[u/mrichter/AliRoot.git] / FMD / AliFMDBaseDigitizer.cxx

/**************************************************************************
 * Copyright(c) 2004, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/
/* $Id$ */
/** @file    AliFMDBaseDigitizer.cxx
    @author  Christian Holm Christensen <cholm@nbi.dk>
    @date    Mon Mar 27 12:38:26 2006
    @brief   FMD Digitizers implementation
    @ingroup FMD_sim
*/
//////////////////////////////////////////////////////////////////////////////
//
//  This class contains the procedures simulation ADC  signal for the
//  Forward Multiplicity detector  : Hits->Digits and Hits->SDigits
// 
//  Digits consists of
//   - Detector #
//   - Ring ID                                             
//   - Sector #     
//   - Strip #
//   - ADC count in this channel                                  
//
//  Digits consists of
//   - Detector #
//   - Ring ID                                             
//   - Sector #     
//   - Strip #
//   - Total energy deposited in the strip
//   - ADC count in this channel                                  
//
// As the Digits and SDigits have so much in common, the classes
// AliFMDDigitizer and AliFMDSDigitizer are implemented via a base
// class AliFMDBaseDigitizer.
//
//                 +---------------------+
//                 | AliFMDBaseDigitizer |
//                 +---------------------+
//                           ^
//                           |
//                +----------+---------+
//                |                    |
//      +-----------------+     +------------------+
//      | AliFMDDigitizer |	| AliFMDSDigitizer |
//      +-----------------+	+------------------+
//
// These classes has several paramters: 
//
//     fPedestal
//     fPedestalWidth
//         (Only AliFMDDigitizer)
//         Mean and width of the pedestal.  The pedestal is simulated
//         by a Guassian, but derived classes my override MakePedestal
//         to simulate it differently (or pick it up from a database).
//
//     fVA1MipRange
//         The dymamic MIP range of the VA1_ALICE pre-amplifier chip 
//
//     fAltroChannelSize
//         The largest number plus one that can be stored in one
//         channel in one time step in the ALTRO ADC chip. 
//
//     fSampleRate
//         How many times the ALTRO ADC chip samples the VA1_ALICE
//         pre-amplifier signal.   The VA1_ALICE chip is read-out at
//         10MHz, while it's possible to drive the ALTRO chip at
//         25MHz.  That means, that the ALTRO chip can have time to
//         sample each VA1_ALICE signal up to 2 times.  Although it's
//         not certain this feature will be used in the production,
//         we'd like have the option, and so it should be reflected in
//         the code.
//
//
// The shaping function of the VA1_ALICE is generally given by 
//
//      f(x) = A(1 - exp(-Bx))
//
// where A is the total charge collected in the pre-amp., and B is a
// paramter that depends on the shaping time of the VA1_ALICE circut.
// 
// When simulating the shaping function of the VA1_ALICe
// pre-amp. chip, we have to take into account, that the shaping
// function depends on the previous value of read from the pre-amp. 
//
// That results in the following algorithm:
//
//    last = 0;
//    FOR charge IN pre-amp. charge train DO 
//      IF last < charge THEN 
//        f(t) = (charge - last) * (1 - exp(-B * t)) + last
//      ELSE
//        f(t) = (last - charge) * exp(-B * t) + charge)
//      ENDIF
//      FOR i IN # samples DO 
//        adc_i = f(i / (# samples))
//      DONE
//      last = charge
//   DONE
//
// Here, 
//
//   pre-amp. charge train 
//       is a series of 128 charges read from the VA1_ALICE chip
//
//   # samples
//       is the number of times the ALTRO ADC samples each of the 128
//       charges from the pre-amp. 
//
// Where Q is the total charge collected by the VA1_ALICE
// pre-amplifier.   Q is then given by 
//
//           E S 
//      Q =  - -
//           e R
//
// where E is the total energy deposited in a silicon strip, R is the
// dynamic range of the VA1_ALICE pre-amp (fVA1MipRange), e is the
// energy deposited by a single MIP, and S ALTRO channel size in each
// time step (fAltroChannelSize).  
//
// The energy deposited per MIP is given by 
//
//      e = M * rho * w 
//
// where M is the universal number 1.664, rho is the density of
// silicon, and w is the depth of the silicon sensor. 
//
// The final ADC count is given by 
//
//      C' = C + P
//
// where P is the (randomized) pedestal (see MakePedestal)
//
// This class uses the class template AliFMDMap<Type> to make an
// internal cache of the energy deposted of the hits.  The class
// template is instantasized as 
//
//  typedef AliFMDMap<std::pair<Float_t, UShort_t> > AliFMDEdepMap;
//
// The first member of the values is the summed energy deposition in a
// given strip, while the second member of the values is the number of
// hits in a given strip.  Using the second member, it's possible to
// do some checks on just how many times a strip got hit, and what
// kind of error we get in our reconstructed hits.  Note, that this
// information is currently not written to the digits tree.  I think a
// QA (Quality Assurance) digit tree is better suited for that task.
// However, the information is there to be used in the future. 
//
//
// Latest changes by Christian Holm Christensen
//
//////////////////////////////////////////////////////////////////////////////

