prepare for the new tracklet fit/attach
[u/mrichter/AliRoot.git] / FMD / AliFMDBaseDigitizer.cxx
CommitLineData
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
090026bf 199#include <TMath.h>
02a27b50 200#include <TTree.h> // ROOT_TTree
201//#include <TRandom.h> // ROOT_TRandom
f95a63c4 202// #include <AliLog.h> // ALILOG_H
203#include "AliFMDDebug.h" // Better debug macros
02a27b50 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
6169f936 210// #include "AliFMDDigit.h" // ALIFMDDIGIT_H
02a27b50 211#include "AliFMDParameters.h" // ALIFMDPARAMETERS_H
6169f936 212// #include <AliRunDigitizer.h> // ALIRUNDIGITIZER_H
02a27b50 213//#include <AliRun.h> // ALIRUN_H
214#include <AliLoader.h> // ALILOADER_H
42f1b2f5 215#include <AliRun.h> // ALILOADER_H
02a27b50 216#include <AliRunLoader.h> // ALIRUNLOADER_H
ef8e8623 217#include <TRandom.h>
02a27b50 218
219//====================================================================
220ClassImp(AliFMDBaseDigitizer)
221#if 0
222 ; // This is here to keep Emacs for indenting the next line
223#endif
224
225//____________________________________________________________________
226AliFMDBaseDigitizer::AliFMDBaseDigitizer()
ef8e8623 227 : fFMD(0),
228 fRunLoader(0),
b5ee4425 229 fEdep(AliFMDMap::kMaxDetectors,
230 AliFMDMap::kMaxRings,
231 AliFMDMap::kMaxSectors,
232 AliFMDMap::kMaxStrips),
2aeec17d 233 fShapingTime(6)
02a27b50 234{
42f1b2f5 235 AliFMDDebug(1, ("Constructed"));
02a27b50 236 // Default ctor - don't use it
237}
238
239//____________________________________________________________________
240AliFMDBaseDigitizer::AliFMDBaseDigitizer(AliRunDigitizer* manager)
241 : AliDigitizer(manager, "AliFMDBaseDigitizer", "FMD Digitizer base class"),
ef8e8623 242 fFMD(0),
02a27b50 243 fRunLoader(0),
244 fEdep(AliFMDMap::kMaxDetectors,
245 AliFMDMap::kMaxRings,
246 AliFMDMap::kMaxSectors,
b5ee4425 247 AliFMDMap::kMaxStrips),
2aeec17d 248 fShapingTime(6)
02a27b50 249{
250 // Normal CTOR
42f1b2f5 251 AliFMDDebug(1, ("Constructed"));
02a27b50 252 SetShapingTime();
253}
254
255//____________________________________________________________________
256AliFMDBaseDigitizer::AliFMDBaseDigitizer(const Char_t* name,
257 const Char_t* title)
258 : AliDigitizer(name, title),
ef8e8623 259 fFMD(0),
02a27b50 260 fRunLoader(0),
261 fEdep(AliFMDMap::kMaxDetectors,
262 AliFMDMap::kMaxRings,
263 AliFMDMap::kMaxSectors,
322be683 264 AliFMDMap::kMaxStrips),
265 fShapingTime(6)
02a27b50 266{
267 // Normal CTOR
42f1b2f5 268 AliFMDDebug(1, (" Constructed"));
02a27b50 269 SetShapingTime();
270}
271
272//____________________________________________________________________
273AliFMDBaseDigitizer::~AliFMDBaseDigitizer()
274{
275 // Destructor
276}
277
278//____________________________________________________________________
279Bool_t
280AliFMDBaseDigitizer::Init()
281{
ef8e8623 282 // Initialization. Get a pointer to the parameter manager, and
283 // initialize it.
02a27b50 284 AliFMDParameters::Instance()->Init();
ef8e8623 285 if (AliLog::GetDebugLevel("FMD","") >= 15)
286 AliFMDParameters::Instance()->Print("");
42f1b2f5 287 return kTRUE;
288}
289
02a27b50 290//____________________________________________________________________
291UShort_t
ef8e8623 292AliFMDBaseDigitizer::MakePedestal(UShort_t detector,
293 Char_t ring,
294 UShort_t sector,
295 UShort_t strip) const
02a27b50 296{
ef8e8623 297 // Make a pedestal. The pedestal value is drawn from a Gaussian
298 // distribution. The mean of the distribution is the measured
299 // pedestal, and the width is the measured noise.
