19 research outputs found
McStas and Mantid integration
McStas and Mantid are two well established software frameworks within the
neutron scattering community. McStas has been primarily used for simulating the
neutron transport of instruments, while Mantid has been primarily used for data
reduction. We report here the status of our work done on the interoperability
between the instrument simulation software McStas and the data reduction
software Mantid. This provides a demonstration of how to successfully link
together two software that otherwise have been developed independently, and in
particular here show how this has been achieved for an instrument simulation
software and a data reduction software. This paper will also provide examples
of some of the expected future enhanced analysis that can be achieved from
combining accurate instrument and sample simulations with software for
correcting raw data. In the case of this work for raw data collected at large
scale neutron facilities.Comment: 17 pages, 12 figures, POSTPRINT with proofs of article submitted to
Journal of Neutron Researc
Polychromatic neutron phase contrast imaging of weakly absorbing samples enabled by phase retrieval
We demonstrate the use of a phase retrieval technique for propagation-based
phase contrast neutron imaging with a polychromatic beam. This enables imaging
samples with low absorption contrast and/or improving the signal-to-noise ratio
to facilitate e.g. time resolved measurements. A metal sample, designed to be
close to a pure phase object, and a bone sample with canals partially filled
with D2O were used for demonstrating the technique. These samples were imaged
with a polychromatic neutron beam followed by phase retrieval. For both samples
the signal-to-noise ratio were significantly improved and in case of the bone
sample, the phase retrieval allowed for separation of bone and D2O, which is
important for example for in situ flow experiments. The use of
deuteration-contrast avoids the use of chemical contrast enhancement and makes
neutron imaging an interesting complementary method to X-ray imaging of bone
Simulation of a suite of generic long-pulse neutron instruments to optimize the time structure of the European Spallation Source
We here describe the result of simulations of 15 generic neutron instruments for the long pulsed European Spallation Source. All instruments have been simulated for 20 different settings of the source time structure, corresponding to pulse lengths between 1 ms and 2 ms; and repetition frequencies between 10 Hz and 25 Hz. The relative change in performance with time structure is given for each instrument, and an unweighted average is calculated. The performance of the instrument suite is proportional to a the peak flux and b the duty cycle to a power of approximately 0.3. This information is an important input to determining the best accelerator parameters. In addition, we find that in our simple guide systems, most neutrons reaching the sample originate from the central 3 5 cm of the moderator. This result can be used as an input in later optimization of the moderator design. We discuss the relevance and validity of defining a single figure of merit for a full facility and compare with evaluations of the individual instrument classes
Using McStas for modelling complex optics, using simple building bricks
The McStas neutron ray-tracing simulation package is a versatile tool for producing accurate neutron simulations, extensively used for design and optimization of instruments, virtual experiments, data analysis and user training. In McStas, component organization and simulation flow is intrinsically linear: the neutron interacts with the beamline components in a sequential order, one by one. Historically, a beamline component with several parts had to be implemented with a complete, internal description of all these parts. e.g. a guide component including all four mirror plates and required logic to allow scattering between the mirrors. For quite a while, users have requested the ability to allow "components inside components" or meta-components, allowing to combine functionality of several simple components to achieve more complex behaviour, i.e. four single mirror plates together defining a guide. We will here show that it is now possible to define meta-components in McStas, and present a set of detailed, validated examples including a guide with an embedded, wedged, polarizing mirror system of the Helmholtz-Zentrum Berlin type. (C) 2010 Elsevier B.V. All rights reserved