| Geant4 Cross Reference |
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3 3
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5 Geant4 - Composite calor 5 Geant4 - Composite calorimeter example
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7 7
8 README 8 README
9 --------------------- 9 ---------------------
10 10
11 CompositeCalorimeter is an example of a test- 11 CompositeCalorimeter is an example of a test-beam simulation used
12 by the CMS Collaboration to validate Geant4 a 12 by the CMS Collaboration to validate Geant4 against real data taken
13 (in 1996) in a CMS Hadron calorimeter test-be 13 (in 1996) in a CMS Hadron calorimeter test-beam.
14 The name "Composite" for this example emphasi 14 The name "Composite" for this example emphasizes that, although the
15 test-beam had the goal of studying the hadron 15 test-beam had the goal of studying the hadronic calorimeter response,
16 part of the data was taken with the presence 16 part of the data was taken with the presence of the electromagnetic
17 crystal calorimeter in front of the hadronic 17 crystal calorimeter in front of the hadronic calorimeter, to better
18 reproduce the situation as in the real CMS ex 18 reproduce the situation as in the real CMS experiment.
19 The geometry of the simulation has been setup 19 The geometry of the simulation has been setup in such a way to allow
20 very easily, at run time (therefore without n 20 very easily, at run time (therefore without need of changing any code;
21 see below for the details) the inclusion or e 21 see below for the details) the inclusion or exclusion of the
22 electromagnetic calorimeter part. 22 electromagnetic calorimeter part.
23 Although some important aspects, for a detail 23 Although some important aspects, for a detailed comparison between
24 test-beam data and simulation, like beam prof 24 test-beam data and simulation, like beam profile, noise, and digitization,
25 have been omitted here (to avoid too many tec 25 have been omitted here (to avoid too many technical details),
26 nevertheless, this example is able to reprodu 26 nevertheless, this example is able to reproduce the main features of
27 most of the relevant observables as measured 27 most of the relevant observables as measured in the real test-beam.
28 The output of this example consists of a set 28 The output of this example consists of a set of histograms
29 and one ntuple which are stored on a ROOT fil 29 and one ntuple which are stored on a ROOT file (default).
30 In our opinion, the most original "lesson" wh 30 In our opinion, the most original "lesson" which is offered by this
31 advanced example for the Geant4 user is to sh 31 advanced example for the Geant4 user is to show how the Geometry and
32 the Sensitive/Hit part of the simulation is t 32 the Sensitive/Hit part of the simulation is treated in a big experiment.
33 Although the details of how this is done vary 33 Although the details of how this is done vary from experiment to
34 experiment (it is worth, for instance, to com 34 experiment (it is worth, for instance, to compare with the Atlas-based
35 advanced example lAr_calorimeter), the main d 35 advanced example lAr_calorimeter), the main driving needs and goals
36 are quite general: to have consistency, but a 36 are quite general: to have consistency, but avoiding duplications
37 and couplings as much as possibile, between S 37 and couplings as much as possibile, between Simulation, Reconstruction,
38 and Visualization. Notice that the solution o 38 and Visualization. Notice that the solution offered in this example
39 by CMS could appear "overdone" for the sake o 39 by CMS could appear "overdone" for the sake of simulating only a
40 relatively simple test-beam setup; but it sho 40 relatively simple test-beam setup; but it should be kept in mind
41 that the same approach is used also for the f 41 that the same approach is used also for the full CMS detector
42 simulation, as well as for any subdetector. 42 simulation, as well as for any subdetector.
43 43
44 44
45 1. Setting up the environment variables 45 1. Setting up the environment variables
46 --------------------------------------- 46 ---------------------------------------
47 47
48 The user should first setup, as "usual", the 48 The user should first setup, as "usual", the Geant4 environmental
49 variables (e.g. the script produced by cmake) 49 variables (e.g. the script produced by cmake)
50 Then the specific setup for this example shou 50 Then the specific setup for this example should be run:
51 51
52 > source envExample.csh in the case 52 > source envExample.csh in the case of C-shell
53 or 53 or
54 > . envExample.sh in the case 54 > . envExample.sh in the case of bash-shell
55 55
56 The analysis part is based on the native g4an 56 The analysis part is based on the native g4analysis tools. As default
57 the output is a ROOT file. This can be change << 57 the output is a ROOT file. This can be changed to XML by commenting
>> 58 the line
>> 59 #include "g4root.hh"
>> 60 in CCalAnalysis.hh and uncommenting
>> 61 #include "g4xml.hh"
58 62
59 63
60 2. Sample run 64 2. Sample run
61 ------------- 65 -------------
62 66
63 Once the environmental variables are setup, y 67 Once the environmental variables are setup, you can get the executable
64 CompositeCalorimeter 68 CompositeCalorimeter
65 by configuring with cmake and then running th 69 by configuring with cmake and then running the compiler.
66 Then, you can execute it using the Geant4 mac 70 Then, you can execute it using the Geant4 macro command input file test.g4mac
67 as follows: 71 as follows:
68 72
69 > ./CompositeCalorimeter test.g4mac 73 > ./CompositeCalorimeter test.g4mac
70 74
71 which simulate a few events, each being a 100 << 75 which simulate 10 events, each being a 100 GeV pi- incident on the
72 electromagnetic crystal calorimeter followed 76 electromagnetic crystal calorimeter followed by the hadronic calorimeter,
73 without magnetic field. 77 without magnetic field.
