1 | UNDERGROUND PHYSICS ADVANCED EXAMPLE - DMX |
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2 | |
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3 | UserRequirements.txt - Alex Howard, e-mail: alexander.howard@cern.ch, 29/11/01. |
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4 | |
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5 | Introduction: |
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6 | |
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7 | This document is an initial introduction to the Dark Matter Example - |
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8 | DMX. A single liquid xenon cell is simulated within Geant4 and the |
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9 | scintillation light produced from interactions from various |
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10 | calibration species is recorded as hits in a PhotoMultiplier Tube |
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11 | (PMT). The output is then written to an ASCII file for future |
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12 | off-line analysis. |
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13 | |
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14 | ------------------------------------------------------------------------------- |
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15 | |
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16 | User Requirements: |
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17 | |
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18 | General |
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19 | |
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20 | UR 1.1: Configure the run management |
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21 | |
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22 | UR 1.2: Configure the event loop |
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23 | |
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24 | |
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25 | |
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26 | Geometry: |
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27 | Experimental set-up: |
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28 | |
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29 | UR 2.1: |
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30 | A "cavern" of dimensions 5m x 6m x 3m with concrete walls is defined |
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31 | as the World Volume. In the centre of the cavern a steel vacuum |
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32 | vessel containing liquid and gaseous xenon is placed. The internal |
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33 | construction of the vessel accurately reproduces an existing prototype |
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34 | Dark Matter detector which allows experimental comparison. The active |
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35 | detector volume is defined by a series of metal rings, complemented by |
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36 | a cover mirror and a PMT immersed in the liquid. Two grids and a |
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37 | thermalising copper shield are also incorporated. The liquid/gas |
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38 | interface is located 6mm away from the mirror surface. A Am241 |
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39 | calibration source is suspended from one of the grids in the liquid |
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40 | phase, above the PMT. |
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41 | |
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42 | XXX================XXX mirror |
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43 | XXX________________XXX gas phase |
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44 | XXX XXX |
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45 | XXX XXX liquid phase |
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46 | XXX XXX |
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47 | XXX.......U........XXX grid + calibrator |
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48 | XXX................XXX grid |
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49 | XXX| |XXX |
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50 | | ___------___ | |
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51 | || PMT || |
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52 | || || |
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53 | |
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54 | An accurate simulation of the above set-up should be carried. |
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55 | |
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56 | UR 2.2: |
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57 | Record the energy deposited in the sensitive volume of the xenon |
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58 | chamber (liquid phase). |
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59 | |
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60 | UR 2.3: |
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61 | Produce scintillation photons with different time constants and light |
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62 | yields depending upon the species of particle causing the excitation - |
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63 | either nuclear recoil or electron recoil type interactions. |
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64 | |
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65 | UR 2.4: |
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66 | Implement reflectivities and transmission probabilities for all materials |
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67 | concerned. |
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68 | |
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69 | UR 2.5: |
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70 | Ray trace the scintillation back to the PMT and record hit times, positions and |
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71 | number of photons. |
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72 | |
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73 | |
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74 | PHYSICS: |
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75 | |
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76 | The following areas of physics should be included: |
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77 | |
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78 | UR 3.1: · Low Energy Electromagnetic - to 250eV for both e and photons |
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79 | Maximum energy range around 10 MeV for any particle |
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80 | UR 3.2: · Compton Scattering |
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81 | UR 3.3: · Photoelectric Effect |
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82 | UR 3.4: · Bremsstrahlung |
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83 | UR 3.5: · Rayleigh Scattering - for both optical photons and hard |
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84 | X-rays/Gammas |
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85 | UR 3.6: · Electromagnetic ionisation |
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86 | UR 3.7: · Delta Rays |
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87 | Produced discretely down to 250eV to allow secondaries and |
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88 | tertiaries to be properly handled |
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89 | UR 3.8: · Heavy Ion Transport - to 250eV for protons, alphas and nuclei |
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90 | Allows separate scintillation time and yield compared to gammas |
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91 | (electrons) |
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92 | UR 3.9: · Radioactive Decay - induced |
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93 | All materials are sensitive to induced activity as a consequence |
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94 | of photo-nuclear or neutron capture |
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95 | UR 3.10: · Radioactive Decay - sources |
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96 | Specific nuclei can be decayed within the geometry to reproduce |
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97 | experimental calibration the experiment |
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98 | UR 3.11: · Neutron tracking from medium energy (few MeV) to thermal capture |
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99 | Discretely transported through-out the volume to give full |
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100 | detector response for both neutron capture activation and |
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101 | elastic and inelastic interaction in the target volume |
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102 | UR 3.12: · Scintillation light production and ray-tracing to PMT |
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103 | Optical photon transport introduced to allow realistic |
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104 | detector response to be produced. |
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105 | |
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106 | ParticleSource: |
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107 | |
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108 | UR 4.1: |
