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02a27b50 | 1 | /************************************************************************** |
2 | * Copyright(c) 2004, ALICE Experiment at CERN, All rights reserved. * | |
3 | * * | |
4 | * Author: The ALICE Off-line Project. * | |
5 | * Contributors are mentioned in the code where appropriate. * | |
6 | * * | |
7 | * Permission to use, copy, modify and distribute this software and its * | |
8 | * documentation strictly for non-commercial purposes is hereby granted * | |
9 | * without fee, provided that the above copyright notice appears in all * | |
10 | * copies and that both the copyright notice and this permission notice * | |
11 | * appear in the supporting documentation. The authors make no claims * | |
12 | * about the suitability of this software for any purpose. It is * | |
13 | * provided "as is" without express or implied warranty. * | |
14 | **************************************************************************/ | |
15 | /* $Id$ */ | |
16 | /** @file AliFMDBaseDigitizer.cxx | |
17 | @author Christian Holm Christensen <cholm@nbi.dk> | |
18 | @date Mon Mar 27 12:38:26 2006 | |
19 | @brief FMD Digitizers implementation | |
20 | @ingroup FMD_sim | |
21 | */ | |
22 | ////////////////////////////////////////////////////////////////////////////// | |
23 | // | |
24 | // This class contains the procedures simulation ADC signal for the | |
25 | // Forward Multiplicity detector : Hits->Digits and Hits->SDigits | |
26 | // | |
27 | // Digits consists of | |
28 | // - Detector # | |
29 | // - Ring ID | |
30 | // - Sector # | |
31 | // - Strip # | |
32 | // - ADC count in this channel | |
33 | // | |
34 | // Digits consists of | |
35 | // - Detector # | |
36 | // - Ring ID | |
37 | // - Sector # | |
38 | // - Strip # | |
39 | // - Total energy deposited in the strip | |
40 | // - ADC count in this channel | |
41 | // | |
42 | // As the Digits and SDigits have so much in common, the classes | |
43 | // AliFMDDigitizer and AliFMDSDigitizer are implemented via a base | |
44 | // class AliFMDBaseDigitizer. | |
45 | // | |
46 | // +---------------------+ | |
47 | // | AliFMDBaseDigitizer | | |
48 | // +---------------------+ | |
49 | // ^ | |
50 | // | | |
51 | // +----------+---------+ | |
52 | // | | | |
53 | // +-----------------+ +------------------+ | |
54 | // | AliFMDDigitizer | | AliFMDSDigitizer | | |
55 | // +-----------------+ +------------------+ | |
56 | // | |
57 | // These classes has several paramters: | |
58 | // | |
59 | // fPedestal | |
60 | // fPedestalWidth | |
61 | // (Only AliFMDDigitizer) | |
62 | // Mean and width of the pedestal. The pedestal is simulated | |
63 | // by a Guassian, but derived classes my override MakePedestal | |
64 | // to simulate it differently (or pick it up from a database). | |
65 | // | |
66 | // fVA1MipRange | |
67 | // The dymamic MIP range of the VA1_ALICE pre-amplifier chip | |
68 | // | |
69 | // fAltroChannelSize | |
70 | // The largest number plus one that can be stored in one | |
71 | // channel in one time step in the ALTRO ADC chip. | |
72 | // | |
73 | // fSampleRate | |
74 | // How many times the ALTRO ADC chip samples the VA1_ALICE | |
75 | // pre-amplifier signal. The VA1_ALICE chip is read-out at | |
76 | // 10MHz, while it's possible to drive the ALTRO chip at | |