74 The output is the ROOT file "ccal.root" . 78 The output is the ROOT file "ccal.root" .
75 See part "8. Analysis / Histogramming" below 79 See part "8. Analysis / Histogramming" below for more details on the
76 content of that file. 80 content of that file.
77 If you run instead: 81 If you run instead:
78 82
79 > ./CompositeCalorimeter 83 > ./CompositeCalorimeter
80 84
81 after having setup the Geant4 visualization v 85 after having setup the Geant4 visualization variables and the PATH,
82 you can visualize the geometry of the apparat 86 you can visualize the geometry of the apparatus, and also see some
83 events. Similarly, you can get a very simple 87 events. Similarly, you can get a very simple graphical user interface
84 that allows to select the particle type, its 88 that allows to select the particle type, its energy, and the number
85 of events (between a limited number of possib 89 of events (between a limited number of possibilities).
86 For more details, see part "9. Visualization 90 For more details, see part "9. Visualization / GUI".
87 91
88 92
89 3. Detector description 93 3. Detector description
90 ----------------------- 94 -----------------------
91 95
92 Let's start with a brief description of the t 96 Let's start with a brief description of the test-beam setup.
93 97
94 There are two possible configurations: 98 There are two possible configurations:
95 i) HCAL only, that is only the hadronic ca 99 i) HCAL only, that is only the hadronic calorimeter is present;
96 ii) ECAL+HCAL, that is the electromagnetic 100 ii) ECAL+HCAL, that is the electromagnetic calorimeter (ECAL)
97 is placed in front of the ha 101 is placed in front of the hadronic calorimeter.
98 ECAL is made of 23 cm long PbWO4 crystals (co 102 ECAL is made of 23 cm long PbWO4 crystals (corresponding to about
99 25.8 radiation lengths, and 1.1 interaction l 103 25.8 radiation lengths, and 1.1 interaction lengths); for the
100 test beam a 7 x 7 = 49 matrix of crystals i 104 test beam a 7 x 7 = 49 matrix of crystals is used.
101 HCAL is a sampling calorimeter, with plastic 105 HCAL is a sampling calorimeter, with plastic scintillator as sensitive
102 part and copper as absorber. 28 scintillator 106 part and copper as absorber. 28 scintillator plates were used with
103 absorber of varying thickness in between, and 107 absorber of varying thickness in between, and also varying thickness
104 and type of scintillator. More precisely: 108 and type of scintillator. More precisely:
105 --- layer 1: 2 cm of Copper 109 --- layer 1: 2 cm of Copper
106 --- layer 2 to 7: 4 cm of Copper 110 --- layer 2 to 7: 4 cm of Copper
107 --- layer 8 to 21: 6 cm of Copper 111 --- layer 8 to 21: 6 cm of Copper
108 --- layer 22 to 27: 8 cm of Copper 112 --- layer 22 to 27: 8 cm of Copper
109 For the scintillators: 2 mm passive Plastic; 113 For the scintillators: 2 mm passive Plastic; 4 mm active Plastic;
110 1 mm passive Plastic. 114 1 mm passive Plastic.
111 The total length of HCAL consists of 152 cm o 115 The total length of HCAL consists of 152 cm of Copper plus 189 mm of Plastic.
112 The dimension orthogonal to the beam directio 116 The dimension orthogonal to the beam direction is 64 cm x 64 cm.
113 The ECAL and HCAL considered here are prototy 117 The ECAL and HCAL considered here are prototypes for the Central and
114 Endcap calorimeters of the CMS detector (whic 118 Endcap calorimeters of the CMS detector (which covers the rapidity
115 region |eta| < 3.0 ; CMS has also a Forward c 119 region |eta| < 3.0 ; CMS has also a Forward calorimeter, which covers
116 the region 3.0 < |eta| < 5.0, but this part w 120 the region 3.0 < |eta| < 5.0, but this part was not considered in
117 this test-beam setup). Notice, however, that 121 this test-beam setup). Notice, however, that there are more layers
118 (28 instead of 19 in the Barrel or 18 in the 122 (28 instead of 19 in the Barrel or 18 in the Endcap) of HCAL in the
119 test-beam setup than in the real CMS detector 123 test-beam setup than in the real CMS detector, in order to study
120 energy containment. Therefore, the ECAL+HCAL 124 energy containment. Therefore, the ECAL+HCAL in the test-beam amounts
121 to more than 11 radiation lengths as for the 125 to more than 11 radiation lengths as for the real CMS detector (the
122 19 layers of the Barrel have each 6 cm of abs 126 19 layers of the Barrel have each 6 cm of absorber, whereas the
123 18 layers of the Endcap have each 6.6 cm of a 127 18 layers of the Endcap have each 6.6 cm of absorber, so that the
124 number of interaction lengths are rougly the 128 number of interaction lengths are rougly the same).