300 AliFMDParameters* param =AliFMDParameters::Instance();
301 Float_t mean =param->GetPedestal(detector,ring,sector,strip);
302 Float_t width =param->GetPedestalWidth(detector,ring,sector,strip);
303 return UShort_t(TMath::Max(gRandom->Gaus(mean, width), 0.));
02a27b50 304}
305
306//____________________________________________________________________
307void
ef8e8623 308AliFMDBaseDigitizer::AddContribution(UShort_t detector,
309 Char_t ring,
310 UShort_t sector,
311 UShort_t strip,
83ad576a 312 Float_t edep,
313 Bool_t isPrimary)
02a27b50 314{
ef8e8623 315 // Add edep contribution from (detector,ring,sector,strip) to cache
316 AliFMDParameters* param = AliFMDParameters::Instance();
317
318 // Check if strip is `dead'
319 if (param->IsDead(detector, ring, sector, strip)) {
320 AliFMDDebug(5, ("FMD%d%c[%2d,%3d] is marked as dead",
321 detector, ring, sector, strip));
322 return;
02a27b50 323 }
ef8e8623 324 // Check if strip is out-side read-out range
325 // if (strip < minstrip || strip > maxstrip) {
326 // AliFMDDebug(5, ("FMD%d%c[%2d,%3d] is outside range [%3d,%3d]",
327 // detector,ring,sector,strip,minstrip,maxstrip));
328 // continue;
329 // }
02a27b50 330
ef8e8623 331 // Give warning in case of double sdigit
332 if (fEdep(detector, ring, sector, strip).fEdep != 0)
333 AliFMDDebug(5, ("Double digit in %d%c(%d,%d)",
334 detector, ring, sector, strip));
02a27b50 335
ef8e8623 336 // Sum energy deposition
83ad576a 337 fEdep(detector, ring, sector, strip).fEdep += edep;
338 fEdep(detector, ring, sector, strip).fN += 1;
339 if (isPrimary)
340 fEdep(detector, ring, sector, strip).fNPrim += 1;
341 AliFMDDebug(15, ("Adding contribution %f to FMD%d%c[%2d,%3d] (%f)",
342 edep, detector, ring, sector, strip,
343 fEdep(detector, ring, sector, strip).fEdep));
344
02a27b50 345}
346
347//____________________________________________________________________
348void
ef8e8623 349AliFMDBaseDigitizer::DigitizeHits() const
02a27b50 350{
351 // For the stored energy contributions in the cache (fEdep), convert
352 // the energy signal to ADC counts, and store the created digit in
353 // the digits array (AliFMD::fDigits)
354 //
42f1b2f5 355 AliFMDDebug(5, ("Will now digitize all the summed signals"));
02a27b50 356 AliFMDGeometry* geometry = AliFMDGeometry::Instance();
357
2aeec17d 358 TArrayI counts(4);
02a27b50 359 for (UShort_t detector=1; detector <= 3; detector++) {
ef8e8623 360 AliFMDDebug(10, ("Processing hits in FMD%d", detector));
02a27b50 361 // Get pointer to subdetector
362 AliFMDDetector* det = geometry->GetDetector(detector);
363 if (!det) continue;
364 for (UShort_t ringi = 0; ringi <= 1; ringi++) {
365 Char_t ring = ringi == 0 ? 'I' : 'O';
ef8e8623 366 AliFMDDebug(10, (" Processing hits in FMD%d%c", detector,ring));
02a27b50 367 // Get pointer to Ring
368 AliFMDRing* r = det->GetRing(ring);
369 if (!r) continue;
370
371 // Get number of sectors
372 UShort_t nSectors = UShort_t(360. / r->GetTheta());
373 // Loop over the number of sectors
374 for (UShort_t sector = 0; sector < nSectors; sector++) {
ef8e8623 375 AliFMDDebug(10, (" Processing hits in FMD%d%c[%2d]",
f95a63c4 376 detector,ring,sector));
02a27b50 377 // Get number of strips
378 UShort_t nStrips = r->GetNStrips();
379 // Loop over the stips
380 Float_t last = 0;
381 for (UShort_t strip = 0; strip < nStrips; strip++) {
382 // Reset the counter array to the invalid value -1
383 counts.Reset(-1);
384 // Reset the last `ADC' value when we've get to the end of a
385 // VA1_ALICE channel.