//      /1
//      |           A(-1 + B + exp(-B))
//      | f(x) dx = ------------------- = 1
//      |                    B
//      / 0
//
// and B is the a parameter defined by the shaping time (fShapingTime).  
//
// Solving the above equation, for A gives
//
//                 B
//      A = ----------------
//          -1 + B + exp(-B)
//
// So, if we define the function g: [0,1] -> [0:1] by 
//
//               / v
//               |              Bu + exp(-Bu) - Bv - exp(-Bv) 
//      g(u,v) = | f(x) dx = -A -----------------------------
//               |                            B
//               / u
//
// we can evaluate the ALTRO sample of the VA1_ALICE pre-amp between
// any two times (u, v), by 
//       
//
//                                B	    Bu + exp(-Bu) - Bv - exp(-Bv)
//      C = Q g(u,v) = - Q ---------------- -----------------------------
//		           -1 + B + exp(-B)              B	            
//
//               Bu + exp(-Bu) - Bv - exp(-Bv) 
//        = -  Q -----------------------------
//                    -1 + B + exp(-B)
//

#include <TMath.h>
#include <TTree.h>		// ROOT_TTree
//#include <TRandom.h>		// ROOT_TRandom
// #include <AliLog.h>		// ALILOG_H
#include "AliFMDDebug.h" // Better debug macros
#include "AliFMDBaseDigitizer.h" // ALIFMDDIGITIZER_H
#include "AliFMD.h"		// ALIFMD_H
#include "AliFMDGeometry.h"	// ALIFMDGEOMETRY_H
#include "AliFMDDetector.h"	// ALIFMDDETECTOR_H
#include "AliFMDRing.h"	        // ALIFMDRING_H
#include "AliFMDHit.h"		// ALIFMDHIT_H
// #include "AliFMDDigit.h"	// ALIFMDDIGIT_H
#include "AliFMDParameters.h"   // ALIFMDPARAMETERS_H
// #include <AliRunDigitizer.h>	// ALIRUNDIGITIZER_H
//#include <AliRun.h>		// ALIRUN_H
#include <AliLoader.h>		// ALILOADER_H
#include <AliRunLoader.h>	// ALIRUNLOADER_H
    
//====================================================================
ClassImp(AliFMDBaseDigitizer)
#if 0
  ; // This is here to keep Emacs for indenting the next line
#endif

//____________________________________________________________________
AliFMDBaseDigitizer::AliFMDBaseDigitizer()  
  : fRunLoader(0),
    fEdep(AliFMDMap::kMaxDetectors, 
	  AliFMDMap::kMaxRings, 
	  AliFMDMap::kMaxSectors, 
	  AliFMDMap::kMaxStrips),
    fShapingTime(0)
{
  // Default ctor - don't use it
}

//____________________________________________________________________
AliFMDBaseDigitizer::AliFMDBaseDigitizer(AliRunDigitizer* manager) 
  : AliDigitizer(manager, "AliFMDBaseDigitizer", "FMD Digitizer base class"), 
    fRunLoader(0),
    fEdep(AliFMDMap::kMaxDetectors, 
	  AliFMDMap::kMaxRings, 
	  AliFMDMap::kMaxSectors, 
	  AliFMDMap::kMaxStrips), 
    fShapingTime(0)
{
  // Normal CTOR
  AliFMDDebug(1, (" processed"));
  SetShapingTime();
}