125 Five values of the magnetic field (parallel t 129 Five values of the magnetic field (parallel to the face of the scintillators)
126 have been considered in the test-beam: 0.0 , 130 have been considered in the test-beam: 0.0 , 0.375 , 0.75 , 1.50 , 3.0 Tesla.
127 131
128 In order to set the magnetic field, you have 132 In order to set the magnetic field, you have to edit the file
129 dataglobal/fmap.tb96 133 dataglobal/fmap.tb96
130 and change the first number (which appears in 134 and change the first number (which appears in the third line of
131 that file, on the first column; the unit bein 135 that file, on the first column; the unit being Tesla):
132 #. Field map 136 #. Field map
133 *DO FLDM 137 *DO FLDM
134 0.0 9 652.0 138 0.0 9 652.0
135 for example, if you want a magnetic field of 139 for example, if you want a magnetic field of 3.0 Tesla the last
136 line must be set as follows (the magnetic fie 140 line must be set as follows (the magnetic field unity is kilo Gauss).
137 30.0 9 652.0 141 30.0 9 652.0
138 142
>> 143 The default stepper in magnetic field is G4ClassicalRK4, but other
>> 144 possibilities can be selected by editing the file
>> 145 src/CCalDetectorConstruction.cc (look at the string "***STEPPER***").
>> 146
139 In order to deactivate either the ECAL or the 147 In order to deactivate either the ECAL or the HCAL, it is enough
140 to comment out the corresponding line in the 148 to comment out the corresponding line in the file g4testbeamhcal96.conf,
141 using "#" as the comment character. For insta 149 using "#" as the comment character. For instance, to have only the HCAL
142 without ECAL: 150 without ECAL:
143 "HcalTB96" "tbhcal96" 151 "HcalTB96" "tbhcal96" 1
144 #"CrystalMatrixModule" "tbhcal96xta 152 #"CrystalMatrixModule" "tbhcal96xtal" 1
145 153
146 154
147 In this test-beam setup, at the back of ECAL, 155 In this test-beam setup, at the back of ECAL, there is also some
148 material for support and readout, which has b 156 material for support and readout, which has been considered in the
149 simulation. For the HCAL, only the fibres are 157 simulation. For the HCAL, only the fibres are close to the test-beam,
150 and because they have the same composition as 158 and because they have the same composition as the scintillators
151 they are adequately represented in the simula 159 they are adequately represented in the simulation; the remaining
152 of the readout, including the photomultiplier 160 of the readout, including the photomultipliers, are in readout boxes
153 far away from the HCAL, and hence are not pre 161 far away from the HCAL, and hence are not present in the simulation.
154 162
155 Let's summarizes now the geometry description 163 Let's summarizes now the geometry description of the simulation.
156 As said in the introduction, this part is the 164 As said in the introduction, this part is the most original and
157 important of this example, but it is quite co 165 important of this example, but it is quite complex and can be fully
158 appreciated only in the context of the CMS so 166 appreciated only in the context of the CMS software framework, in
159 particular in the relation between Simulation 167 particular in the relation between Simulation, Reconstruction, and
160 Visualization. Therefore we limit ourself to 168 Visualization. Therefore we limit ourself to only few considerations,
161 pointing to the internal CMS documentation fo 169 pointing to the internal CMS documentation for more details.
162 170
163 --- In order to share the same geometrical an 171 --- In order to share the same geometrical and physical information
164 about CMS between Simulation, Reconstruct 172 about CMS between Simulation, Reconstruction, and Visualization,
165 avoiding inconsistencies, duplications, a 173 avoiding inconsistencies, duplications, and unnecessary dependecies,
166 all these information is store, once for 174 all these information is store, once for all, in common databases
167 (typically in XML format), instead of put 175 (typically in XML format), instead of putting them inside C++ classes,
168 as usually done in simpler detector descr 176 as usually done in simpler detector descriptions (in most of the
169 the Geant4 examples, novice or advanced, 177 the Geant4 examples, novice or advanced, the geometry information
170 is kept inside the concrete class which i 178 is kept inside the concrete class which inherits from
171 G4VUserDetectorConstruction). For simplic 179 G4VUserDetectorConstruction). For simplicity, in this example,
172 these "databases" are nothing more than A 180 these "databases" are nothing more than ASCII files:
173 181
174 datageom/ : tbhcal96.geom, tbhcal96hca 182 datageom/ : tbhcal96.geom, tbhcal96hcal.geom, tbhcal96xtal.geom
175 store the information abou 183 store the information about the experimental Hall,
176 the HCAL, and the ECAL, re 184 the HCAL, and the ECAL, respectively.
177 185
178 dataconf/ : g4testbeamhcal96.conf, tes 186 dataconf/ : g4testbeamhcal96.conf, testbeamhcal96.conf
179 store the information abou 187 store the information about which configuration
180 (HCAL only, or ECAL+HACL) 188 (HCAL only, or ECAL+HACL) is considered, in the
181 Simulation and Reconstruct 189 Simulation and Reconstruction, respectively.
182 190
183 dataglobal/ : fmap.tb96, material.cms, 191 dataglobal/ : fmap.tb96, material.cms, rotation.cms
184 The first one is the magne 192 The first one is the magnetic field map (how the
185 intensity of the magnetic 193 intensity of the magnetic field, in the direction
186 orthogonal to the beam dir 194 orthogonal to the beam direction, varies along
187 the beam axis). The second 195 the beam axis). The second one, material.cms,
188 keeps the full collection 196 keeps the full collection of all materials used in
189 the CMS detector (not only 197 the CMS detector (not only in the calorimeters,
190 although we are simulating 198 although we are simulating only them in this example!).
