293 // Apply the effect of electronic coupling between channels
295 Double_t signalLeft=0, signalRight=0,signal=0;
297 for(ix=0;ix<GetNStrips();ix++){
299 if(ix>0.)signalLeft = fMapA2->GetSignal(0,ix-1)*fDCS->GetCouplingPL();
300 else signalLeft = 0.0;
301 if(ix<(GetNStrips()-1)) signalRight = fMapA2->GetSignal(0,ix+1)*
302 fDCS->GetCouplingPR();
303 else signalRight = 0.0;
304 signal = signalLeft + signalRight;
305 fMapA2->AddSignal(0,ix,signal);
306 if(signal>0.0) pList->AddNoise(0,ix,module,signal);
308 signalLeft = signalRight = signal = 0.0;
310 if(ix>0.) signalLeft = fMapA2->GetSignal(1,ix-1)*fDCS->GetCouplingNL();
311 else signalLeft = 0.0;
312 if(ix<(GetNStrips()-1)) signalRight = fMapA2->GetSignal(1,ix+1)*
313 fDCS->GetCouplingNR();
314 else signalRight = 0.0;
315 signal = signalLeft + signalRight;
316 fMapA2->AddSignal(1,ix,signal);
317 if(signal>0.0) pList->AddNoise(1,ix,module,signal);
318 } // loop over strips
320 //______________________________________________________________________
321 Float_t AliITSsimulationSSD::F(Float_t av, Float_t x, Float_t s) {
322 // Computes the integral of a gaussian using Error Function
323 Float_t sqrt2 = TMath::Sqrt(2.0);
324 Float_t sigm2 = sqrt2*s;
327 integral = 0.5 * TMath::Erf( (x - av) / sigm2);
330 //______________________________________________________________________
331 void AliITSsimulationSSD::IntegrateGaussian(Int_t k,Double_t par, Double_t w,
333 Double_t inf, Double_t sup,
334 AliITSTableSSD *tav) {
335 // integrate the diffusion gaussian
336 // remind: inf and sup are w-3sigma and w+3sigma
337 // we could define them here instead of passing them
338 // this way we are free to introduce asimmetry
340 Double_t a=0.0, b=0.0;
341 Double_t dXCharge1 = 0.0, dXCharge2 = 0.0;
342 // dXCharge1 and 2 are the charge to two neighbouring strips
343 // Watch that we only involve at least two strips
344 // Numbers greater than 2 of strips in a cluster depend on
345 // geometry of the track and delta rays, not charge diffusion!
347 Double_t strip = TMath::Floor(w); // closest strip on the left
349 if ( TMath::Abs((strip - w)) < 0.5) {
350 // gaussian mean is closer to strip on the left
351 a = inf; // integration starting point
352 if((strip+0.5)<=sup) {
353 // this means that the tail of the gaussian goes beyond
354 // the middle point between strips ---> part of the signal
355 // is given to the strip on the right
356 b = strip + 0.5; // integration stopping point
357 dXCharge1 = F( w, b, sigma) - F(w, a, sigma);
358 dXCharge2 = F( w, sup, sigma) - F(w ,b, sigma);
360 // this means that all the charge is given to the strip on the left
362 dXCharge1 = 0.9973; // gaussian integral at 3 sigmas
365 dXCharge1 = par * dXCharge1;// normalize by mean of number of carriers
366 dXCharge2 = par * dXCharge2;
368 // for the time being, signal is the charge
369 // in ChargeToSignal signal is converted in ADC channel
370 fMapA2->AddSignal(k,(Int_t)strip,dXCharge1);
371 tav->Add(k,(Int_t)strip);
372 if(((Int_t) strip) < (GetNStrips()-1)) {
373 // strip doesn't have to be the last (remind: last=GetNStrips()-1)
374 // otherwise part of the charge is lost
375 fMapA2->AddSignal(k,((Int_t)strip+1),dXCharge2);
376 tav->Add(k,((Int_t)(strip+1)));
381 // gaussian mean is closer to strip on the right
382 strip++; // move to strip on the rigth
383 b = sup; // now you know where to stop integrating
384 if((strip-0.5)>=inf) {
385 // tail of diffusion gaussian on the left goes left of
386 // middle point between strips
387 a = strip - 0.5; // integration starting point
388 dXCharge1 = F(w, b, sigma) - F(w, a, sigma);
389 dXCharge2 = F(w, a, sigma) - F(w, inf, sigma);
392 dXCharge1 = 0.9973; // gaussian integral at 3 sigmas
395 dXCharge1 = par * dXCharge1; // normalize by means of carriers
396 dXCharge2 = par * dXCharge2;
398 // for the time being, signal is the charge
399 // in ChargeToSignal signal is converted in ADC channel
400 fMapA2->AddSignal(k,(Int_t)strip,dXCharge1);
401 tav->Add(k,(Int_t)strip);
402 if(((Int_t) strip) > 0) {
403 // strip doesn't have to be the first
404 // otherwise part of the charge is lost
405 fMapA2->AddSignal(k,((Int_t)strip-1),dXCharge2);
406 tav->Add(k,((Int_t)(strip-1)));
412 //______________________________________________________________________
