[430] | 1 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> |
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| 6 | <meta name="Originator" content="Skowron"> |
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| 7 | <link rel="stylesheet" type="text/css" href="../ptc_general/madxdoc_ps.css"> |
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| 8 | <title>PTC_TRACKLINE</title> |
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| 9 | <style> |
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| 10 | </style> |
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| 11 | </head> |
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| 12 | <body ="" bgcolor="#ffffff"> |
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| 13 | <div style="text-align: center;"> |
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| 14 | <center> EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH |
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| 15 | <img src="http://cern.ch/madx/icons/mx7_25.gif" align="right"> |
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| 16 | <h1>PTC_TRACKLINE</h1> |
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| 17 | <h2>PERFORMS A PARTICLE TRAJECTORY TRACKING WITH ACCELERATION USING PTC</h2> |
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| 18 | </center> |
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| 19 | </div> |
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| 20 | <div class="madxdocContent"> |
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| 21 | <!-- ########################################################## --> |
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| 22 | <!-- ########################################################## --> |
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| 23 | <!-- ########################################################## --> |
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| 24 | <h3 style="margin-top: 0cm; text-align: left; text-indent: 0cm;" |
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| 25 | align="center"> <span> USER MANUAL </span> |
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| 26 | </h3> |
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| 27 | <!-- ########################################################## --> |
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| 28 | <h4>SYNOPSIS</h4> |
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| 29 | |
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| 30 | <pre><big> |
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| 31 | |
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| 32 | PTC_TRACKLINE, |
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| 33 | turns [integer, 1, 0 ] , |
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| 34 | onetable [logical, false, true ], |
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| 35 | everystep [logical, false, true], |
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| 36 | tableallsteps [logical, false, true], |
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| 37 | gcs [logical, false, true], |
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| 38 | file [string, "track", "track" ], |
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| 39 | rootntuple [logical, false, true], |
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| 40 | extension [string, "", ""]; |
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| 41 | </big></pre> |
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| 42 | |
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| 43 | <table cellpadding="2" cellspacing="2" border="0" width="100%"> |
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| 44 | <tbody> |
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| 45 | |
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| 46 | <tr> |
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| 47 | <th valign="Middle" width="150" align="Center"> Parameter Name </th> |
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| 48 | <th valign="Top" width="100" align="Center"> Type </th> |
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| 49 | <th valign="Middle" width="300" align="Center" colspan="2"> Default value </th> |
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| 50 | <th valign="Middle" align="Center"> Description </th> |
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| 51 | |
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| 52 | </tr> |
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| 53 | |
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| 54 | <tr> |
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| 55 | <th valign="Middle" align="Center"> </th> |
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| 56 | <th valign="Middle" align="Center"> </th> |
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| 57 | <th valign="Middle" align="Center" width="150" > Not present </th> |
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| 58 | <th valign="Middle" align="Center" width="150" > Present, but value not specified </th> |
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| 59 | <th valign="Middle" align="Center"> </th> |
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| 60 | |
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| 61 | </tr> |
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| 62 | |
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| 63 | <tr> |
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| 64 | <td valign="Top" align="center"> turns </td> |
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| 65 | <td valign="Top" align="Center"> integer </td> |
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| 66 | <td valign="Top" align="Center"> 1 </td> |
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| 67 | <td valign="Top" align="Center"> - </td> |
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| 68 | <td valign="Top" align="Left"> Number of turns </td> |
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| 69 | </tr> |
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| 70 | |
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| 71 | <tr> |
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| 72 | <td valign="Top" align="center"> onetable </td> |
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| 73 | <td valign="Top" align="Center"> logical </td> |
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| 74 | <td valign="Top" align="Center"> false </td> |
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| 75 | <td valign="Top" align="Center"> true </td> |
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| 76 | <td valign="Top" align="Left"> If false, tracking data are written to a single table |
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| 77 | for each track for each observation point. Table names follow |
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| 78 | the naming <i>filename</i>.obsMMMM.pNNNN, where <br> |
