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17 The simulation is done in two steps, one which describes the detector geometry
18 and material and one which does the particle tracking and stores the hits
19 and digits in a TTree itself written on a disk file. These two steps are
20 steered through the Config.C file(<a href="PHOSConfig_Central.C">example</a>),
21 a root macro launched at the AliRoot prompt. To customize this file you must:
25 select a file name for the root output:
27 //=======================================================================
28 // Create the output file
29 sprintf(filename,"<b>myfilename</b>.root");
33 Define your event generator and simulations parameters:
35 AliGenCocktail *gener = new AliGenCocktail(); // Cocktail class
36 gener->SetPtRange(.02,10.00); // Transverse momentum range
37 gener->SetPhiRange(180.,360.); // Azimuthal angle range
38 gener->SetYRange(-0.25,0.25); // Pseudorapidity range
39 gener->SetOrigin(0,0,0); // Vertex position
40 gener->SetSigma(0,0,5.6); // Sigma in (X,Y,Z) (cm) on IP position
41 gener->Init(); // Initialize the generator
45 Select the detector seen by the tracking:
47 Int_t iPHOS=1; // PHOS is in
48 Int_t iPMD=0; // PMD is out
52 Create a PHOS object (<b>GPS2</b> is so far the unique configuration option, see below):
55 //=================== PHOS parameters ===========================
56 AliPHOS *PHOS = new AliPHOSv0("PHOS","<b>GPS2</b>");
61 You van now run the simulation by entering the following command at the aliroot prompt:
63 aliroot> gAlice->Run(1,"PHOSConfig_Central.C");
72 PHOS consists of two distinct parts. The calorimeter, named EMCA, consists
73 of the PbW04 crystals within their housing. The crystals are assembled
74 in <i>fNModules</i> modules of <i>fNPhi </i>rows along the x-axis direction
75 and <i>fNZ</i> modules along the z-axis direction. Since the total number
76 of crystals and their layout within ALICE is presently (11/11/1999) not
77 final it was decided to fully parametrize the geometry. A change in any
78 of the three previously defined parameters will provide automatically a
79 new layout of the modules.
80 <br>The second part of PHOS is the charged particle identifier. Since until
81 end of 2000 no decision will be taken on the final design of this element
82 two or more versions can be considered. Today (11/11/1999) only one version
83 is implemented and is named PPSD for PHOS Pre-Shower Detector. It consists
84 of a first layer of <i>fNumberOfModulesPhi</i> x <i>fNumberOfModulesZ </i>gas
85 detectors per PHOS module, each detectors being subdivided into <i>fNumberOfPadsPhi</i>
86 x <i>fNumberOfPadsZ </i>gas cells, a Lead converter and a second layer
87 of gas detectors identical to the first layer. This second part is positionned
88 on top of the EMCA module.
90 The class <a href="AliPHOSv0.html"> AliPHOSv0 </a> ( <a href="AliPHOSv0_Tree.ps"> inheritance tree </a>)
91 describes this geometry. We have defined also a class
92 <a href="AliPHOSv1.html"> AliPHOSv1 </a> ( <a href="AliPHOSv1_Tree.ps"> inheritance tree </a>)
93 which in addition contains the photodiode response and the light transport through the crystal.
95 The parameters of the geometry are given in class <a href="AliPHOSGeometry.html"> AliPHOSGeometry </a>( <a href="AliPHOSGeometry_Tree.ps"> inheritance tree </a>)
98 <img SRC=" images/EMCinAlice.gif" ALT="Geant Tree for PHOS" >
100 <b> Figure 1.a: </b> <i> GEANT Tree which describes the EMC-PHOS geometry </i>
104 <img SRC=" images/PPSDinAlice.gif" ALT="Geant Tree for PHOS" >
106 <b> Figure 1.b: </b> <i> GEANT Tree which describes the PPSD-PHOS geometry </i>
113 <img SRC="aliphossimulation.gif" ALT="Geom/Simul class diagram" >
115 <b> Figure 2.: </b> <i> Class diagram for the geometry/simulation package </i>
118 <a href="AliPHOS.html"><i><u>AliPHOS</u></a> : </i>This is the base class. It derives from <i>AliDetector.
119 </i>It's only purpose is to describe the materials
120 (à la <i>AliMC</i>) needed for the EMCA and PPSD construction.
122 <i><u> <a href="AliPHOSv0.html">AliPHOSv4</u></i></a>: It derives from <i>AliPHOS</i>.