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109 | Implement a generic particle source that allows various particles, ions and |
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110 | nuclei to be fired or decayed anywhere within the volume. |
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111 | |
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112 | UR 4.2: |
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113 | Allow confinement of the particle source to within given volumes and randomly |
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114 | select particle or ion production within that volume. |
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115 | |
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116 | UR 4.3: |
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117 | Allow various source shapes - point, sphere and cylinder have been |
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118 | implemented. |
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119 | |
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120 | UR 4.4: !!!! not in ours !!! |
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121 | Allow spectrum of energies to be chosen as well as a monoenergetic particle |
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122 | type. |
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123 | |
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124 | |
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125 | Radioactive Decay Module: |
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126 | |
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127 | UR 5.1: |
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128 | Allows specific ions to be decayed within set nuclear limits and energies and |
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129 | positions - linked to Particle Source above. |
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130 | |
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131 | UR 5.2: |
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132 | Can control induced activity to specific volumes. |
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133 | |
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134 | UR 5.3: |
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135 | Allows increased functionality in terms of choice of weighting for the decay |
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136 | and other non-analogue MC techniques. |
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137 | |
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138 | |
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139 | Analysis: |
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140 | |
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141 | UR 6.1: |
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142 | Outputs to file "hits.out" the event number (Evt #), the energy |
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143 | deposited in the liquid phase (Etot, MeV), the number of hits in LXe |
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144 | (LXe hits), the time of the first hit (LXeTime, ns), the number of PMT |
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145 | hits (PMT hits), the average PMT hit time relative to the first hit in |
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146 | LXe (PmtTime, ns), the first particle to hit the LXe (First hit) and |
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147 | flags the type of particles depositing energy - gamma, neutron, |
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148 | electron, positron, proton, other (Flags). |
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149 | |
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150 | UR 6.2: |
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151 | The "First hit" and "Flags" described above constitute a record of |
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152 | particle type history important for identifying and differentiating |
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153 | between elastic and inelastic neutron interactions. |
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154 | |
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155 | |
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156 | |
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157 | Visualisation: |
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158 | |
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159 | UR 7.1: |
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160 | Visualise the experimental set-up. |
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161 | |
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162 | UR 7.2: |
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163 | Visualise tracks in the experimental set-up. |
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164 | |
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165 | UR 7.3: |
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166 | Allow the choice between scintillation light, PMT photocathode hits, |
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167 | and full tracking to be displayed. |
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168 | |
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169 | UR 7.4: |
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170 | Allow the user to choose specific track colours for gammas, neutrons, |
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171 | charged-plus and charged-minus tracks. |
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172 | |
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173 | UR 7.5: |
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174 | Allow output to stored interactive files using the HEPREP interface which can |
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175 | then be read into Wired and other XML packages. |
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176 | |
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177 | |
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178 | User Interface: |
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179 | |
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180 | UR 8.1: |
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181 | |
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182 | Allow control of the particle source via the /dmx/gun control: |
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183 | |
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184 | Command directory path : /dmx/gun/ |
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185 | Guidance : |
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186 | Particle Source control commands. |
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187 | |
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188 | Sub-directories : |
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189 | Commands : |
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190 | 1) List * List available particles. |
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191 | 2) particle * Set particle to be generated. |
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192 | 3) direction * Set momentum direction. |
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193 | 4) energy * Set kinetic energy. |
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194 | 5) position * Set starting position of the particle. |
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195 | 6) ion * Set properties of ion to be generated. |
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196 | 7) type * Sets source distribution type. |
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197 | 8) shape * Sets source shape type. |
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198 | 9) centre * Set centre coordinates of source. |
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199 | 10) halfz * Set z half length of source. |
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200 | 11) radius * Set radius of source. |
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201 | 12) confine * Confine source to volume (NULL to unset). |
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202 | 13) angtype * Sets angular source distribution type |
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203 | 14) energytype * Sets energy distribution type |
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204 | 15) verbose * Set Verbose level for gun |
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205 | |
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206 | |
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207 | UR 8.2: |
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208 | Control verbosities via: |
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209 | The user should have the ability to change several features including |
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210 | a) verbosities can be controlled for |
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211 | /control/verbose |
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212 | /run/verbose |
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213 | /tracking/verbose |
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214 | /hits/verbose |
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215 | /grdm/verbose |
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216 | /dmx/gun/verbose |
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217 | |
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218 | |
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219 | UR 8.3: |
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220 | Control the output to the screen into Modulo N events: |
