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A simple, reactor-based example instrument for MX diffraction is the instrument file templateNMX.instr of the McStas distribution.

Also see [[Generating a new Laue file]]

A snapshot of the contents dating from early 2015 is provided below and shows example use of

  • The Single_crystal component
  • SPLIT for boosting simulation stats

For the Rubredoxin.lau system, the Single_crystal component has suggested to use a SPLIT repetition number of 43, corresponding to the average number of active reflections in the system . That chosen split value will give you an efficiency factor of 43 in production of reflected neutrons from the sample.


  • McStas instrument definition URL=
  • Instrument: templateLaue
  • %Identification
  • Written by: K. Nielsen
  • Date: June 2nd, 2010
  • Origin: ILL
  • Release: McStas CVS-080208
  • Version: $Revision: 5074 $
  • Modified by: EF, PW
  • %INSTRUMENT_SITE: Templates
  • A simple Laue NMX diffractometer for macromolecules, adapted from the classic
  • templateLaue instrument.
  • %Description
  • A single crystal sample is illuminated with a white cold beam.
  • Based on a Laue tutorial written by K. Nielsen, Feb 7, 2000.
  • Example: templateNMX REPS=50 reflections=Rubredoxin.lau Detector: det_I=210.788
  • Example: templateNMX REPS=700 reflections=PPase_D_P1.lau Detector: det_I=29.6512
  • %Parameters
  • %End

/* Change name of instrument and input parameters with default values */
DEFINE INSTRUMENT templateNMX(REPS=43, string reflections="Rubredoxin.lau")


COMPONENT Origin = Progress_bar()

COMPONENT source = Source_simple(
radius=0.02, focus_xw=0.001, focus_yh=0.001,
lambda0=7, dlambda=5, flux=1e12)

COMPONENT slit = Slit(
xwidth=0.001, yheight=0.001)
AT (0,0,5) RELATIVE source

SPLIT REPS COMPONENT sample = Single_crystal(
xwidth=0.001, yheight=0.001, zdepth=0.001, mosaic=1e-3,
AT (0,0,0.10) RELATIVE slit

Unknown macro: { if (!SCATTERED) ABSORB; /* perfect beam stop */%}

COMPONENT det= PSD_monitor_4PI(radius=1, nx=360,ny=180,filename="psd")
AT (0,0,0) RELATIVE sample


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