Line data Source code
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: AliFMDHitDigitizer.cxx 28055 2008-08-18 00:33:20Z cholm $ */
16 : /** @file AliFMDHitDigitizer.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
26 : //
27 : // Digits consists of
28 : // - Detector #
29 : // - Ring ID
30 : // - Sector #
31 : // - Strip #
32 : // - ADC count in this channel
33 : //
34 : // As the Digits and SDigits have so much in common, the classes
35 : // AliFMDHitDigitizer and AliFMDSDigitizer are implemented via a base
36 : // class AliFMDBaseDigitizer.
37 : //
38 : // +---------------------+
39 : // | AliFMDBaseDigitizer |
40 : // +---------------------+
41 : // ^
42 : // |
43 : // +----------+---------+
44 : // | |
45 : // +-----------------+ +------------------+
46 : // | AliFMDHitDigitizer | | AliFMDSDigitizer |
47 : // +-----------------+ +------------------+
48 : //
49 : // These classes has several paramters:
50 : //
51 : // fPedestal
52 : // fPedestalWidth
53 : // (Only AliFMDHitDigitizer)
54 : // Mean and width of the pedestal. The pedestal is simulated
55 : // by a Guassian, but derived classes my override MakePedestal
56 : // to simulate it differently (or pick it up from a database).
57 : //
58 : // fVA1MipRange
59 : // The dymamic MIP range of the VA1_ALICE pre-amplifier chip
60 : //
61 : // fAltroChannelSize
62 : // The largest number plus one that can be stored in one
63 : // channel in one time step in the ALTRO ADC chip.
64 : //
65 : // fSampleRate
66 : // How many times the ALTRO ADC chip samples the VA1_ALICE
67 : // pre-amplifier signal. The VA1_ALICE chip is read-out at
68 : // 10MHz, while it's possible to drive the ALTRO chip at
69 : // 25MHz. That means, that the ALTRO chip can have time to
70 : // sample each VA1_ALICE signal up to 2 times. Although it's
71 : // not certain this feature will be used in the production,
72 : // we'd like have the option, and so it should be reflected in
73 : // the code.
74 : //
75 : // These parameters are fetched from OCDB via the mananger AliFMDParameters.
76 : //
77 : // The shaping function of the VA1_ALICE is generally given by
78 : //
79 : // f(x) = A(1 - exp(-Bx))
80 : //
81 : // where A is the total charge collected in the pre-amp., and B is a
82 : // paramter that depends on the shaping time of the VA1_ALICE circut.
83 : //
84 : // When simulating the shaping function of the VA1_ALICe
85 : // pre-amp. chip, we have to take into account, that the shaping
86 : // function depends on the previous value of read from the pre-amp.
87 : //
88 : // That results in the following algorithm:
89 : //
90 : // last = 0;
91 : // FOR charge IN pre-amp. charge train DO
92 : // IF last < charge THEN
93 : // f(t) = (charge - last) * (1 - exp(-B * t)) + last
94 : // ELSE
95 : // f(t) = (last - charge) * exp(-B * t) + charge)
96 : // ENDIF
97 : // FOR i IN # samples DO
98 : // adc_i = f(i / (# samples))
99 : // DONE
100 : // last = charge
101 : // DONE
102 : //
103 : // Here,
104 : //
105 : // pre-amp. charge train
106 : // is a series of 128 charges read from the VA1_ALICE chip
107 : //
108 : // # samples
109 : // is the number of times the ALTRO ADC samples each of the 128
110 : // charges from the pre-amp.
111 : //
112 : // Where Q is the total charge collected by the VA1_ALICE
113 : // pre-amplifier. Q is then given by
114 : //
115 : // E S
116 : // Q = - -
117 : // e R
118 : //
119 : // where E is the total energy deposited in a silicon strip, R is the
120 : // dynamic range of the VA1_ALICE pre-amp (fVA1MipRange), e is the
121 : // energy deposited by a single MIP, and S ALTRO channel size in each
122 : // time step (fAltroChannelSize).
