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>
25 #include "AliITSmodule.h"
26 #include "AliITSMapA2.h"
27 #include "AliITSpList.h"
28 #include "AliITSresponseSSD.h"
29 #include "AliITSsegmentationSSD.h"
30 #include "AliITSdcsSSD.h"
33 #include "AliITSgeom.h"
34 #include "AliITSsimulationSSD.h"
36 ClassImp(AliITSsimulationSSD);
37 ////////////////////////////////////////////////////////////////////////
39 // Written by Enrico Fragiacomo
42 // AliITSsimulationSSD is the simulation of SSDs.
44 //----------------------------------------------------------------------
45 AliITSsimulationSSD::AliITSsimulationSSD(){
49 fDifConst[0] = fDifConst[1] = 0.0;
50 fDriftVel[0] = fDriftVel[1] = 0.0;
53 //----------------------------------------------------------------------
54 AliITSsimulationSSD::AliITSsimulationSSD(AliITSsegmentation *seg,
55 AliITSresponse *resp){
59 fDifConst[0] = fDifConst[1] = 0.0;
60 fDriftVel[0] = fDriftVel[1] = 0.0;
62 Init((AliITSsegmentationSSD*)seg,(AliITSresponseSSD*)resp);
64 //----------------------------------------------------------------------
65 void AliITSsimulationSSD::Init(AliITSsegmentationSSD *seg,
66 AliITSresponseSSD *resp){
71 Float_t noise[2] = {0.,0.};
72 fResponse->GetNoiseParam(noise[0],noise[1]); // retrieves noise parameters
73 fDCS = new AliITSdcsSSD(seg,resp);
75 SetDriftVelocity(); // use default values in .h file
76 SetIonizeE(); // use default values in .h file
77 SetDiffConst(); // use default values in .h file
78 fMapA2 = new AliITSMapA2(fSegmentation);
80 //______________________________________________________________________
81 AliITSsimulationSSD& AliITSsimulationSSD::operator=(
82 const AliITSsimulationSSD &s){
85 if(this==&s) return *this;
87 this->fDCS = new AliITSdcsSSD(*(s.fDCS));
88 this->fMapA2 = s.fMapA2;
89 this->fIonE = s.fIonE;
90 this->fDifConst[0] = s.fDifConst[0];
91 this->fDifConst[1] = s.fDifConst[1];
92 this->fDriftVel[0] = s.fDriftVel[0];
93 this->fDriftVel[1] = s.fDriftVel[1];
96 //______________________________________________________________________
97 AliITSsimulationSSD::AliITSsimulationSSD(const AliITSsimulationSSD &source){
102 //______________________________________________________________________
103 AliITSsimulationSSD::~AliITSsimulationSSD() {
108 //______________________________________________________________________
109 void AliITSsimulationSSD::DigitiseModule(AliITSmodule *mod,
110 Int_t dummy0,Int_t dummy1) {
111 // Digitizes hits for one SSD module
112 Int_t module = mod->GetIndex();
113 AliITSpList *pList = new AliITSpList(2,GetNStrips());
115 HitsToAnalogDigits(mod,pList);
116 SDigitToDigit(module,pList);
121 //______________________________________________________________________
122 void AliITSsimulationSSD::SDigitiseModule(AliITSmodule *mod,Int_t dummy0,
124 // Produces Summable/Analog digits and writes them to the SDigit tree.
125 AliITSpList *pList = new AliITSpList(2,GetNStrips());
127 HitsToAnalogDigits(mod,pList);
134 //______________________________________________________________________
135 void AliITSsimulationSSD::SDigitToDigit(Int_t module,AliITSpList *pList){
136 // Takes the pList and finishes the digitization.
138 FillMapFrompList(pList);
140 ApplyNoise(pList,module);
141 ApplyCoupling(pList,module);
143 ChargeToSignal(pList);
145 //______________________________________________________________________
146 void AliITSsimulationSSD::HitsToAnalogDigits(AliITSmodule *mod,
148 // Loops over all hits to produce Analog/floating point digits. This
149 // is also the first task in producing standard digits.
