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4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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14 **************************************************************************/
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
22 //////////////////////////////////////////////////////////////////////////////
24 // This class contains the procedures simulation ADC signal for the
25 // Forward Multiplicity detector : Hits->Digits and Hits->SDigits
32 // - ADC count in this channel
39 // - Total energy deposited in the strip
40 // - ADC count in this channel
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.
46 // +---------------------+
47 // | AliFMDBaseDigitizer |
48 // +---------------------+
51 // +----------+---------+
53 // +-----------------+ +------------------+
54 // | AliFMDDigitizer | | AliFMDSDigitizer |
55 // +-----------------+ +------------------+
57 // These classes has several paramters:
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).
67 // The dymamic MIP range of the VA1_ALICE pre-amplifier chip
70 // The largest number plus one that can be stored in one
71 // channel in one time step in the ALTRO ADC chip.
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
84 // The shaping function of the VA1_ALICE is generally given by
86 // f(x) = A(1 - exp(-Bx))
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.
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.
95 // That results in the following algorithm:
98 // FOR charge IN pre-amp. charge train DO
99 // IF last < charge THEN
100 // f(t) = (charge - last) * (1 - exp(-B * t)) + last
102 // f(t) = (last - charge) * exp(-B * t) + charge)
104 // FOR i IN # samples DO
105 // adc_i = f(i / (# samples))
112 // pre-amp. charge train
113 // is a series of 128 charges read from the VA1_ALICE chip
116 // is the number of times the ALTRO ADC samples each of the 128
117 // charges from the pre-amp.
119 // Where Q is the total charge collected by the VA1_ALICE
120 // pre-amplifier. Q is then given by
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).
131 // The energy deposited per MIP is given by
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.
138 // The final ADC count is given by
142 // where P is the (randomized) pedestal (see MakePedestal)
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
148 // typedef AliFMDMap<std::pair<Float_t, UShort_t> > AliFMDEdepMap;
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.
160 // Latest changes by Christian Holm Christensen
162 //////////////////////////////////////////////////////////////////////////////
165 // | A(-1 + B + exp(-B))
166 // | f(x) dx = ------------------- = 1
170 // and B is the a parameter defined by the shaping time (fShapingTime).
172 // Solving the above equation, for A gives
175 // A = ----------------
178 // So, if we define the function g: [0,1] -> [0:1] by
181 // | Bu + exp(-Bu) - Bv - exp(-Bv)
182 // g(u,v) = | f(x) dx = -A -----------------------------
186 // we can evaluate the ALTRO sample of the VA1_ALICE pre-amp between
187 // any two times (u, v), by
190 // B Bu + exp(-Bu) - Bv - exp(-Bv)
191 // C = Q g(u,v) = - Q ---------------- -----------------------------
192 // -1 + B + exp(-B) B
194 // Bu + exp(-Bu) - Bv - exp(-Bv)
195 // = - Q -----------------------------
200 #include <TTree.h> // ROOT_TTree
201 //#include <TRandom.h> // ROOT_TRandom
202 // #include <AliLog.h> // ALILOG_H
203 #include "AliFMDDebug.h" // Better debug macros
204 #include "AliFMDBaseDigitizer.h" // ALIFMDDIGITIZER_H
205 #include "AliFMD.h" // ALIFMD_H
206 #include "AliFMDGeometry.h" // ALIFMDGEOMETRY_H
207 #include "AliFMDDetector.h" // ALIFMDDETECTOR_H
208 #include "AliFMDRing.h" // ALIFMDRING_H
209 #include "AliFMDHit.h" // ALIFMDHIT_H
210 // #include "AliFMDDigit.h" // ALIFMDDIGIT_H
211 #include "AliFMDParameters.h" // ALIFMDPARAMETERS_H
212 // #include <AliRunDigitizer.h> // ALIRUNDIGITIZER_H
213 //#include <AliRun.h> // ALIRUN_H
214 #include <AliLoader.h> // ALILOADER_H
215 #include <AliRun.h> // ALILOADER_H
216 #include <AliRunLoader.h> // ALIRUNLOADER_H