123 : //
124 : // The energy deposited per MIP is given by
125 : //
126 : // e = M * rho * w
127 : //
128 : // where M is the universal number 1.664, rho is the density of
129 : // silicon, and w is the depth of the silicon sensor.
130 : //
131 : // The final ADC count is given by
132 : //
133 : // C' = C + P
134 : //
135 : // where P is the (randomized) pedestal (see MakePedestal)
136 : //
137 : // This class uses the class template AliFMDMap<Type> to make an
138 : // internal cache of the energy deposted of the hits. The class
139 : // template is instantasized as
140 : //
141 : // typedef AliFMDMap<std::pair<Float_t, UShort_t> > AliFMDEdepMap;
142 : //
143 : // The first member of the values is the summed energy deposition in a
144 : // given strip, while the second member of the values is the number of
145 : // hits in a given strip. Using the second member, it's possible to
146 : // do some checks on just how many times a strip got hit, and what
147 : // kind of error we get in our reconstructed hits. Note, that this
148 : // information is currently not written to the digits tree. I think a
149 : // QA (Quality Assurance) digit tree is better suited for that task.
150 : // However, the information is there to be used in the future.
151 : //
152 : //
153 : // Latest changes by Christian Holm Christensen
154 : //
155 : //////////////////////////////////////////////////////////////////////////////
156 :
157 : // /1
158 : // | A(-1 + B + exp(-B))
159 : // | f(x) dx = ------------------- = 1
160 : // | B
161 : // / 0
162 : //
163 : // and B is the a parameter defined by the shaping time (fShapingTime).
164 : //
165 : // Solving the above equation, for A gives
166 : //
167 : // B
168 : // A = ----------------
169 : // -1 + B + exp(-B)
170 : //
171 : // So, if we define the function g: [0,1] -> [0:1] by
172 : //
173 : // / v
174 : // | Bu + exp(-Bu) - Bv - exp(-Bv)
175 : // g(u,v) = | f(x) dx = -A -----------------------------
176 : // | B
177 : // / u
178 : //
179 : // we can evaluate the ALTRO sample of the VA1_ALICE pre-amp between
180 : // any two times (u, v), by
181 : //
182 : //
183 : // B Bu + exp(-Bu) - Bv - exp(-Bv)
184 : // C = Q g(u,v) = - Q ---------------- -----------------------------
185 : // -1 + B + exp(-B) B
186 : //
187 : // Bu + exp(-Bu) - Bv - exp(-Bv)
188 : // = - Q -----------------------------
189 : // -1 + B + exp(-B)
190 : //
191 :
192 : #include <TTree.h> // ROOT_TTree
193 : #include "AliFMDDebug.h" // Better debug macros
194 : #include "AliFMDHitDigitizer.h" // ALIFMDDIGITIZER_H
195 : #include "AliFMD.h" // ALIFMD_H
196 : #include "AliFMDDigit.h" // ALIFMDDIGIT_H
197 : #include "AliFMDParameters.h" // ALIFMDPARAMETERS_H
198 : #include <AliRun.h> // ALIRUN_H
199 : #include <AliLoader.h> // ALILOADER_H
200 : #include <AliRunLoader.h> // ALIRUNLOADER_H
201 : #include <AliFMDHit.h>
202 : #include <AliStack.h>
203 : #include <TFile.h>
204 : #include <TParticle.h>
205 :
206 : //====================================================================
207 12 : ClassImp(AliFMDHitDigitizer)
208 : #if 0
209 : ;
210 : #endif
211 :
212 : //____________________________________________________________________
213 : AliFMDHitDigitizer::AliFMDHitDigitizer(AliFMD* fmd, Output_t output)
214 1 : : AliFMDBaseDigitizer("FMD", (output == kDigits ?