150 Int_t indexRange[4] = {0,0,0,0};
151 static Bool_t first = kTRUE;
152 Int_t lasttrack = -2;
154 Double_t x0=0.0, y0=0.0, z0=0.0;
155 Double_t x1=0.0, y1=0.0, z1=0.0;
157 Int_t module = mod->GetIndex();
159 TObjArray *hits = mod->GetHits();
160 Int_t nhits = hits->GetEntriesFast();
161 if (nhits<=0) return;
163 module = mod->GetIndex();
164 if ( mod->GetLayer() == 6 ) GetSegmentation()->SetLayer(6);
165 if ( mod->GetLayer() == 5 ) GetSegmentation()->SetLayer(5);
167 for(Int_t i=0; i<nhits; i++) {
168 // LineSegmentL returns 0 if the hit is entering
169 // If hits is exiting returns positions of entering and exiting hits
170 // Returns also energy loss
172 if (mod->LineSegmentL(i, x0, x1, y0, y1, z0, z1, de, idtrack)) {
173 HitToDigit(module, x0, y0, z0, x1, y1, z1, de, indexRange, first);
175 if (lasttrack != idtrack || i==(nhits-1)) {
176 GetList(idtrack,i,module,pList,indexRange);
181 } // end loop over hits
184 //----------------------------------------------------------------------
185 void AliITSsimulationSSD::HitToDigit(Int_t module, Double_t x0, Double_t y0,
186 Double_t z0, Double_t x1, Double_t y1,
187 Double_t z1, Double_t de,
188 Int_t *indexRange, Bool_t first) {
189 // Turns hits in SSD module into one or more digits.
191 Float_t tang[2] = {0.0,0.0};
192 GetSegmentation()->Angles(tang[0], tang[1]);//stereo<<->tan(stereo)~=stereo
194 Double_t dex=0.0, dey=0.0, dez=0.0;
195 Double_t pairs; // pair generation energy per step.
196 Double_t sigma[2] = {0.,0.};// standard deviation of the diffusion gaussian
197 Double_t tdrift[2] = {0.,0.}; // time of drift
199 Double_t inf[2], sup[2], par0[2];
201 // Steps in the module are determined "manually" (i.e. No Geant)
202 // NumOfSteps divide path between entering and exiting hits in steps
203 Int_t numOfSteps = NumOfSteps(x1, y1, z1, dex, dey, dez);
205 // Enery loss is equally distributed among steps
207 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],
268 } // end for loop over side (0=Pside, 1=Nside)
272 //______________________________________________________________________
273 void AliITSsimulationSSD::ApplyNoise(AliITSpList *pList,Int_t module){
276 Double_t signal,noise;
277 Double_t noiseP[2] = {0.,0.};
280 fResponse->GetNoiseParam(a,b); // retrieves noise parameters
281 noiseP[0] = (Double_t) a; noiseP[1] = (Double_t) b;
282 for(k=0;k<2;k++){ // both sides (0=Pside, 1=Nside)
283 for(ix=0;ix<GetNStrips();ix++){ // loop over strips
284 noise = gRandom->Gaus(0,noiseP[k]);// get noise to signal
285 signal = noise + fMapA2->GetSignal(k,ix);//get signal from map
286 if(signal<0.) signal=0.0; // in case noise is negative...
287 fMapA2->SetHit(k,ix,signal); // give back signal to map
288 if(signal>0.0) pList->AddNoise(k,ix,module,noise);
290 } // loop over k (P or N side)
292 //______________________________________________________________________
293 void AliITSsimulationSSD::ApplyCoupling(AliITSpList *pList,Int_t module) {
294 // Apply the effect of electronic coupling between channels
296 Double_t signalLeft=0, signalRight=0,signal=0;
298 for(ix=0;ix<GetNStrips();ix++){
300 if(ix>0.)signalLeft = fMapA2->GetSignal(0,ix-1)*fDCS->GetCouplingPL();
301 else signalLeft = 0.0;
302 if(ix<(GetNStrips()-1)) signalRight = fMapA2->GetSignal(0,ix+1)*
303 fDCS->GetCouplingPR();
304 else signalRight = 0.0;
305 signal = signalLeft + signalRight;
306 fMapA2->AddSignal(0,ix,signal);
307 if(signal>0.0) pList->AddNoise(0,ix,module,signal);
309 signalLeft = signalRight = signal = 0.0;
311 if(ix>0.) signalLeft = fMapA2->GetSignal(1,ix-1)*fDCS->GetCouplingNL();
312 else signalLeft = 0.0;
313 if(ix<(GetNStrips()-1)) signalRight = fMapA2->GetSignal(1,ix+1)*
314 fDCS->GetCouplingNR();
315 else signalRight = 0.0;
316 signal = signalLeft + signalRight;
317 fMapA2->AddSignal(1,ix,signal);
318 if(signal>0.0) pList->AddNoise(1,ix,module,signal);
319 } // loop over strips
321 //______________________________________________________________________
322 Float_t AliITSsimulationSSD::F(Float_t av, Float_t x, Float_t s) {
323 // Computes the integral of a gaussian using Error Function
324 Float_t sqrt2 = TMath::Sqrt(2.0);
325 Float_t sigm2 = sqrt2*s;
328 integral = 0.5 * TMath::Erf( (x - av) / sigm2);
331 //______________________________________________________________________
332 void AliITSsimulationSSD::IntegrateGaussian(Int_t k,Double_t par, Double_t w,
334 Double_t inf, Double_t sup,
335 Int_t *indexRange, Bool_t first) {
336 // integrate the diffusion gaussian
337 // remind: inf and sup are w-3sigma and w+3sigma
338 // we could define them here instead of passing them
339 // this way we are free to introduce asimmetry
341 Double_t a=0.0, b=0.0;
342 Double_t dXCharge1 = 0.0, dXCharge2 = 0.0;
343 // dXCharge1 and 2 are the charge to two neighbouring strips
344 // Watch that we only involve at least two strips
345 // Numbers greater than 2 of strips in a cluster depend on
346 // geometry of the track and delta rays, not charge diffusion!
