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0001 UNDERGROUND PHYSICS ADVANCED EXAMPLE - DMX
0002
0003 UserRequirements.txt - Alex Howard, e-mail: alexander.howard@cern.ch, 29/11/01.
0004
0005 Introduction:
0006
0007 This document is an initial introduction to the Dark Matter Example -
0008 DMX. A single liquid xenon cell is simulated within Geant4 and the
0009 scintillation light produced from interactions from various
0010 calibration species is recorded as hits in a PhotoMultiplier Tube
0011 (PMT). The output is then written to an ASCII file for future
0012 off-line analysis.
0013
0014 -------------------------------------------------------------------------------
0015
0016 User Requirements:
0017
0018 General
0019
0020 UR 1.1: Configure the run management
0021
0022 UR 1.2: Configure the event loop
0023
0024
0025
0026 Geometry:
0027 Experimental set-up:
0028
0029 UR 2.1:
0030 A "cavern" of dimensions 5m x 6m x 3m with concrete walls is defined
0031 as the World Volume. In the centre of the cavern a steel vacuum
0032 vessel containing liquid and gaseous xenon is placed. The internal
0033 construction of the vessel accurately reproduces an existing prototype
0034 Dark Matter detector which allows experimental comparison. The active
0035 detector volume is defined by a series of metal rings, complemented by
0036 a cover mirror and a PMT immersed in the liquid. Two grids and a
0037 thermalising copper shield are also incorporated. The liquid/gas
0038 interface is located 6mm away from the mirror surface. A Am241
0039 calibration source is suspended from one of the grids in the liquid
0040 phase, above the PMT.
0041
0042 XXX================XXX mirror
0043 XXX________________XXX gas phase
0044 XXX XXX
0045 XXX XXX liquid phase
0046 XXX XXX
0047 XXX.......U........XXX grid + calibrator
0048 XXX................XXX grid
0049 XXX| |XXX
0050 | ___------___ |
0051 || PMT ||
0052 || ||
0053
0054 An accurate simulation of the above set-up should be carried.
0055
0056 UR 2.2:
0057 Record the energy deposited in the sensitive volume of the xenon
0058 chamber (liquid phase).
0059
0060 UR 2.3:
0061 Produce scintillation photons with different time constants and light
0062 yields depending upon the species of particle causing the excitation -
0063 either nuclear recoil or electron recoil type interactions.
0064
0065 UR 2.4:
0066 Implement reflectivities and transmission probabilities for all materials
0067 concerned.
0068
0069 UR 2.5:
0070 Ray trace the scintillation back to the PMT and record hit times, positions and
0071 number of photons.
0072
0073
0074 PHYSICS:
0075
0076 The following areas of physics should be included:
0077
0078 UR 3.1: · Low Energy Electromagnetic - to 250eV for both e and photons
0079 Maximum energy range around 10 MeV for any particle
0080 UR 3.2: · Compton Scattering
0081 UR 3.3: · Photoelectric Effect
0082 UR 3.4: · Bremsstrahlung
0083 UR 3.5: · Rayleigh Scattering - for both optical photons and hard
0084 X-rays/Gammas
0085 UR 3.6: · Electromagnetic ionisation
0086 UR 3.7: · Delta Rays
0087 Produced discretely down to 250eV to allow secondaries and
0088 tertiaries to be properly handled
0089 UR 3.8: · Heavy Ion Transport - to 250eV for protons, alphas and nuclei
0090 Allows separate scintillation time and yield compared to gammas
0091 (electrons)
0092 UR 3.9: · Radioactive Decay - induced
0093 All materials are sensitive to induced activity as a consequence
0094 of photo-nuclear or neutron capture
0095 UR 3.10: · Radioactive Decay - sources
0096 Specific nuclei can be decayed within the geometry to reproduce
0097 experimental calibration the experiment
0098 UR 3.11: · Neutron tracking from medium energy (few MeV) to thermal capture
0099 Discretely transported through-out the volume to give full
0100 detector response for both neutron capture activation and
0101 elastic and inelastic interaction in the target volume
0102 UR 3.12: · Scintillation light production and ray-tracing to PMT
0103 Optical photon transport introduced to allow realistic
0104 detector response to be produced.