77 | // 25MHz. That means, that the ALTRO chip can have time to | |
78 | // sample each VA1_ALICE signal up to 2 times. Although it's | |
79 | // not certain this feature will be used in the production, | |
80 | // we'd like have the option, and so it should be reflected in | |
81 | // the code. | |
82 | // | |
83 | // | |
84 | // The shaping function of the VA1_ALICE is generally given by | |
85 | // | |
86 | // f(x) = A(1 - exp(-Bx)) | |
87 | // | |
88 | // where A is the total charge collected in the pre-amp., and B is a | |
89 | // paramter that depends on the shaping time of the VA1_ALICE circut. | |
90 | // | |
91 | // When simulating the shaping function of the VA1_ALICe | |
92 | // pre-amp. chip, we have to take into account, that the shaping | |
93 | // function depends on the previous value of read from the pre-amp. | |
94 | // | |
95 | // That results in the following algorithm: | |
96 | // | |
97 | // last = 0; | |
98 | // FOR charge IN pre-amp. charge train DO | |
99 | // IF last < charge THEN | |
100 | // f(t) = (charge - last) * (1 - exp(-B * t)) + last | |
101 | // ELSE | |
102 | // f(t) = (last - charge) * exp(-B * t) + charge) | |
103 | // ENDIF | |
104 | // FOR i IN # samples DO | |
105 | // adc_i = f(i / (# samples)) | |
106 | // DONE | |
107 | // last = charge | |
108 | // DONE | |
109 | // | |
110 | // Here, | |
111 | // | |
112 | // pre-amp. charge train | |
113 | // is a series of 128 charges read from the VA1_ALICE chip | |
114 | // | |
115 | // # samples | |
116 | // is the number of times the ALTRO ADC samples each of the 128 | |
117 | // charges from the pre-amp. | |
118 | // | |
119 | // Where Q is the total charge collected by the VA1_ALICE | |
120 | // pre-amplifier. Q is then given by | |
121 | // | |
122 | // E S | |
123 | // Q = - - | |
124 | // e R | |
125 | // | |
126 | // where E is the total energy deposited in a silicon strip, R is the | |
127 | // dynamic range of the VA1_ALICE pre-amp (fVA1MipRange), e is the | |
128 | // energy deposited by a single MIP, and S ALTRO channel size in each | |
129 | // time step (fAltroChannelSize). | |
130 | // | |
131 | // The energy deposited per MIP is given by | |
132 | // | |
133 | // e = M * rho * w | |
134 | // | |
135 | // where M is the universal number 1.664, rho is the density of | |
136 | // silicon, and w is the depth of the silicon sensor. | |
137 | // | |
138 | // The final ADC count is given by | |
139 | // | |
140 | // C' = C + P | |
141 | // | |
142 | // where P is the (randomized) pedestal (see MakePedestal) | |
143 | // | |
144 | // This class uses the class template AliFMDMap<Type> to make an | |
145 | // internal cache of the energy deposted of the hits. The class | |
146 | // template is instantasized as | |
147 | // | |
148 | // typedef AliFMDMap<std::pair<Float_t, UShort_t> > AliFMDEdepMap; | |
149 | // | |
150 | // The first member of the values is the summed energy deposition in a | |
151 | // given strip, while the second member of the values is the number of | |
152 | // hits in a given strip. Using the second member, it's possible to | |
153 | // do some checks on just how many times a strip got hit, and what | |
154 | // kind of error we get in our reconstructed hits. Note, that this | |
155 | // information is currently not written to the digits tree. I think a | |
