Changing madia cuts to avoid too large EM showers in the beam pipe (Andreas)
[u/mrichter/AliRoot.git] / FMD / AliFMDBaseDigitizer.cxx
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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
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()
223 : fRunLoader(0)
224{
225 // Default ctor - don't use it
226}
227
228//____________________________________________________________________
229AliFMDBaseDigitizer::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//____________________________________________________________________
243AliFMDBaseDigitizer::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//____________________________________________________________________
258AliFMDBaseDigitizer::~AliFMDBaseDigitizer()
259{
260 // Destructor
261}
262
263//____________________________________________________________________
264Bool_t
265AliFMDBaseDigitizer::Init()
266{
267 // Initialization
268 AliFMDParameters::Instance()->Init();
269 return kTRUE;
270}
271
272
273//____________________________________________________________________
274UShort_t
275AliFMDBaseDigitizer::MakePedestal(UShort_t,
276 Char_t,
277 UShort_t,
278 UShort_t) const
279{
280 // Make a pedestal
281 return 0;
282}
283
284//____________________________________________________________________
285void
286AliFMDBaseDigitizer::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//____________________________________________________________________
371void
372AliFMDBaseDigitizer::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//____________________________________________________________________
427void
428AliFMDBaseDigitizer::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);
02a27b50 478
479 // In case we don't oversample, just return the end value.
480 if (rate == 1) {
8ec606c2 481 counts[0] = UShort_t(TMath::Min(edep * convF + ped, Float_t(maxAdc)));
482 AliDebug(2, Form("FMD%d%c[%2d,%3d]: converting ELoss %f to ADC %d (%f)",
483 detector,ring,sector,strip,edep,counts[0],convF));
02a27b50 484 return;
485 }
486
487 // Create a pedestal
488 Float_t b = fShapingTime;
489 for (Ssiz_t i = 0; i < rate; i++) {
490 Float_t t = Float_t(i) / rate;
491 Float_t s = edep + (last - edep) * TMath::Exp(-b * t);
492 counts[i] = UShort_t(TMath::Min(s * convF + ped, Float_t(maxAdc)));
493 }
494}
495
496
497
498//____________________________________________________________________
499//
500// EOF
501//
502
503
504
505