//____________________________________________________________________
AliFMDBaseDigitizer::AliFMDBaseDigitizer(const Char_t* name, 
					 const Char_t* title) 
  : AliDigitizer(name, title),
    fRunLoader(0),
    fEdep(AliFMDMap::kMaxDetectors, 
	  AliFMDMap::kMaxRings, 
	  AliFMDMap::kMaxSectors, 
	  AliFMDMap::kMaxStrips)
{
  // Normal CTOR
  AliFMDDebug(1, (" processed"));
  SetShapingTime();
}

//____________________________________________________________________
AliFMDBaseDigitizer::~AliFMDBaseDigitizer()
{
  // Destructor
}

//____________________________________________________________________
Bool_t 
AliFMDBaseDigitizer::Init()
{
  // Initialization
  AliFMDParameters::Instance()->Init();
  return kTRUE;
}
 

//____________________________________________________________________
UShort_t
AliFMDBaseDigitizer::MakePedestal(UShort_t, 
				  Char_t, 
				  UShort_t, 
				  UShort_t) const 
{ 
  // Make a pedestal
  return 0; 
}

//____________________________________________________________________
void
AliFMDBaseDigitizer::SumContributions(AliFMD* fmd) 
{
  // Sum energy deposited contributions from each hit in a cache
  // (fEdep).  
  if (!fRunLoader) 
    Fatal("SumContributions", "no run loader");
  
  // Clear array of deposited energies 
  fEdep.Reset();
  
  // Get the FMD loader 
  AliLoader* inFMD = fRunLoader->GetLoader("FMDLoader");
  // And load the hits 
  inFMD->LoadHits("READ");
  
  // Get the tree of hits 
  TTree* hitsTree = inFMD->TreeH();
  if (!hitsTree)  {
    // Try again 
    inFMD->LoadHits("READ");
    hitsTree = inFMD->TreeH();
  }
  
  // Get the FMD branch 
  TBranch* hitsBranch = hitsTree->GetBranch("FMD");
  if (hitsBranch) fmd->SetHitsAddressBranch(hitsBranch);
  else            AliFatal("Branch FMD hit not found");
  
  // Get a list of hits from the FMD manager 
  TClonesArray *fmdHits = fmd->Hits();
  
  // Get number of entries in the tree 
  Int_t ntracks  = Int_t(hitsTree->GetEntries());
  
  AliFMDParameters* param = AliFMDParameters::Instance();
  Int_t read = 0;
  // Loop over the tracks in the 
  for (Int_t track = 0; track < ntracks; track++)  {
    // Read in entry number `track' 
    read += hitsBranch->GetEntry(track);
    
    // Get the number of hits 
    Int_t nhits = fmdHits->GetEntries ();
    for (Int_t hit = 0; hit < nhits; hit++) {
      // Get the hit number `hit'
      AliFMDHit* fmdHit = 
	static_cast<AliFMDHit*>(fmdHits->UncheckedAt(hit));
      
      // Extract parameters 
      UShort_t detector = fmdHit->Detector();
      Char_t   ring     = fmdHit->Ring();
      UShort_t sector   = fmdHit->Sector();
      UShort_t strip    = fmdHit->Strip();
      Float_t  edep     = fmdHit->Edep();
      // UShort_t minstrip = param->GetMinStrip(detector, ring, sector, strip);
      // UShort_t maxstrip = param->GetMaxStrip(detector, ring, sector, strip);
      // Check if strip is `dead' 
      AliFMDDebug(2, ("Hit in FMD%d%c[%2d,%3d]=%f",
		      detector, ring, sector, strip, edep));
      if (param->IsDead(detector, ring, sector, strip)) { 
	AliFMDDebug(1, ("FMD%d%c[%2d,%3d] is marked as dead", 
			 detector, ring, sector, strip));
	continue;
      }
      // Check if strip is out-side read-out range 
      // if (strip < minstrip || strip > maxstrip) {
      //   AliFMDDebug(5, ("FMD%d%c[%2d,%3d] is outside range [%3d,%3d]", 
      //		    detector,ring,sector,strip,minstrip,maxstrip));
      //   continue;
      // }
	
