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14 | ||
15 | <body dir="ltr" lang="en-US"> | |
16 | <p style="margin-top: 0.42cm; margin-bottom: 0.5cm; page-break-after: avoid;"> | |
17 | <font face="Albany, sans-serif"><font size="4">============================================================================</font></font></p> | |
18 | <p style="margin-top: 0.42cm; margin-bottom: 0.5cm; page-break-after: avoid;"> | |
19 | <font face="Albany, sans-serif"><font size="4">Description of ALICE ITS | |
20 | Geometry Code (Rev. 1,00 - April, 30<sup>th</sup> | |
21 | 2008 - M. Sitta)</font></font></p> | |
22 | <p style="margin-top: 0.42cm; margin-bottom: 0.5cm; page-break-after: avoid;"> | |
23 | <font face="Albany, sans-serif"><font size="4">============================================================================</font></font></p> | |
24 | <p style="margin-bottom: 0cm;"><a name="Content"></a><strong><font style="font-size: 16pt;" size="4">Content</font></strong> | |
25 | </p> | |
26 | <p style="margin-bottom: 0cm;"><br> | |
27 | </p> | |
28 | <ol> | |
29 | <li><p style="margin-bottom: 0cm;"><a href="#punto%201">General | |
30 | description</a></p> | |
31 | </li><li><p style="margin-bottom: 0cm;"><a href="#punto%202"> | |
32 | Detector-specific classes</a></p> | |
33 | </li><li><p style="margin-bottom: 0cm;"><a href="#punto%203">Initialization | |
34 | </a></p> | |
35 | </li><li><p style="margin-bottom: 0cm;"><a href="#punto%204">Main | |
36 | methods</a></p> | |
37 | </li><li><p style="margin-bottom: 0cm;"><a href="#punto%205">Helper | |
38 | classes AliITSgeom and AliITSgeomTGeo</a></p> | |
39 | </li></ol> | |
40 | <p style="margin-bottom: 0cm;"><br> | |
41 | </p> | |
42 | <p style="margin-bottom: 0cm;"><br> | |
43 | </p> | |
44 | <p><a name="punto 1"></a><strong><a href="#Content" name="punto 1">General | |
45 | description</a></strong></p> | |
46 | <p style="margin-bottom: 0cm;">The <font face="Courier 10 Pitch"> | |
47 | AliITSv11Hybrid</font> class describes the overall ITS geometry. It is a | |
48 | mix between the old geometry (originally coded in the | |
49 | <font face="Courier 10 Pitch">AliITSvPPRasymmFMD</font> class) and the new | |
50 | TGeo geometry (v11). The "old" part is described using Geant3 volumes, while | |
51 | the "new" one using TGeo volumes; moreover the new part is more adherent to | |
52 | the technical drawings and so is more realistic. | |
53 | </p> | |
54 | <p style="margin-bottom: 0cm;">Proper flags, set in the | |
55 | <font face="Courier 10 Pitch">AliITSInitGeometry</font> class, determine | |
56 | whether the old or the new part is used. | |
57 | </p> | |
58 | <p style="margin-bottom: 0cm;">Currently all the sensitive detectors and their | |
59 | supports, the mechanical supports and part of the services (namely the SDD | |
60 | cables) are described in the new geometry. The rest of the services and some | |
61 | other mechanics are (sometimes partly) described in the old geometry. Work is | |
62 | in progress to move everything in the new geometry. | |
63 | </p> | |
64 | <p style="margin-bottom: 0cm;"><br> | |
65 | </p> | |
66 | <p style="margin-bottom: 0cm;">================================================================================</p> | |
67 | <p style="margin-bottom: 0cm;"><br> | |
68 | </p> | |
69 | <p><a name="punto 2"></a><strong><a href="#Content" name="punto 2"> | |
70 | Detector-specific classes</a></strong></p> | |
71 | <p style="margin-bottom: 0cm;">The old geometry is fully described in the | |
72 | <font face="Courier 10 Pitch">AliITSv11Hybrid</font> class. For the new | |
73 | geometry on the other hand, a set of specific classes are defined | |
74 | </p> | |
75 | <p style="margin-bottom: 0cm;"><br> | |
76 | </p> | |
77 | <p style="margin-bottom: 0cm;">-> <font face="Courier 10 Pitch"> | |
78 | AliITSv11GeometrySPD</font> describes the whole SPD geometry | |
79 | </p> | |
80 | <p style="margin-bottom: 0cm;">-> <font face="Courier 10 Pitch"> | |
81 | AliITSv11GeometrySDD</font> describes the whole SDD geometry | |
82 | </p> | |
83 | <p style="margin-bottom: 0cm;">-> <font face="Courier 10 Pitch"> | |
84 | AliITSv11GeometrySSD</font> describes the whole SSD geometry | |
85 | </p> | |
86 | <p style="margin-bottom: 0cm;">-> <font face="Courier 10 Pitch"> | |
87 | AliITSv11GeometrySupport</font> describes the geometry of some mechanical | |
88 | supports (thermal shields and support cylinders and cones) | |
89 | </p> | |
90 | <p style="margin-bottom: 0cm;"><br> | |
91 | </p> | |
92 | <p style="margin-bottom: 0cm;">================================================================================</p> | |
93 | <p style="margin-bottom: 0cm;"><br> | |
94 | </p> | |
95 | <p><a name="punto 3"></a><strong><a href="#Content" name="punto 3"> | |
96 | Initialization</a></strong></p> | |
97 | <p style="margin-bottom: 0cm;">To initialize an object of the | |
98 | <font face="Courier 10 Pitch">AliITSv11Hybrid</font> class it is enough to | |
