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McStas: NPI_tof_dhkl_detector

[ Identification | Description | Input parameters | Links ]

The NPI_tof_dhkl_detector Component

Identification

  • Site:
  • Author: Jan Saroun, saroun@ujf.cas.cz
  • Origin:
  • Date: July 1, 2017

Description

A cylindrical detector which converts time-of-flight data (x,y,z,time) to a 1D diffractogram in dhkl.
The detector model includes finite detection depth, spatial and time resolution. Optionally, the component
exports position and time coordinates of detection events in an ASCII file.

The component can also handle setups employing a modulation chopper for peak multiplexing at a long pulse source,
as proposed for the diffractometer BEER@ESS. In this case, the component requires chopper parameters
(modulation period, width of the primary unmodulated pulse), and a file with estimated dhkl values.
The component then estimates valid regions on the angle/tof map, excluding areas assumed to be empty
or with overlaping lines. This map is exported together with the diffractogram.

Tips for usage:
1) Centre the detector at the sample axis, keep z-axis parallel to the incident beam.
2) Set the radius equal to the distance from the sample axis to the front face of the detection volume.
3) Linst-Lc is used to determine "instrumental" wavelength as lambda = h/m_n*time/(Linst-Lc);

Input parameters

Parameters in boldface are required; the others are optional.
NameUnitDescriptionDefault
ndNumber of bins for dhkl in the 1D diffractograms.200
naNumber of bins for scattering angles in the 2D maps.800
ntNumber of bins for time of flight in the 2D maps.800
nevNumber of detection events to export in "events.dat" (only modulation mode, set 1 for no export)1
filenamestrName of file in which to store the detector data.0
radiusmRadius of detector.2
yheightmHeight of detector.0.3
zdepthmThickness of the detection volume.0.01
amindegminimum of scattering angle to be detected.75
amaxdegmaximum of scattering angle to be detected.105
d_minAAminimum of inter-planar spacing to be detected.1
d_maxAAmaximum of inter-planar spacing to be detected.3
time0sTime delay of the wavelength definition chopper with respect to the source pulse.
LinstmDistance from the source to the detector.
LcmDistance from the source to the pulse chopper (set 0 for a short pulse source).
res_xmSpatial resolution along x (Gaussian FWHM).0
res_ymSpatial resolution along y (Gaussian FWHM).0
res_tsTime resolution (Gaussian FWHM). Readout only, path to capture is accounted for by the tracing code.0
mu1/cm/AACapture coefficient for the detection medium.1.0
mod_shiftfloatRelative shift of the modulation pattern (delta_d/d, constant for all reflections).0
modulation1|0Switch on/off the modulation regime (BEER multiplexing technique).0
mod_dtsModulation period.0
mod_twidthsWidth of the primary source pulse.0
mod_d0_tablestrName of a file with the list of dhkl estimates (one per line).0
verbose1|0Switch for extended reporting.0
restore_neutron1|0Switch for restoring of previous neutron state.1
AT ( , , ) RELATIVE
ROTATED ( , , ) RELATIVE

Links


[ Identification | Description | Input parameters | Links ]

Generated on 2024-01-03 11:47:43


Last Modified: Wednesday, 03-Jan-2024 19:59:11 CET
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