New GetUID method
[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
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
6169f936 208// #include "AliFMDDigit.h" // ALIFMDDIGIT_H
02a27b50 209#include "AliFMDParameters.h" // ALIFMDPARAMETERS_H
6169f936 210// #include <AliRunDigitizer.h> // ALIRUNDIGITIZER_H
02a27b50 211//#include <AliRun.h> // ALIRUN_H
212#include <AliLoader.h> // ALILOADER_H
213#include <AliRunLoader.h> // ALIRUNLOADER_H
214
215//====================================================================
216ClassImp(AliFMDBaseDigitizer)
217#if 0
218 ; // This is here to keep Emacs for indenting the next line
219#endif
220
221//____________________________________________________________________
222AliFMDBaseDigitizer::AliFMDBaseDigitizer()
b5ee4425 223 : fRunLoader(0),
224 fEdep(AliFMDMap::kMaxDetectors,
225 AliFMDMap::kMaxRings,
226 AliFMDMap::kMaxSectors,
227 AliFMDMap::kMaxStrips),
228 fShapingTime(0)
02a27b50 229{
230 // Default ctor - don't use it
231}
232
233//____________________________________________________________________
234AliFMDBaseDigitizer::AliFMDBaseDigitizer(AliRunDigitizer* manager)
235 : AliDigitizer(manager, "AliFMDBaseDigitizer", "FMD Digitizer base class"),
236 fRunLoader(0),
237 fEdep(AliFMDMap::kMaxDetectors,
238 AliFMDMap::kMaxRings,
239 AliFMDMap::kMaxSectors,
b5ee4425 240 AliFMDMap::kMaxStrips),
241 fShapingTime(0)
02a27b50 242{
243 // Normal CTOR
244 AliDebug(1," processed");
245 SetShapingTime();
246}
247
248//____________________________________________________________________
249AliFMDBaseDigitizer::AliFMDBaseDigitizer(const Char_t* name,
250 const Char_t* title)
251 : AliDigitizer(name, title),
252 fRunLoader(0),
253 fEdep(AliFMDMap::kMaxDetectors,
254 AliFMDMap::kMaxRings,
255 AliFMDMap::kMaxSectors,
256 AliFMDMap::kMaxStrips)
257{
258 // Normal CTOR
259 AliDebug(1," processed");
260 SetShapingTime();
261}
262
263//____________________________________________________________________
264AliFMDBaseDigitizer::~AliFMDBaseDigitizer()
265{
266 // Destructor
267}
268
269//____________________________________________________________________
270Bool_t
271AliFMDBaseDigitizer::Init()
272{
273 // Initialization
274 AliFMDParameters::Instance()->Init();
275 return kTRUE;
276}
277
278
279//____________________________________________________________________
280UShort_t
281AliFMDBaseDigitizer::MakePedestal(UShort_t,
282 Char_t,
283 UShort_t,
284 UShort_t) const
285{
286 // Make a pedestal
287 return 0;
288}
289
290//____________________________________________________________________
291void
292AliFMDBaseDigitizer::SumContributions(AliFMD* fmd)
293{
294 // Sum energy deposited contributions from each hit in a cache
295 // (fEdep).