156 | // QA (Quality Assurance) digit tree is better suited for that task. | |
157 | // However, the information is there to be used in the future. | |
158 | // | |
159 | // | |
160 | // Latest changes by Christian Holm Christensen | |
161 | // | |
162 | ////////////////////////////////////////////////////////////////////////////// | |
163 | ||
164 | // /1 | |
165 | // | A(-1 + B + exp(-B)) | |
166 | // | f(x) dx = ------------------- = 1 | |
167 | // | B | |
168 | // / 0 | |
169 | // | |
170 | // and B is the a parameter defined by the shaping time (fShapingTime). | |
171 | // | |
172 | // Solving the above equation, for A gives | |
173 | // | |
174 | // B | |
175 | // A = ---------------- | |
176 | // -1 + B + exp(-B) | |
177 | // | |
178 | // So, if we define the function g: [0,1] -> [0:1] by | |
179 | // | |
180 | // / v | |
181 | // | Bu + exp(-Bu) - Bv - exp(-Bv) | |
182 | // g(u,v) = | f(x) dx = -A ----------------------------- | |
183 | // | B | |
184 | // / u | |
185 | // | |
186 | // we can evaluate the ALTRO sample of the VA1_ALICE pre-amp between | |
187 | // any two times (u, v), by | |
188 | // | |
189 | // | |
190 | // B Bu + exp(-Bu) - Bv - exp(-Bv) | |
191 | // C = Q g(u,v) = - Q ---------------- ----------------------------- | |
192 | // -1 + B + exp(-B) B | |
193 | // | |
194 | // Bu + exp(-Bu) - Bv - exp(-Bv) | |
195 | // = - Q ----------------------------- | |
196 | // -1 + B + exp(-B) | |
197 | // | |
198 | ||
199 | #include <TTree.h> // ROOT_TTree | |
200 | //#include <TRandom.h> // ROOT_TRandom | |
201 | #include <AliLog.h> // ALILOG_H | |
202 | #include "AliFMDBaseDigitizer.h" // ALIFMDDIGITIZER_H | |
203 | #include "AliFMD.h" // ALIFMD_H | |
204 | #include "AliFMDGeometry.h" // ALIFMDGEOMETRY_H | |
205 | #include "AliFMDDetector.h" // ALIFMDDETECTOR_H | |
206 | #include "AliFMDRing.h" // ALIFMDRING_H | |
207 | #include "AliFMDHit.h" // ALIFMDHIT_H | |
208 | #include "AliFMDDigit.h" // ALIFMDDIGIT_H | |
209 | #include "AliFMDParameters.h" // ALIFMDPARAMETERS_H | |
210 | #include <AliRunDigitizer.h> // ALIRUNDIGITIZER_H | |
211 | //#include <AliRun.h> // ALIRUN_H | |
212 | #include <AliLoader.h> // ALILOADER_H | |
213 | #include <AliRunLoader.h> // ALIRUNLOADER_H | |
214 | ||
215 | //==================================================================== | |
216 | ClassImp(AliFMDBaseDigitizer) | |
217 | #if 0 | |
218 | ; // This is here to keep Emacs for indenting the next line | |
219 | #endif | |
220 | ||
221 | //____________________________________________________________________ | |
222 | AliFMDBaseDigitizer::AliFMDBaseDigitizer() | |
223 | : fRunLoader(0) | |
224 | { | |
225 | // Default ctor - don't use it | |
226 | } | |
227 | ||
228 | //____________________________________________________________________ | |
229 | AliFMDBaseDigitizer::AliFMDBaseDigitizer(AliRunDigitizer* manager) | |
230 | : AliDigitizer(manager, "AliFMDBaseDigitizer", "FMD Digitizer base class"), | |
231 | fRunLoader(0), | |
232 | fEdep(AliFMDMap::kMaxDetectors, | |
233 | AliFMDMap::kMaxRings, | |
234 | AliFMDMap::kMaxSectors, | |
235 | AliFMDMap::kMaxStrips) | |
236 | { | |
237 | // Normal CTOR | |
238 | AliDebug(1," processed"); | |
239 | SetShapingTime(); | |
240 | } | |
241 | ||
242 | //____________________________________________________________________ | |