413 Int_t AliITSsimulationSSD::NumOfSteps(Double_t x, Double_t y, Double_t z,
414 Double_t & dex,Double_t & dey,Double_t & dez){
416 // it also returns steps for each coord
417 //AliITSsegmentationSSD *seg = new AliITSsegmentationSSD();
419 Double_t step = 25E-4;
420 //step = (Double_t) seg->GetStepSize(); // step size (cm)
421 Int_t numOfSteps = (Int_t) (TMath::Sqrt(x*x+y*y+z*z)/step);
423 if (numOfSteps < 1) numOfSteps = 1; // one step, at least
425 // we could condition the stepping depending on the incident angle
433 //----------------------------------------------------------------------
434 void AliITSsimulationSSD::GetList(Int_t label,Int_t hit,Int_t mod,
435 AliITSpList *pList,AliITSTableSSD *tav) {
436 // loop over nonzero digits
440 for(Int_t k=0; k<2; k++) {
443 signal = fMapA2->GetSignal(k,ix);
448 // check the signal magnitude
449 for(i=0;i<pList->GetNSignals(k,ix);i++){
450 signal -= pList->GetTSignal(k,ix,i);
452 // compare the new signal with already existing list
453 if(signal>0)pList->AddSignal(k,ix,label,hit,mod,signal);
455 } // end of loop on strips
456 } // end of loop on P/N side
459 //----------------------------------------------------------------------
460 void AliITSsimulationSSD::ChargeToSignal(AliITSpList *pList) {
462 static AliITS *aliITS = (AliITS*)gAlice->GetModule("ITS");
463 Float_t threshold = 0.;
464 Int_t digits[3], tracks[3],hits[3],j1;
465 Float_t charges[3] = {0.0,0.0,0.0};
467 Float_t noise[2] = {0.,0.};
469 ((AliITSresponseSSD*)fResponse)->GetNoiseParam(noise[0],noise[1]);
471 for(Int_t k=0;k<2;k++){ // both sides (0=Pside, 1=Nside)
472 // Threshold for zero-suppression
473 // It can be defined in AliITSresponseSSD
474 // threshold = (Float_t)fResponse->MinVal(k);
475 // I prefer to think adjusting the threshold "manually", looking
476 // at the scope, and considering noise standard deviation
477 threshold = 4.0*noise[k]; // 4 times noise is a choice
478 for(Int_t ix=0;ix<GetNStrips();ix++){ // loop over strips
479 if(fMapA2->GetSignal(k,ix) <= threshold)continue;
480 // convert to ADC signal
481 signal = ((AliITSresponseSSD*)fResponse)->DEvToADC(
482 fMapA2->GetSignal(k,ix));
483 if(signal>1024.) signal = 1024.;//if exceeding, accumulate last one
486 digits[2] = (Int_t) signal;
487 for(j1=0;j1<3;j1++){ // only three in digit.
488 tracks[j1] = pList->GetTrack(k,ix,j1);
489 hits[j1] = pList->GetHit(k,ix,j1);
492 aliITS->AddSimDigit(2,0,digits,tracks,hits,charges);
496 //______________________________________________________________________
497 void AliITSsimulationSSD::WriteSDigits(AliITSpList *pList){
498 // Fills the Summable digits Tree
500 static AliITS *aliITS = (AliITS*)gAlice->GetModule("ITS");
502 pList->GetMaxMapIndex(ni,nj);
503 for(i=0;i<ni;i++)for(j=0;j<nj;j++){
504 if(pList->GetSignalOnly(i,j)>0.0){
505 aliITS->AddSumDigit(*(pList->GetpListItem(i,j)));
506 // cout << "pListSSD: " << *(pList->GetpListItem(i,j)) << endl;
511 //______________________________________________________________________
512 void AliITSsimulationSSD::FillMapFrompList(AliITSpList *pList){
513 // Fills fMap2A from the pList of Summable digits
516 for(k=0;k<2;k++)for(ix=0;ix<GetNStrips();ix++)
517 fMapA2->AddSignal(k,ix,pList->GetSignal(k,ix));
520 //______________________________________________________________________
521 void AliITSsimulationSSD::Print(ostream *os){
522 //Standard output format for this class
524 //AliITSsimulation::Print(os);
526 *os << fDifConst[0] <<","<< fDifConst[1] <<",";
527 *os << fDriftVel[0] <<","<< fDriftVel[1];
528 //*os <<","; fDCS->Print(os);
529 //*os <<","; fMapA2->Print(os);
531 //______________________________________________________________________
532 void AliITSsimulationSSD::Read(istream *is){
533 // Standard output streaming function.
535 //AliITSsimulation::Read(is);
537 *is >> fDifConst[0] >> fDifConst[1];
538 *is >> fDriftVel[0] >> fDriftVel[1];
542 //______________________________________________________________________
543 ostream &operator<<(ostream &os,AliITSsimulationSSD &source){
544 // Standard output streaming function.
549 //______________________________________________________________________
550 istream &operator>>(istream &os,AliITSsimulationSSD &source){
551 // Standard output streaming function.
556 //______________________________________________________________________