99 | call its constructor in the <font face="Courier 10 Pitch">Config.C</font> | |
100 | macro | |
101 | </p> | |
102 | <p style="margin-bottom: 0cm;"><font face="Courier 10 Pitch"> | |
103 | AliITSv11Hybrid *ITS = new AliITSv11Hybrid("ITS","ITS detailed version with TGeo description");</font> | |
104 | </p> | |
105 | <p style="margin-bottom: 0cm;">the first string is the detector name (which | |
106 | is actually ignored, and internally set to "ITS"), the second string is an | |
107 | arbitrary title. Both strings are passed to the <font face="Courier 10 Pitch"> | |
108 | AliITS</font> constructor. | |
109 | </p> | |
110 | <p style="margin-bottom: 0cm;"><br> | |
111 | </p> | |
112 | <p style="margin-bottom: 0cm;">The class constructor initializes its private | |
113 | members, creates an object for each detector-specific class and sets their | |
114 | names, and sets the defaults for some detector parameters. | |
115 | </p> | |
116 | <p style="margin-bottom: 0cm;"><br> | |
117 | </p> | |
118 | <p style="margin-bottom: 0cm;">================================================================================</p> | |
119 | <p style="margin-bottom: 0cm;"><br> | |
120 | </p> | |
121 | <p><a name="punto 4"></a><strong><a href="#Content" name="punto 4">Main | |
122 | Methods</a></strong></p> | |
123 | <p style="margin-bottom: 0cm;">The main methods of the | |
124 | <font face="Courier 10 Pitch">AliITSv11Hybrid</font> class are | |
125 | </p> | |
126 | <p style="margin-bottom: 0cm;"><br> | |
127 | </p> | |
128 | <ul> | |
129 | <li><font face="Courier 10 Pitch">AliITSv11Hybrid::CreateGeometry</font> first | |
130 | calls <font face="Courier 10 Pitch">CreateOldGeometry</font> to define the | |
131 | old (Geant3) volumes (the ones still active according to the aforementioned | |
132 | flags); then it calls specific methods of the detector classes to create | |
133 | the new geometry</li> | |
134 | <li><font face="Courier 10 Pitch">AliITSv11Hybrid::CreateOldGeometry</font> | |
135 | creates the old geometry volumes; flags are used to determine which sections | |
136 | are to be skipped because already coded in the detector-specific classes</li> | |
137 | <li><font face="Courier 10 Pitch">AliITSv11Hybrid::CreateMaterials</font> | |
138 | defines all materials and mediums used in the ITS geometry description</li> | |
139 | <li><font face="Courier 10 Pitch">AliITSv11Hybrid::AddAlignableVolumes</font> | |
140 | creates entries for alignable volumes associating the symbolic volume name | |
141 | with the corresponding volume path</li> | |
142 | <li><font face="Courier 10 Pitch">AliITSv11Hybrid::StepManager</font> is | |
143 | called at every step in the ITS to save hits according to the subdetector | |
144 | which the particle is in</li> | |
145 | </ul> | |
146 | <p style="margin-bottom: 0cm;"><br> | |
147 | </p> | |
148 | <p style="margin-bottom: 0cm;">================================================================================</p> | |
149 | <p style="margin-bottom: 0cm;"><br> | |
150 | </p> | |
151 | <p><a name="punto 5"></a><strong><a href="#Content" name="punto 5">Helper | |
152 | classes AliITSgeom and AliITSgeomTGeo</a></strong></p> | |
153 | <p style="margin-bottom: 0cm;"><font face="Courier 10 Pitch">AliITSgeomTGeo | |
154 | </font> is a simple interface class to TGeoManager. It is used in the | |
155 | simulation and reconstruction in order to query the TGeo ITS geometry. | |
156 | </p> | |
157 | <p style="margin-bottom: 0cm;">It has methods such as for example<br> | |
158 | <font face="Courier 10 Pitch">GetModuleIndex</font> to compute the module | |
159 | index number from the layer, ladder, and detector numbers<br> | |
160 | <font face="Courier 10 Pitch">GetModuleId</font> to compute the layer, | |
161 | ladder and detector number given the module index number<br> | |
162 | <font face="Courier 10 Pitch">GetLayer</font> to compute the layer number | |
163 | for a given the module index<br> | |
164 | <font face="Courier 10 Pitch">GetMatrix</font> to get the | |
165 | transformation matrix for a given module by quering the TGeoManager<br> | |
166 | <font face="Courier 10 Pitch">GetTranslation</font> and | |
167 | <font face="Courier 10 Pitch">GetRotation</font> to get the translation | |
168 | vector or the rotation matrix for a given module by quering the | |
169 | TGeoManager<br> | |
170 | <font face="Courier 10 Pitch">LocalToGlobal</font> and | |
171 | <font face="Courier 10 Pitch">GlobalToLocal</font> to make the conversion | |
172 | from the local sensitive reference system to the global reference system | |
173 | and vice-versa, for an arbitrary local or global position | |
174 | </p> | |
175 | <p style="margin-bottom: 0cm;"><br> | |
176 | </p> | |
177 | <p style="margin-bottom: 0cm;">Similarly the <font face="Courier 10 Pitch"> | |
178 | AliITSgeom</font> class contains other methods for querying and | |
179 | interfacing the ITS geometry. | |
180 | </p> | |
181 | <p style="margin-bottom: 0cm;"><br> | |
182 | </p> | |
183 | ||
184 | </body></html> |