In the McStas formulation of a neutron scattering instrument, all
objects apart from the neutron ray are referred to as components. This
includes for instance
- Source The exit of a neutron production facility, where
neutron rays of certain velocities are emitted into some
portion of space
- Monochromator (Idealized) crystal used to select a
neutrons of a single wavelength
1 to probe the sample with (monochromator) or to
analyze (analyzer)
- Sample An object altering the neutron physical properties
in some sense, examples used here are
- Vanadium. Scatters incoming neutron rays incoherently
- PowderN. Can be thought of as a large number of crystals,
each scattering neutron rays according to the Bragg law, thereby
producing N concentric Debye Scherrer cones. This sample also
has the posibility of adding inchoherent, eleasticly scattered
neutron rays.
- Monitors Objects monitoring or registering neutron ray
characteristics. In the exercises below are used different types
of detectors or monitors:
- Monitor. Single monitor, detecting the number of flying
through a plane. (User defined opening size)
- PSD_monitor. Square monitor, detecting the number of
neutron rays passing through a plane, divided into
pixels. Square regions of a plane. (User defined resolution
and opening size)
- PSD_monitor_4PI. As PSD_monitor but shaped like a sphere.
- L_monitor. Wavelength monitor, measuring the different
wavelengths of the passing neutron rays. (L is for
)
- Monitor_nD. General monitor for detecting all sorts of
physical properties of the neutron ray. In our cases used with
options
- 'single' - as PSD_monitor but only one small square
- 'banana' - as PSD_monitor but shaped like a curved,
horizontal band
- Collimators Devices controling the direction and divergence
of the neutron ray.
- Collimator_linear A series of parallel absorbing neutron plates
that limits the beam divergence.
Typical values are
to
.
More information on the McStas components is available by using the
mcdoc
program (You may need to set the BROWSER system variable
to your webbrowser of choice):
mcdoc -s
, Shows a html list of all the components
mcdoc Monitor.comp
, Shows the documentation for a given component
mcdoc -M
, brings up the McStas manual in PDF format
mcdoc -c
, brings up the McStas component manual in PDF format
root
2010-07-15