126 It sets up the geometry for the Root display (<i>AliPHOSv4::BuildGeometry()</i>)
127 and for the GEANT tracking (<i>AliPHOSv4::CreateGeometry()</i>).
130 It watches the tracks passing through the active media of EMCA and PPSD
131 (<i>AliPHOSv4::StepManager()</i>).
134 It stores the hits (<i>AliPHOSv4::AddHit()</i>), using the <i>AliPHOSHit</i>
138 It stores the digits (<i>AliPHOSv4::FinishEvent()</i>), using the <i>AliPHOSDigit</i>
143 <a href="AliPHOSv1.html"><i><u>AliPHOSv1</u></i></a> : derives from <i>AliPHOSv0</i> and includes the light transport
144 in the crystal and the response of the PIN photodiode à la O. H. Oddland.
146 <a href="AliPHOSvFast.html"><i><u>AliPHOSvFast</u></i></a> : used for <a href="fastsimulation.html">fast simulation</a>.
148 <a href="AliPHOSGeometry.html"<i><u>AliPHOSGeometry</u></i>: It derives from <i>TObject</i> to make it
149 persistent. It is a singleton, i.e., a pointer to the unique instance of
150 this class is obtained by:
153 AliPHOSGeometry * Geom = AliPHOSGeometry::GetInstance()
158 It sets the various parameters for the geometry description and provides
159 the method to access all the parameters. To avoid cumbersome macros at
160 run time these parameters can only be changed manually in the source code.
163 It provides the method to convert the absolute detector Id (crystal in
164 EMCA or pad in PPSD) into a relative Id : PHOS module number, PPSD module
165 number, row, column (<i>AliPHOSGeometry::AbsToRelNumbering()</i>) and the
166 reverse operation (<i>AliPHOSGeometry::RelToAbsNumbering()</i>).
169 It provides the method to convert an absolute Id into a three-vector giving
170 the position of the detector in ALICE (<i>AliPHOSGeometry::RelPosInAlice()</i>).
174 <a href="AliPHOSHitt.html"<i><u>AliPHOSHit</u></i></a>: It derives from <i>AliHit</i>. It stores the
175 hits as the pair (absolute Id, deposited energy). The hits presently are stored in the hit TTree
176 as one hit per elementary cell (EMC crystal or PPSD gas cell) (See the
177 the AddHit() method in <i>AliPHOSv0</i>).
179 <a href="AliPHOSDigit.html"<i><u>AliPHOSDigit</u></i></a> : It derives from <i>AliDigit</i>. It stores
180 the digits as the pair (absolute Id, energy) in the digit TTree (see
181 the FinishEvent() method in <i>AliPHOSv0</i>).
189 AliPHOS * phos = new AliPHOSv4("PHOS", char * name) ;
192 where name can take the following values:
195 <i>GPS2</i>: will create EMCA plus PPSD
198 <img SRC="images/AliPHOSv0AllViews.gif" ALT="ROOT display of PHOS: All Views" >
199 <b> Figure 3a.: </b> <i> ROOT Display of ALICE: All Views </i>
201 <img SRC="images/AliPHOSv0FrontView.gif" ALT="ROOT display of PHOS: Front View" >
202 <b> Figure 3b.: </b> <i> ROOT Display of ALICE: Front Views </i>
204 <img SRC="images/AliPHOSv03DView1.gif" ALT="ROOT display of PHOS: 3D View" >
205 <b> Figure 3c.: </b> <i> ROOT Display of ALICE: All View3 </i>
207 <img SRC="images/AliPHOSv0PPSDFrontView.gif" ALT="Zoom on PPSD: Front View " >
208 <b> Figure 4.a: </b> <i> ROOT Display of ALICE: zoom on PPSD, Front Views </i>
210 <img SRC="images/AliPHOSv0PPSDPerspectiveView.gif" ALT="Zoom on PPSD: Perspective View " >
211 <b> Figure 4.b: </b> <i> ROOT Display of ALICE: zoom on PPSD, Perspective View </i>
215 more to come from Protvino (EMCA plus other CPV type)</li>
218 EMCA consists of 5 modules of 64x64 modules each, positionned at
219 azimuthal angles -40, -20, 0, +20, +40 (see figures). PPSD consists per
220 EMCA module of 2 layers of 4x4 gas detectors each, each detector having
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224 © <a href="mailto:schutz@in2p3.fr">>Groupe Photons Subatech (Yves SCHUTZ)</a>
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228 <!-- Created: Wed Nov 17 12:16:58 CET 1999 -->
230 Last modified: Tue Mar 14 18:38:42 CET 2000
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