
================================   MAMON   =====================================


 MAMON (Multiple beAM diffractiON) is an widget based graphical interface to 
 calculate the Umweganregung peak location plot (the diffracted wavelength 
 lambda vs. the azimutal angle angle Psi) for a given primary reflection in 
 perfect cubic crystals.

 In other words, if a crystal is set with a particular Bragg angle to match 
 a given reflection (inputs: H,K,L) at a given wavelength (input: WaveLength), 
 many other (secondary) reflections are excited when the crystal is rotated 
 around the azimutal angle Psi, without changing the Bragg angle. 
 The plot (WaveLength,Psi) of the possible reflections is calculated and
 contain all possible reflection curves up to a maximum reflection 
 (input: H Max,  K Max, L Max). The intersection of these curves with an
 horizontal line at the wavelength of the primary reflection (input: WaveLength)
 gives the position of the peaks in the unweg plot. The width of each peak 
 depends on the pendent of the curve at the intersection. For that, the 
 Psi1 and Psi2 intersection angles with a band of width (input: DeltaWaveLength)
 are calculated. With this width and the intensity of the diffraction line, 
 it is possible to compute a Gaussian that "roughly" describe the peak.
 

 The program computes first all Miller indices hkl associated to the
 different crystal planes which meet the diffraction condition (multiple
 diffraction events) in the two-beam multiple diffraction approximation.

 Translated into the reciprocal space this means that two or more knots of the
 reciprocal lattice come across the Ewald's sphere of radius 1/lambda (where
 lambda is the wavelength) at the same time when this is rotated of an angle 
 Psi, say, about one diffraction vector P = (H,K,L).

 The azimuthal angle Psi is calculated relative to an arbitrarily chosen 
 reference direction perpendicular to the scattering vector of the primary 
 reflection.  The user can specify the energy and the angular range as well 
 as the max hkl values considered

 The theoretical frame of the program is essentially provided in:
  1) B.H. Cole et al, "Simultaneous Diffraction: Indexing Umweganregungen 
     Peaks in Simple Cases", Acta Cryst. (1962), 15, 138-144

 The peak intensity is calculated with the approximated method described in:
  2) K. Yvon et al., "LAZY PULVERIX, a computer program for calculating X-ray 
     and neutron diffraction powder patterns", J. Appl. Cryst. (1977), 10, 73-74

  Basically, the intensity I is calculated as I= M L P F**2, being
       M: multiplicity factor, 
       P: Polarization factor, 
       L: Lorentz factor (L=1/[sin_theta**2  cos_theta])
       Theta is the Bragg angle. 
       F is calculated considering the scattering factor f0 calculated using
         using the coefficients tabulated in the file mamon.f0.
  Obviously, this intensity is not correct because:
       - The formula is not valid for perfect crystals, only for powders.
       - The total intensity must be the sum of the primary reflection
         plus the intensity of the so-called operative reflections plus the
         contribution of the cooperative ones. 
       - Anomalous scattering factors are not considered. 

 The crystal group symmetries represented in the program are: simple cubic, 
 body-centered cubic, face-centered cubic. In particular the selection rules
 for reflections peculiar of the diamond structure are also built in in the 
 code.



 DESCRIPTION OF THE CONTROLS IN THE MAIN WINDOW:

  File:
   MAMON input parameters: This option allows to save the current
		parameters to a file for later loading. It also allows
		to save the current parameters as defaults for being
		used when the application is initialized. In the last
		case, the file is named "application".xop (where 
		"application " is the name of the current XOP
		application) and is written in the directory pointed
		by the XOP_DEFAULTS_DIR environment variable (which
		must be set). The parameter file is ASCII and can be
		read and edited with care.
  Quit: to exit from the program

 Set_Parameters:
  Set Parameters: to define the parameters for the calculation.
		The same result is obtained pressing the "Set Parameters"
		button in the main BM window. 
               Please refer to the information under the HELP
		button for a complete description of the parameters. 
  Set Defaults: Sets the default parameters.

  Show: Display results
    Plot 
        Spaghettis: Plots the MAMON unweganregung "spaghetti" plot results.
        Unweg: Plots the MAMON unweganregung plot, i.e., the peaks
               obtained when scanning the Psi angle. They are calculated
               from a band in the spaghetti plot centered at the 
               position defined in "WaveLength" and with width equal
               to the value in DeltaWaveLength (A).
    View 
        Spaghettis: Displays the MAMON output text file mamon_spaghetti.dat, 
          which contains:
          h,k,l     the Miller indices of the current Umweganregung event 
          theta     the cooresponding Bragg angle
          F(hkl)    the absolute value of the calculated structure factor. 
                    The Debye-Waller factor is not taken into acount
          Intensity the reflection intensity
          Beta      angle between the projectons of the vectors r = (h,k,l) (which
          meets the Bragg condition at the same time as P) and 
          k0 = (e0x,e0y,e0z)/lambda on the plane perpendicular to P
          [e0 is the unit vector]. Let's call these projections r_perp
                    and k0_perp, respectively
          Psi0      angle between a reference axis perpendicular to P 
                    (calculated by the program) and r_perp
          Psi       rotation angle around the main diffraction vector
  
          calib     (not relevant for its use in this context)
                    lambda [Angstrom] as calculated from eq. 4 of ref. 1. 
                    This eq. gives the relationship between primary as well as 
                    operative reflection and k0 for simultaneous diffraction 
                    to occur.
        Unweg: Displays the MAMON output text file mamon_unweg.dat, containing
                    the spaghetti lines that lie in the band defined by the 
                    the horizontal line at WaveLength and with width DeltaWaveLength.
                    For each line that intersect, a line contains:
          Psi1:     The first intersection angle in deg.
          Psi2:     The second intersection angle in deg.
          Intensity: The curve intensity.
          H,K,L     The reflection Miller planes. 

  Help:   Shows the BM help (this text).

 COPYRIGHT:
	MAMON belongs to XOP package and it is distributed within XOP.
	PLEASE REFER TO THE XOP COPYRIGHT NOTICE BEFORE USING IT.

 CREDITS:
	Published calculations made with XOP should refer:

	  M. Sanchez del Rio and R. J. Dejus "XOP: Recent Developments"
	  SPIE proceedings vol. 3448, pp.340-345, 1998.

 LAST MODIFICATION: msr/msr/03-02-03