218 //====================================================================
219 ClassImp(AliFMDBaseDigitizer)
221 ; // This is here to keep Emacs for indenting the next line
224 //____________________________________________________________________
225 AliFMDBaseDigitizer::AliFMDBaseDigitizer()
227 fEdep(AliFMDMap::kMaxDetectors,
228 AliFMDMap::kMaxRings,
229 AliFMDMap::kMaxSectors,
230 AliFMDMap::kMaxStrips),
233 AliFMDDebug(1, ("Constructed"));
234 // Default ctor - don't use it
237 //____________________________________________________________________
238 AliFMDBaseDigitizer::AliFMDBaseDigitizer(AliRunDigitizer* manager)
239 : AliDigitizer(manager, "AliFMDBaseDigitizer", "FMD Digitizer base class"),
241 fEdep(AliFMDMap::kMaxDetectors,
242 AliFMDMap::kMaxRings,
243 AliFMDMap::kMaxSectors,
244 AliFMDMap::kMaxStrips),
248 AliFMDDebug(1, ("Constructed"));
252 //____________________________________________________________________
253 AliFMDBaseDigitizer::AliFMDBaseDigitizer(const Char_t* name,
255 : AliDigitizer(name, title),
257 fEdep(AliFMDMap::kMaxDetectors,
258 AliFMDMap::kMaxRings,
259 AliFMDMap::kMaxSectors,
260 AliFMDMap::kMaxStrips),
264 AliFMDDebug(1, (" Constructed"));
268 //____________________________________________________________________
269 AliFMDBaseDigitizer::~AliFMDBaseDigitizer()
274 //____________________________________________________________________
276 AliFMDBaseDigitizer::Init()
279 AliFMDParameters::Instance()->Init();
280 if (AliLog::GetDebugLevel("FMD","") >= 10)
281 AliFMDParameters::Instance()->Print("ALL");
285 //____________________________________________________________________
287 AliFMDBaseDigitizer::Exec(Option_t* /*option*/)
289 AliFMDDebug(1, ("Executing digitizer"));
291 AliLoader* outFMD = 0;
292 if (!SetupLoaders(fmd, outFMD)) return;
293 if (!LoopOverInput(fmd)) return;
295 // Digitize the event
299 AliFMDDebug(5, ("Calling output tree"));
300 OutputTree(outFMD, fmd);
304 //____________________________________________________________________
306 AliFMDBaseDigitizer::SetupLoaders(AliFMD*& fmd, AliLoader*& outFMD)
308 // Set-up input/output loaders.
309 AliFMDDebug(5, ("Setting up run-loaders"));
311 // Get the output manager and the FMD output manager
312 TString outFolder(fManager->GetOutputFolderName());
313 AliRunLoader* out = AliRunLoader::GetRunLoader(outFolder.Data());
314 outFMD = out->GetLoader("FMDLoader");
316 AliError("Cannot get the FMDLoader output folder");
320 // Get the input loader
321 TString inFolder(fManager->GetInputFolderName(0));
322 fRunLoader = AliRunLoader::GetRunLoader(inFolder.Data());
324 AliError("Can not find Run Loader for input stream 0");
328 // Get the AliRun object
329 if (!fRunLoader->GetAliRun()) {
330 AliWarning("Loading gAlice");
331 fRunLoader->LoadgAlice();
334 // Get the AliRun object
335 AliRun* run = fRunLoader->GetAliRun();
337 AliError("Can not get Run from Run Loader");
341 // Get the AliFMD object
342 fmd = static_cast<AliFMD*>(run->GetDetector("FMD"));
344 AliError("Can not get FMD from gAlice");
350 //____________________________________________________________________
352 AliFMDBaseDigitizer::LoopOverInput(AliFMD* fmd)
355 AliError("No digitisation manager defined");
359 Int_t nFiles= fManager->GetNinputs();
360 AliFMDDebug(1, (" Digitizing event number %d, got %d inputs",
361 fManager->GetOutputEventNr(), nFiles));
362 for (Int_t inputFile = 0; inputFile < nFiles; inputFile++) {
363 AliFMDDebug(5, ("Now reading input # %d", inputFile));
364 // Get the current loader
366 AliRunLoader::GetRunLoader(fManager->GetInputFolderName(inputFile));
368 Error("Exec", Form("no run loader for input file # %d", inputFile));
371 // Cache contriutions
372 AliFMDDebug(5, ("Now summing the contributions from input # %d",inputFile));
373 SumContributions(fmd);
379 //____________________________________________________________________
381 AliFMDBaseDigitizer::MakePedestal(UShort_t,
390 //____________________________________________________________________
392 AliFMDBaseDigitizer::SumContributions(AliFMD* fmd)
394 // Sum energy deposited contributions from each hit in a cache
397 Fatal("SumContributions", "no run loader");
399 // Clear array of deposited energies
