README file for ALICE Forward Multiplicity Detector Off-line Code
    =================================================================

Introduction:
-------------

This file contains a short overview of the FMD code.   It is by no
means authoritative  - only the code is good for that.  However, I'll
try to explain things a bit here. 

Structure:
----------

There are 4 libraries build for the FMD.  These are 

* libFMDbase:
  This contains the basic stuff, like data classes and managers. 

* libFMDsim: 
  This contains code used by the simulation only.  That includes the
  detector class AliFMD and it's derivatives.  It also contains the
  code for building the geometry, as well as the digitisers and raw
  data writer. 

* libFMDrec:
  Code needed for the reconstruction.  This include the reconstruction
  code itself, as well as a raw data reader.

* libFMDutil:
  This is a special library that contains various utility classes for
  the FMD expert/developer/tester.  It includes code to read all data
  produced by the FMD, a simple event display, and code to make fake
  calibration and alignment data.  This library is _not_ loaded by
  aliroot automatically. The user has to load it herself:

     gSystem->Load("libFMDutil.so");

The content of these libraries is detailed more below. 

libFMDbase:
-----------

This currently (18th or March 2006) contains the classes 

  AliFMDBaseDigit
  AliFMDDigit
  AliFMDSDigit
	Base class for digits, real digits, and summable digits.  The
        are all data classes that holds the ADC value(s) for a single
	strip. 
  
  AliFMDBoolMap:
	A map of booleans, one for each strip.
  
  AliFMDUShortMap:
	A map of unsigned short integers, one for each strip. 
  
  AliFMDDetector
  AliFMD1
  AliFMD2
  AliFMD3:
	3 classes that holds the parameters for each of the 3
	FMD sub-detectors.  These derive from AliFMDDetector, and are
	managed by AliFMDGeometry.  Each of these also contains the
	translation from sensor reference frame to global reference
	frame. 

  AliFMDRing:
	Parameters for the FMD rings (inner and outer type).  These are
	managed by AliFMDGeometry. 
  
  AliFMDGeometry: 
	Manager of FMD geometry data. All code queries this manager
	for geometry parameters, so that the data is always consistent. 
  
  AliFMDParameters:
	Manager of FMD parameters, like calibration parameters.  This
	class fetches data from CDB if necessary.   All code queries
	this manager for parameters, so that the data is always
	consistent. 
  
  AliFMDCalibPedestal
  AliFMDCalibGain
  AliFMDCalibSampleRate
  AliFMDAltroMapping:
	Containers of calibration parameters.  These correspond to the
	pedestal and its width, the gain of each strip, the
	oversampling rate used in read-out, and the map from hardware
	address to detector. 
  

libFMDsim:
----------

This currently (18th or March 2006) contains the classes 

  AliFMDEdepMap  
	Cache of energy deposited and total number of hits for each
	strip.  The digitiser AliFMDDigitizer uses this to store
	simulation data before making digits. 

  AliFMDHit  
	A hit in the FMD active elements, as described by the
	simulation back-end during transport. 

  AliFMD  
  AliFMDv0  
  AliFMDv1  
	Simulation drivers for the FMD.  AliFMD is the base
	class. AliFMDv0 corresponds to a simulation where no hits are
	created, but the material distribution is right.   AliFMDv1 is
	like AliFMDv0, except that hits are produced. 

  AliFMDGeometryBuilder  
	Build the FMD geometry in terms of TGeo objects.  The
	information for building the geometry is retrieved from
	AliFMDGeometry. 

  AliFMDBaseDigitizer  
  AliFMDDigitizer  
  AliFMDSDigitizer 
	Base class for the digitisers.  AliFMDDigitizer makes `real'
	digits (AliFMDDigit) from hits, and AliFMDSDigitizer makes
	summable digits from hits. 
 
  AliFMDRawWriter  
	Writes a pseudo raw data file from the digits created by the
	digitisers.  It uses the AliFMDAltroMapping from
	AliFMDParameters to make the mapping from detector coordinates
	to hardware addresses. 

libFMDrec:
----------

This currently (18th or March 2006) contains the classes 

  AliFMDReconstructor  
	Reconstruct (in a naiive way) the charged particle
	multiplicity in the FMD strips.   This also writes an
	AliESDFMD object to the ESD files (that class is in libESD). 

  AliFMDRecPoint  
	Reconstructed point in the FMD.  These objects are made
	AliFMDReconstructor. 

  AliFMDRawStream  
  AliFMDRawReader  
	Classes to read raw data files. 

libFMDutil:
-----------

This currently (18th or March 2006) contains the classes 

  AliFMDInput  
  AliFMDInputHits  
  AliFMDInputDigits  
  AliFMDInputSDigits  
  AliFMDInputRecPoints  
	Base class, and concrete classes to read in FMD generated
	data.  These provide a simple and unified way of getting the
	data.  Hooks are defined to process hits, tracks, digits, and
	reconstructed points, as well as geometry and ESD data.   See
	for example the scripts `DrawHits.C', `DrawHitsDigits.C',
	`DrawHitsRecs.C', `DrawDigitsRecs.C' in the `scripts'
	sub-directory.

  AliFMDDisplay  
	Simple event display for FMD data, including hits, digits,
	reconstructed points and ESD data. 

  AliFMDCalibFaker  
  AliFMDAlignFaker  
	Classes to write fake (or dummy) calibration and alignment
	data.  These derive from TTask.  The usage of these classes
	is simple:

		AliFMDCalibFaker f;
		f.Set... // Set parameters if needed 
		f.Exec();

Authors:
--------

  Alla Maevskaya		<[email protected]>	
  Christian Holm Christensen 	<[email protected]>

----------------------------------------------------------------------
Local Variables:
	mode: text
End:

 LocalWords:  libFMDbase libFMDsim AliFMD libFMDutil aliroot gSystem naiive ESD
 LocalWords:  CDB AliFMDGeometry AliFMDDetector AliFMDUShortMap AliFMDBoolMap
 LocalWords:  AliFMDBaseDigit AliFMDDigit AliFMDSDigit AliFMDRing AliFMDEdepMap
 LocalWords:  AliFMDParameters AliFMDCalibPedestal AliFMDCalibGain AliFMDHit
 LocalWords:  AliFMDCalibSampleRate AliFMDAltroMapping AliFMDv AliFMDDigitizer
 LocalWords:  AliFMDGeometryBuilder AliFMDBaseDigitizer AliFMDSDigitizer TGeo
 LocalWords:  AliFMDRawWriter libFMDrec AliESDFMD AliFMDReconstructor libESD
 LocalWords:  AliFMDRecPoint AliFMDRawStream AliFMDRawReader AliFMDInput TTask
 LocalWords:  AliFMDInputHits AliFMDInputDigits AliFMDInputSDigits Maevskaya
 LocalWords:  AliFMDInputRecPoints AliFMDDisplay AliFMDCalibFaker Holm booleans
 LocalWords:  AliFMDAlignFaker