Line data Source code
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 <AliDigitizationInput.h>
36 : #endif
37 : #ifndef ALIFMDEdepMAP_H
38 : # include "AliFMDEdepMap.h"
39 : #endif
40 : //====================================================================
41 : class TClonesArray;
42 : class AliFMD;
43 : class AliLoader;
44 : class AliRunLoader;
45 : class 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 : */
156 : class AliFMDBaseDigitizer : public AliDigitizer
157 : {
158 : public:
159 : /** CTOR */
160 : AliFMDBaseDigitizer();
161 : /** Normal CTOR
162 : @param manager Manager of digitization */
163 : AliFMDBaseDigitizer(AliDigitizationInput * digInp);
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();
173 :
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 4 : void SetShapingTime(Float_t B=10) { fShapingTime = B; }
185 : /** @return Get the shaping time */
186 0 : Float_t GetShapingTime() const { return fShapingTime; }
187 :
188 0 : void SetStoreTrackRefs(Bool_t store=kTRUE) { fStoreTrackRefs = store; }
189 0 : Bool_t IsStoreTrackRefs() const { return fStoreTrackRefs; }
190 :
191 : protected:
192 : /** For the stored energy contributions in the cache, convert the
193 : energy signal to ADC counts, and store the created digit in
194 : the digits array
195 : @param fmd Pointer to detector */
196 : virtual void DigitizeHits() const;
197 : /** Convert the total energy deposited to a (set of) ADC count(s).
198 : See also the class description for more details.
199 : @param edep Total energy deposited in detector
200 : @param last Last charge collected in previous VA1 channnel
201 : @param detector Detector #
202 : @param ring Ring ID
203 : @param sector Sector #
204 : @param strip Strip #
205 : @param counts Array holding the counts on return */
206 : virtual void ConvertToCount(Float_t edep,
207 : Float_t last,
208 : UShort_t detector,
209 : Char_t ring,
210 : UShort_t sector,
211 : UShort_t strip,
212 : TArrayI& counts) const;
213 : /** Make a pedestal
214 : @param detector Detector #
215 : @param ring Ring ID
216 : @param sector Sector #
217 : @param strip Strip #
218 : @return Pedestal value */
219 : virtual UShort_t MakePedestal(UShort_t detector,
220 : Char_t ring,
221 : UShort_t sector,
222 : UShort_t strip) const;
223 : /** Add noise to each sample */
224 0 : virtual void AddNoise(TArrayI&) const {}
225 :
226 : /** Add edep contribution from (detector,ring,sector,strip) to cache */
227 : virtual void AddContribution(UShort_t detector,
228 : Char_t ring,
229 : UShort_t sector,
230 : UShort_t strip,
231 : Float_t edep,
232 : Bool_t isPrimary,
233 : Int_t nTrackno,
234 : Int_t* tracknos);
235 : /** Add a digit to output */
236 : virtual void AddDigit(UShort_t detector,
237 : Char_t ring,
238 : UShort_t sector,
239 : UShort_t strip,
240 : Float_t edep,
241 : UShort_t count1,
242 : Short_t count2,
243 : Short_t count3,
244 : Short_t count4,
245 : UShort_t ntot,
246 : UShort_t nprim,
247 : const TArrayI& refs) const;
248 : /** Make the output tree using the passed loader
249 : @param loader
250 : @return The generated tree. */
251 : virtual TTree* MakeOutputTree(AliLoader* loader);
252 : /** Store the data using the loader
253 : @param loader The loader */
254 : virtual void StoreDigits(const AliLoader* loader);
255 :
256 : AliFMD* fFMD; // Detector object
257 : AliRunLoader* fRunLoader; //! Run loader
258 : AliFMDEdepMap fEdep; // Cache of Energy from hits
259 : Float_t fShapingTime; // Shaping profile parameter
260 : Bool_t fStoreTrackRefs; // Wether to store track references
261 : mutable Int_t fIgnoredLabels; //! Number of labels not assigned
262 :
263 : /** Copy CTOR
264 : @param o object to copy from */
265 : AliFMDBaseDigitizer(const AliFMDBaseDigitizer& o)
266 0 : : AliDigitizer(o),
267 0 : fFMD(o.fFMD),
268 0 : fRunLoader(0),
269 0 : fEdep(o.fEdep),
270 0 : fShapingTime(o.fShapingTime),
271 0 : fStoreTrackRefs(o.fStoreTrackRefs),
272 0 : fIgnoredLabels(o.fIgnoredLabels)
273 0 : {}
274 : /**
275 : * Assignment operator
276 : *
277 : * @return Reference to this object
278 : */
279 : AliFMDBaseDigitizer& operator=(const AliFMDBaseDigitizer& o);
280 :
281 16 : ClassDef(AliFMDBaseDigitizer,5) // Base class for FMD digitizers
282 : };
283 :
284 :
285 : #endif
286 : //____________________________________________________________________
287 : //
288 : // Local Variables:
289 : // mode: C++
290 : // End:
291 : //
292 : //
293 : // EOF
294 : //
295 :
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