[807] | 1 | UNDERGROUND PHYSICS ADVANCED EXAMPLE - DMX |
---|
| 2 | |
---|
| 3 | UserRequirements.txt - Alex Howard, e-mail: alexander.howard@cern.ch, 29/11/01. |
---|
| 4 | |
---|
| 5 | Introduction: |
---|
| 6 | |
---|
| 7 | This document is an initial introduction to the Dark Matter Example - |
---|
| 8 | DMX. A single liquid xenon cell is simulated within Geant4 and the |
---|
| 9 | scintillation light produced from interactions from various |
---|
| 10 | calibration species is recorded as hits in a PhotoMultiplier Tube |
---|
| 11 | (PMT). The output is then written to an ASCII file for future |
---|
| 12 | off-line analysis. |
---|
| 13 | |
---|
| 14 | ------------------------------------------------------------------------------- |
---|
| 15 | |
---|
| 16 | User Requirements: |
---|
| 17 | |
---|
| 18 | General |
---|
| 19 | |
---|
| 20 | UR 1.1: Configure the run management |
---|
| 21 | |
---|
| 22 | UR 1.2: Configure the event loop |
---|
| 23 | |
---|
| 24 | |
---|
| 25 | |
---|
| 26 | Geometry: |
---|
| 27 | Experimental set-up: |
---|
| 28 | |
---|
| 29 | UR 2.1: |
---|
| 30 | A "cavern" of dimensions 5m x 6m x 3m with concrete walls is defined |
---|
| 31 | as the World Volume. In the centre of the cavern a steel vacuum |
---|
| 32 | vessel containing liquid and gaseous xenon is placed. The internal |
---|
| 33 | construction of the vessel accurately reproduces an existing prototype |
---|
| 34 | Dark Matter detector which allows experimental comparison. The active |
---|
| 35 | detector volume is defined by a series of metal rings, complemented by |
---|
| 36 | a cover mirror and a PMT immersed in the liquid. Two grids and a |
---|
| 37 | thermalising copper shield are also incorporated. The liquid/gas |
---|
| 38 | interface is located 6mm away from the mirror surface. A Am241 |
---|
| 39 | calibration source is suspended from one of the grids in the liquid |
---|
| 40 | phase, above the PMT. |
---|
| 41 | |
---|
| 42 | XXX================XXX mirror |
---|
| 43 | XXX________________XXX gas phase |
---|
| 44 | XXX XXX |
---|
| 45 | XXX XXX liquid phase |
---|
| 46 | XXX XXX |
---|
| 47 | XXX.......U........XXX grid + calibrator |
---|
| 48 | XXX................XXX grid |
---|
| 49 | XXX| |XXX |
---|
| 50 | | ___------___ | |
---|
| 51 | || PMT || |
---|
| 52 | || || |
---|
| 53 | |
---|
| 54 | An accurate simulation of the above set-up should be carried. |
---|
| 55 | |
---|
| 56 | UR 2.2: |
---|
| 57 | Record the energy deposited in the sensitive volume of the xenon |
---|
| 58 | chamber (liquid phase). |
---|
| 59 | |
---|
| 60 | UR 2.3: |
---|
| 61 | Produce scintillation photons with different time constants and light |
---|
| 62 | yields depending upon the species of particle causing the excitation - |
---|
| 63 | either nuclear recoil or electron recoil type interactions. |
---|
| 64 | |
---|
| 65 | UR 2.4: |
---|
| 66 | Implement reflectivities and transmission probabilities for all materials |
---|
| 67 | concerned. |
---|
| 68 | |
---|
| 69 | UR 2.5: |
---|
| 70 | Ray trace the scintillation back to the PMT and record hit times, positions and |
---|
| 71 | number of photons. |
---|
| 72 | |
---|
| 73 | |
---|
| 74 | PHYSICS: |
---|
| 75 | |
---|
| 76 | The following areas of physics should be included: |
---|
| 77 | |
---|
| 78 | UR 3.1: · Low Energy Electromagnetic - to 250eV for both e and photons |
---|
| 79 | Maximum energy range around 10 MeV for any particle |
---|
| 80 | UR 3.2: · Compton Scattering |
---|
| 81 | UR 3.3: · Photoelectric Effect |
---|
