[ Identification | Description | Examples | Input parameters | Links ]

The FRMII_SPODI_MULTI Instrument

Simple monochromator diffractometer for powders

Identification

Description

SPODI is a high-resolution thermal neutron diffractometer at the research
reactor Heinz Maier-Leibnitz (FRM II) especially dedicated to structural
studies of complex systems. Unique features like a very large monochromator
take-off angle of 155 degrees and a 5 m monochromator-sample distance in its
standard configuration achieve both high-resolution and a good profile shape
for a broad scattering angle range of 160 degrees. Two-dimensional data are
collected by an array of 80 vertical position sensitive 3He detectors
typically during 40 resolution steps of 0.05 degrees.

List of available wavelengths in A delivered by germanium monochromator:
Reflection    Take-off 155 degrees, L2=5m      Take-off 135 degrees, L2=2.8m
Ge 331            2.536 A                           2.396 A
Ge 551            1.549 A                           1.463 A
Ge 771            1.111 A                           1.050 A

The implemented model corresponds to the standard setup with the take-off angle
of 155 degrees, Ge 551 reflection giving rise to the wavelength of ~1.5482 AA,
and L2 of 5 m.

Examples

(Test cases in bold)

Input parameters

Parameters in boldface are required; the others are optional.
NameUnitDescriptionDefault
lambdaAWavelength; if 0, calculated from HKLmono and TOA1.5482
HKLmonostrMiller indices of the Ge-monochromator reflection"551"
TOAdegTake-Off Angle; if 0, calculated from HKLmono and lambda0
L2mDistance from the monochromator to the sample5.0
DsamplemSample diameter8e-3
HsamplemSample height40e-3
PowderstrLAZ/HKL/PCR/CIF file for powder description"Na2Ca3Al2F14.laz"
Holder Flag to enable (1) / disable (0) the vanadium sample holder0
StartThetadegStart angle of the detector system relative to the beam0
ResStepdegResolution step in degrees (standard is 0.05 deg)0.05
iResStepdegIndex number of resolution step (between 0 and 39 for standard 0.05 deg)0

Links


[ Identification | Description | Examples | Input parameters | Links ]

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