402 // Get the FMD loader
403 AliLoader* inFMD = fRunLoader->GetLoader("FMDLoader");
405 AliFMDDebug(5, ("Will read hits"));
406 inFMD->LoadHits("READ");
408 // Get the tree of hits
409 AliFMDDebug(5, ("Will get hit tree"));
410 TTree* hitsTree = inFMD->TreeH();
413 AliFMDDebug(5, ("First attempt failed, try again"));
414 inFMD->LoadHits("READ");
415 hitsTree = inFMD->TreeH();
418 // Get the FMD branch
419 AliFMDDebug(5, ("Will now get the branch"));
420 TBranch* hitsBranch = hitsTree->GetBranch("FMD");
421 if (hitsBranch) fmd->SetHitsAddressBranch(hitsBranch);
422 else AliFatal("Branch FMD hit not found");
424 // Get a list of hits from the FMD manager
425 AliFMDDebug(5, ("Get array of FMD hits"));
426 TClonesArray *fmdHits = fmd->Hits();
428 // Get number of entries in the tree
429 AliFMDDebug(5, ("Get # of tracks"));
430 Int_t ntracks = Int_t(hitsTree->GetEntries());
431 AliFMDDebug(5, ("We got %d tracks", ntracks));
433 AliFMDParameters* param = AliFMDParameters::Instance();
435 // Loop over the tracks in the
436 for (Int_t track = 0; track < ntracks; track++) {
437 // Read in entry number `track'
438 read += hitsBranch->GetEntry(track);
440 // Get the number of hits
441 Int_t nhits = fmdHits->GetEntries ();
442 for (Int_t hit = 0; hit < nhits; hit++) {
443 // Get the hit number `hit'
445 static_cast<AliFMDHit*>(fmdHits->UncheckedAt(hit));
447 // Extract parameters
448 UShort_t detector = fmdHit->Detector();
449 Char_t ring = fmdHit->Ring();
450 UShort_t sector = fmdHit->Sector();
451 UShort_t strip = fmdHit->Strip();
452 Float_t edep = fmdHit->Edep();
453 AliFMDDebug(10, ("Hit in FMD%d%c[%2d,%3d]=%f",
454 detector, ring, sector, strip, edep));
455 // Check if strip is `dead'
456 if (param->IsDead(detector, ring, sector, strip)) {
457 AliFMDDebug(1, ("FMD%d%c[%2d,%3d] is marked as dead",
458 detector, ring, sector, strip));
461 // UShort_t minstrip = param->GetMinStrip(detector, ring, sector, strip);
462 // UShort_t maxstrip = param->GetMaxStrip(detector, ring, sector, strip);
463 // Check if strip is out-side read-out range
464 // if (strip < minstrip || strip > maxstrip) {
465 // AliFMDDebug(5, ("FMD%d%c[%2d,%3d] is outside range [%3d,%3d]",
466 // detector,ring,sector,strip,minstrip,maxstrip));
470 // Give warning in case of double hit
471 if (fEdep(detector, ring, sector, strip).fEdep != 0)
472 AliFMDDebug(5, ("Double hit in %d%c(%d,%d)",
473 detector, ring, sector, strip));
475 // Sum energy deposition
476 fEdep(detector, ring, sector, strip).fEdep += edep;
477 fEdep(detector, ring, sector, strip).fN += 1;
478 // Add this to the energy deposited for this strip
481 AliFMDDebug(5, ("Size of cache: %d bytes, read %d bytes",
482 sizeof(fEdep), read));
486 //____________________________________________________________________
488 AliFMDBaseDigitizer::DigitizeHits(AliFMD* fmd) const
490 // For the stored energy contributions in the cache (fEdep), convert
491 // the energy signal to ADC counts, and store the created digit in
492 // the digits array (AliFMD::fDigits)
494 AliFMDDebug(5, ("Will now digitize all the summed signals"));
495 AliFMDGeometry* geometry = AliFMDGeometry::Instance();
498 for (UShort_t detector=1; detector <= 3; detector++) {
499 AliFMDDebug(5, ("Processing hits in FMD%d", detector));
500 // Get pointer to subdetector
501 AliFMDDetector* det = geometry->GetDetector(detector);
503 for (UShort_t ringi = 0; ringi <= 1; ringi++) {
504 Char_t ring = ringi == 0 ? 'I' : 'O';
505 AliFMDDebug(5, (" Processing hits in FMD%d%c", detector,ring));
506 // Get pointer to Ring
507 AliFMDRing* r = det->GetRing(ring);
510 // Get number of sectors
511 UShort_t nSectors = UShort_t(360. / r->GetTheta());
512 // Loop over the number of sectors
513 for (UShort_t sector = 0; sector < nSectors; sector++) {
514 AliFMDDebug(5, (" Processing hits in FMD%d%c[%2d]",
515 detector,ring,sector));
516 // Get number of strips
517 UShort_t nStrips = r->GetNStrips();
518 // Loop over the stips
520 for (UShort_t strip = 0; strip < nStrips; strip++) {
521 // Reset the counter array to the invalid value -1
523 // Reset the last `ADC' value when we've get to the end of a
524 // VA1_ALICE channel.