296 if (!fRunLoader)
297 Fatal("SumContributions", "no run loader");
298
299 // Clear array of deposited energies
300 fEdep.Reset();
301
302 // Get the FMD loader
303 AliLoader* inFMD = fRunLoader->GetLoader("FMDLoader");
304 // And load the hits
305 inFMD->LoadHits("READ");
306
307 // Get the tree of hits
308 TTree* hitsTree = inFMD->TreeH();
309 if (!hitsTree) {
310 // Try again
311 inFMD->LoadHits("READ");
312 hitsTree = inFMD->TreeH();
313 }
314
315 // Get the FMD branch
316 TBranch* hitsBranch = hitsTree->GetBranch("FMD");
317 if (hitsBranch) fmd->SetHitsAddressBranch(hitsBranch);
318 else AliFatal("Branch FMD hit not found");
319
320 // Get a list of hits from the FMD manager
321 TClonesArray *fmdHits = fmd->Hits();
322
323 // Get number of entries in the tree
324 Int_t ntracks = Int_t(hitsTree->GetEntries());
325
326 AliFMDParameters* param = AliFMDParameters::Instance();
327 Int_t read = 0;
328 // Loop over the tracks in the
329 for (Int_t track = 0; track < ntracks; track++) {
330 // Read in entry number `track'
331 read += hitsBranch->GetEntry(track);
332
333 // Get the number of hits
334 Int_t nhits = fmdHits->GetEntries ();
335 for (Int_t hit = 0; hit < nhits; hit++) {
336 // Get the hit number `hit'
337 AliFMDHit* fmdHit =
338 static_cast<AliFMDHit*>(fmdHits->UncheckedAt(hit));
339
340 // Extract parameters
341 UShort_t detector = fmdHit->Detector();
342 Char_t ring = fmdHit->Ring();
343 UShort_t sector = fmdHit->Sector();
344 UShort_t strip = fmdHit->Strip();
345 Float_t edep = fmdHit->Edep();
15b17c89 346 // UShort_t minstrip = param->GetMinStrip(detector, ring, sector, strip);
347 // UShort_t maxstrip = param->GetMaxStrip(detector, ring, sector, strip);
02a27b50 348 // Check if strip is `dead'
349 if (param->IsDead(detector, ring, sector, strip)) {
350 AliDebug(5, Form("FMD%d%c[%2d,%3d] is marked as dead",
351 detector, ring, sector, strip));
352 continue;
353 }
354 // Check if strip is out-side read-out range
15b17c89 355 // if (strip < minstrip || strip > maxstrip) {
356 // AliDebug(5, Form("FMD%d%c[%2d,%3d] is outside range [%3d,%3d]",
357 // detector,ring,sector,strip,minstrip,maxstrip));
358 // continue;
359 // }
02a27b50 360
361 // Give warning in case of double hit
362 if (fEdep(detector, ring, sector, strip).fEdep != 0)
363 AliDebug(5, Form("Double hit in %d%c(%d,%d)",
364 detector, ring, sector, strip));
365
366 // Sum energy deposition
367 fEdep(detector, ring, sector, strip).fEdep += edep;
368 fEdep(detector, ring, sector, strip).fN += 1;
369 // Add this to the energy deposited for this strip
370 } // hit loop
371 } // track loop
372 AliDebug(1, Form("Size of cache: %d bytes, read %d bytes",
373 sizeof(fEdep), read));
374}
375
376//____________________________________________________________________
377void
378AliFMDBaseDigitizer::DigitizeHits(AliFMD* fmd) const
379{
380 // For the stored energy contributions in the cache (fEdep), convert
381 // the energy signal to ADC counts, and store the created digit in
382 // the digits array (AliFMD::fDigits)
383 //
384 AliFMDGeometry* geometry = AliFMDGeometry::Instance();
385
386 TArrayI counts(3);
387 for (UShort_t detector=1; detector <= 3; detector++) {
388 // Get pointer to subdetector
389 AliFMDDetector* det = geometry->GetDetector(detector);
390 if (!det) continue;
391 for (UShort_t ringi = 0; ringi <= 1; ringi++) {
392 Char_t ring = ringi == 0 ? 'I' : 'O';
393 // Get pointer to Ring
394 AliFMDRing* r = det->GetRing(ring);
395 if (!r) continue;
396
397 // Get number of sectors
398 UShort_t nSectors = UShort_t(360. / r->GetTheta());
399 // Loop over the number of sectors
400 for (UShort_t sector = 0; sector < nSectors; sector++) {
401 // Get number of strips
402 UShort_t nStrips = r->GetNStrips();
403 // Loop over the stips
404 Float_t last = 0;
405 for (UShort_t strip = 0; strip < nStrips; strip++) {
406 // Reset the counter array to the invalid value -1
407 counts.Reset(-1);
408 // Reset the last `ADC' value when we've get to the end of a
409 // VA1_ALICE channel.