191 The third one, rotation.cm 199 The third one, rotation.cms, collects a set of useful
192 rotation parameters (angle 200 rotation parameters (angles).
193 201
194 datavis/ : tbhcal96.vis, tbhcal96hcal. 202 datavis/ : tbhcal96.vis, tbhcal96hcal.vis, tbhcal96xtal.vis
195 visualization information for, re 203 visualization information for, respectively, the
196 experimental Hall, HCAL, an 204 experimental Hall, HCAL, and ECAL.
197 205
198 --- In order to allow an high degree of flexi 206 --- In order to allow an high degree of flexibility, at the geometry
199 level the user can choose which subsystem 207 level the user can choose which subsystem of the detector setup
200 should be simulated and can activate or d 208 should be simulated and can activate or deactivate the sensitive
201 parts, subsystem by subsystem. This can b 209 parts, subsystem by subsystem. This can be done at run time,
202 by modifying one of the above database in 210 by modifying one of the above database information, without need
203 of putting the hands on the code, recompi 211 of putting the hands on the code, recompiling, etc.
204 212
205 --- There are two "parallel geometry factorie 213 --- There are two "parallel geometry factories": one described by "core"
206 classes, which are independent from the S 214 classes, which are independent from the Simulation (and therefore
207 can be used, for instance, by the Reconst 215 can be used, for instance, by the Reconstruction); and one which
208 is specific of the Simulation. In the lat 216 is specific of the Simulation. In the latter case (Geant4 side of
209 the geometry model), all the geometry fac 217 the geometry model), all the geometry factories are derived from the
210 base class CCalG4Albe. Furthermore, using 218 base class CCalG4Albe. Furthermore, using double inheritance, each
211 of them derives also from the counterpart 219 of them derives also from the counterpart in the "core" hierarchy.
212 The design of the CCalG4Able class helps 220 The design of the CCalG4Able class helps a modular approach and easy
213 interchanging at the level of subdetector 221 interchanging at the level of subdetectors, allowing a straightforward
214 transition from the simulation of the ent 222 transition from the simulation of the entire CMS detector to that of
215 just a part of it, or to a test-beam geom 223 just a part of it, or to a test-beam geometry, as indeed in this example.
216 Of course this modular, flexible, and gen 224 Of course this modular, flexible, and general approach does not come
217 for free: the price to pay here is its co 225 for free: the price to pay here is its complexity, which would be
218 otherwise unjustified if we limited ourse 226 otherwise unjustified if we limited ourself to the pure simulation
219 of a relatively simple test-beam setup. 227 of a relatively simple test-beam setup.
220 228
221 --- See "10. Classes Overview" below for a sc 229 --- See "10. Classes Overview" below for a schematic summary of the
222 various classes involved in the Geometry 230 various classes involved in the Geometry description of this example.
223 231
224 232
225 4. Physics processes 233 4. Physics processes
226 -------------------- 234 --------------------
227 235
228 The factory physics list is used, therefore t << 236 By the default, one of the ufficial High Energy Physics List for
229 is steered by the environmental variable PHYS << 237 Calorimetry, QGSP_BIC_EMY, is used in this example, so that it
230 (Note: if this environmental variable is not << 238 allows to test the low-energy electromagnetic.
231 which is used is FTFP_BERT). << 239 However, it is very easy to use instead either LHEP, QGSP, or QGSC.
232 << 240 To do so, it is enough to comment/uncomment a line in the main
>> 241 CompositeCalorimeter.cc : for example, if you want to use LHEP
>> 242 instead of the default QGSP_BIC_EMY you have to change it as follows:
>> 243
>> 244 //***LOOKHERE*** CHOOSE THE PHYSICS LIST.
>> 245 runManager->SetUserInitialization(new LHEP); // LHEP
>> 246 // runManager->SetUserInitialization(new QGSP); // QGSP
>> 247 // runManager->SetUserInitialization(new QGSC); // QGSC
>> 248 // runManager->SetUserInitialization(new QGSP_BIC_EMY); // QGSP_BIC_EMY
>> 249 //***endLOOKHERE***
>> 250
>> 251 Notice that, for most of the cases (and certainly also in this case
>> 252 in which we don't even take into account the beam profile, noise
>> 253 and digitization!) the faster LHEP Physics List would be good enough
>> 254 for calorimetry studies.