525 if (strip % 128 == 0) last = 0;
527 Float_t edep = fEdep(detector, ring, sector, strip).fEdep;
528 ConvertToCount(edep, last, detector, ring, sector, strip, counts);
531 // The following line was introduced - wrongly - by Peter
532 // Hristov. It _will_ break the digitisation and the
533 // following reconstruction. The behviour of the
534 // digitisation models exactly the front-end as it should
535 // (no matter what memory concuption it may entail). The
536 // check should be on zero suppression, since that's what
537 // models the front-end - if zero suppression is turned on
538 // in the front-end, then we can suppress empty digits -
539 // otherwise we shoud never do that. Note, that the line
540 // affects _both_ normal digitisation and digitisation for
541 // summable digits, since the condition is on the energy
542 // deposition and not on the actual number of counts. If
543 // this line should go anywhere, it should be in the
544 // possible overloaded AliFMDSDigitizer::AddDigit - not
547 // if (edep<=0) continue;
548 AddDigit(fmd, detector, ring, sector, strip, edep,
549 UShort_t(counts[0]), Short_t(counts[1]),
550 Short_t(counts[2]), Short_t(counts[3]));
551 AliFMDDebug(10, (" Adding digit in FMD%d%c[%2d,%3d]=%d",
552 detector,ring,sector,strip,counts[0]));
554 // This checks if the digit created will give the `right'
555 // number of particles when reconstructed, using a naiive
556 // approach. It's here only as a quality check - nothing
558 CheckDigit(digit, fEdep(detector, ring, sector, strip).fN,
567 //____________________________________________________________________
569 AliFMDBaseDigitizer::ConvertToCount(Float_t edep,
575 TArrayI& counts) const
577 // Convert the total energy deposited to a (set of) ADC count(s).
581 // Energy_Deposited ALTRO_Channel_Size
582 // ADC = -------------------------- ------------------- + pedestal
583 // Energy_Deposition_Of_1_MIP VA1_ALICE_MIP_Range
585 // Energy_Deposited fAltroChannelSize
586 // = --------------------------------- ----------------- + pedestal
587 // 1.664 * Si_Thickness * Si_Density fVA1MipRange
590 // = Energy_Deposited * ConversionFactor + pedestal
592 // However, this is modified by the response function of the
593 // VA1_ALICE pre-amp. chip in case we are doing oversampling of the
596 // In that case, we get N=fSampleRate values of the ADC, and the
597 // `EnergyDeposited' is a function of which sample where are
598 // calculating the ADC for
600 // ADC_i = f(EnergyDeposited, i/N, Last) * ConversionFactor + pedestal
602 // where Last is the Energy deposited in the previous strip.
604 // Here, f is the shaping function of the VA1_ALICE. This is given
607 // | (E - l) * (1 - exp(-B * t) + l if E > l
609 // | (l - E) * exp(-B * t) + E otherwise
612 // = E + (l - E) * ext(-B * t)
614 AliFMDParameters* param = AliFMDParameters::Instance();
615 Float_t convF = 1./param->GetPulseGain(detector,ring,sector,strip);
616 Int_t ped = MakePedestal(detector,ring,sector,strip);
617 Int_t maxAdc = param->GetAltroChannelSize()-1;
619 AliWarning(Form("Maximum ADC is %d < 0, forcing it to 1023", maxAdc));
622 UShort_t rate = param->GetSampleRate(detector,ring,sector,strip);
623 if (rate < 1 || rate > 4) rate = 1;
625 // In case we don't oversample, just return the end value.
627 Float_t a = edep * convF + ped;
629 counts[0] = UShort_t(TMath::Min(a, Float_t(maxAdc)));
630 AliFMDDebug(10, ("FMD%d%c[%2d,%3d]: converting ELoss %f to "
632 detector,ring,sector,strip,edep,counts[0],convF,ped));
637 Float_t b = fShapingTime;
638 for (Ssiz_t i = 0; i < rate; i++) {
639 Float_t t = Float_t(i) / rate + 1./rate;
640 Float_t s = edep + (last - edep) * TMath::Exp(-b * t);
641 Float_t a = Int_t(s * convF + ped);
643 counts[i] = UShort_t(TMath::Min(a, Float_t(maxAdc)));
649 //____________________________________________________________________