This new feature is important for the construction of neutron-scattering instruments geared toward the study of magnetism in matter. This unique Monte Carlo tool automatically deals with unexpected events and takes into account the imperfections of instrument elements, such as surface roughness and chopper jitter, and complex element features, such as the time-energy distribution of the neutron pulse. Elements or element features can be turned on and off, or can be adjusted continuously, thereby allowing the user to assess their impact on instrument performance, which is not usually possible in an actual experiment. Screen shot of a list of elements that can be accessed through MCWeb and incorporated in the design of an instrument. Screen shot of the form used to define an element to be incorporated in an instrument.
Users can add their own element types or use a large library of pre-defined elements.
An online help feature assists users in defining each element and parameter. A neutron emitted by the moderator travels down the instrument axis, through the aperture, and hits the ellipsoidal mirror. The neutron is reflected, then scattered by the sample, and detected in the position-sensitive detector. The spatial distribution of neutron intensity in the detector reflects certain features of the microstructure of the sample material. A mirror with the shape of a portion of an ellipsoid was incorporated into the NISP design.