>> 255
233 256
234 5. Particle Generator 257 5. Particle Generator
235 --------------------- 258 ---------------------
236 259
237 The 1996 test-beam has been taken with the fo 260 The 1996 test-beam has been taken with the following particles:
238 --- 225 GeV muons (for calibration) 261 --- 225 GeV muons (for calibration)
239 --- 10 to 300 GeV pions 262 --- 10 to 300 GeV pions
240 --- 10 to 300 GeV electrons 263 --- 10 to 300 GeV electrons
241 therefore the standard Geant4 Particle Gun ha 264 therefore the standard Geant4 Particle Gun has been used as primary
242 generator. Notice that, for the sake of keepi 265 generator. Notice that, for the sake of keeping the example not too
243 complicated, the proper simulation of the bea 266 complicated, the proper simulation of the beam profile and
244 beam contamination have been neglected. 267 beam contamination have been neglected.
245 268
246 269
247 6. Hits 270 6. Hits
248 ------- 271 -------
249 272
250 In CMS there are two groups of hits: Tracker- 273 In CMS there are two groups of hits: Tracker-like and Calorimeter-like.
251 Only the latter one appears in this example. 274 Only the latter one appears in this example.
252 For the same reasons, as seen for the Geometr 275 For the same reasons, as seen for the Geometry, of consistency without
253 duplication of information and unnecessary co 276 duplication of information and unnecessary coupling between Simulation,
254 Reconstruction, and Visualization, the simula 277 Reconstruction, and Visualization, the simulation calorimeter hit class,
255 CCalG4Hit, doubly inherits from the common Ge 278 CCalG4Hit, doubly inherits from the common Geant4 abstract class for
256 all hits, G4VHit, and from the "core" (i.e. s 279 all hits, G4VHit, and from the "core" (i.e. simulation independent)
257 CMS calorimeter hit class, CCalHit. 280 CMS calorimeter hit class, CCalHit.
258 A new Hit object is created 281 A new Hit object is created
259 - for each new particle entering the calori 282 - for each new particle entering the calorimeter;
260 - for each detector unit (i.e cristal or fi 283 - for each detector unit (i.e cristal or fiber or scintillator layer);
261 - for each nanosecond of the shower develop 284 - for each nanosecond of the shower development;
262 The information stored in each CCalHit object 285 The information stored in each CCalHit object is the following:
263 - Entry : local coordinates of the entranc 286 - Entry : local coordinates of the entrance point of the particle
264 in the unit where the shower sta 287 in the unit where the shower starts;
265 - the TrackID : Identification number of t 288 - the TrackID : Identification number of the incident particle;
266 - the IncidentEnergy : kinetic energy of t 289 - the IncidentEnergy : kinetic energy of that incident particle;
267 - the UnitID : the identification number of 290 - the UnitID : the identification number of the detector unit
268 (crystal, or fiber, or scint 291 (crystal, or fiber, or scintillator layer);
269 - the TimeSlice : the time interval, in nan 292 - the TimeSlice : the time interval, in nanoseconds, in which the
270 hit has been created; 293 hit has been created;
271 - the EnergyDeposit : the energy deposit in 294 - the EnergyDeposit : the energy deposit in this hit.
272 Notice that all hit objects created for a giv 295 Notice that all hit objects created for a given shower have the same
273 values for the first three pieces of informat 296 values for the first three pieces of information.
274 297
275 298
276 No Noise and Digitization 299 No Noise and Digitization
277 -------------------------- 300 --------------------------
278 301
279 In order to keep the complexity of this examp 302 In order to keep the complexity of this example to a reasonable
280 level, both noise and digitization effects ha 303 level, both noise and digitization effects have not been included.
281 304
282 305
283 7. User Actions 306 7. User Actions
284 ---------------- 307 ----------------
285 308
286 In this example. there have been used the fol 309 In this example. there have been used the following User Actions:
287 310
288 --- G4UserRunAction (the derived, concrete cl 311 --- G4UserRunAction (the derived, concrete class is CCalRunAction):
289 it is used to invoke the Analysis object 312 it is used to invoke the Analysis object at the beginning of
290 the Run, to instantiate it and passing it 313 the Run, to instantiate it and passing it the Run number, and
291 at the end of the Run, to inform it that 314 at the end of the Run, to inform it that the Run is finished
292 and therefore the histograms, ntuples, et 315 and therefore the histograms, ntuples, etc. must be closed.
293 316
294 --- G4UserEventAction (the derived, concrete 317 --- G4UserEventAction (the derived, concrete class is CCalEndOfEventAction):
295 it is used to examine, at the end of the 318 it is used to examine, at the end of the Event, all collected
296 (calorimeter) hits, extract the various o 319 (calorimeter) hits, extract the various observables which are
297 interesting (to the goal of understanding 320 interesting (to the goal of understanding things like: the effect
298 of magnetic field on scintiallator; choic 321 of magnetic field on scintiallator; choice of the absorber
299 thickness by optimizing resolution versus 322 thickness by optimizing resolution versus containment; impact of
300 the absorber depth in the energy caontain 323 the absorber depth in the energy caontainment; electromagnetic
301 calorimeter contribution in the electron 324 calorimeter contribution in the electron - pion separation; etc.)
302 and finally call the analysis object to s 325 and finally call the analysis object to store such selected
303 information on histograms and/or in the n 326 information on histograms and/or in the ntuple.
304 The name of the class "CCalEndOfEventActi 327 The name of the class "CCalEndOfEventAction" is motivated by the
305 fact that at the beginning of the Event n 328 fact that at the beginning of the Event nothing is done.