      // Give warning in case of double hit 
      if (fEdep(detector, ring, sector, strip).fEdep != 0)
	AliFMDDebug(5, ("Double hit in %d%c(%d,%d)", 
			 detector, ring, sector, strip));
      
      // Sum energy deposition
      fEdep(detector, ring, sector, strip).fEdep  += edep;
      fEdep(detector, ring, sector, strip).fN     += 1;
      // Add this to the energy deposited for this strip
    }  // hit loop
  } // track loop
  AliFMDDebug(1, ("Size of cache: %d bytes, read %d bytes", 
		   sizeof(fEdep), read));
}

//____________________________________________________________________
void
AliFMDBaseDigitizer::DigitizeHits(AliFMD* fmd) const
{
  // For the stored energy contributions in the cache (fEdep), convert
  // the energy signal to ADC counts, and store the created digit in
  // the digits array (AliFMD::fDigits)
  //
  AliFMDGeometry* geometry = AliFMDGeometry::Instance();
  
  TArrayI counts(3);
  for (UShort_t detector=1; detector <= 3; detector++) {
    AliFMDDebug(5, ("Processing hits in FMD%d", detector));
    // Get pointer to subdetector 
    AliFMDDetector* det = geometry->GetDetector(detector);
    if (!det) continue;
    for (UShort_t ringi = 0; ringi <= 1; ringi++) {
      Char_t ring = ringi == 0 ? 'I' : 'O';
      AliFMDDebug(5, (" Processing hits in FMD%d%c", detector,ring));
      // Get pointer to Ring
      AliFMDRing* r = det->GetRing(ring);
      if (!r) continue;
      
      // Get number of sectors 
      UShort_t nSectors = UShort_t(360. / r->GetTheta());
      // Loop over the number of sectors 
      for (UShort_t sector = 0; sector < nSectors; sector++) {
	AliFMDDebug(5, ("  Processing hits in FMD%d%c[%2d]", 
			detector,ring,sector));
	// Get number of strips 
	UShort_t nStrips = r->GetNStrips();
	// Loop over the stips 
	Float_t last = 0;
	for (UShort_t strip = 0; strip < nStrips; strip++) {
	  // Reset the counter array to the invalid value -1 
	  counts.Reset(-1);
	  // Reset the last `ADC' value when we've get to the end of a
	  // VA1_ALICE channel. 
	  if (strip % 128 == 0) last = 0;
	  
	  Float_t edep = fEdep(detector, ring, sector, strip).fEdep;
	  ConvertToCount(edep, last, detector, ring, sector, strip, counts);
	  last = edep;
	  AddDigit(fmd, detector, ring, sector, strip, edep, 
		   UShort_t(counts[0]), Short_t(counts[1]), 
		   Short_t(counts[2]));
	  AliFMDDebug(10, ("   Adding digit in FMD%d%c[%2d,%3d]=%d", 
			  detector,ring,sector,strip,counts[0]));
#if 0
	  // This checks if the digit created will give the `right'
	  // number of particles when reconstructed, using a naiive
	  // approach.  It's here only as a quality check - nothing
	  // else. 
	  CheckDigit(digit, fEdep(detector, ring, sector, strip).fN,
		     counts);
#endif
	} // Strip
      } // Sector 
    } // Ring 
  } // Detector 
}