| 82 | UR 3.4: · Bremsstrahlung |
---|
| 83 | UR 3.5: · Rayleigh Scattering - for both optical photons and hard |
---|
| 84 | X-rays/Gammas |
---|
| 85 | UR 3.6: · Electromagnetic ionisation |
---|
| 86 | UR 3.7: · Delta Rays |
---|
| 87 | Produced discretely down to 250eV to allow secondaries and |
---|
| 88 | tertiaries to be properly handled |
---|
| 89 | UR 3.8: · Heavy Ion Transport - to 250eV for protons, alphas and nuclei |
---|
| 90 | Allows separate scintillation time and yield compared to gammas |
---|
| 91 | (electrons) |
---|
| 92 | UR 3.9: · Radioactive Decay - induced |
---|
| 93 | All materials are sensitive to induced activity as a consequence |
---|
| 94 | of photo-nuclear or neutron capture |
---|
| 95 | UR 3.10: · Radioactive Decay - sources |
---|
| 96 | Specific nuclei can be decayed within the geometry to reproduce |
---|
| 97 | experimental calibration the experiment |
---|
| 98 | UR 3.11: · Neutron tracking from medium energy (few MeV) to thermal capture |
---|
| 99 | Discretely transported through-out the volume to give full |
---|
| 100 | detector response for both neutron capture activation and |
---|
| 101 | elastic and inelastic interaction in the target volume |
---|
| 102 | UR 3.12: · Scintillation light production and ray-tracing to PMT |
---|
| 103 | Optical photon transport introduced to allow realistic |
---|
| 104 | detector response to be produced. |
---|
| 105 | |
---|
| 106 | ParticleSource: |
---|
| 107 | |
---|
| 108 | UR 4.1: |
---|
| 109 | Implement a generic particle source that allows various particles, ions and |
---|
| 110 | nuclei to be fired or decayed anywhere within the volume. |
---|
| 111 | |
---|
| 112 | UR 4.2: |
---|
| 113 | Allow confinement of the particle source to within given volumes and randomly |
---|
| 114 | select particle or ion production within that volume. |
---|
| 115 | |
---|
| 116 | UR 4.3: |
---|
| 117 | Allow various source shapes - point, sphere and cylinder have been |
---|
| 118 | implemented. |
---|
| 119 | |
---|
| 120 | UR 4.4: !!!! not in ours !!! |
---|
| 121 | Allow spectrum of energies to be chosen as well as a monoenergetic particle |
---|
| 122 | type. |
---|
| 123 | |
---|
| 124 | |
---|
| 125 | Radioactive Decay Module: |
---|
| 126 | |
---|
| 127 | UR 5.1: |
---|
| 128 | Allows specific ions to be decayed within set nuclear limits and energies and |
---|
| 129 | positions - linked to Particle Source above. |
---|
| 130 | |
---|
| 131 | UR 5.2: |
---|
| 132 | Can control induced activity to specific volumes. |
---|
| 133 | |
---|
| 134 | UR 5.3: |
---|
| 135 | Allows increased functionality in terms of choice of weighting for the decay |
---|
| 136 | and other non-analogue MC techniques. |
---|
| 137 | |
---|
| 138 | |
---|
| 139 | Analysis: |
---|
| 140 | |
---|
| 141 | UR 6.1: |
---|
| 142 | Outputs to file "hits.out" the event number (Evt #), the energy |
---|
| 143 | deposited in the liquid phase (Etot, MeV), the number of hits in LXe |
---|
| 144 | (LXe hits), the time of the first hit (LXeTime, ns), the number of PMT |
---|
| 145 | hits (PMT hits), the average PMT hit time relative to the first hit in |
---|
| 146 | LXe (PmtTime, ns), the first particle to hit the LXe (First hit) and |
---|
| 147 | flags the type of particles depositing energy - gamma, neutron, |
---|
| 148 | electron, positron, proton, other (Flags). |
---|
| 149 | |
---|
| 150 | UR 6.2: |
---|
| 151 | The "First hit" and "Flags" described above constitute a record of |
---|
| 152 | particle type history important for identifying and differentiating |
