class AliFMD: public AliDetector

 Destructor for base class AliFMD

 Create the geometry of Forward Multiplicity Detector.  The actual
 construction of the geometry is delegated to the class
 AliFMDGeometryBuilder, invoked by the singleton manager
 AliFMDGeometry.

 Define the materials and tracking mediums needed by the FMD
 simulation.   These mediums are made by sending the messages
 AliMaterial, AliMixture, and AliMedium to the passed AliModule
 object module.   The defined mediums are

	FMD Si$		Silicon (active medium in sensors)
	FMD C$		Carbon fibre (support cone for FMD3 and vacuum pipe)
	FMD Al$		Aluminium (honeycomb support plates)
	FMD PCB$	Printed Circuit Board (FEE board with VA1_3)
	FMD Chip$	Electronics chips (currently not used)
	FMD Air$	Air (Air in the FMD)
	FMD Plastic$	Plastic (Support legs for the hybrid cards)

 The geometry builder should really be the one that creates the
 materials, but the architecture of AliROOT makes that design
 akward.  What should happen, was that the AliFMDGeometryBuilder
 made the mediums, and that this class retrives pointers from the
 TGeoManager, and registers the mediums here.  Alas, it's not
 really that easy.

 Initialize the detector

 Called at the end of the an event in simulations.  If the debug
 level is high enough, then the `bad' hits are printed.

 Create Tree branches for the FMD.

 Options:

    H          Make a branch of TClonesArray of AliFMDHit's
    D          Make a branch of TClonesArray of AliFMDDigit's
    S          Make a branch of TClonesArray of AliFMDSDigit's

 Set branch address for the Hits, Digits, and SDigits Tree.

 Set the TClonesArray to read hits into.

 Set the TClonesArray to read hits into.

 Add a hit to the hits tree

 The information of the two arrays are decoded as

 Parameters
    track	 	     Track #
    ivol[0]  [UShort_t ] Detector #
    ivol[1]	 [Char_t   ] Ring ID
    ivol[2]	 [UShort_t ] Sector #
    ivol[3]	 [UShort_t ] Strip #
    hits[0]	 [Float_t  ] Track's X-coordinate at hit
    hits[1]	 [Float_t  ] Track's Y-coordinate at hit
    hits[3]  [Float_t  ] Track's Z-coordinate at hit
    hits[4]  [Float_t  ] X-component of track's momentum
    hits[5]	 [Float_t  ] Y-component of track's momentum
    hits[6]	 [Float_t  ] Z-component of track's momentum
    hits[7]	 [Float_t  ] Energy deposited by track
    hits[8]	 [Int_t    ] Track's particle Id #
    hits[9]	 [Float_t  ] Time when the track hit

 Add a hit to the list

 Parameters:

    track	  Track #
    detector  Detector # (1, 2, or 3)
    ring	  Ring ID ('I' or 'O')
    sector	  Sector # (For inner/outer rings: 0-19/0-39)
    strip	  Strip # (For inner/outer rings: 0-511/0-255)
    x	  Track's X-coordinate at hit
    y	  Track's Y-coordinate at hit
    z	  Track's Z-coordinate at hit
    px	  X-component of track's momentum
    py	  Y-component of track's momentum
    pz	  Z-component of track's momentum
    edep	  Energy deposited by track
    pdg	  Track's particle Id #
    t	  Time when the track hit
    l         Track length through the material.
    stop      Whether track was stopped or disappeared

 Add a digit to the Digit tree

 Paramters

    digits[0]  [UShort_t] Detector #
    digits[1]  [Char_t]   Ring ID
    digits[2]  [UShort_t] Sector #
    digits[3]  [UShort_t] Strip #
    digits[4]  [UShort_t] ADC Count
    digits[5]  [Short_t]  ADC Count, -1 if not used
    digits[6]  [Short_t]  ADC Count, -1 if not used

 add a real digit - as coming from data

 Parameters

    detector  Detector # (1, 2, or 3)
    ring	  Ring ID ('I' or 'O')
    sector	  Sector # (For inner/outer rings: 0-19/0-39)
    strip	  Strip # (For inner/outer rings: 0-511/0-255)
    count1    ADC count (a 10-bit word)
    count2    ADC count (a 10-bit word), or -1 if not used
    count3    ADC count (a 10-bit word), or -1 if not used

 Add a digit to the SDigit tree

 Paramters

    digits[0]  [UShort_t] Detector #
    digits[1]  [Char_t]   Ring ID
    digits[2]  [UShort_t] Sector #
    digits[3]  [UShort_t] Strip #
    digits[4]  [Float_t]  Total energy deposited
    digits[5]  [UShort_t] ADC Count
    digits[6]  [Short_t]  ADC Count, -1 if not used
    digits[7]  [Short_t]  ADC Count, -1 if not used

 add a summable digit

 Parameters

    detector  Detector # (1, 2, or 3)
    ring	  Ring ID ('I' or 'O')
    sector	  Sector # (For inner/outer rings: 0-19/0-39)
    strip	  Strip # (For inner/outer rings: 0-511/0-255)
    edep      Total energy deposited
    count1    ADC count (a 10-bit word)
    count2    ADC count (a 10-bit word), or -1 if not used
    count3    ADC count (a 10-bit word), or -1 if not used

 Reset number of digits and the digits array for this detector.

 Initialize hit array if not already, and return pointer to it.

 Initialize digit array if not already, and return pointer to it.

 Initialize digit array if not already, and return pointer to it.

 Create AliFMDDigit's from AliFMDHit's.  This is done by making a
 AliFMDDigitizer, and executing that code.

 Create AliFMDSDigit's from AliFMDHit's.  This is done by creating
 an AliFMDSDigitizer object, and executing it.

 Create a digitizer object

 Turn digits into raw data.

 This uses the class AliFMDRawWriter to do the job.   Please refer
 to that class for more information.

 Turn digits into raw data.

 This uses the class AliFMDRawWriter to do the job.   Please refer
 to that class for more information.

 Browse this object.

 Create entries for alignable volumes associating the symbolic volume
 name with the corresponding volume path. Needs to be syncronized with
 eventual changes in the geometry.

 This code was made by Raffaele Grosso <rgrosso@mail.cern.ch>.  I
 (cholm) will probably want to change it.   For one, I think it
 should be the job of the geometry manager to deal with this.

 Wheter to make a detailed geometry
@param use If true, make detailed geometry  

 This member function is called when ever a track deposites
      energy (or similar) in an FMD tracking medium.  In this base
      class this member function is pure abstract.   In concrete
      sub-classes, the member function may make hits or other
stuff. 

 Get the array of summable digits
@return summable digits 

 Assignment operator
      @param other Object to assign from
@return Reference to this object