243 | AliFMDBaseDigitizer::AliFMDBaseDigitizer(const Char_t* name, | |
244 | const Char_t* title) | |
245 | : AliDigitizer(name, title), | |
246 | fRunLoader(0), | |
247 | fEdep(AliFMDMap::kMaxDetectors, | |
248 | AliFMDMap::kMaxRings, | |
249 | AliFMDMap::kMaxSectors, | |
250 | AliFMDMap::kMaxStrips) | |
251 | { | |
252 | // Normal CTOR | |
253 | AliDebug(1," processed"); | |
254 | SetShapingTime(); | |
255 | } | |
256 | ||
257 | //____________________________________________________________________ | |
258 | AliFMDBaseDigitizer::~AliFMDBaseDigitizer() | |
259 | { | |
260 | // Destructor | |
261 | } | |
262 | ||
263 | //____________________________________________________________________ | |
264 | Bool_t | |
265 | AliFMDBaseDigitizer::Init() | |
266 | { | |
267 | // Initialization | |
268 | AliFMDParameters::Instance()->Init(); | |
269 | return kTRUE; | |
270 | } | |
271 | ||
272 | ||
273 | //____________________________________________________________________ | |
274 | UShort_t | |
275 | AliFMDBaseDigitizer::MakePedestal(UShort_t, | |
276 | Char_t, | |
277 | UShort_t, | |
278 | UShort_t) const | |
279 | { | |
280 | // Make a pedestal | |
281 | return 0; | |
282 | } | |
283 | ||
284 | //____________________________________________________________________ | |
285 | void | |
286 | AliFMDBaseDigitizer::SumContributions(AliFMD* fmd) | |
287 | { | |
288 | // Sum energy deposited contributions from each hit in a cache | |
289 | // (fEdep). | |
290 | if (!fRunLoader) | |
291 | Fatal("SumContributions", "no run loader"); | |
292 | ||
293 | // Clear array of deposited energies | |
294 | fEdep.Reset(); | |
295 | ||
296 | // Get the FMD loader | |
297 | AliLoader* inFMD = fRunLoader->GetLoader("FMDLoader"); | |
298 | // And load the hits | |
299 | inFMD->LoadHits("READ"); | |
300 | ||
301 | // Get the tree of hits | |
302 | TTree* hitsTree = inFMD->TreeH(); | |
303 | if (!hitsTree) { | |
304 | // Try again | |
305 | inFMD->LoadHits("READ"); | |
306 | hitsTree = inFMD->TreeH(); | |
307 | } | |
308 | ||
309 | // Get the FMD branch | |
310 | TBranch* hitsBranch = hitsTree->GetBranch("FMD"); | |
311 | if (hitsBranch) fmd->SetHitsAddressBranch(hitsBranch); | |
312 | else AliFatal("Branch FMD hit not found"); | |
313 | ||
314 | // Get a list of hits from the FMD manager | |
315 | TClonesArray *fmdHits = fmd->Hits(); | |
316 | ||
317 | // Get number of entries in the tree | |
318 | Int_t ntracks = Int_t(hitsTree->GetEntries()); | |
319 | ||
320 | AliFMDParameters* param = AliFMDParameters::Instance(); | |
321 | Int_t read = 0; | |
322 | // Loop over the tracks in the | |
323 | for (Int_t track = 0; track < ntracks; track++) { | |
324 | // Read in entry number `track' | |
325 | read += hitsBranch->GetEntry(track); | |
326 | ||
327 | // Get the number of hits | |
328 | Int_t nhits = fmdHits->GetEntries (); | |
329 | for (Int_t hit = 0; hit < nhits; hit++) { | |
330 | // Get the hit number `hit' | |
331 | AliFMDHit* fmdHit = | |
332 | static_cast<AliFMDHit*>(fmdHits->UncheckedAt(hit)); | |
333 | ||
334 | // Extract parameters | |
335 | UShort_t detector = fmdHit->Detector(); | |
336 | Char_t ring = fmdHit->Ring(); | |
337 | UShort_t sector = fmdHit->Sector(); | |
338 | UShort_t strip = fmdHit->Strip(); | |
339 | Float_t edep = fmdHit->Edep(); | |
340 | UShort_t minstrip = param->GetMinStrip(detector, ring, sector, strip); | |