306 329
307 --- G4UserSteppingAction (the derived, concre 330 --- G4UserSteppingAction (the derived, concrete class is CCalSteppingAction):
308 it is used to extract some "unphysical" i 331 it is used to extract some "unphysical" information (that is not
309 experimentally measurable, although inter 332 experimentally measurable, although interesting for a better
310 understanding of the shower development), 333 understanding of the shower development), namely the lateral profile
311 and the deposit as a function of the time 334 and the deposit as a function of the time (see "8.Analysis/Histogramming
312 for more details"), which is available on 335 for more details"), which is available only from simulation, and then,
313 at the end of Event, the analysis object 336 at the end of Event, the analysis object is invoked to store such
314 information on histograms. 337 information on histograms.
315 Please notice that the stepping action is 338 Please notice that the stepping action is not used to create hits.
316 339
317 --- G4UserStackingAction (the derived, concre 340 --- G4UserStackingAction (the derived, concrete class is CCalStackingAction):
318 it is used to ensure that the same track 341 it is used to ensure that the same track ID of the particle
319 originating a shower appears in all hits 342 originating a shower appears in all hits (calorimeter hit objects
320 of class CCalHit) of the shower, in any c 343 of class CCalHit) of the shower, in any calorimeter part.
321 344
322 345
323 8. Analysis / Histogramming 346 8. Analysis / Histogramming
324 ---------------------------- 347 ----------------------------
325 348
326 The analysis part of CompositeCalorimeter is 349 The analysis part of CompositeCalorimeter is kept in class CCalAnalysis,
327 and is based on the g4tool interfaces. 350 and is based on the g4tool interfaces.
328 Both the histograms and the ntuple are saved 351 Both the histograms and the ntuple are saved at the end of the run in the
329 ROOT file "ccal.root" (default: this can be c 352 ROOT file "ccal.root" (default: this can be changed to XML or to other
330 formats supported by the g4analysis tools). 353 formats supported by the g4analysis tools).
331 Please note that in a multiple run session, t 354 Please note that in a multiple run session, the last run always overrides
332 the output file. 355 the output file.
333 What the histograms and the variables of the 356 What the histograms and the variables of the ntuple represent is
334 explained below: 357 explained below:
335 358
336 Histograms h100 - h127 : energy deposit (in 359 Histograms h100 - h127 : energy deposit (in GeV) in the sensitive part
337 (plastic scintillato 360 (plastic scintillator layer) of one Hadronic
338 calorimeter module ( 361 calorimeter module (there are 28 modules, numbered
339 from 0 to 27, and th 362 from 0 to 27, and the corresponding histogram has
340 ID = 100 + number of 363 ID = 100 + number of module).
341 Ntuple variables hcal0 - hcal27 : provide t 364 Ntuple variables hcal0 - hcal27 : provide the same information.
342 365
343 Histograms h200 - h248 : energy deposit (in 366 Histograms h200 - h248 : energy deposit (in GeV) in one crystal
344 electromagnetic towe 367 electromagnetic towers (there are a matrix of
345 7 x 7 = 49 towers, n 368 7 x 7 = 49 towers, numbered from 0 to 48, and
346 the corresponding hi 369 the corresponding histogram has
347 ID = 200 + number of 370 ID = 200 + number of tower).
348 Ntuple variables ecal0 - ecal48 : provide t 371 Ntuple variables ecal0 - ecal48 : provide the same information.
349 372
350 Histograms h300 - h339 : total energy depos 373 Histograms h300 - h339 : total energy deposit (in GeV) in any
351 electromagnetic crys 374 electromagnetic crystal tower or hadronic module
352 (either in a sensiti 375 (either in a sensitive or insensitive layer)
353 in one of the 40 nan 376 in one of the 40 nanosecond time slices: in other
354 words, histogram 30 377 words, histogram 300+I , where I = 0 - 39,
355 contains the total d 378 contains the total deposit energy between
356 I and I+1 nanosecond 379 I and I+1 nanoseconds after the "collision".
357 (Notice that the tim 380 (Notice that the time window considered,
358 40 nanoseconds, is 381 40 nanoseconds, is larger than the LHC
359 bunch-crossing of 2 382 bunch-crossing of 25 nanoseconds.)
360 383
361 Histograms h400 - h469 : energy profile (in 384 Histograms h400 - h469 : energy profile (in GeV), summed over all layers
362 sensitive (plastic s 385 sensitive (plastic scintillator) and insensitive
363 (copper absorber), a 386 (copper absorber), as a function of the radial
364 distance (in centime 387 distance (in centimeter) from the beam axis
365 ( ID histo = 400 + r 388 ( ID histo = 400 + radial distance in cm ).
366 389
367 Histogram h4000 : total energy deposit (in 390 Histogram h4000 : total energy deposit (in GeV) in the sensitive parts
368 of either the electromagne 391 of either the electromagnetic or hadronic calorimeters.
369 Ntuple variable edep provides the same info 392 Ntuple variable edep provides the same information.
370 393
371 Other ntuple variables are the following: 394 Other ntuple variables are the following:
372 --- elab : energy (in GeV) of the inci 395 --- elab : energy (in GeV) of the incident particle.