215 : "FMD Hit->Digit digitizer" :
216 : "FMD Hit->SDigit digitizer")),
217 1 : fOutput(output),
218 1 : fHoldTime(2e-6),
219 1 : fStack(0)
220 5 : {
221 1 : fFMD = fmd;
222 2 : }
223 :
224 : //____________________________________________________________________
225 : AliFMDHitDigitizer&
226 : AliFMDHitDigitizer::operator=(const AliFMDHitDigitizer& o)
227 : {
228 : /**
229 : * Assignment operator
230 : *
231 : * @param o Object to assign from
232 : * @return Reference to this
233 : */
234 0 : if (&o == this) return *this;
235 0 : AliFMDBaseDigitizer::operator=(o);
236 0 : fHoldTime = o.fHoldTime;
237 0 : fOutput = o.fOutput;
238 0 : fStack = o.fStack;
239 0 : return *this;
240 0 : }
241 :
242 : //____________________________________________________________________
243 : void
244 : AliFMDHitDigitizer::Digitize(Option_t* /*option*/)
245 : {
246 : // Run this digitizer
247 : // Get an inititialize parameter manager
248 2 : AliFMDParameters::Instance()->Init();
249 1 : if (AliLog::GetDebugLevel("FMD","") >= 10)
250 0 : AliFMDParameters::Instance()->Print("ALL");
251 :
252 : // Get loader, and ask it to read in the hits
253 1 : AliLoader* loader = fFMD->GetLoader();
254 1 : if (!loader) {
255 0 : AliError("Failed to get loader from detector object");
256 0 : return;
257 : }
258 1 : loader->LoadHits("READ");
259 :
260 : // Get the run loader
261 1 : AliRunLoader* runLoader = loader->GetRunLoader();
262 1 : if (!runLoader) {
263 0 : AliError("Failed to get run loader from loader");
264 0 : return;
265 : }
266 :
267 : // Now loop over events
268 1 : Int_t nEvents = runLoader->GetNumberOfEvents();
269 11 : for (Int_t event = 0; event < nEvents; event++) {
270 : // Get the current event folder.
271 4 : TFolder* folder = loader->GetEventFolder();
272 4 : if (!folder) {
273 0 : AliError("Failed to get event folder from loader");
274 0 : return;
275 : }
276 :
277 : // Get the run-loader of this event.
278 8 : const char* loaderName = AliRunLoader::GetRunLoaderName();
279 : AliRunLoader* thisLoader =
280 4 : static_cast<AliRunLoader*>(folder->FindObject(loaderName));
281 4 : if (!thisLoader) {
282 0 : AliError(Form("Failed to get loader '%s' from event folder", loaderName));
283 0 : return;
284 : }
285 :
286 : // Read in the event
287 8 : AliFMDDebug(1, ("Now digitizing (Hits->%s) event # %d",
288 : (fOutput == kDigits ? "digits" : "sdigits"), event));
289 4 : thisLoader->GetEvent(event);
290 :
291 : // Load kinematics to get primary information for SDigits
292 4 : fStack = 0;
293 4 : if (fOutput == kSDigits) {
294 4 : if (thisLoader->LoadKinematics("READ")) {
295 0 : AliError("Failed to get kinematics from event loader");
296 0 : return;
297 : }
298 8 : AliFMDDebug(5, ("Loading stack of kinematics"));
299 4 : fStack = thisLoader->Stack();
300 4 : }
301 :
302 : // Check that we have the hits
303 7 : if (!loader->TreeH() && loader->LoadHits()) {
304 0 : AliError("Failed to load hits");
305 0 : return;
306 : }
307 4 : TTree* hitsTree = loader->TreeH();
308 4 : TBranch* hitsBranch = hitsTree->GetBranch(fFMD->GetName());
309 4 : if (!hitsBranch) {
310 0 : AliError("Failed to get hits branch in tree");
311 0 : return;
312 : }
313 : // Check that we can make the output digits - This must come
314 : // before AliFMD::SetBranchAddress
315 4 : TTree* outTree = MakeOutputTree(loader);
316 4 : if (!outTree) {
317 0 : AliError("Failed to get output tree");
318 0 : return;
319 : }
320 8 : AliFMDDebug(5, ("Output tree name for %s is '%s'",
321 : (fOutput == kDigits ? "digits" : "sdigits"),
322 : outTree->GetName()));