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| 79 | <i>filename</i> is settable prefix with <b> file </b> parameter (see below),<br> |
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| 80 | MMMM is observation point number and <br> |
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| 81 | NNNN is track number <br> |
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| 82 | <p> |
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| 83 | If true, all data are written to single table called onetable </td> |
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| 84 | </tr> |
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| 85 | |
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| 86 | <tr> |
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| 87 | <td valign="Top" align="center"> file </td> |
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| 88 | <td valign="Top" align="Center"> string </td> |
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| 89 | <td valign="Top" align="Center"> "track" </td> |
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| 90 | <td valign="Top" align="Center"> "track" </td> |
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| 91 | <td valign="Top" align="Left"> Name of file where track parameters are written, |
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| 92 | see description of onetable switch above |
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| 93 | </td> |
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| 94 | </tr> |
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| 95 | |
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| 96 | <tr> |
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| 97 | <td valign="Top" align="center"> rootntuple </td> |
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| 98 | <td valign="Top" align="Center"> logical </td> |
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| 99 | <td valign="Top" align="Center"> false </td> |
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| 100 | <td valign="Top" align="Center"> true </td> |
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| 101 | <td valign="Top" align="Left"> Stores data to ROOT file as ntuple. |
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| 102 | Accessible only if RPLOT plugin is available. |
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| 103 | i.e. only if madxp is dynamically linked |
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| 104 | and RPLOT plugin is present |
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| 105 | </td> |
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| 106 | </tr> |
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| 107 | |
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| 108 | |
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| 109 | <tr> |
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| 110 | <td valign="Top" align="center"> everystep </td> |
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| 111 | <td valign="Top" align="Center"> logical </td> |
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| 112 | <td valign="Top" align="Center"> false </td> |
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| 113 | <td valign="Top" align="Center"> true </td> |
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| 114 | <td valign="Top" align="Left"> Switches on track parameters recording every integration step. |
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| 115 | Normally tracking data are stored only at the end of each element. |
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| 116 | Everystep mode allows the user to get finer data points. |
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| 117 | It implies usage of the so called node (thin) layout. |
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| 118 | <p> |
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| 119 | Track parameters are stored for each step in thintracking_ptc.txt file. |
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| 120 | Storage of parameters in a table for each step might be very memory |
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| 121 | consuming. To switch it off use <b>tableallsteps</b> |
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| 122 | <p> |
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| 123 | Collective effects can be taken to the account only using this mode |
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| 124 | (this feature of PTC is not interfaced into MAD-X). |
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| 125 | |
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| 126 | </td> |
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| 127 | </tr> |
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| 128 | |
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| 129 | |
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| 130 | <tr> |
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| 131 | <td valign="Top" align="center"> gcs </td> |
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| 132 | <td valign="Top" align="Center"> logical </td> |
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| 133 | <td valign="Top" align="Center"> false </td> |
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| 134 | <td valign="Top" align="Center"> true </td> |
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| 135 | <td valign="Top" align="Left"> Instructs the code to store track parameters in |
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| 136 | Global Coordinate System - normally it starts at the |
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| 137 | entrance phase of the first element. |
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| 138 | </td> |
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| 139 | </tr> |
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| 140 | |
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| 141 | |
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| 142 | </tbody> |
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| 143 | </table> |
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| 144 | |
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| 145 | <!-- <font color="#ff0000"><b>Non existing.</b></font> --> |
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| 146 | |
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| 147 | |
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| 148 | <h4> Description </h4> |
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| 149 | |
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| 150 | <p>This MAD-X command performs ray tracking that takes to the account |
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| 151 | acceleration in traveling wave cavities. It must be invoked in the scope of |
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| 152 | correctly initialized <a href="../ptc_general/ptc_general.html"> PTC |