386 if (strip % 128 == 0) last = 0;
387
83ad576a 388 Float_t edep = fEdep(detector, ring, sector, strip).fEdep;
389 UShort_t ntot = fEdep(detector, ring, sector, strip).fN;
390 UShort_t nprim = fEdep(detector, ring, sector, strip).fNPrim;
391 if (edep > 0)
392 AliFMDDebug(15, ("Edep = %f for FMD%d%c[%2d,%3d]",
393 edep, detector, ring, sector, strip));
02a27b50 394 ConvertToCount(edep, last, detector, ring, sector, strip, counts);
395 last = edep;
8b26caab 396
83ad576a 397
8b26caab 398 // The following line was introduced - wrongly - by Peter
399 // Hristov. It _will_ break the digitisation and the
400 // following reconstruction. The behviour of the
401 // digitisation models exactly the front-end as it should
402 // (no matter what memory concuption it may entail). The
403 // check should be on zero suppression, since that's what
404 // models the front-end - if zero suppression is turned on
405 // in the front-end, then we can suppress empty digits -
406 // otherwise we shoud never do that. Note, that the line
407 // affects _both_ normal digitisation and digitisation for
408 // summable digits, since the condition is on the energy
409 // deposition and not on the actual number of counts. If
410 // this line should go anywhere, it should be in the
411 // possible overloaded AliFMDSDigitizer::AddDigit - not
412 // here.
413 //
414 // if (edep<=0) continue;
ef8e8623 415 AddDigit(detector, ring, sector, strip, edep,
02a27b50 416 UShort_t(counts[0]), Short_t(counts[1]),
83ad576a 417 Short_t(counts[2]), Short_t(counts[3]),
418 ntot, nprim);
ef8e8623 419 AliFMDDebug(15, (" Adding digit in FMD%d%c[%2d,%3d]=%d",
f95a63c4 420 detector,ring,sector,strip,counts[0]));
02a27b50 421#if 0
422 // This checks if the digit created will give the `right'
423 // number of particles when reconstructed, using a naiive
424 // approach. It's here only as a quality check - nothing
425 // else.
426 CheckDigit(digit, fEdep(detector, ring, sector, strip).fN,
427 counts);
428#endif
429 } // Strip
430 } // Sector
431 } // Ring
432 } // Detector
433}
434
435//____________________________________________________________________
436void
437AliFMDBaseDigitizer::ConvertToCount(Float_t edep,
438 Float_t last,
439 UShort_t detector,
440 Char_t ring,
441 UShort_t sector,
442 UShort_t strip,
443 TArrayI& counts) const
444{
445 // Convert the total energy deposited to a (set of) ADC count(s).
446 //
447 // This is done by
448 //
449 // Energy_Deposited ALTRO_Channel_Size
450 // ADC = -------------------------- ------------------- + pedestal
451 // Energy_Deposition_Of_1_MIP VA1_ALICE_MIP_Range
452 //
453 // Energy_Deposited fAltroChannelSize
454 // = --------------------------------- ----------------- + pedestal
455 // 1.664 * Si_Thickness * Si_Density fVA1MipRange
456 //
457 //
458 // = Energy_Deposited * ConversionFactor + pedestal
459 //
460 // However, this is modified by the response function of the
461 // VA1_ALICE pre-amp. chip in case we are doing oversampling of the
462 // VA1_ALICE output.
463 //
464 // In that case, we get N=fSampleRate values of the ADC, and the
465 // `EnergyDeposited' is a function of which sample where are
466 // calculating the ADC for
467 //
468 // ADC_i = f(EnergyDeposited, i/N, Last) * ConversionFactor + pedestal
469 //
470 // where Last is the Energy deposited in the previous strip.
