[u/mrichter/AliRoot.git] / FMD / AliFMDSDigitizer.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    AliFMDSDigitizer.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 <TTree.h>		// ROOT_TTree
//#include <TRandom.h>		// ROOT_TRandom
#include <AliLog.h>		// ALILOG_H
#include "AliFMDSDigitizer.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(AliFMDSDigitizer)

//____________________________________________________________________
AliFMDSDigitizer::AliFMDSDigitizer()  
{
  // Default ctor - don't use it
}

//____________________________________________________________________
AliFMDSDigitizer::AliFMDSDigitizer(const Char_t* headerFile, 
				   const Char_t* /* sdigfile */)
  : AliFMDBaseDigitizer("FMDSDigitizer", "FMD SDigitizer")
{
  // Normal CTOR
  AliDebug(1," processed");

  fRunLoader = AliRunLoader::GetRunLoader(); // Open(headerFile);
  if (!fRunLoader) 
    Fatal("AliFMDSDigitizer", "cannot open session, header file '%s'",
	  headerFile);
  AliLoader* loader = fRunLoader->GetLoader("FMDLoader");
  if (!loader) 
    Fatal("AliFMDSDigitizer", "cannot find FMD loader in specified event");

  // Add task to tasks folder 
  loader->PostSDigitizer(this);

}

//____________________________________________________________________
AliFMDSDigitizer::~AliFMDSDigitizer() 
{
  // Destructor
  AliLoader* loader = fRunLoader->GetLoader("FMDLoader");
  loader->CleanSDigitizer();
}

//____________________________________________________________________
void
AliFMDSDigitizer::Exec(Option_t*) 
{
  // Get the output manager 
  if (!fRunLoader) {
    Error("Exec", "Run loader is not set");
    return;
  }
  if (!fRunLoader->GetAliRun()) fRunLoader->LoadgAlice();
  if (!fRunLoader->TreeE())     fRunLoader->LoadHeader();
  
  AliLoader* fmdLoader = fRunLoader->GetLoader("FMDLoader");
  if (!fmdLoader) Fatal("Exec", "no FMD loader");
  
  // Get the AliFMD object 
  AliFMD* fmd = 
    static_cast<AliFMD*>(fRunLoader->GetAliRun()->GetDetector("FMD"));
  if (!fmd) {
    AliError("Can not get FMD from gAlice");
    return;
  }

  Int_t nEvents = Int_t(fRunLoader->TreeE()->GetEntries());
  for (Int_t event = 0; event < nEvents; event++) {
    AliDebug(1,Form(" Digitizing event number %d", event));
    // Get the current loader 
    fRunLoader->GetEvent(event);

    if (!fmdLoader->TreeS()) fmdLoader->MakeTree("S");
    // Make a branch
    fmd->MakeBranch("S");
    
    // Cache contriutions 
    SumContributions(fmd);

    // Digitize the event 
    DigitizeHits(fmd);

    fmdLoader->TreeS()->Reset();
    fmdLoader->TreeS()->Fill();
    fmdLoader->WriteSDigits("OVERWRITE");
  }
}

//____________________________________________________________________
void
AliFMDSDigitizer::AddDigit(AliFMD*  fmd,
			   UShort_t detector, 
			   Char_t   ring,
			   UShort_t sector, 
			   UShort_t strip, 
			   Float_t  edep, 
			   UShort_t count1, 
			   Short_t  count2, 
			   Short_t  count3) const
{
  // Add a summable digit
  fmd->AddSDigitByFields(detector, ring, sector, strip, edep, 
			 count1, count2, count3); 
}