0105
0106 ParticleSource:
0107
0108 UR 4.1:
0109 Implement a generic particle source that allows various particles, ions and
0110 nuclei to be fired or decayed anywhere within the volume.
0111
0112 UR 4.2:
0113 Allow confinement of the particle source to within given volumes and randomly
0114 select particle or ion production within that volume.
0115
0116 UR 4.3:
0117 Allow various source shapes - point, sphere and cylinder have been
0118 implemented.
0119
0120 UR 4.4: !!!! not in ours !!!
0121 Allow spectrum of energies to be chosen as well as a monoenergetic particle
0122 type.
0123
0124
0125 Radioactive Decay Module:
0126
0127 UR 5.1:
0128 Allows specific ions to be decayed within set nuclear limits and energies and
0129 positions - linked to Particle Source above.
0130
0131 UR 5.2:
0132 Can control induced activity to specific volumes.
0133
0134 UR 5.3:
0135 Allows increased functionality in terms of choice of weighting for the decay
0136 and other non-analogue MC techniques.
0137
0138
0139 Analysis:
0140
0141 UR 6.1:
0142 Outputs to file "hits.out" the event number (Evt #), the energy
0143 deposited in the liquid phase (Etot, MeV), the number of hits in LXe
0144 (LXe hits), the time of the first hit (LXeTime, ns), the number of PMT
0145 hits (PMT hits), the average PMT hit time relative to the first hit in
0146 LXe (PmtTime, ns), the first particle to hit the LXe (First hit) and
0147 flags the type of particles depositing energy - gamma, neutron,
0148 electron, positron, proton, other (Flags).
0149
0150 UR 6.2:
0151 The "First hit" and "Flags" described above constitute a record of
0152 particle type history important for identifying and differentiating
0153 between elastic and inelastic neutron interactions.
0154
0155
0156
0157 Visualisation:
0158
0159 UR 7.1:
0160 Visualise the experimental set-up.
0161
0162 UR 7.2:
0163 Visualise tracks in the experimental set-up.
0164
0165 UR 7.3:
0166 Allow the choice between scintillation light, PMT photocathode hits,
0167 and full tracking to be displayed.
0168
0169 UR 7.4:
0170 Allow the user to choose specific track colours for gammas, neutrons,
0171 charged-plus and charged-minus tracks.
0172
0173 UR 7.5:
0174 Allow output to stored interactive files using the HEPREP interface which can
0175 then be read into Wired and other XML packages.
0176
0177
0178 User Interface:
0179
0180 UR 8.1:
0181
0182 Allow control of the particle source via the /dmx/gun control:
0183
0184 Command directory path : /dmx/gun/
0185 Guidance :
0186 Particle Source control commands.
0187
0188 Sub-directories :
0189 Commands :
0190 1) List * List available particles.
0191 2) particle * Set particle to be generated.
0192 3) direction * Set momentum direction.
0193 4) energy * Set kinetic energy.
0194 5) position * Set starting position of the particle.
0195 6) ion * Set properties of ion to be generated.
0196 7) type * Sets source distribution type.
0197 8) shape * Sets source shape type.
0198 9) centre * Set centre coordinates of source.
0199 10) halfz * Set z half length of source.
0200 11) radius * Set radius of source.
0201 12) confine * Confine source to volume (NULL to unset).