471 //
472 // Here, f is the shaping function of the VA1_ALICE. This is given
473 // by
474 //
475 // | (E - l) * (1 - exp(-B * t) + l if E > l
476 // f(E, t, l) = <
477 // | (l - E) * exp(-B * t) + E otherwise
478 //
479 //
480 // = E + (l - E) * ext(-B * t)
481 //
482 AliFMDParameters* param = AliFMDParameters::Instance();
83ad576a 483 Float_t convF = (param->GetDACPerMIP() / param->GetEdepMip() *
484 param->GetPulseGain(detector,ring,sector,strip));
a9579262 485 Int_t ped = MakePedestal(detector,ring,sector,strip);
486 Int_t maxAdc = param->GetAltroChannelSize()-1;
487 if (maxAdc < 0) {
488 AliWarning(Form("Maximum ADC is %d < 0, forcing it to 1023", maxAdc));
489 maxAdc = 1023;
490 }
02a27b50 491 UShort_t rate = param->GetSampleRate(detector,ring,sector,strip);
ef8e8623 492 AliFMDDebug(15, ("Sample rate for FMD%d%c[%2d,%3d] = %d",
83ad576a 493 detector, ring, sector, strip, rate));
ef8e8623 494 if (rate < 1 || rate > 4) {
495 AliWarning(Form("Invalid sample rate for for FMD%d%c[%2d,%3d] = %d",
496 detector, ring, sector, strip, rate));
497 rate = 1;
498 }
499
02a27b50 500 // In case we don't oversample, just return the end value.
501 if (rate == 1) {
a9579262 502 Float_t a = edep * convF + ped;
503 if (a < 0) a = 0;
504 counts[0] = UShort_t(TMath::Min(a, Float_t(maxAdc)));
ef8e8623 505 AliFMDDebug(15, ("FMD%d%c[%2d,%3d]: converting ELoss %f to "
a9579262 506 "ADC %4d (%f,%d)",
507 detector,ring,sector,strip,edep,counts[0],convF,ped));
02a27b50 508 return;
509 }
83ad576a 510
02a27b50 511
512 // Create a pedestal
513 Float_t b = fShapingTime;
514 for (Ssiz_t i = 0; i < rate; i++) {
2aeec17d 515 Float_t t = Float_t(i) / rate + 1./rate;
a9579262 516 Float_t s = edep + (last - edep) * TMath::Exp(-b * t);
517 Float_t a = Int_t(s * convF + ped);
518 if (a < 0) a = 0;
519 counts[i] = UShort_t(TMath::Min(a, Float_t(maxAdc)));
02a27b50 520 }
83ad576a 521 AliFMDDebug(15, ("Converted edep = %f to ADC (%x,%x,%x,%x) "
522 "[gain: %f=(%f/%f*%f), pedestal: %d, rate: %d]",
523 edep, counts[0], counts[1], counts[2], counts[3],
524 convF, param->GetDACPerMIP(),param->GetEdepMip(),
525 param->GetPulseGain(detector,ring,sector,strip),
526 ped, rate));
02a27b50 527}
528
ef8e8623 529//____________________________________________________________________
530void
531AliFMDBaseDigitizer::AddDigit(UShort_t detector,
532 Char_t ring,
533 UShort_t sector,
534 UShort_t strip,
535 Float_t /* edep */,
536 UShort_t count1,
537 Short_t count2,
538 Short_t count3,
83ad576a 539 Short_t count4,
540 UShort_t /* ntot */,
541 UShort_t /* nprim */) const
ef8e8623 542{
543 // Add a digit or summable digit
544
545 fFMD->AddDigitByFields(detector, ring, sector, strip,
546 count1, count2, count3, count4);
547}
02a27b50 548
ef8e8623 549//____________________________________________________________________
550TTree*
551AliFMDBaseDigitizer::MakeOutputTree(AliLoader* loader)
552{
553 // Create output tree using loader. If the passed loader differs
554 // from the currently set loader in the FMD object, reset the FMD
555 // loader to be the passed loader. This is for the cases wher the
556 // output is different from the output.
557 AliFMDDebug(5, ("Making digits tree"));
558 loader->LoadDigits("UPDATE"); // "RECREATE");
559 TTree* out = loader->TreeD();
560 if (!out) loader->MakeTree("D");
561 out = loader->TreeD();
562 if (out) {
563 out->Reset();
564 if (loader != fFMD->GetLoader())
565 fFMD->SetLoader(loader);
566 fFMD->MakeBranch("D");
567 }
568 return out;
569}
570
571//____________________________________________________________________
572void
573AliFMDBaseDigitizer::StoreDigits(AliLoader* loader)
574{
575 // Write the digits to disk
576 AliFMDDebug(5, ("Storing %d digits", fFMD->Digits()->GetEntries()));
577 loader->WriteDigits("OVERWRITE");
578 loader->UnloadDigits();
579 // Reset the digits in the AliFMD object
580 fFMD->ResetDigits();
581}
02a27b50 582
583//____________________________________________________________________
584//
585// EOF
586//
587
588
589
590