prepare for the new tracklet fit/attach
[u/mrichter/AliRoot.git] / FMD / AliFMDBaseDigitizer.h
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02a27b50 1#ifndef ALIFMDBASEDIGITIZER_H
2#define ALIFMDBASEDIGITIZER_H
3/* Copyright(c) 1998-2000, ALICE Experiment at CERN, All rights
4 * reserved.
5 *
6 * See cxx source for full Copyright notice
7 */
8// Classses to make Hits into digits and summable digits.
9//
10// Digits consists of
11// - Detector #
12// - Ring ID
13// - Sector #
14// - Strip #
15// - ADC count in this channel
16//
17// Summable digits consists of
18// - Detector #
19// - Ring ID
20// - Sector #
21// - Strip #
22// - Total energy deposited in the strip
23// - ADC count in this channel
24//
25/** @file AliFMDBaseDigitizer.h
26 @author Christian Holm Christensen <cholm@nbi.dk>
27 @date Mon Mar 27 12:38:26 2006
28 @brief FMD Digitizers declaration
29 @ingroup FMD_sim
30*/
31#ifndef ALIDIGITIZER_H
32# include <AliDigitizer.h>
33#endif
34#ifndef ALIRUNDIGITIZER_H
35# include <AliRunDigitizer.h>
36#endif
37#ifndef ALIFMDEdepMAP_H
38# include "AliFMDEdepMap.h"
39#endif
40//====================================================================
41class TClonesArray;
42class AliFMD;
43class AliLoader;
44class AliRunLoader;
45class AliFMDDigit;
46
47
48//====================================================================
49/** @class AliFMDBaseDigitizer AliFMDDigitizer.h <FMD/AliFMDDigitizer>
50 @brief Base class for digitizers.
51
52 This class contains the procedures simulation ADC signal for the
53 Forward Multiplicity detector : Hits->Digits and Hits->SDigits
54
55 Digits consists of
56 - Detector #
57 - Ring ID
58 - Sector #
59 - Strip #
60 - ADC count in this channel
61
62 Summable digits consists of
63 - Detector #
64 - Ring ID
65 - Sector #
66 - Strip #
67 - Total energy deposited in the strip
68 - ADC count in this channel
69
70 As the Digits and SDigits have so much in common, the classes
71 AliFMDDigitizer and AliFMDSDigitizer are implemented via a base
72 class AliFMDBaseDigitizer.
73 @verbatim
74 +---------------------+
75 | AliFMDBaseDigitizer |
76 +---------------------+
77 ^
78 |
79 +----------+---------+
80 | |
81 +-----------------+ +------------------+
82 | AliFMDDigitizer | | AliFMDSDigitizer |
83 +-----------------+ +------------------+
84 @endverbatim
85 These classes uses parameters fetched from the AliFMDParameters
86 manager.
87
88 The shaping function of the VA1 is generally given by
89 @f[
90 f(x) = A(1 - \exp(-Bx))
91 @f]
92 where A is the total charge collected in the pre-amp., and B is a
93 paramter that depends on the shaping time of the VA1 circut.
94
95 When simulating the shaping function of the VA1 pre-amp. chip, we
96 have to take into account, that the shaping function depends on
97 the previous value of read from the pre-amp.
98
99 That results in the following algorithm:
100 @code
101 last = 0;
102 for (i=0; i < n_pre_amp_charge; i++) {
103 charge = GetCharge(i);
104 if (last < charge)
105 f(t) = (charge - last) * (1 - exp(-B * t)) + last
106 else
107 f(t) = (last - charge) * exp(-B * t) + charge)
108 for (j=0; j < sample_rate; j++)
109 adc[j] = f(i / (# samples))
110 last = charge
111 }
112 @endcode
113 Here, the first loop is over all charges collected by the VA1
114 chip, and the @c sample_rate is how many times the ALTRO ADC
115 samples each of the 128 charges from the pre-amp.
116
117 The @c charge is the total charge @f$ Q@f$ collected by the VA1
118 pre-amplifier for a strip. @f$ Q@f$ is then given by
119 @f[
120 Q = \frac{E}{e}\frac{S}{r}
121 @f]
122 where @f$ E@f$ is the total energy deposited in a silicon strip,
123 @f$ R@f$ is the dynamic range of the VA1 pre-amp, @f$ e@f$ is the
124 energy deposited by a single MIP, and @f$ S@f$ ALTRO channel size
125 in each time step.
126
127 The energy deposited per MIP is given by
128 @f$
129 e = M \rho w
130 @f$
131 where @f$ M@f$ is the universal number
132 @f$ 1.664 \mbox{keV}\mbox{cm}^{2}\mbox{g}^{-1}@f$, @f$ \rho@f$ is
133 the density of silicon, and @f$ w@f$ is the depth of the silicon
134 sensor.
135
136 The final ADC count is given by
137 @f[
138 C' = C + P
139 @f]
140 where @f$ P@f$ is the (randomized) pedestal.