0202 13) angtype * Sets angular source distribution type
0203 14) energytype * Sets energy distribution type
0204 15) verbose * Set Verbose level for gun
0205
0206
0207 UR 8.2:
0208 Control verbosities via:
0209 The user should have the ability to change several features including
0210 a) verbosities can be controlled for
0211 /control/verbose
0212 /run/verbose
0213 /tracking/verbose
0214 /hits/verbose
0215 /process/had/rdm/verbose
0216 /dmx/gun/verbose
0217
0218
0219 UR 8.3:
0220 Control the output to the screen into Modulo N events:
0221 using printModulo control.
0222
0223 Command /dmx/printModulo
0224 Guidance :
0225 Print events modulo n
0226 Range of parameters : EventNb>0
0227
0228 Parameter : EventNb
0229 Parameter type : i
0230 Omittable : False
0231
0232
0233 UR 8.4:
0234 Draw commands controlled via /dmx/draw/:
0235
0236 DM Example draw commands.
0237
0238 Sub-directories :
0239 Commands :
0240 1) drawColours * Tracks drawn by Event (standard colours) or
0241 by Step (custom colours)
0242 2) drawTracks * Which tracks to draw in the event
0243 3) drawHits * Set flag to draw hits in PMT.
0244 4) neutronColour * Colour of neutron in the event
0245 5) gammaColour * Colour of gamma in the event
0246 6) opticalColour * Colour of gamma in the event
0247 7) chargedplusColour * colour of chargedplus in the event
0248 8) chargedminusColour * colour of chargedminus in the event
0249
0250
0251
0252 UR 8.5:
0253 Control the files to be saved - PMT hits and event summary in terms of
0254 energy deposit and number of photon hits observed.
0255
0256 Command /dmx/savePmt
0257 Guidance :
0258 Set flag to save (x,y,z) of hits in PMT
0259 into file 'pmt.out'
0260 Default = false
0261
0262 Parameter : savePmtFlag
0263 Parameter type : b
0264 Omittable : False
0265
0266
0267 Command /dmx/saveHits
0268 Guidance :
0269 Set flag to save hits in each run
0270 into file 'hits.out'
0271 Default = true
0272
0273 Parameter : saveHitsFlag
0274 Parameter type : b
0275 Omittable : False
0276
0277
0278
0279 UR 8.6:
0280 Allow the suppression of physics processes within specific volumes in
0281 order to optimise running of the neutron transport code.
0282
0283 Gammas may be killed in the concrete wall in order to reduce
0284 processing time significantly.
0285
0286 Command /dmx/KillGammasInConcrete
0287 Guidance :
0288 Kills gammas produced by neutrons in the concrete wall
0289 Default = false
0290
0291 Parameter : KillGammasFlag
0292 Parameter type : b
0293 Omittable : False
0294 Default value : 0
0295
0296
0297
0298 CUTS:
0299
0300 UR 9.1:
0301 User can apply special cuts to time and step length to tracks. If the
0302 global time is exceeded then the track is killed.
0303
0304 UR 9.2:
0305 Allow gammas to be killed in the concrete wall in order to optimise
0306 processing time for neutron transport.
0307
0308 ------------------------------------------------------------------------------
0309
0310
0311
0312 Background Information/Links
0313
0314 Information on the experimental side of this project can be obtained from the
0315 following:
0316
0317 Who we are:
0318 Imperial College High Energy Physics Group -> http://www.hep.ph.ic.ac.uk/
0319
0320 Imperial College Astrophysics -> http://astro.ic.ac.uk/
0321
0322 Dark Matter collaboration and existing experimental programme:
0323 Boulby Collaboration Home Page -> http://hepwww.rl.ac.uk/ukdmc/
0324
0325
0326 Full Users Requirement Document
0327
0328 A draft of the full users requirement document for the advanced example can be
0329 downloaded/viewed at the following:
0330
0331 Word Document ->
0332 http://icva.hep.ph.ic.ac.uk/~howard/g4_project/urd_draft1.doc
0333
0334 Web Page ->
0335 http://icva.hep.ph.ic.ac.uk/~howard/g4_project/urd_draft1.htm
0336
0337
0338
0339
0340