//____________________________________________________________________
//
// 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 AliFMDSDigitizer.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
6169f936	199	// #include <TTree.h> // ROOT_TTree
02a27b50	200	//#include <TRandom.h> // ROOT_TRandom
	201	#include <AliLog.h> // ALILOG_H
	202	#include "AliFMDSDigitizer.h" // ALIFMDDIGITIZER_H
	203	#include "AliFMD.h" // ALIFMD_H
6169f936	204	// #include "AliFMDGeometry.h" // ALIFMDGEOMETRY_H
	205	// #include "AliFMDDetector.h" // ALIFMDDETECTOR_H
	206	// #include "AliFMDRing.h" // ALIFMDRING_H
02a27b50	207	#include "AliFMDHit.h" // ALIFMDHIT_H
6169f936	208	// #include "AliFMDDigit.h" // ALIFMDDIGIT_H
	209	// #include "AliFMDParameters.h" // ALIFMDPARAMETERS_H
	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	//====================================================================
	216	ClassImp(AliFMDSDigitizer)
	217
	218	//____________________________________________________________________
	219	AliFMDSDigitizer::AliFMDSDigitizer()
	220	{
	221	// Default ctor - don't use it
	222	}
	223
	224	//____________________________________________________________________
	225	AliFMDSDigitizer::AliFMDSDigitizer(const Char_t* headerFile,
	226	const Char_t* /* sdigfile */)
	227	: AliFMDBaseDigitizer("FMDSDigitizer", "FMD SDigitizer")
	228	{
	229	// Normal CTOR
	230	AliDebug(1," processed");
	231
	232	fRunLoader = AliRunLoader::GetRunLoader(); // Open(headerFile);
	233	if (!fRunLoader)
	234	Fatal("AliFMDSDigitizer", "cannot open session, header file '%s'",
	235	headerFile);
	236	AliLoader* loader = fRunLoader->GetLoader("FMDLoader");
	237	if (!loader)
	238	Fatal("AliFMDSDigitizer", "cannot find FMD loader in specified event");
	239
	240	// Add task to tasks folder
	241	loader->PostSDigitizer(this);
	242
	243	}
	244
	245	//____________________________________________________________________
	246	AliFMDSDigitizer::~AliFMDSDigitizer()
	247	{
	248	// Destructor
	249	AliLoader* loader = fRunLoader->GetLoader("FMDLoader");
	250	loader->CleanSDigitizer();
	251	}
	252
	253	//____________________________________________________________________
	254	void
	255	AliFMDSDigitizer::Exec(Option_t*)
	256	{
	257	// Get the output manager
	258	if (!fRunLoader) {
	259	Error("Exec", "Run loader is not set");
	260	return;
	261	}
	262	if (!fRunLoader->GetAliRun()) fRunLoader->LoadgAlice();
	263	if (!fRunLoader->TreeE()) fRunLoader->LoadHeader();
	264
	265	AliLoader* fmdLoader = fRunLoader->GetLoader("FMDLoader");
	266	if (!fmdLoader) Fatal("Exec", "no FMD loader");
	267
	268	// Get the AliFMD object
	269	AliFMD* fmd =
	270	static_cast<AliFMD*>(fRunLoader->GetAliRun()->GetDetector("FMD"));
	271	if (!fmd) {
	272	AliError("Can not get FMD from gAlice");
	273	return;
	274	}
275
276	Int_t nEvents = Int_t(fRunLoader->TreeE()->GetEntries());
277	for (Int_t event = 0; event < nEvents; event++) {
278	AliDebug(1,Form(" Digitizing event number %d", event));
279	// Get the current loader
280	fRunLoader->GetEvent(event);
281
282	if (!fmdLoader->TreeS()) fmdLoader->MakeTree("S");
283	// Make a branch
284	fmd->MakeBranch("S");
285
286	// Cache contriutions
287	SumContributions(fmd);
288
289	// Digitize the event
290	DigitizeHits(fmd);
291
292	fmdLoader->TreeS()->Reset();
293	fmdLoader->TreeS()->Fill();
294	fmdLoader->WriteSDigits("OVERWRITE");
295	}
296	}
297
298	//____________________________________________________________________
299	void
300	AliFMDSDigitizer::AddDigit(AliFMD* fmd,
301	UShort_t detector,
302	Char_t ring,
303	UShort_t sector,
304	UShort_t strip,
305	Float_t edep,
306	UShort_t count1,
307	Short_t count2,
308	Short_t count3) const
309	{
310	// Add a summable digit
311	fmd->AddSDigitByFields(detector, ring, sector, strip, edep,
312	count1, count2, count3);
313	}
314
315
316
317	//____________________________________________________________________
318	//
319	// EOF
320	//
321
322
323
324