141
142 This class uses the class template AliFMDEdepMap to make an
143 internal cache of the energy deposted of the hits. The class
144 template is instantasized as
145
146 The first member of the values is the summed energy deposition in a
147 given strip, while the second member of the values is the number of
148 hits in a given strip. Using the second member, it's possible to
149 do some checks on just how many times a strip got hit, and what
150 kind of error we get in our reconstructed hits. Note, that this
151 information is currently not written to the digits tree. I think a
152 QA (Quality Assurance) digit tree is better suited for that task.
153 However, the information is there to be used in the future.
154 @ingroup FMD_sim
155 */
156class AliFMDBaseDigitizer : public AliDigitizer
157{
158public:
159 /** CTOR */
160 AliFMDBaseDigitizer();
161 /** Normal CTOR
162 @param manager Manager of digitization */
163 AliFMDBaseDigitizer(AliRunDigitizer * manager);
164 /** Normal ctor
165 @param name Name
166 @param title Title */
167 AliFMDBaseDigitizer(const Char_t* name, const Char_t* title);
168 /** DTOR */
169 virtual ~AliFMDBaseDigitizer();
170
171 /** Initialize */
172 virtual Bool_t Init();
42f1b2f5 173
02a27b50 174 /** The response shape of the VA1 shaping circuit is approximently
175 given by
176 @f[
177 f(x) = A(1 - \exp(-Bx))
178 @f]
179 where @f$ A@f$ is the total charge collected by the pre-amp.,
180 and @f$ B@f$ is parameter that depends on the shaping time of
181 the @b VA1 pre-amp. This member function sets the parameter @f$
182 B@f$
183 @param B */
184 void SetShapingTime(Float_t B=10) { fShapingTime = B; }
185 /** @return Get the shaping time */
186 Float_t GetShapingTime() const { return fShapingTime; }
187protected:
02a27b50 188 /** For the stored energy contributions in the cache, convert the
189 energy signal to ADC counts, and store the created digit in
190 the digits array
191 @param fmd Pointer to detector */
ef8e8623 192 virtual void DigitizeHits() const;
02a27b50 193 /** Convert the total energy deposited to a (set of) ADC count(s).
194 See also the class description for more details.
195 @param edep Total energy deposited in detector
196 @param last Last charge collected in previous VA1 channnel
197 @param detector Detector #
198 @param ring Ring ID
199 @param sector Sector #
200 @param strip Strip #
201 @param counts Array holding the counts on return */
202 virtual void ConvertToCount(Float_t edep,
203 Float_t last,
204 UShort_t detector,
205 Char_t ring,
206 UShort_t sector,
207 UShort_t strip,
208 TArrayI& counts) const;
209 /** Make a pedestal
210 @param detector Detector #
211 @param ring Ring ID
212 @param sector Sector #
213 @param strip Strip #
214 @return Pedestal value */
215 virtual UShort_t MakePedestal(UShort_t detector,
216 Char_t ring,
217 UShort_t sector,
218 UShort_t strip) const;
219 /** Add noise to each sample */
220 virtual void AddNoise(TArrayI&) const {}
ef8e8623 221
222 /** Add edep contribution from (detector,ring,sector,strip) to cache */
223 virtual void AddContribution(UShort_t detector,
224 Char_t ring,
225 UShort_t sector,
226 UShort_t strip,
83ad576a 227 Float_t edep,
228 Bool_t isPrimary);
02a27b50 229 /** Add a digit to output */
ef8e8623 230 virtual void AddDigit(UShort_t detector,
231 Char_t ring,
232 UShort_t sector,
233 UShort_t strip,
234 Float_t edep,
235 UShort_t count1,
236 Short_t count2,
237 Short_t count3,
83ad576a 238 Short_t count4,
239 UShort_t ntot,
240 UShort_t nprim) const;
ef8e8623 241 /** Make the output tree using the passed loader
242 @param loader
243 @return The generated tree. */
244 virtual TTree* MakeOutputTree(AliLoader* loader);
245 /** Store the data using the loader
246 @param loader The loader */
247 virtual void StoreDigits(AliLoader* loader);
02a27b50 248
ef8e8623 249 AliFMD* fFMD;
02a27b50 250 AliRunLoader* fRunLoader; //! Run loader
251 AliFMDEdepMap fEdep; // Cache of Energy from hits
252 Float_t fShapingTime; // Shaping profile parameter
253
254 /** Copy CTOR
255 @param o object to copy from */
256 AliFMDBaseDigitizer(const AliFMDBaseDigitizer& o)
b5ee4425 257 : AliDigitizer(o),
ef8e8623 258 fFMD(o.fFMD),
b5ee4425 259 fRunLoader(0),
ef8e8623 260 fEdep(o.fEdep),
261 fShapingTime(o.fShapingTime)
b5ee4425 262 {}
02a27b50 263 /** Assignment operator
264 @return Reference to this object */
ef8e8623 265 AliFMDBaseDigitizer& operator=(const AliFMDBaseDigitizer& o)
266 {
267 AliDigitizer::operator=(o);
268 fRunLoader = o.fRunLoader;
269 fEdep = o.fEdep;
270 fShapingTime = o.fShapingTime;
271 return *this;
272 }
02a27b50 273 ClassDef(AliFMDBaseDigitizer,2) // Base class for FMD digitizers
274};
275
276
277#endif
278//____________________________________________________________________
279//
280// Local Variables:
281// mode: C++
282// End:
283//
284//
285// EOF
286//
287