348 Double_t strip = TMath::Floor(w); // clostest strip on the left
350 if ( TMath::Abs((strip - w)) < 0.5) {
351 // gaussian mean is closer to strip on the left
352 a = inf; // integration starting point
353 if((strip+0.5)<=sup) {
354 // this means that the tail of the gaussian goes beyond
355 // the middle point between strips ---> part of the signal
356 // is given to the strip on the right
357 b = strip + 0.5; // integration stopping point
358 dXCharge1 = F( w, b, sigma) - F(w, a, sigma);
359 dXCharge2 = F( w, sup, sigma) - F(w ,b, sigma);
361 // this means that all the charge is given to the strip on the left
363 dXCharge1 = 0.9973; // gaussian integral at 3 sigmas
367 dXCharge1 = par * dXCharge1;// normalize by mean of number of carriers
368 dXCharge2 = par * dXCharge2;
370 // for the time being, signal is the charge
371 // in ChargeToSignal signal is converted in ADC channel
372 fMapA2->AddSignal(k,(Int_t)strip,dXCharge1);
373 if(((Int_t) strip) < (GetNStrips()-1)) {
374 // strip doesn't have to be the last (remind: last=GetNStrips()-1)
375 // otherwise part of the charge is lost
376 fMapA2->AddSignal(k,((Int_t)strip+1),dXCharge2);
381 indexRange[k*2+0] = indexRange[k*2+1]=(Int_t) strip;
385 indexRange[k*2+0]=TMath::Min(indexRange[k*2+0],(Int_t) strip);
386 indexRange[k*2+1]=TMath::Max(indexRange[k*2+1],(Int_t) strip);
390 // gaussian mean is closer to strip on the right
391 strip++; // move to strip on the rigth
392 b = sup; // now you know where to stop integrating
393 if((strip-0.5)>=inf) {
394 // tail of diffusion gaussian on the left goes left of
395 // middle point between strips
396 a = strip - 0.5; // integration starting point
397 dXCharge1 = F(w, b, sigma) - F(w, a, sigma);
398 dXCharge2 = F(w, a, sigma) - F(w, inf, sigma);
401 dXCharge1 = 0.9973; // gaussian integral at 3 sigmas
405 dXCharge1 = par * dXCharge1; // normalize by means 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 if(((Int_t) strip) > 0) {
412 // strip doesn't have to be the first
413 // otherwise part of the charge is lost
414 fMapA2->AddSignal(k,((Int_t)strip-1),dXCharge2);
419 indexRange[k*2+0]=indexRange[k*2+1]=(Int_t) strip;
423 indexRange[k*2+0]=TMath::Min(indexRange[k*2+0],(Int_t) strip);
424 indexRange[k*2+1]=TMath::Max(indexRange[k*2+1],(Int_t) strip);
428 //______________________________________________________________________
429 Int_t AliITSsimulationSSD::NumOfSteps(Double_t x, Double_t y, Double_t z,
430 Double_t & dex,Double_t & dey,Double_t & dez){
432 // it also returns steps for each coord
433 //AliITSsegmentationSSD *seg = new AliITSsegmentationSSD();
435 Double_t step = 25E-4;
436 //step = (Double_t) seg->GetStepSize(); // step size (cm)
437 Int_t numOfSteps = (Int_t) (TMath::Sqrt(x*x+y*y+z*z)/step);
439 if (numOfSteps < 1) numOfSteps = 1; // one step, at least
441 // we could condition the stepping depending on the incident angle
449 //----------------------------------------------------------------------
450 void AliITSsimulationSSD::GetList(Int_t label,Int_t hit,Int_t mod,
451 AliITSpList *pList,Int_t *indexRange) {
452 // loop over nonzero digits
456 for(Int_t k=0; k<2; k++) {
457 for(ix=indexRange[k*2+0];ix<indexRange[k*2+1]+1;ix++){
458 // if(indexRange[k*2+0]<indexRange[k*2+1])
459 signal = fMapA2->GetSignal(k,ix);
460 if(signal==0.0) continue;
461 // check the signal magnitude
462 for(i=0;i<pList->GetNSignals(k,ix);i++)