//____________________________________________________________________
void
AliFMDBaseDigitizer::ConvertToCount(Float_t   edep, 
				    Float_t   last,
				    UShort_t  detector, 
				    Char_t    ring, 
				    UShort_t  sector, 
				    UShort_t  strip,
				    TArrayI&  counts) const
{
  // Convert the total energy deposited to a (set of) ADC count(s). 
  // 
  // This is done by 
  // 
  //               Energy_Deposited      ALTRO_Channel_Size
  //    ADC = -------------------------- ------------------- + pedestal
  //          Energy_Deposition_Of_1_MIP VA1_ALICE_MIP_Range
  //
  //               Energy_Deposited             fAltroChannelSize
  //        = --------------------------------- ----------------- + pedestal 
  //          1.664 * Si_Thickness * Si_Density   fVA1MipRange	 
  //          
  // 
  //        = Energy_Deposited * ConversionFactor + pedestal
  // 
  // However, this is modified by the response function of the
  // VA1_ALICE pre-amp. chip in case we are doing oversampling of the
  // VA1_ALICE output. 
  // 
  // In that case, we get N=fSampleRate values of the ADC, and the
  // `EnergyDeposited' is a function of which sample where are
  // calculating the ADC for 
  // 
  //     ADC_i = f(EnergyDeposited, i/N, Last) * ConversionFactor + pedestal 
  // 
  // where Last is the Energy deposited in the previous strip. 
  // 
  // Here, f is the shaping function of the VA1_ALICE.   This is given
  // by 
  //                       
  //                    |   (E - l) * (1 - exp(-B * t) + l   if E > l
  //       f(E, t, l) = <
  //                    |   (l - E) * exp(-B * t) + E        otherwise
  //                       
  // 
  //                  = E + (l - E) * ext(-B * t)
  // 
  AliFMDParameters* param = AliFMDParameters::Instance();
  Float_t  convF          = 1./param->GetPulseGain(detector,ring,sector,strip);
  Int_t    ped            = MakePedestal(detector,ring,sector,strip);
  Int_t    maxAdc         = param->GetAltroChannelSize()-1;
  if (maxAdc < 0) {
    AliWarning(Form("Maximum ADC is %d < 0, forcing it to 1023", maxAdc));
    maxAdc = 1023;
  }
  UShort_t rate           = param->GetSampleRate(detector,ring,sector,strip);
  if (rate < 1 || rate > 3) rate = 1;
  
  // In case we don't oversample, just return the end value. 
  if (rate == 1) {
    Float_t    a = edep * convF + ped;
    if (a < 0) a = 0;
    counts[0]    = UShort_t(TMath::Min(a, Float_t(maxAdc)));
    AliFMDDebug(2, ("FMD%d%c[%2d,%3d]: converting ELoss %f to "
		     "ADC %4d (%f,%d)",
		     detector,ring,sector,strip,edep,counts[0],convF,ped));
    return;
  }
  
  // Create a pedestal 
  Float_t b = fShapingTime;
  for (Ssiz_t i = 0; i < rate;  i++) {
    Float_t t  = Float_t(i) / rate;
    Float_t s  = edep + (last - edep) * TMath::Exp(-b * t);
    Float_t a  = Int_t(s * convF + ped);
    if (a < 0) a = 0;
    counts[i]  = UShort_t(TMath::Min(a, Float_t(maxAdc)));
  }
}