341 | UShort_t maxstrip = param->GetMaxStrip(detector, ring, sector, strip); | |
342 | // Check if strip is `dead' | |
343 | if (param->IsDead(detector, ring, sector, strip)) { | |
344 | AliDebug(5, Form("FMD%d%c[%2d,%3d] is marked as dead", | |
345 | detector, ring, sector, strip)); | |
346 | continue; | |
347 | } | |
348 | // Check if strip is out-side read-out range | |
349 | if (strip < minstrip || strip > maxstrip) { | |
350 | AliDebug(5, Form("FMD%d%c[%2d,%3d] is outside range [%3d,%3d]", | |
351 | detector, ring, sector, strip, minstrip, maxstrip)); | |
352 | continue; | |
353 | } | |
354 | ||
355 | // Give warning in case of double hit | |
356 | if (fEdep(detector, ring, sector, strip).fEdep != 0) | |
357 | AliDebug(5, Form("Double hit in %d%c(%d,%d)", | |
358 | detector, ring, sector, strip)); | |
359 | ||
360 | // Sum energy deposition | |
361 | fEdep(detector, ring, sector, strip).fEdep += edep; | |
362 | fEdep(detector, ring, sector, strip).fN += 1; | |
363 | // Add this to the energy deposited for this strip | |
364 | } // hit loop | |
365 | } // track loop | |
366 | AliDebug(1, Form("Size of cache: %d bytes, read %d bytes", | |
367 | sizeof(fEdep), read)); | |
368 | } | |
369 | ||
370 | //____________________________________________________________________ | |
371 | void | |
372 | AliFMDBaseDigitizer::DigitizeHits(AliFMD* fmd) const | |
373 | { | |
374 | // For the stored energy contributions in the cache (fEdep), convert | |
375 | // the energy signal to ADC counts, and store the created digit in | |
376 | // the digits array (AliFMD::fDigits) | |
377 | // | |
378 | AliFMDGeometry* geometry = AliFMDGeometry::Instance(); | |
379 | ||
380 | TArrayI counts(3); | |
381 | for (UShort_t detector=1; detector <= 3; detector++) { | |
382 | // Get pointer to subdetector | |
383 | AliFMDDetector* det = geometry->GetDetector(detector); | |
384 | if (!det) continue; | |
385 | for (UShort_t ringi = 0; ringi <= 1; ringi++) { | |
386 | Char_t ring = ringi == 0 ? 'I' : 'O'; | |
387 | // Get pointer to Ring | |
388 | AliFMDRing* r = det->GetRing(ring); | |
389 | if (!r) continue; | |
390 | ||
391 | // Get number of sectors | |
392 | UShort_t nSectors = UShort_t(360. / r->GetTheta()); | |
393 | // Loop over the number of sectors | |
394 | for (UShort_t sector = 0; sector < nSectors; sector++) { | |
395 | // Get number of strips | |
396 | UShort_t nStrips = r->GetNStrips(); | |
397 | // Loop over the stips | |
398 | Float_t last = 0; | |
399 | for (UShort_t strip = 0; strip < nStrips; strip++) { | |
400 | // Reset the counter array to the invalid value -1 | |
401 | counts.Reset(-1); | |
402 | // Reset the last `ADC' value when we've get to the end of a | |
403 | // VA1_ALICE channel. | |
404 | if (strip % 128 == 0) last = 0; | |
405 | ||
406 | Float_t edep = fEdep(detector, ring, sector, strip).fEdep; | |
407 | ConvertToCount(edep, last, detector, ring, sector, strip, counts); | |
408 | last = edep; | |
409 | AddDigit(fmd, detector, ring, sector, strip, edep, | |
410 | UShort_t(counts[0]), Short_t(counts[1]), | |
411 | Short_t(counts[2])); | |
412 | #if 0 | |
413 | // This checks if the digit created will give the `right' | |
414 | // number of particles when reconstructed, using a naiive | |
415 | // approach. It's here only as a quality check - nothing | |
416 | // else. | |