---|
| 153 | between elastic and inelastic neutron interactions. |
---|
| 154 | |
---|
| 155 | |
---|
| 156 | |
---|
| 157 | Visualisation: |
---|
| 158 | |
---|
| 159 | UR 7.1: |
---|
| 160 | Visualise the experimental set-up. |
---|
| 161 | |
---|
| 162 | UR 7.2: |
---|
| 163 | Visualise tracks in the experimental set-up. |
---|
| 164 | |
---|
| 165 | UR 7.3: |
---|
| 166 | Allow the choice between scintillation light, PMT photocathode hits, |
---|
| 167 | and full tracking to be displayed. |
---|
| 168 | |
---|
| 169 | UR 7.4: |
---|
| 170 | Allow the user to choose specific track colours for gammas, neutrons, |
---|
| 171 | charged-plus and charged-minus tracks. |
---|
| 172 | |
---|
| 173 | UR 7.5: |
---|
| 174 | Allow output to stored interactive files using the HEPREP interface which can |
---|
| 175 | then be read into Wired and other XML packages. |
---|
| 176 | |
---|
| 177 | |
---|
| 178 | User Interface: |
---|
| 179 | |
---|
| 180 | UR 8.1: |
---|
| 181 | |
---|
| 182 | Allow control of the particle source via the /dmx/gun control: |
---|
| 183 | |
---|
| 184 | Command directory path : /dmx/gun/ |
---|
| 185 | Guidance : |
---|
| 186 | Particle Source control commands. |
---|
| 187 | |
---|
| 188 | Sub-directories : |
---|
| 189 | Commands : |
---|
| 190 | 1) List * List available particles. |
---|
| 191 | 2) particle * Set particle to be generated. |
---|
| 192 | 3) direction * Set momentum direction. |
---|
| 193 | 4) energy * Set kinetic energy. |
---|
| 194 | 5) position * Set starting position of the particle. |
---|
| 195 | 6) ion * Set properties of ion to be generated. |
---|
| 196 | 7) type * Sets source distribution type. |
---|
| 197 | 8) shape * Sets source shape type. |
---|
| 198 | 9) centre * Set centre coordinates of source. |
---|
| 199 | 10) halfz * Set z half length of source. |
---|
| 200 | 11) radius * Set radius of source. |
---|
| 201 | 12) confine * Confine source to volume (NULL to unset). |
---|
| 202 | 13) angtype * Sets angular source distribution type |
---|
| 203 | 14) energytype * Sets energy distribution type |
---|
| 204 | 15) verbose * Set Verbose level for gun |
---|
| 205 | |
---|
| 206 | |
---|
| 207 | UR 8.2: |
---|
| 208 | Control verbosities via: |
---|
| 209 | The user should have the ability to change several features including |
---|
| 210 | a) verbosities can be controlled for |
---|
| 211 | /control/verbose |
---|
| 212 | /run/verbose |
---|
| 213 | /tracking/verbose |
---|
| 214 | /hits/verbose |
---|
| 215 | /grdm/verbose |
---|
| 216 | /dmx/gun/verbose |
---|
| 217 | |
---|
| 218 | |
---|
| 219 | UR 8.3: |
---|
| 220 | Control the output to the screen into Modulo N events: |
---|
| 221 | using printModulo control. |
---|
| 222 | |
---|
| 223 | Command /dmx/printModulo |
---|
| 224 | Guidance : |
---|
| 225 | Print events modulo n |
---|
| 226 | Range of parameters : EventNb>0 |
---|
| 227 | |
---|
| 228 | Parameter : EventNb |
---|
| 229 | Parameter type : i |
---|
| 230 | Omittable : False |
---|
| 231 | |
---|
| 232 | |
---|
| 233 | UR 8.4: |
---|
| 234 | Draw commands controlled via /dmx/draw/: |
---|
| 235 | |
---|
| 236 | DM Example draw commands. |
---|
| 237 | |
---|
| 238 | Sub-directories : |
---|
| 239 | Commands : |
---|
| 240 | 1) drawColours * Tracks drawn by Event (standard colours) or |
---|
| 241 | by Step (custom colours) |
---|
| 242 | 2) drawTracks * Which tracks to draw in the event |
---|
| 243 | 3) drawHits * Set flag to draw hits in PMT. |
---|
| 244 | 4) neutronColour * Colour of neutron in the event |
