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