78 lines
3.3 KiB
HTML
78 lines
3.3 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<html><head><title>Conescan.radi</title></head><body>
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<h2>Conescan </h2>
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<p>A conescan is a possibly useful procedure when setting up a single crystal
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diffraction experiment. The first thing which needs to be done when
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starting a single crystal experiment is the determination of the UB
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matrix. In order to do that at least two reflections need to be
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located through a search procedure. Now, consider the situation when
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one reflection has been found and indexed. Then it is known that other
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reflections can be found on a cone
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with an opening angle determined by the lattice parameters and the
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indices of the target reflection around the first (center)
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reflection. The SICS conescan module allows to do just that, do a scan
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around a given center reflection. The syntax is:
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</p></p><dl><dt>conescan list
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<dd> lists all the parameters of the conescan
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<dt>conescan cell
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<dd> prints the cell constants.
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<dt>conescan cell a b c alpha beta gamma
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<dd> sets new cell constants.
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<dt>conescan center
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<dd> prints the current values for the center reflection
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<dt>conescan center h k l
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<dd> uses h, k, l as the indices of the center
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reflection. Motor positions are read from motors.
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<dt>conescan center h k l stt om chi phi
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<dd> defines a center position
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complete with all angles.
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<dt>conescan target
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<dd> prints the current target for the conescan
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<dt>conescan target h k l
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<dd> defines the target indices for the conescan.
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<dt>conescan qscale
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<dd> prints the Q scale for the conescan. The conescan
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module calculates the length of then scattering vector from the
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lattice parameters and the indices. When the lattice constants are
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only approximatly known it might be useful to vary the scattering
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vector length for the conescan a little. This can be doen with the
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qscale factor.
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<dt>conescan qscale value
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<dd> sets a new value for the qscale factor
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<dt>conescan run step mode preset
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<dd> starts a conescan with the nstep width
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step, the couent mode mode and the preset preset.
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<dt>conescan run
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<dd> starts a conescan with defaults: step = .5,
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mode = monitor, preset = 10000
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<p></dl>This is the simple usage of the conescan. In fact cone is implemented
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as a virtual motor. This means that arbitray scans can be performed on
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cone as with any other motor. As with any other motor, cone can also
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be driven to a cone angle.
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</p></p><h3>Implementation Reference </h3>
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<p>The conescan commands are just wrapper routines around the cone and
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ubcalc module which actually work together to implement the
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conescan. The ubcalc module, documented elsewhere, holds the cell
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constants and the center reflection.
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</p></p><p>The cone module does the actual cone calculation. Cone can be
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configured with commands:
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<dl></p><dt>cone center
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<dd> prints the number of the reflection in ubcalc to use as
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a center.
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<dt>cone center num
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<dd> sets the reflection in ubcalc to use a the center
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for driving on the cone. Set to 0 to use the first reflection in
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ubcalc.
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<dt>cone target
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<dd> prints the target reflection indices for the cone.
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<dt>cone target h k l
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<dd> sets the target reflection indices.
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<dt>cone qscale
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<dd> prints the current value of the scattering vector scale.
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<dt>cone qscale val
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<dd> sets a value for the scaling factor for the
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scattering vector. Values should be close to 1.0;
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</dl></body></html>
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