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221 | using printModulo control. |
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222 | |
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223 | Command /dmx/printModulo |
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224 | Guidance : |
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225 | Print events modulo n |
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226 | Range of parameters : EventNb>0 |
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227 | |
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228 | Parameter : EventNb |
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229 | Parameter type : i |
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230 | Omittable : False |
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231 | |
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232 | |
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233 | UR 8.4: |
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234 | Draw commands controlled via /dmx/draw/: |
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235 | |
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236 | DM Example draw commands. |
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237 | |
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238 | Sub-directories : |
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239 | Commands : |
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240 | 1) drawColours * Tracks drawn by Event (standard colours) or |
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241 | by Step (custom colours) |
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242 | 2) drawTracks * Which tracks to draw in the event |
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243 | 3) drawHits * Set flag to draw hits in PMT. |
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244 | 4) neutronColour * Colour of neutron in the event |
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245 | 5) gammaColour * Colour of gamma in the event |
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246 | 6) opticalColour * Colour of gamma in the event |
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247 | 7) chargedplusColour * colour of chargedplus in the event |
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248 | 8) chargedminusColour * colour of chargedminus in the event |
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249 | |
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250 | |
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251 | |
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252 | UR 8.5: |
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253 | Control the files to be saved - PMT hits and event summary in terms of |
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254 | energy deposit and number of photon hits observed. |
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255 | |
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256 | Command /dmx/savePmt |
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257 | Guidance : |
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258 | Set flag to save (x,y,z) of hits in PMT |
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259 | into file 'pmt.out' |
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260 | Default = false |
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261 | |
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262 | Parameter : savePmtFlag |
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263 | Parameter type : b |
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264 | Omittable : False |
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265 | |
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266 | |
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267 | Command /dmx/saveHits |
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268 | Guidance : |
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269 | Set flag to save hits in each run |
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270 | into file 'hits.out' |
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271 | Default = true |
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272 | |
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273 | Parameter : saveHitsFlag |
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274 | Parameter type : b |
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275 | Omittable : False |
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276 | |
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277 | |
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278 | |
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279 | UR 8.6: |
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280 | Allow the suppression of physics processes within specific volumes in |
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281 | order to optimise running of the neutron transport code. |
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282 | |
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283 | Gammas may be killed in the concrete wall in order to reduce |
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284 | processing time significantly. |
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285 | |
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286 | Command /dmx/KillGammasInConcrete |
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287 | Guidance : |
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288 | Kills gammas produced by neutrons in the concrete wall |
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289 | Default = false |
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290 | |
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291 | Parameter : KillGammasFlag |
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292 | Parameter type : b |
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293 | Omittable : False |
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294 | Default value : 0 |
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295 | |
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296 | |
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297 | |
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298 | CUTS: |
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299 | |
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300 | UR 9.1: |
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301 | User can apply special cuts to time and step length to tracks. If the |
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302 | global time is exceeded then the track is killed. |
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303 | |
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304 | UR 9.2: |
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305 | Allow gammas to be killed in the concrete wall in order to optimise |
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306 | processing time for neutron transport. |
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307 | |
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308 | ------------------------------------------------------------------------------ |
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309 | |
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310 | |
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311 | |
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312 | Background Information/Links |
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313 | |
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314 | Information on the experimental side of this project can be obtained from the |
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315 | following: |
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316 | |
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317 | Who we are: |
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318 | Imperial College High Energy Physics Group -> http://www.hep.ph.ic.ac.uk/ |
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319 | |
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320 | Imperial College Astrophysics -> http://astro.ic.ac.uk/ |
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321 | |
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322 | Dark Matter collaboration and existing experimental programme: |
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323 | Boulby Collaboration Home Page -> http://hepwww.rl.ac.uk/ukdmc/ |
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324 | |
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325 | |
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326 | Full Users Requirement Document |
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327 | |
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328 | A draft of the full users requirement document for the advanced example can be |
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329 | downloaded/viewed at the following: |
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330 | |
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331 | Word Document -> |
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332 | http://icva.hep.ph.ic.ac.uk/~howard/g4_project/urd_draft1.doc |
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333 | |
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334 | Web Page -> |
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335 | http://icva.hep.ph.ic.ac.uk/~howard/g4_project/urd_draft1.htm |
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336 | |
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337 | |
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338 | |
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339 | |
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340 | |
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