463 signal -= pList->GetTSignal(k,ix,i);
464 // compare the new signal with already existing list
465 pList->AddSignal(k,ix,label,hit,mod,signal);
466 } // end of loop pixels in x
467 } // end of loop over pixels in z
469 //----------------------------------------------------------------------
470 void AliITSsimulationSSD::ChargeToSignal(AliITSpList *pList) {
472 static AliITS *aliITS = (AliITS*)gAlice->GetModule("ITS");
473 Float_t threshold = 0.;
474 Int_t digits[3], tracks[3],hits[3],j1;
475 Float_t charges[3] = {0.0,0.0,0.0};
477 Float_t noise[2] = {0.,0.};
479 ((AliITSresponseSSD*)fResponse)->GetNoiseParam(noise[0],noise[1]);
481 for(Int_t k=0;k<2;k++){ // both sides (0=Pside, 1=Nside)
482 // Threshold for zero-suppression
483 // It can be defined in AliITSresponseSSD
484 // threshold = (Float_t)fResponse->MinVal(k);
485 // I prefer to think adjusting the threshold "manually", looking
486 // at the scope, and considering noise standard deviation
487 threshold = 4.0*noise[k]; // 4 times noise is a choice
488 for(Int_t ix=0;ix<GetNStrips();ix++){ // loop over strips
489 if(fMapA2->GetSignal(k,ix) <= threshold) continue;
490 // convert to ADC signal
491 signal = ((AliITSresponseSSD*)fResponse)->DEvToADC(
492 fMapA2->GetSignal(k,ix));
493 if(signal>1024.) signal = 1024.;//if exceeding, accumulate last one
496 digits[2] = (Int_t) signal;
497 for(j1=0;j1<3;j1++){ // only three in digit.
498 tracks[j1] = pList->GetTrack(k,ix,j1);
499 hits[j1] = pList->GetHit(k,ix,j1);
502 aliITS->AddSimDigit(2,0,digits,tracks,hits,charges);
506 //______________________________________________________________________
507 void AliITSsimulationSSD::WriteSDigits(AliITSpList *pList){
508 // Fills the Summable digits Tree
510 static AliITS *aliITS = (AliITS*)gAlice->GetModule("ITS");
512 pList->GetMaxMapIndex(ni,nj);
513 for(i=0;i<ni;i++)for(j=0;j<nj;j++){
514 if(pList->GetSignalOnly(i,j)>0.0){
515 aliITS->AddSumDigit(*(pList->GetpListItem(i,j)));
516 // cout << "pListSSD: " << *(pList->GetpListItem(i,j)) << endl;
521 //______________________________________________________________________
522 void AliITSsimulationSSD::FillMapFrompList(AliITSpList *pList){
523 // Fills fMap2A from the pList of Summable digits
526 for(k=0;k<2;k++)for(ix=0;ix<GetNStrips();ix++)
527 fMapA2->AddSignal(k,ix,pList->GetSignal(k,ix));
530 //______________________________________________________________________
531 void AliITSsimulationSSD::Print(ostream *os){
532 //Standard output format for this class
534 //AliITSsimulation::Print(os);
536 *os << fDifConst[0] <<","<< fDifConst[1] <<",";
537 *os << fDriftVel[0] <<","<< fDriftVel[1];
538 //*os <<","; fDCS->Print(os);
539 //*os <<","; fMapA2->Print(os);
541 //______________________________________________________________________
542 void AliITSsimulationSSD::Read(istream *is){
543 // Standard output streaming function.
545 //AliITSsimulation::Read(is);
547 *is >> fDifConst[0] >> fDifConst[1];
548 *is >> fDriftVel[0] >> fDriftVel[1];
552 //______________________________________________________________________
553 ostream &operator<<(ostream &os,AliITSsimulationSSD &source){
554 // Standard output streaming function.
559 //______________________________________________________________________
560 istream &operator>>(istream &os,AliITSsimulationSSD &source){
561 // Standard output streaming function.
566 //______________________________________________________________________