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 **************************************************************************/
18 Revision 1.12 2000/04/07 11:12:33 fca
19 G4 compatibility changes
21 Revision 1.11 2000/03/22 13:42:26 fca
22 SetGenerator does not replace an existing generator, ResetGenerator does
24 Revision 1.10 2000/02/23 16:25:22 fca
25 AliVMC and AliGeant3 classes introduced
26 ReadEuclid moved from AliRun to AliModule
28 Revision 1.9 1999/12/03 10:54:01 fca
31 Revision 1.8 1999/10/01 09:54:33 fca
32 Correct logics for Lego StepManager
34 Revision 1.7 1999/09/29 09:24:29 fca
35 Introduction of the Copyright and cvs Log
39 //////////////////////////////////////////////////////////////
40 //////////////////////////////////////////////////////////////
42 // Utility class to evaluate the material budget from
43 // a given radius to the surface of an arbitrary cylinder
44 // along radial directions from the centre:
47 // - Interaction length
50 // Geantinos are shot in the bins in the fNtheta bins in theta
51 // and fNphi bins in phi with specified rectangular limits.
52 // The statistics are accumulated per
53 // fRadMin < r < fRadMax and <0 < z < fZMax
55 // To activate this option, you can do:
56 // Root > gAlice.RunLego();
57 // or Root > .x menu.C then select menu item "RunLego"
58 // Note that when calling gAlice->RunLego, an optional list
59 // of arguments may be specified.
63 <img src="picts/alilego.gif">
67 //////////////////////////////////////////////////////////////
78 //___________________________________________
87 //___________________________________________
88 AliLego::AliLego(const char *title, Int_t ntheta, Float_t themin, Float_t themax,
89 Int_t nphi, Float_t phimin, Float_t phimax,
90 Float_t rmin, Float_t rmax, Float_t zmax)
91 : TNamed("Lego Generator",title)
93 // specify the angular limits and the size of the rectangular box
95 fGener = new AliLegoGenerator(ntheta, themin, themax,
96 nphi, phimin, phimax, rmin, rmax, zmax);
98 gAlice->ResetGenerator(fGener);
100 Float_t etamin = -TMath::Log(TMath::Tan(TMath::Min((Double_t)themax*kDegrad/2,TMath::Pi()/2-1.e-10)));
101 Float_t etamax = -TMath::Log(TMath::Tan(TMath::Max((Double_t)themin*kDegrad/2, 1.e-10)));
103 fHistRadl = new TH2F("hradl","Radiation length map",
104 nphi,phimin,phimax,ntheta,themin,themax);
105 fHistAbso = new TH2F("habso","Interaction length map",
106 nphi,phimin,phimax,ntheta,themin,themax);
107 fHistGcm2 = new TH2F("hgcm2","g/cm2 length map",
108 nphi,phimin,phimax,ntheta,themin,themax);
109 fHistReta = new TH2F("hetar","Radiation length vs. eta",
110 nphi,phimin,phimax,ntheta,etamin,etamax);
114 //___________________________________________
123 //___________________________________________
124 void AliLego::BeginEvent()
126 // --- Set to 0 radiation length, absorption length and g/cm2 ---
132 //___________________________________________
133 void AliLego::FinishEvent()
135 Double_t thed, phid, eta;
136 thed = fGener->CurTheta()*kRaddeg;
137 phid = fGener->CurPhi()*kRaddeg;
138 eta = -TMath::Log(TMath::Tan(TMath::Max(
139 TMath::Min((Double_t)(fGener->CurTheta())/2,
140 TMath::Pi()/2-1.e-10),1.e-10)));
142 fHistRadl->Fill(phid,thed,fTotRadl);
143 fHistAbso->Fill(phid,thed,fTotAbso);
144 fHistGcm2->Fill(phid,thed,fTotGcm2);
145 fHistReta->Fill(phid,eta,fTotRadl);
148 //___________________________________________
149 void AliLego::FinishRun()
151 // Store histograms in current Root file
157 // Delete histograms from memory
158 fHistRadl->Delete(); fHistRadl=0;
159 fHistAbso->Delete(); fHistAbso=0;
160 fHistGcm2->Delete(); fHistGcm2=0;
161 fHistReta->Delete(); fHistReta=0;
166 //___________________________________________
167 void AliLego::StepManager()
169 // called from AliRun::Stepmanager from gustep.