---|
| 245 | 5) gammaColour * Colour of gamma in the event |
---|
| 246 | 6) opticalColour * Colour of gamma in the event |
---|
| 247 | 7) chargedplusColour * colour of chargedplus in the event |
---|
| 248 | 8) chargedminusColour * colour of chargedminus in the event |
---|
| 249 | |
---|
| 250 | |
---|
| 251 | |
---|
| 252 | UR 8.5: |
---|
| 253 | Control the files to be saved - PMT hits and event summary in terms of |
---|
| 254 | energy deposit and number of photon hits observed. |
---|
| 255 | |
---|
| 256 | Command /dmx/savePmt |
---|
| 257 | Guidance : |
---|
| 258 | Set flag to save (x,y,z) of hits in PMT |
---|
| 259 | into file 'pmt.out' |
---|
| 260 | Default = false |
---|
| 261 | |
---|
| 262 | Parameter : savePmtFlag |
---|
| 263 | Parameter type : b |
---|
| 264 | Omittable : False |
---|
| 265 | |
---|
| 266 | |
---|
| 267 | Command /dmx/saveHits |
---|
| 268 | Guidance : |
---|
| 269 | Set flag to save hits in each run |
---|
| 270 | into file 'hits.out' |
---|
| 271 | Default = true |
---|
| 272 | |
---|
| 273 | Parameter : saveHitsFlag |
---|
| 274 | Parameter type : b |
---|
| 275 | Omittable : False |
---|
| 276 | |
---|
| 277 | |
---|
| 278 | |
---|
| 279 | UR 8.6: |
---|
| 280 | Allow the suppression of physics processes within specific volumes in |
---|
| 281 | order to optimise running of the neutron transport code. |
---|
| 282 | |
---|
| 283 | Gammas may be killed in the concrete wall in order to reduce |
---|
| 284 | processing time significantly. |
---|
| 285 | |
---|
| 286 | Command /dmx/KillGammasInConcrete |
---|
| 287 | Guidance : |
---|
| 288 | Kills gammas produced by neutrons in the concrete wall |
---|
| 289 | Default = false |
---|
| 290 | |
---|
| 291 | Parameter : KillGammasFlag |
---|
| 292 | Parameter type : b |
---|
| 293 | Omittable : False |
---|
| 294 | Default value : 0 |
---|
| 295 | |
---|
| 296 | |
---|
| 297 | |
---|
| 298 | CUTS: |
---|
| 299 | |
---|
| 300 | UR 9.1: |
---|
| 301 | User can apply special cuts to time and step length to tracks. If the |
---|
| 302 | global time is exceeded then the track is killed. |
---|
| 303 | |
---|
| 304 | UR 9.2: |
---|
| 305 | Allow gammas to be killed in the concrete wall in order to optimise |
---|
| 306 | processing time for neutron transport. |
---|
| 307 | |
---|
| 308 | ------------------------------------------------------------------------------ |
---|
| 309 | |
---|
| 310 | |
---|
| 311 | |
---|
| 312 | Background Information/Links |
---|
| 313 | |
---|
| 314 | Information on the experimental side of this project can be obtained from the |
---|
| 315 | following: |
---|
| 316 | |
---|
| 317 | Who we are: |
---|
| 318 | Imperial College High Energy Physics Group -> http://www.hep.ph.ic.ac.uk/ |
---|
| 319 | |
---|
| 320 | Imperial College Astrophysics -> http://astro.ic.ac.uk/ |
---|
| 321 | |
---|
| 322 | Dark Matter collaboration and existing experimental programme: |
---|
| 323 | Boulby Collaboration Home Page -> http://hepwww.rl.ac.uk/ukdmc/ |
---|
| 324 | |
---|
| 325 | |
---|
| 326 | Full Users Requirement Document |
---|
| 327 | |
---|
| 328 | A draft of the full users requirement document for the advanced example can be |
---|
| 329 | downloaded/viewed at the following: |
---|
| 330 | |
---|
| 331 | Word Document -> |
---|
| 332 | http://icva.hep.ph.ic.ac.uk/~howard/g4_project/urd_draft1.doc |
---|
| 333 | |
---|
| 334 | Web Page -> |
---|
| 335 | http://icva.hep.ph.ic.ac.uk/~howard/g4_project/urd_draft1.htm |
---|
| 336 | |
---|
| 337 | |
---|
| 338 | |
---|
| 339 | |
---|
| 340 | |
---|