//____________________________________________________________________
//
// EOF
//
Commit	Line	Data
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
02a27b50	201	//#include <TRandom.h> // ROOT_TRandom
f95a63c4	202	// #include <AliLog.h> // ALILOG_H
f95a63c4	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
	215	#include <AliRunLoader.h> // ALIRUNLOADER_H
	216
	217	//====================================================================
	218	ClassImp(AliFMDBaseDigitizer)
	219	#if 0
	220	; // This is here to keep Emacs for indenting the next line
	221	#endif
	222
	223	//____________________________________________________________________
	224	AliFMDBaseDigitizer::AliFMDBaseDigitizer()
b5ee4425	225	: fRunLoader(0),
	226	fEdep(AliFMDMap::kMaxDetectors,
	227	AliFMDMap::kMaxRings,
	228	AliFMDMap::kMaxSectors,
	229	AliFMDMap::kMaxStrips),
	230	fShapingTime(0)
02a27b50	231	{
	232	// Default ctor - don't use it
	233	}
	234
	235	//____________________________________________________________________
	236	AliFMDBaseDigitizer::AliFMDBaseDigitizer(AliRunDigitizer* manager)
	237	: AliDigitizer(manager, "AliFMDBaseDigitizer", "FMD Digitizer base class"),
	238	fRunLoader(0),
	239	fEdep(AliFMDMap::kMaxDetectors,
	240	AliFMDMap::kMaxRings,
	241	AliFMDMap::kMaxSectors,
b5ee4425	242	AliFMDMap::kMaxStrips),
b5ee4425	243	fShapingTime(0)
02a27b50	244	{
02a27b50	245	// Normal CTOR
f95a63c4	246	AliFMDDebug(1, (" processed"));
02a27b50	247	SetShapingTime();
	248	}
	249
	250	//____________________________________________________________________
	251	AliFMDBaseDigitizer::AliFMDBaseDigitizer(const Char_t* name,
	252	const Char_t* title)
	253	: AliDigitizer(name, title),
	254	fRunLoader(0),
	255	fEdep(AliFMDMap::kMaxDetectors,
	256	AliFMDMap::kMaxRings,
	257	AliFMDMap::kMaxSectors,
	258	AliFMDMap::kMaxStrips)
	259	{
	260	// Normal CTOR
f95a63c4	261	AliFMDDebug(1, (" processed"));
02a27b50	262	SetShapingTime();
	263	}
	264
	265	//____________________________________________________________________
	266	AliFMDBaseDigitizer::~AliFMDBaseDigitizer()
	267	{
	268	// Destructor
	269	}
	270
	271	//____________________________________________________________________
	272	Bool_t
	273	AliFMDBaseDigitizer::Init()
	274	{
	275	// Initialization
	276	AliFMDParameters::Instance()->Init();
	277	return kTRUE;
	278	}
	279
	280
	281	//____________________________________________________________________
	282	UShort_t
	283	AliFMDBaseDigitizer::MakePedestal(UShort_t,
	284	Char_t,
	285	UShort_t,
	286	UShort_t) const
	287	{
	288	// Make a pedestal
	289	return 0;
	290	}
	291
	292	//____________________________________________________________________
	293	void
	294	AliFMDBaseDigitizer::SumContributions(AliFMD* fmd)
	295	{
	296	// Sum energy deposited contributions from each hit in a cache
	297	// (fEdep).
	298	if (!fRunLoader)
	299	Fatal("SumContributions", "no run loader");
	300
	301	// Clear array of deposited energies
	302	fEdep.Reset();
	303
	304	// Get the FMD loader
	305	AliLoader* inFMD = fRunLoader->GetLoader("FMDLoader");
	306	// And load the hits
	307	inFMD->LoadHits("READ");
	308
	309	// Get the tree of hits
	310	TTree* hitsTree = inFMD->TreeH();
	311	if (!hitsTree) {
	312	// Try again
	313	inFMD->LoadHits("READ");
	314	hitsTree = inFMD->TreeH();
	315	}
	316
	317	// Get the FMD branch
	318	TBranch* hitsBranch = hitsTree->GetBranch("FMD");
	319	if (hitsBranch) fmd->SetHitsAddressBranch(hitsBranch);
	320	else AliFatal("Branch FMD hit not found");
	321
	322	// Get a list of hits from the FMD manager
	323	TClonesArray *fmdHits = fmd->Hits();
	324
	325	// Get number of entries in the tree
326	Int_t ntracks = Int_t(hitsTree->GetEntries());
327
