1 /**************************************************************************
2 * Copyright(c) 2004, 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 **************************************************************************/
16 /** @file AliFMDRing.cxx
17 @author Christian Holm Christensen <cholm@nbi.dk>
18 @date Mon Mar 27 12:47:43 2006
19 @brief FMD ring geometry parameters
21 //__________________________________________________________________
23 // Utility class to help implement collection of FMD modules into
24 // rings. This is used by AliFMDDetector and AliFMDGeometry.
26 // The AliFMDGeometry object owns the AliFMDRing objects, and the
27 // AliFMDDetector objects reference these. That is, the AliFMDRing
28 // objects are share amoung the AliFMDDetector objects.
30 // Latest changes by Christian Holm Christensen
33 // #include <AliLog.h> // ALILOG_H
34 #include "AliFMDRing.h" // ALIFMDRING_H
35 // #include <TMath.h> // ROOT_TMath
36 #include <TVector2.h> // ROOT_TVector2
38 //====================================================================
41 ; // This is here to keep Emacs for indenting the next line
44 //____________________________________________________________________
45 AliFMDRing::AliFMDRing(Char_t id)
46 : TNamed(Form("FMD%c", id), "Forward multiplicity ring"),
58 SetPrintboardThickness();
63 if (fId == 'I' || fId == 'i') {
69 else if (fId == 'O' || fId == 'o') {
77 //____________________________________________________________________
82 Double_t tanTheta = TMath::Tan(fTheta * TMath::Pi() / 180.);
83 Double_t tanTheta2 = TMath::Power(tanTheta,2);
84 Double_t r2 = TMath::Power(fWaferRadius,2);
85 Double_t yA = tanTheta * fLowR;
86 Double_t lr2 = TMath::Power(fLowR, 2);
87 Double_t hr2 = TMath::Power(fHighR,2);
88 Double_t xD = fLowR + TMath::Sqrt(r2 - tanTheta2 * lr2);
89 Double_t xD2 = TMath::Power(xD,2);
90 Double_t yB = TMath::Sqrt(r2 - hr2 + 2 * fHighR * xD - xD2);
91 Double_t xC = ((xD + TMath::Sqrt(-tanTheta2 * xD2 + r2
94 Double_t yC = tanTheta * xC;
97 fVerticies.AddAt(new TVector2(fLowR, -yA), 0);
98 fVerticies.AddAt(new TVector2(xC, -yC), 1);
99 fVerticies.AddAt(new TVector2(fHighR, -yB), 2);
100 fVerticies.AddAt(new TVector2(fHighR, yB), 3);
101 fVerticies.AddAt(new TVector2(xC, yC), 4);
102 fVerticies.AddAt(new TVector2(fLowR, yA), 5);
104 // A's length. Corresponds to distance from nominal beam line to the
105 // cornor of the active silicon element.
106 fMinR = GetVertex(5)->Mod();
107 // A's length. Corresponds to distance from nominal beam line to the
108 // cornor of the active silicon element.
111 fRingDepth = (fSiThickness + fPrintboardThickness
112 + fCopperThickness + fChipThickness
113 + fLegLength + fModuleSpacing + fSpacing);
116 //____________________________________________________________________
118 AliFMDRing::GetVertex(Int_t i) const
120 // Get the i'th vertex of polygon shape
121 return static_cast<TVector2*>(fVerticies.At(i));
124 //____________________________________________________________________
126 AliFMDRing::GetStripRadius(UShort_t strip) const
128 // Return the nominal strip radius
129 Double_t rmax = GetMaxR();
130 Double_t stripoff = GetMinR();
131 Double_t dstrip = (rmax - stripoff) / GetNStrips();
132 return (strip + .5) * dstrip + stripoff; // fLowR
135 //____________________________________________________________________
137 AliFMDRing::Detector2XYZ(UShort_t sector,
143 // Translate detector coordinates (this,sector,strip) to global
144 // coordinates (x,y,z)
145 if (sector >= GetNSectors()) {
146 Error("Detector2XYZ", "Invalid sector number %d (>=%d) in ring %c",
147 sector, GetNSectors(), fId);
150 if (strip >= GetNStrips()) {
151 Error("Detector2XYZ", "Invalid strip number %d (>=%d)",
152 strip, GetNStrips(), fId);
155 Double_t phi = Float_t(sector + .5) / GetNSectors() * 2 * TMath::Pi();
156 Double_t r = Float_t(strip + .5) / GetNStrips() * (fHighR - fLowR) + fLowR;
157 x = r * TMath::Cos(phi);
158 y = r * TMath::Sin(phi);
159 if (((sector / 2) % 2) == 1)
160 z += TMath::Sign(fModuleSpacing, z);
163 //____________________________________________________________________
165 AliFMDRing::XYZ2Detector(Double_t x,
169 UShort_t& strip) const
171 // Translate global coordinates (x,y,z) to detector coordinates
172 // (this,sector,strip)
174 Double_t r = TMath::Sqrt(x * x + y * y);
175 Int_t str = Int_t((r - fMinR) / GetPitch());
176 if (str < 0 || str >= GetNStrips()) return kFALSE;
178 Double_t phi = TMath::ATan2(y, x) * 180. / TMath::Pi();
179 if (phi < 0) phi = 360. + phi;
180 Int_t sec = Int_t(phi / fTheta);
181 if (sec < 0 || sec >= GetNSectors()) return kFALSE;
182 if ((sec / 2) % 2 == 1) {
183 if (TMath::Abs(z - TMath::Sign(fModuleSpacing, z)) >= 0.01)
186 else if (TMath::Abs(z) >= 0.01) return kFALSE;