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| 153 | environment</a>, i.e. after <a href="../ptc_general/ptc_general.html"> |
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| 154 | PTC_CREATE_UNIVERSE and PTC_CREATE_LAYOUT commands </a> |
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| 155 | and before corresponding <a href="../ptc_general/ptc_general.html"> |
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| 156 | PTC_STOP </a>. |
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| 157 | All tracks that are spawned with |
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| 158 | <a href="../ptc_track/ptc_track.html"> PTC_START </a> |
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| 159 | commands beforehand PTC_TRACKLINE command is issued are tracked. Track |
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| 160 | parameters are dumped at every defined observation point |
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| 161 | (see <a href="../ptc_track/ptc_track.html"> PTC_OBSERVE command</a>). |
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| 162 | Please note that MAD-X always creates observation point at the end of a |
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| 163 | sequence. Depending on value of onetable switch, all output information |
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| 164 | is stored in one table (and also file), or in one table per track per |
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| 165 | observation point is written if the switch is false. The user must note |
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| 166 | that track parameters plotting (see <a href="../plot/plot.html"> PLOT |
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| 167 | command</a>) is only possible if onetable switch is set to false |
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| 168 | (status as for Feb. 2006). |
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| 169 | This unfortunate solution is the legacy of the regular MAD-X track |
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| 170 | command, that is designed for |
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| 171 | circular machines where the user usually tracks a few particles for |
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| 172 | many turns rather then many particles for one turn each. </p> |
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| 173 | |
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| 174 | <p>Tracks that do not fit in aperture are immediately stopped. |
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| 175 | </p> |
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| 176 | |
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| 177 | <p>Behavior of PTC calculations can be adapted with |
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| 178 | <a href="../ptc_auxiliaries/PTC_SetSwitch.html"> PTC_SETSWITCH command </a> |
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| 179 | and with appropriate switches of |
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| 180 | <a href="http://cern.ch/madx/ptc_general/ptc_general.html"> |
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| 181 | PTC_CREATE_LAYOUT command</a>. |
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| 182 | </p> |
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| 183 | |
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| 184 | <!-- ########################################################## --> |
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| 185 | <h4> Command parameters and switches </h4> |
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| 186 | <div> |
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| 187 | <dl> |
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| 188 | <dt><b> turns </b></dt> |
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| 189 | <dd> |
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| 190 | <i> integer, default value 1, no default value if value explicitly not specified </i> |
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| 191 | <p> Number of turns around sequence. If layout is not closed then its value is enforced to 1. </p> |
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| 192 | </dd> |
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| 193 | |
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| 194 | <dt><b> onetable </b></dt> |
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| 195 | <dd> |
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| 196 | <i> boolean, default value false, if value explicitly not specified then true </i> |
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| 197 | <p> If true then only one table is created and one file is written |
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| 198 | to disk. If false one file per track per observation point is written. |
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| 199 | File format is filename.obsNNNN.pMMMM, where NNNN and MMMM are numbers |
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| 200 | of observation point and track, respectively. Filename is defined by |
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| 201 | the switch described below. |
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| 202 | </p> |
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| 203 | </dd> |
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| 204 | |
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| 205 | <dt><b> file </b></dt> |
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| 206 | <dd> |
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| 207 | <i> character string, default is "track" </i> |
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| 208 | <p> name of file where track parameters are written, see description of onetable switch above. </p> |
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| 209 | </dd> |
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| 210 | </dl> |
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| 211 | </div> |
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| 212 | |
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| 213 | <!-- ############################################################ --> |
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| 214 | <!-- ############################################################ --> |
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| 215 | <!-- ############################################################ --> |
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| 216 | |
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| 217 | <h3> PROGRAMMERS MANUAL </h3> |
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| 218 | |
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| 219 | The routine PTC_TRACKLINE is implemented in file madx_ptc_trackcavs.f90 |
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| 220 | Its single parameter is the number of observation points. |