323 4 : if (AliLog::GetDebugLevel("FMD","") >= 5) {
324 0 : TFile* file = outTree->GetCurrentFile();
325 0 : if (!file) {
326 0 : AliWarning("Output tree has no file!");
327 0 : }
328 : else {
329 0 : AliFMDDebug(5, ("Output tree file %s content:", file->GetName()));
330 0 : file->ls();
331 : }
332 0 : }
333 :
334 : // Set-up the branch addresses
335 4 : fFMD->SetTreeAddress();
336 :
337 : // Now sum all contributions in cache
338 4 : SumContributions(hitsBranch);
339 4 : loader->UnloadHits();
340 :
341 : // And now digitize the hits
342 4 : DigitizeHits();
343 :
344 : // Write digits to tree
345 4 : Int_t write = outTree->Fill();
346 8 : AliFMDDebug(5, ("Wrote %d bytes to digit tree", write));
347 :
348 : // Store the digits
349 4 : StoreDigits(loader);
350 :
351 4 : }
352 2 : }
353 :
354 : //____________________________________________________________________
355 : TTree*
356 : AliFMDHitDigitizer::MakeOutputTree(AliLoader* loader)
357 : {
358 : /**
359 : * Make the output tree using the passed loader
360 : *
361 : * @param loader
362 : * @return The generated tree.
363 : */
364 8 : if (fOutput == kDigits)
365 0 : return AliFMDBaseDigitizer::MakeOutputTree(loader);
366 :
367 8 : AliFMDDebug(5, ("Making sdigits tree"));
368 4 : loader->LoadSDigits("UPDATE"); // RECREATE");
369 4 : TTree* out = loader->TreeS();
370 8 : if (!out) loader->MakeTree("S");
371 4 : out = loader->TreeS();
372 4 : if (out) {
373 4 : out->Reset();
374 4 : fFMD->MakeBranch("S");
375 4 : }
376 : return out;
377 4 : }
378 :
379 :
380 : //____________________________________________________________________
381 : void
382 : AliFMDHitDigitizer::SumContributions(TBranch* hitsBranch)
383 : {
384 : // Sum energy deposited contributions from each hit in a cache
385 : // (fEdep).
386 :
387 : // Clear array of deposited energies
388 8 : fEdep.Reset();
389 :
390 : // Get a list of hits from the FMD manager
391 8 : AliFMDDebug(5, ("Get array of FMD hits"));
392 4 : TClonesArray *fmdHits = fFMD->Hits();
393 :
394 :
395 : // Get number of entries in the tree
396 8 : AliFMDDebug(5, ("Get # of tracks"));
397 4 : Int_t ntracks = Int_t(hitsBranch->GetEntries());
398 8 : AliFMDDebug(5, ("We got %d tracks", ntracks));
399 :
400 : Int_t read = 0;
401 : // Loop over the tracks in the
402 232 : for (Int_t track = 0; track < ntracks; track++) {
403 : // Read in entry number `track'
404 112 : read += hitsBranch->GetEntry(track);
405 :
406 : // Get the number of hits
407 112 : Int_t nhits = fmdHits->GetEntries ();
408 444 : for (Int_t hit = 0; hit < nhits; hit++) {
409 : // Get the hit number `hit'
410 : AliFMDHit* fmdHit =
411 110 : static_cast<AliFMDHit*>(fmdHits->UncheckedAt(hit));
412 :
413 : // Ignore hits that arrive too late
414 110 : if (fmdHit->Time() > fHoldTime) continue;
415 :
416 :
417 : // Check if this is a primary particle
418 : Bool_t isPrimary = kTRUE;
419 110 : Int_t trackno = -1;
420 110 : if (fStack) {
421 110 : trackno = fmdHit->Track();
422 220 : AliFMDDebug(10, ("Will get track # %d/%d from entry # %d",
423 : trackno, fStack->GetNtrack(), track));
424 110 : if (fStack->GetNtrack() < trackno) {
425 0 : AliError(Form("Track number %d/%d out of bounds",
426 : trackno, fStack->GetNtrack()));
427 0 : continue;
428 : }
429 : #if 1
430 110 : isPrimary = fStack->IsPhysicalPrimary(trackno);
431 : #else // This is our hand-crafted code. We use the ALICE definition
432 : TParticle* part = fStack->Particle(trackno);
433 : isPrimary = part->IsPrimary();
434 : if (!isPrimary) {
435 : // Extended testing of mother status - this is for Pythia6.