410 if (strip % 128 == 0) last = 0;
411
412 Float_t edep = fEdep(detector, ring, sector, strip).fEdep;
413 ConvertToCount(edep, last, detector, ring, sector, strip, counts);
414 last = edep;
415 AddDigit(fmd, detector, ring, sector, strip, edep,
416 UShort_t(counts[0]), Short_t(counts[1]),
417 Short_t(counts[2]));
418#if 0
419 // This checks if the digit created will give the `right'
420 // number of particles when reconstructed, using a naiive
421 // approach. It's here only as a quality check - nothing
422 // else.
423 CheckDigit(digit, fEdep(detector, ring, sector, strip).fN,
424 counts);
425#endif
426 } // Strip
427 } // Sector
428 } // Ring
429 } // Detector
430}
431
432//____________________________________________________________________
433void
434AliFMDBaseDigitizer::ConvertToCount(Float_t edep,
435 Float_t last,
436 UShort_t detector,
437 Char_t ring,
438 UShort_t sector,
439 UShort_t strip,
440 TArrayI& counts) const
441{
442 // Convert the total energy deposited to a (set of) ADC count(s).
443 //
444 // This is done by
445 //
446 // Energy_Deposited ALTRO_Channel_Size
447 // ADC = -------------------------- ------------------- + pedestal
448 // Energy_Deposition_Of_1_MIP VA1_ALICE_MIP_Range
449 //
450 // Energy_Deposited fAltroChannelSize
451 // = --------------------------------- ----------------- + pedestal
452 // 1.664 * Si_Thickness * Si_Density fVA1MipRange
453 //
454 //
455 // = Energy_Deposited * ConversionFactor + pedestal
456 //
457 // However, this is modified by the response function of the
458 // VA1_ALICE pre-amp. chip in case we are doing oversampling of the
459 // VA1_ALICE output.
460 //
461 // In that case, we get N=fSampleRate values of the ADC, and the
462 // `EnergyDeposited' is a function of which sample where are
463 // calculating the ADC for
464 //
465 // ADC_i = f(EnergyDeposited, i/N, Last) * ConversionFactor + pedestal
466 //
467 // where Last is the Energy deposited in the previous strip.
468 //
469 // Here, f is the shaping function of the VA1_ALICE. This is given
470 // by
471 //
472 // | (E - l) * (1 - exp(-B * t) + l if E > l
473 // f(E, t, l) = <
474 // | (l - E) * exp(-B * t) + E otherwise
475 //
476 //
477 // = E + (l - E) * ext(-B * t)
478 //
479 AliFMDParameters* param = AliFMDParameters::Instance();
480 Float_t convF = 1/param->GetPulseGain(detector,ring,sector,strip);
481 UShort_t ped = MakePedestal(detector,ring,sector,strip);
15b17c89 482 UInt_t maxAdc = param->GetAltroChannelSize()-1;
02a27b50 483 UShort_t rate = param->GetSampleRate(detector,ring,sector,strip);
02a27b50 484
485 // In case we don't oversample, just return the end value.
486 if (rate == 1) {
8ec606c2 487 counts[0] = UShort_t(TMath::Min(edep * convF + ped, Float_t(maxAdc)));
488 AliDebug(2, Form("FMD%d%c[%2d,%3d]: converting ELoss %f to ADC %d (%f)",
489 detector,ring,sector,strip,edep,counts[0],convF));
02a27b50 490 return;
491 }
492
493 // Create a pedestal
494 Float_t b = fShapingTime;
495 for (Ssiz_t i = 0; i < rate; i++) {
496 Float_t t = Float_t(i) / rate;
497 Float_t s = edep + (last - edep) * TMath::Exp(-b * t);
498 counts[i] = UShort_t(TMath::Min(s * convF + ped, Float_t(maxAdc)));
499 }
500}
501
502
503
504//____________________________________________________________________
505//
506// EOF
507//
508
509
510
511