VITESS Module Evaluation 2D (eval_elast2)

The module eval_elast2 is supposed to be used for elastic
scattering (e.g. powder diffraction, SANS).

The diffractogram or spectra file will contain the neutron probabilities counted for each
segment of the evaluation interval (with respect to the evaluation parameter
of interest).

The following information has to be given as an input:

evaluation parameter: choose between scattering angle vs. wavelength and
  scattering angle vs. TOF

spectra file: the name of the spectra file which will contain
  the evaluated data has to be given.

number of bins in X and Y: number of bins determines the segmentation of the
  scattering angle and wavelength or TOF direction.
  It is therewiththe number of values written to the file.

minimum, maximum: the bounds of the interval for the evaluation parameter.
increase to next bin X and Y: for a logarithmic binning the percentage has to be given
  by which the upper limit of each bin exceeds its lower limit.
  If this value is set, the given 'number of bins' is ignored 

dead-spot: only needed if the direct beam points to the detector
   (as in the case of SANS).
   All neutrons with a scattering angle(2 theta) between 0 and dead-spot [deg]
   will therefore not be considered in the evaluation.

probability weight: if one deactivates the probability weight each
   neutron is considered with the weight 1, otherwise (default)
   the attributed probabilities (due to the operations of the modules before)
   are considered.

time of flight:  if the wavelength of the neutrons shall be
   determined by time of flight analysis (i.e. each wavelength is
   calculated from the flight path and the flight time)
   this option must be activated when using scattering angle vs. wavelength.

flight path [cm]: length of total neutron flight path,
   needed only for time of flight analysis.

time offset [ms]: global shift of the neutron time t  t-TimeOffset [ms],
   useful to shift the temporal reference point for the time of flight analysis
begin, end of evaluation: the bounds of the time interval for the evaluation.
   Only neutrons arriving in that time interval are considered in the
   evaluation
color, mincolor, maxcolor: either the exact color is needed for evaluation (0 is any) or 
   the color has to be in the range between mincolor and maxcolor (-1 is any color range).


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