436 : Int_t mother1 = part->GetFirstMother();
437 : TParticle* mother = fStack->Particle(mother1);
438 : if (!mother || mother->GetStatusCode() > 1)
439 : isPrimary = kTRUE;
440 : AliFMDDebug(15,
441 : ("Track %d secondary, mother: %d - %s - status %d: %s",
442 : trackno, mother1,
443 : (mother ? "found" : "not found"),
444 : (mother ? mother->GetStatusCode() : -1),
445 : (isPrimary ? "primary" : "secondary")));
446 : }
447 : #endif
448 110 : }
449 :
450 : // Extract parameters
451 220 : AliFMDDebug(15,("Adding contribution %7.5f for FMD%d%c[%2d,%3d] "
452 : " for trackno %6d (%s)",
453 : fmdHit->Edep(),
454 : fmdHit->Detector(),
455 : fmdHit->Ring(),
456 : fmdHit->Sector(),
457 : fmdHit->Strip(),
458 : trackno,
459 : (isPrimary ? "primary" : "secondary")));
460 220 : AddContribution(fmdHit->Detector(),
461 110 : fmdHit->Ring(),
462 110 : fmdHit->Sector(),
463 110 : fmdHit->Strip(),
464 110 : fmdHit->Edep(),
465 110 : isPrimary,
466 : 1,
467 : &trackno);
468 220 : } // hit loop
469 : } // track loop
470 8 : AliFMDDebug(5, ("Size of cache: %d bytes, read %d bytes",
471 : int(sizeof(fEdep)), read));
472 4 : }
473 :
474 :
475 : //____________________________________________________________________
476 : UShort_t
477 : AliFMDHitDigitizer::MakePedestal(UShort_t detector,
478 : Char_t ring,
479 : UShort_t sector,
480 : UShort_t strip) const
481 : {
482 : // Make a pedestal
483 614400 : if (fOutput == kSDigits) return 0;
484 0 : return AliFMDBaseDigitizer::MakePedestal(detector, ring, sector, strip);
485 204800 : }
486 :
487 :
488 :
489 : //____________________________________________________________________
490 : void
491 : AliFMDHitDigitizer::AddDigit(UShort_t detector,
492 : Char_t ring,
493 : UShort_t sector,
494 : UShort_t strip,
495 : Float_t edep,
496 : UShort_t count1,
497 : Short_t count2,
498 : Short_t count3,
499 : Short_t count4,
500 : UShort_t ntotal,
501 : UShort_t nprim,
502 : const TArrayI& refs) const
503 : {
504 : // Add a digit or summable digit
505 409600 : if (fOutput == kDigits) {
506 0 : AliFMDDebug(15,("Adding digit for FMD%d%c[%2d,%3d] = (%x,%x,%x,%x)",
507 : detector, ring, sector, strip,
508 : count1, count2, count3, count4));
509 0 : AliFMDBaseDigitizer::AddDigit(detector, ring, sector, strip, 0,
510 : count1, count2, count3, count4,
511 : ntotal, nprim, refs);
512 0 : return;
513 : }
514 204800 : if (edep <= 0) {
515 409386 : AliFMDDebug(15, ("Digit edep = %f <= 0 for FMD%d%c[%2d,%3d]",
516 : edep, detector, ring, sector, strip));
517 : return;
518 : }
519 110 : if (count1 == 0 && count2 <= 0 && count3 <= 0 && count4 <= 0) {
520 2 : AliFMDDebug(15, ("Digit counts = (%x,%x,%x,%x) <= 0 for FMD%d%c[%2d,%3d]",