417 | CheckDigit(digit, fEdep(detector, ring, sector, strip).fN, | |
418 | counts); | |
419 | #endif | |
420 | } // Strip | |
421 | } // Sector | |
422 | } // Ring | |
423 | } // Detector | |
424 | } | |
425 | ||
426 | //____________________________________________________________________ | |
427 | void | |
428 | AliFMDBaseDigitizer::ConvertToCount(Float_t edep, | |
429 | Float_t last, | |
430 | UShort_t detector, | |
431 | Char_t ring, | |
432 | UShort_t sector, | |
433 | UShort_t strip, | |
434 | TArrayI& counts) const | |
435 | { | |
436 | // Convert the total energy deposited to a (set of) ADC count(s). | |
437 | // | |
438 | // This is done by | |
439 | // | |
440 | // Energy_Deposited ALTRO_Channel_Size | |
441 | // ADC = -------------------------- ------------------- + pedestal | |
442 | // Energy_Deposition_Of_1_MIP VA1_ALICE_MIP_Range | |
443 | // | |
444 | // Energy_Deposited fAltroChannelSize | |
445 | // = --------------------------------- ----------------- + pedestal | |
446 | // 1.664 * Si_Thickness * Si_Density fVA1MipRange | |
447 | // | |
448 | // | |
449 | // = Energy_Deposited * ConversionFactor + pedestal | |
450 | // | |
451 | // However, this is modified by the response function of the | |
452 | // VA1_ALICE pre-amp. chip in case we are doing oversampling of the | |
453 | // VA1_ALICE output. | |
454 | // | |
455 | // In that case, we get N=fSampleRate values of the ADC, and the | |
456 | // `EnergyDeposited' is a function of which sample where are | |
457 | // calculating the ADC for | |
458 | // | |
459 | // ADC_i = f(EnergyDeposited, i/N, Last) * ConversionFactor + pedestal | |
460 | // | |
461 | // where Last is the Energy deposited in the previous strip. | |
462 | // | |
463 | // Here, f is the shaping function of the VA1_ALICE. This is given | |
464 | // by | |
465 | // | |
466 | // | (E - l) * (1 - exp(-B * t) + l if E > l | |
467 | // f(E, t, l) = < | |
468 | // | (l - E) * exp(-B * t) + E otherwise | |
469 | // | |
470 | // | |
471 | // = E + (l - E) * ext(-B * t) | |
472 | // | |
473 | AliFMDParameters* param = AliFMDParameters::Instance(); | |
474 | Float_t convF = 1/param->GetPulseGain(detector,ring,sector,strip); | |
475 | UShort_t ped = MakePedestal(detector,ring,sector,strip); | |
476 | UInt_t maxAdc = param->GetAltroChannelSize(); | |
477 | UShort_t rate = param->GetSampleRate(detector,ring,sector,strip); | |
478 | UShort_t size = param->GetAltroChannelSize(); | |
479 | ||
480 | // In case we don't oversample, just return the end value. | |
481 | if (rate == 1) { | |
8ec606c2 | 482 | counts[0] = UShort_t(TMath::Min(edep * convF + ped, Float_t(maxAdc))); |
483 | AliDebug(2, Form("FMD%d%c[%2d,%3d]: converting ELoss %f to ADC %d (%f)", | |
484 | detector,ring,sector,strip,edep,counts[0],convF)); | |
02a27b50 | 485 | return; |
486 | } | |
487 | ||
488 | // Create a pedestal | |
489 | Float_t b = fShapingTime; | |
490 | for (Ssiz_t i = 0; i < rate; i++) { | |
491 | Float_t t = Float_t(i) / rate; | |
492 | Float_t s = edep + (last - edep) * TMath::Exp(-b * t); | |
493 | counts[i] = UShort_t(TMath::Min(s * convF + ped, Float_t(maxAdc))); | |
494 | } | |
495 | } | |
496 | ||
497 | ||
498 | ||
499 | //____________________________________________________________________ | |
500 | // | |
501 | // EOF | |
502 | // | |
503 | ||
504 | ||
505 | ||
506 |