170 // Accumulate the 3 parameters step by step
173 Float_t a,z,dens,radl,absl;
176 Float_t step = gMC->TrackStep();
178 Float_t vect[3], dir[3];
179 TLorentzVector pos, mom;
181 gMC->TrackPosition(pos);
182 gMC->TrackMomentum(mom);
183 gMC->CurrentMaterial(a,z,dens,radl,absl);
187 // --- See if we have to stop now
188 if (TMath::Abs(pos[2]) > fGener->ZMax() ||
189 pos[0]*pos[0] +pos[1]*pos[1] > fGener->RadMax()*fGener->RadMax()) {
190 if (gMC->TrackLength()) {
191 // Not the first step, add past contribution
200 // --- See how long we have to go
206 t = fGener->PropagateCylinder(vect,dir,fGener->RadMax(),fGener->ZMax());
209 fTotAbso += step/absl;
210 fTotRadl += step/radl;
211 fTotGcm2 += step*dens;
215 ClassImp(AliLegoGenerator)
217 //___________________________________________
218 AliLegoGenerator::AliLegoGenerator(Int_t ntheta, Float_t themin,
219 Float_t themax, Int_t nphi,
220 Float_t phimin, Float_t phimax,
221 Float_t rmin, Float_t rmax, Float_t zmax) :
222 AliGenerator(0), fRadMin(rmin), fRadMax(rmax), fZMax(zmax), fNtheta(ntheta),
223 fNphi(nphi), fThetaBin(ntheta), fPhiBin(-1), fCurTheta(0), fCurPhi(0)
226 SetPhiRange(phimin,phimax);
227 SetThetaRange(themin,themax);
232 //___________________________________________
233 void AliLegoGenerator::Generate()
235 // Create a geantino with kinematics corresponding to the current
236 // bins in theta and phi.
240 const Int_t mpart = 0;
241 Float_t orig[3], pmom[3];
242 Float_t t, cost, sint, cosp, sinp;
244 // Prepare for next step
245 if(fThetaBin>=fNtheta-1)
246 if(fPhiBin>=fNphi-1) {
247 Warning("Generate","End of Lego Generation");
251 printf("Generating rays in phi bin:%d\n",fPhiBin);
255 fCurTheta = (fThetaMin+(fThetaBin+0.5)*(fThetaMax-fThetaMin)/fNtheta);
256 fCurPhi = (fPhiMin+(fPhiBin+0.5)*(fPhiMax-fPhiMin)/fNphi);
257 cost = TMath::Cos(fCurTheta);
258 sint = TMath::Sin(fCurTheta);
259 cosp = TMath::Cos(fCurPhi);
260 sinp = TMath::Sin(fCurPhi);
266 // --- Where to start
267 orig[0] = orig[1] = orig[2] = 0;
268 Float_t dalicz = 3000;
270 t = PropagateCylinder(orig,pmom,fRadMin,dalicz);
274 if (TMath::Abs(orig[2]) > fZMax) return;
277 Float_t polar[3]={0.,0.,0.};
279 gAlice->SetTrack(1, 0, mpart, pmom, orig, polar, 0, "LEGO ray", ntr);
283 //___________________________________________
284 Float_t AliLegoGenerator::PropagateCylinder(Float_t *x, Float_t *v, Float_t r, Float_t z)
286 // Propagate to cylinder from inside
288 Double_t hnorm, sz, t, t1, t2, t3, sr;
290 const Float_t kSmall = 1e-8;
291 const Float_t kSmall2 = kSmall*kSmall;
293 // ---> Find intesection with Z planes
297 hnorm = TMath::Sqrt(1/(d[0]*d[0]+d[1]*d[1]+d[2]*d[2]));
301 if (d[2] > kSmall) sz = (z-x[2])/d[2];
302 else if (d[2] < -kSmall) sz = -(z+x[2])/d[2];
303 else sz = 1.e10; // ---> Direction parallel to X-Y, no intersection
305 // ---> Intersection with cylinders
306 // Intersection point (x,y,z)
307 // (x,y,z) is on track : x=X(1)+t*D(1)
310 // (x,y,z) is on cylinder : x**2 + y**2 = R**2
312 // (D(1)**2+D(2)**2)*t**2
313 // +2.*(X(1)*D(1)+X(2)*D(2))*t
314 // +X(1)**2+X(2)**2-R**2=0
315 // ---> Solve second degree equation
316 t1 = d[0]*d[0] + d[1]*d[1];
318 t = sz; // ---> Track parallel to the z-axis, take distance to planes
320 t2 = x[0]*d[0] + x[1]*d[1];
321 t3 = x[0]*x[0] + x[1]*x[1];
322 // ---> It should be positive, but there may be numerical problems
323 sr = (t2 +TMath::Sqrt(TMath::Max(t2*t2-(t3-r*r)*t1,0.)))/t1;
324 // ---> Find minimum distance between planes and cylinder
325 t = TMath::Min(sz,sr);