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| 221 | |
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| 222 | <p>The call sequence from MAD-X interpreter is the following <br> |
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| 223 | exec_command in madxp.c; <br> |
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| 224 | pro_ptc_trackline in madxn.c; This routine creates appropriates tables |
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| 225 | where the track parameters are stored, and after execution of the |
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| 226 | Fortran routine dumps filled table(s) to files.<br> |
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| 227 | w_ptc_trackline_ in wrap.f90; Just interface to the appropriate Fortran |
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| 228 | module <br> |
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| 229 | ptc_trackline in madx_ptc_trackline.f90 |
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| 230 | </p> |
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| 231 | |
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| 232 | <p>The key routine that enables appropriate calculation of beam and |
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| 233 | track parameters in the presence of traveling wave cavities is |
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| 234 | setcavities. </p> |
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| 235 | |
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| 236 | <p>Firstly, the ptc_trackline routine finds out which are the |
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| 237 | observation points. |
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| 238 | For this purpose array of integers observedelements is allocated. Its |
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| 239 | length is equal to the number of elements in the sequence. |
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| 240 | All elements are zero by default. If an element with an index n is an |
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| 241 | observation point |
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| 242 | then observedelements[n] is equal to 1. This solution enables fast |
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| 243 | checking if track parameters |
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| 244 | should be sent to a table after a given element. </p> |
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| 245 | |
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| 246 | <p>Further <a href="../ptc_auxiliaries/PTC_SetCavities.html">setcavities subroutine</a> |
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| 247 | is called if it was not executed yet before. </p> |
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| 248 | |
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| 249 | <p>PTC_TRACKLINE reads the track initial parameters from the table with |
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| 250 | the help of gettrack |
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| 251 | function (implemented in C in file madxn.c). For the performance |
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| 252 | reasons gettrack creates a two dimensional array and buffers there all |
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| 253 | the initial track parameters upon first call. The array is destroyed |
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| 254 | with a call of deletetrackstrarpositions function that is performed at |
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| 255 | the very end of ptc_trackline subroutine. |
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| 256 | </p> |
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| 257 | |
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| 258 | <p>Tracking itself is implemented in a doubly nested loop. |
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| 259 | The external one goes over all initiated tracks, |
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| 260 | and the internal one performs tracking of a given track element by element. |
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| 261 | The key PTC routine is called TRACK. It propagates a track described by |
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| 262 | an array of 6 real numbers, denoted as X in equations below. |
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| 263 | The important issue is that they are the canonical variables. In order |
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| 264 | to follow the standard MAD-X representation the values that are written |
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| 265 | to tables and files are scaled appropriately to the reference momentum |
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| 266 | for a given element. In the general case it changes along the line if |
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| 267 | traveling wave cavities are present. |
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| 268 | Hence, momenta xp, yp and zp are |
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| 269 | </p> |
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| 270 | |
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| 271 | <pre> |
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| 272 | zp=sqrt((1+x(5))**2 - x(2)**2 - x(4)**2) <br> |
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| 273 | xp = x(2)/zp<br> |
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| 274 | yp = x(4)/zp<br> |
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| 275 | </pre> |
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| 276 | |
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| 277 | where array x containing 6 elements is the track position in the PTC |
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| 278 | representation, i.e. x(1) is horizontal spacial coordinate, x(2) - |
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| 279 | horizontal momentum, |
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| 280 | x(3) - vertical spacial coordinate, x(4) - vertical momentum, |
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| 281 | x(5) - δp/p<sub>0</sub>c, x(6) - longitudinal coordinate |
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| 282 | (caution, the exact meaning depends on the PTC settings, see |
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| 283 | <a href="../ptc_auxiliaries/PTC_SetSwitch.html"> PTC_SETSWITCH command </a>). |
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| 284 | |
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| 285 | </div> |
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| 286 | </body> |
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| 287 | </html> |
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