328	AliFMDParameters* param = AliFMDParameters::Instance();
329	Int_t read = 0;
330	// Loop over the tracks in the
331	for (Int_t track = 0; track < ntracks; track++) {
332	// Read in entry number `track'
333	read += hitsBranch->GetEntry(track);
334
335	// Get the number of hits
336	Int_t nhits = fmdHits->GetEntries ();
337	for (Int_t hit = 0; hit < nhits; hit++) {
338	// Get the hit number `hit'
339	AliFMDHit* fmdHit =
340	static_cast<AliFMDHit*>(fmdHits->UncheckedAt(hit));
341
342	// Extract parameters
343	UShort_t detector = fmdHit->Detector();
344	Char_t ring = fmdHit->Ring();
345	UShort_t sector = fmdHit->Sector();
346	UShort_t strip = fmdHit->Strip();
347	Float_t edep = fmdHit->Edep();
15b17c89	348	// UShort_t minstrip = param->GetMinStrip(detector, ring, sector, strip);
15b17c89	349	// UShort_t maxstrip = param->GetMaxStrip(detector, ring, sector, strip);
02a27b50	350	// Check if strip is `dead'
f95a63c4	351	AliFMDDebug(2, ("Hit in FMD%d%c[%2d,%3d]=%f",
f95a63c4	352	detector, ring, sector, strip, edep));
02a27b50	353	if (param->IsDead(detector, ring, sector, strip)) {
f95a63c4	354	AliFMDDebug(1, ("FMD%d%c[%2d,%3d] is marked as dead",
02a27b50	355	detector, ring, sector, strip));
	356	continue;
	357	}
	358	// Check if strip is out-side read-out range
15b17c89	359	// if (strip < minstrip \|\| strip > maxstrip) {
f95a63c4	360	// AliFMDDebug(5, ("FMD%d%c[%2d,%3d] is outside range [%3d,%3d]",
15b17c89	361	// detector,ring,sector,strip,minstrip,maxstrip));
	362	// continue;
	363	// }
02a27b50	364
	365	// Give warning in case of double hit
	366	if (fEdep(detector, ring, sector, strip).fEdep != 0)
f95a63c4	367	AliFMDDebug(5, ("Double hit in %d%c(%d,%d)",
02a27b50	368	detector, ring, sector, strip));
	369
	370	// Sum energy deposition
	371	fEdep(detector, ring, sector, strip).fEdep += edep;
	372	fEdep(detector, ring, sector, strip).fN += 1;
	373	// Add this to the energy deposited for this strip
	374	} // hit loop
	375	} // track loop
f95a63c4	376	AliFMDDebug(1, ("Size of cache: %d bytes, read %d bytes",
02a27b50	377	sizeof(fEdep), read));
	378	}
	379
	380	//____________________________________________________________________
	381	void
	382	AliFMDBaseDigitizer::DigitizeHits(AliFMD* fmd) const
	383	{
	384	// For the stored energy contributions in the cache (fEdep), convert
	385	// the energy signal to ADC counts, and store the created digit in
	386	// the digits array (AliFMD::fDigits)
	387	//
	388	AliFMDGeometry* geometry = AliFMDGeometry::Instance();
	389
	390	TArrayI counts(3);
	391	for (UShort_t detector=1; detector <= 3; detector++) {
f95a63c4	392	AliFMDDebug(5, ("Processing hits in FMD%d", detector));
02a27b50	393	// Get pointer to subdetector
	394	AliFMDDetector* det = geometry->GetDetector(detector);
	395	if (!det) continue;
	396	for (UShort_t ringi = 0; ringi <= 1; ringi++) {
	397	Char_t ring = ringi == 0 ? 'I' : 'O';
f95a63c4	398	AliFMDDebug(5, (" Processing hits in FMD%d%c", detector,ring));
02a27b50	399	// Get pointer to Ring
	400	AliFMDRing* r = det->GetRing(ring);
	401	if (!r) continue;
	402
	403	// Get number of sectors
	404	UShort_t nSectors = UShort_t(360. / r->GetTheta());
	405	// Loop over the number of sectors
	406	for (UShort_t sector = 0; sector < nSectors; sector++) {
f95a63c4	407	AliFMDDebug(5, (" Processing hits in FMD%d%c[%2d]",
f95a63c4	408	detector,ring,sector));
02a27b50	409	// Get number of strips
	410	UShort_t nStrips = r->GetNStrips();
	411	// Loop over the stips
	412	Float_t last = 0;
	413	for (UShort_t strip = 0; strip < nStrips; strip++) {
	414	// Reset the counter array to the invalid value -1
	415	counts.Reset(-1);
	416	// Reset the last `ADC' value when we've get to the end of a
	417	// VA1_ALICE channel.