373 --- xpos, ypos, zpos : position (in mm 396 --- xpos, ypos, zpos : position (in mm) from where the projectile
374 has been shot. 397 has been shot.
375 --- edec, edhc : total energy deposit 398 --- edec, edhc : total energy deposit (in GeV) in the sensitive
376 parts of, respectivel 399 parts of, respectively, the electromagnetic
377 and hadronic calorime 400 and hadronic calorimeters. Notice that their
378 sum edec+edhc coinc 401 sum edec+edhc coincides with edep
379 402
380 Notice that lateral profile (400-469) and ti 403 Notice that lateral profile (400-469) and time-slice (300-339)
381 histograms show purely Monte Carlo quantitie 404 histograms show purely Monte Carlo quantities, which cannot be
382 experimentally measured. 405 experimentally measured.
383 Please be careful that the range of the hist 406 Please be careful that the range of the histograms has been chosen
384 in such a way to contain most of the entries 407 in such a way to contain most of the entries, but only few histograms
385 fill a large fraction of that range, whereas 408 fill a large fraction of that range, whereas the remaining majority
386 fill only the first few bins (corresponding 409 fill only the first few bins (corresponding to lower energy), and,
387 therefore, when plotted they look almost emp 410 therefore, when plotted they look almost empty, but they are not,
388 and the results are sensible. We suggest to 411 and the results are sensible. We suggest to plot the ntuple's variables,
389 rather than the histograms, when the same in 412 rather than the histograms, when the same information is available
390 from the ntuple. 413 from the ntuple.
391 414
392 415
393 9. Visualization / GUI 416 9. Visualization / GUI
394 ----------------------- 417 -----------------------
395 418
396 If you setup one of the following Geant4 envi 419 If you setup one of the following Geant4 environmental variables:
397 G4VIS_USE_DAWN 420 G4VIS_USE_DAWN
398 G4VIS_USE_VRML 421 G4VIS_USE_VRML
399 G4VIS_USE_OPENGLX 422 G4VIS_USE_OPENGLX
400 which correspond to the use of DAWN, VRML, an 423 which correspond to the use of DAWN, VRML, and OPENGLX, respectively,
401 as visualization engine of Geant4, and set pr 424 as visualization engine of Geant4, and set properly the corresponding
402 PATH as well, it is then possible to visual 425 PATH as well, it is then possible to visualize the detector and also
403 some events. 426 some events.
404 To do so, you have to run 427 To do so, you have to run
405 > ./CompositeCalorimeter 428 > ./CompositeCalorimeter
406 without input file: you then see the detector 429 without input file: you then see the detector; after that,
407 you can select the particle gun and its energ 430 you can select the particle gun and its energy, in the
408 case you want something different from the th 431 case you want something different from the the default
409 (which is a 100 GeV pi-), for example: 432 (which is a 100 GeV pi-), for example:
410 Idle> /gun/particle e- 433 Idle> /gun/particle e-
411 Idle> /gun/energy 200 GeV 434 Idle> /gun/energy 200 GeV
412 and then run some events, for example: 435 and then run some events, for example:
413 Idle> /run/beamOn 3 436 Idle> /run/beamOn 3
414 437
>> 438 Notice that, by default, OGL is used for the visualization,
>> 439 because it is quite fast and it does not produce any files in
>> 440 output. However, you can always choose something else, for example
>> 441 VRML2FILE or DAWNFILE, either interactively as follows:
>> 442 Idle> /vis/open DAWNFILE
>> 443 or by changing the default, by editing the file (main program)
>> 444 CompositeCalorimeter.cc and comment/uncomment the lines
>> 445 in such a way to have, at the end:
>> 446 visCommand = "/vis/open DAWNFILE";
>> 447 // visCommand = "/vis/open VRML2FILE";
>> 448 // visCommand = "/vis/open OGL";
>> 449
415 The tracks that are shown include both charge 450 The tracks that are shown include both charged and neutral particles
416 of any momentum: if you want instead only cha 451 of any momentum: if you want instead only charged, or only neutral,
417 then you have simply to edit src/CCalEndOfEv 452 then you have simply to edit src/CCalEndOfEventAction.cc
418 at the end of the method EndOfEventAction a 453 at the end of the method EndOfEventAction and uncomment the line
419 where the condition on the charge is made (it 454 where the condition on the charge is made (it should then be
420 straighforward to eventual add some other con 455 straighforward to eventual add some other conditions, for example
421 if you want to see only those particles that 456 if you want to see only those particles that satisfy certain
422 kinematic conditions). 457 kinematic conditions).
423 458
424 Rather than to specify "by hand" the type of 459 Rather than to specify "by hand" the type of particle gun,
425 its energy, and the number of events, it is p 460 its energy, and the number of events, it is possible to have
426 a very simple GUI (graphical user interface) 461 a very simple GUI (graphical user interface) from which to make
427 such choices, between a limited set of possib 462 such choices, between a limited set of possibilities, via menus.
428 Such GUI is based on Motif XmCommand widget, 463 Such GUI is based on Motif XmCommand widget, but it would be
429 straightforward, eventually, to make the nece 464 straightforward, eventually, to make the necessary changes
430 in order to use a different one. 465 in order to use a different one.