521 : count1, count2, count3, count4,
522 : detector, ring, sector, strip));
523 : return;
524 : }
525 212 : AliFMDDebug(15, ("Adding sdigit for FMD%d%c[%2d,%3d] = "
526 : "(%x,%x,%x,%x) [%d/%d] %d",
527 : detector, ring, sector, strip,
528 : count1, count2, count3, count4, nprim, ntotal, refs.fN));
529 212 : fFMD->AddSDigitByFields(detector, ring, sector, strip, edep,
530 : count1, count2, count3, count4,
531 318 : ntotal, nprim, fStoreTrackRefs ? refs.fArray : 0);
532 212 : if (fStoreTrackRefs && nprim > 3) fIgnoredLabels += nprim - 3;
533 204800 : }
534 :
535 : //____________________________________________________________________
536 : void
537 : AliFMDHitDigitizer::CheckDigit(AliFMDDigit* digit,
538 : UShort_t nhits,
539 : const TArrayI& counts)
540 : {
541 : // Check that digit is consistent
542 0 : AliFMDParameters* param = AliFMDParameters::Instance();
543 0 : UShort_t det = digit->Detector();
544 0 : Char_t ring = digit->Ring();
545 0 : UShort_t sec = digit->Sector();
546 0 : UShort_t str = digit->Strip();
547 0 : Float_t mean = param->GetPedestal(det,ring,sec,str);
548 0 : Float_t width = param->GetPedestalWidth(det,ring,sec,str);
549 0 : UShort_t range = param->GetVA1MipRange();
550 0 : UShort_t size = param->GetAltroChannelSize();
551 0 : Int_t integral = counts[0];
552 0 : if (counts[1] >= 0) integral += counts[1];
553 0 : if (counts[2] >= 0) integral += counts[2];
554 0 : if (counts[3] >= 0) integral += counts[3];
555 0 : integral -= Int_t(mean + 2 * width);
556 0 : if (integral < 0) integral = 0;
557 :
558 0 : Float_t convF = Float_t(range) / size;
559 0 : Float_t mips = integral * convF;
560 0 : if (mips > Float_t(nhits) + .5 || mips < Float_t(nhits) - .5)
561 0 : Warning("CheckDigit", "Digit -> %4.2f MIPS != %d +/- .5 hits",
562 0 : mips, nhits);
563 0 : }
564 :
565 : //____________________________________________________________________
566 : void
567 : AliFMDHitDigitizer::StoreDigits(const AliLoader* loader)
568 : {
569 : /**
570 : * Store the data using the loader
571 : *
572 : * @param loader The loader
573 : */
574 8 : if (fOutput == kDigits) {
575 0 : AliFMDBaseDigitizer::StoreDigits(loader);
576 0 : return;
577 : }
578 8 : AliFMDDebug(5, ("Storing %d sdigits", fFMD->SDigits()->GetEntries()));
579 : // Write the digits to disk
580 4 : loader->WriteSDigits("OVERWRITE");
581 4 : loader->UnloadSDigits();
582 : // Reset the digits in the AliFMD object
583 4 : fFMD->ResetSDigits();
584 8 : }
585 :
586 :
587 : //____________________________________________________________________
588 : //
589 : // EOF
590 : //
591 :
592 :
593 :
594 :
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