	418	if (strip % 128 == 0) last = 0;
	419
	420	Float_t edep = fEdep(detector, ring, sector, strip).fEdep;
	421	ConvertToCount(edep, last, detector, ring, sector, strip, counts);
	422	last = edep;
	423	AddDigit(fmd, detector, ring, sector, strip, edep,
	424	UShort_t(counts[0]), Short_t(counts[1]),
	425	Short_t(counts[2]));
f95a63c4	426	AliFMDDebug(10, (" Adding digit in FMD%d%c[%2d,%3d]=%d",
f95a63c4	427	detector,ring,sector,strip,counts[0]));
02a27b50	428	#if 0
	429	// This checks if the digit created will give the `right'
	430	// number of particles when reconstructed, using a naiive
	431	// approach. It's here only as a quality check - nothing
	432	// else.
	433	CheckDigit(digit, fEdep(detector, ring, sector, strip).fN,
	434	counts);
	435	#endif
	436	} // Strip
	437	} // Sector
	438	} // Ring
	439	} // Detector
	440	}
	441
	442	//____________________________________________________________________
	443	void
	444	AliFMDBaseDigitizer::ConvertToCount(Float_t edep,
	445	Float_t last,
	446	UShort_t detector,
	447	Char_t ring,
	448	UShort_t sector,
	449	UShort_t strip,
	450	TArrayI& counts) const
	451	{
	452	// Convert the total energy deposited to a (set of) ADC count(s).
	453	//
	454	// This is done by
	455	//
	456	// Energy_Deposited ALTRO_Channel_Size
	457	// ADC = -------------------------- ------------------- + pedestal
	458	// Energy_Deposition_Of_1_MIP VA1_ALICE_MIP_Range
	459	//
	460	// Energy_Deposited fAltroChannelSize
	461	// = --------------------------------- ----------------- + pedestal
	462	// 1.664 * Si_Thickness * Si_Density fVA1MipRange
	463	//
	464	//
	465	// = Energy_Deposited * ConversionFactor + pedestal
	466	//
	467	// However, this is modified by the response function of the
	468	// VA1_ALICE pre-amp. chip in case we are doing oversampling of the
	469	// VA1_ALICE output.
	470	//
	471	// In that case, we get N=fSampleRate values of the ADC, and the
	472	// `EnergyDeposited' is a function of which sample where are
	473	// calculating the ADC for
	474	//
	475	// ADC_i = f(EnergyDeposited, i/N, Last) * ConversionFactor + pedestal
	476	//
	477	// where Last is the Energy deposited in the previous strip.
	478	//
	479	// Here, f is the shaping function of the VA1_ALICE. This is given
	480	// by
	481	//
	482	// \| (E - l) * (1 - exp(-B * t) + l if E > l
	483	// f(E, t, l) = <
	484	// \| (l - E) * exp(-B * t) + E otherwise
	485	//
	486	//
	487	// = E + (l - E) * ext(-B * t)
	488	//
	489	AliFMDParameters* param = AliFMDParameters::Instance();
a9579262	490	Float_t convF = 1./param->GetPulseGain(detector,ring,sector,strip);
	491	Int_t ped = MakePedestal(detector,ring,sector,strip);
	492	Int_t maxAdc = param->GetAltroChannelSize()-1;
	493	if (maxAdc < 0) {
	494	AliWarning(Form("Maximum ADC is %d < 0, forcing it to 1023", maxAdc));
	495	maxAdc = 1023;
	496	}
02a27b50	497	UShort_t rate = param->GetSampleRate(detector,ring,sector,strip);
a9579262	498	if (rate < 1 \|\| rate > 3) rate = 1;
02a27b50	499
	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)));
f95a63c4	505	AliFMDDebug(2, ("FMD%d%c[%2d,%3d]: converting ELoss %f to "
a9579262	506	"ADC %4d (%f,%d)",
a9579262	507	detector,ring,sector,strip,edep,counts[0],convF,ped));
02a27b50	508	return;
	509	}
	510
	511	// Create a pedestal
	512	Float_t b = fShapingTime;
	513	for (Ssiz_t i = 0; i < rate; i++) {
a9579262	514	Float_t t = Float_t(i) / rate;
	515	Float_t s = edep + (last - edep) * TMath::Exp(-b * t);
	516	Float_t a = Int_t(s * convF + ped);
	517	if (a < 0) a = 0;
	518	counts[i] = UShort_t(TMath::Min(a, Float_t(maxAdc)));
02a27b50	519	}
	520	}
	521
	522
	523
	524	//____________________________________________________________________
	525	//
	526	// EOF
	527	//
	528
	529
	530
	531