431 The only thing you need to do to get the GUI 466 The only thing you need to do to get the GUI is to setup
432 the following Geant4 environmental variables: 467 the following Geant4 environmental variables:
433 G4UI_BUILD_XM_SESSION=1 468 G4UI_BUILD_XM_SESSION=1
434 G4UI_USE_XM=1 469 G4UI_USE_XM=1
435 Then, if you run the executable without speci 470 Then, if you run the executable without specifying a macro file
436 (like test.g4mac): 471 (like test.g4mac):
437 > $G4WORKDIR/bin/$G4SYSTEM/CompositeCalo 472 > $G4WORKDIR/bin/$G4SYSTEM/CompositeCalorimeter
438 a window automatically pops out, with the men 473 a window automatically pops out, with the menus where you
439 can make your selection of particle type, ene 474 can make your selection of particle type, energy, and number
440 of events to be run. 475 of events to be run.
441 476
442 477
443 10. Classes Overview 478 10. Classes Overview
444 --------------------- 479 ---------------------
445 480
446 This is a schematic overview of the classes d 481 This is a schematic overview of the classes defined in this example:
447 482
448 CCalPrimaryGeneratorAction 483 CCalPrimaryGeneratorAction
449 CCalPrimaryGeneratorMessenger 484 CCalPrimaryGeneratorMessenger
450 User action for primaries generator. 485 User action for primaries generator.
451 486
452 CCalDetectorConstruction 487 CCalDetectorConstruction
453 CCalAMaterial 488 CCalAMaterial
454 CCalDataSet 489 CCalDataSet
455 CCalDetector 490 CCalDetector
456 CCalEcal 491 CCalEcal
457 CCalEcalOrganization 492 CCalEcalOrganization
458 CCalG4Able 493 CCalG4Able
459 CCalG4Ecal 494 CCalG4Ecal
460 CCalG4Hall 495 CCalG4Hall
461 CCalG4Hcal 496 CCalG4Hcal
462 CCalGeometryConfiguration 497 CCalGeometryConfiguration
463 CCalHall 498 CCalHall
464 CCalHcal 499 CCalHcal
465 CCalHcalOrganization 500 CCalHcalOrganization
466 CCalMagneticField 501 CCalMagneticField
467 CCalMaterial 502 CCalMaterial
468 CCalMaterialFactory 503 CCalMaterialFactory
469 CCalRotationMatrixFactory 504 CCalRotationMatrixFactory
470 CCalVOrganization 505 CCalVOrganization
471 CCalVisManager 506 CCalVisManager
472 CCalVisualisable 507 CCalVisualisable
473 CCaloOrganization 508 CCaloOrganization
474 CCalutils 509 CCalutils
475 Geometry and material definitions for the de 510 Geometry and material definitions for the detector.
476 Notice in particular that: 511 Notice in particular that:
477 CCalHall, CCalEcal, CCalHcal derive 512 CCalHall, CCalEcal, CCalHcal derive from CCalDetector;
478 CCalG4Hall, CCalG4Ecal, CCalG4Hcal d 513 CCalG4Hall, CCalG4Ecal, CCalG4Hcal derive from the above
479 corresponding classes and from CC 514 corresponding classes and from CCalG4Able;
480 CCalEcalOrganization, CCalHcalOrgani 515 CCalEcalOrganization, CCalHcalOrganization derive from
481 CCalVOrganization : each sensitiv 516 CCalVOrganization : each sensitive cell has an unique
482 number for detector organization 517 number for detector organization (this is a software
483 ID not an hardware/electronic one 518 ID not an hardware/electronic one).
484 519
485 CCalHit 520 CCalHit
486 CCalG4Hit 521 CCalG4Hit
487 CCalG4HitCollection 522 CCalG4HitCollection
488 CCalSDList 523 CCalSDList
489 CCalSensAssign 524 CCalSensAssign
490 CCalSensitiveConfiguration 525 CCalSensitiveConfiguration
491 CCalSensitiveDetectors 526 CCalSensitiveDetectors
492 CCaloSD 527 CCaloSD
493 Hit and Sensitive Detectors. 528 Hit and Sensitive Detectors.
494 Notice in particular that: 529 Notice in particular that:
495 CCalG4Hit derives from G4VHit and CC 530 CCalG4Hit derives from G4VHit and CCalHit;
496 CCaloSD derives from G4VSensitiveDet 531 CCaloSD derives from G4VSensitiveDetector.
497 532
498 CCalActionInitializer <<
499 User-action initialization. <<
500 <<
501 CCalAnalysis 533 CCalAnalysis
502 Analysis manager class. << 534 Analysis manager class which uses Anaphe.
503 535
504 CCalRunAction 536 CCalRunAction
505 User run action class. 537 User run action class.
506 538
507 CCalEndOfEventAction 539 CCalEndOfEventAction
508 User event action class. 540 User event action class.
509 541
510 CCalStackingAction 542 CCalStackingAction
511 User Stacking action class. 543 User Stacking action class.
512 544
513 CCalSteppingAction 545 CCalSteppingAction
514 User Stepping action class. 546 User Stepping action class.
515 547