Design of a wavelength frame multiplication system using acceptance diagrams

The concept of Wavelength Frame Multiplication (WFM) was developed to extend the usable wavelength range on long pulse neutron sources for instruments using pulse shaping choppers. For some instruments, it is combined with a pulse shaping double chopper, which defines a constant wavelength resolution, and a set of frame overlap choppers that prevent spurious neutrons from reaching the detector thus avoiding systematic errors in the calculation of wavelength from time of flight. Due to its complexity, the design of such a system is challenging and there are several criteria that need to be accounted for. In this work, the design of the WFM chopper system for the potential future liquids reflectometer at the European Spallation Source (ESS) is presented, which makes use of acceptance diagrams. They prove to be a powerful tool for understanding the work principle of the system and recognizing potential problems. The authors assume that the presented study can be useful for design or upgrade of further instruments, in particular the ones planned for the ESS.Comment: Published in Nuclear Instruments and Methods in Physics Research, Section

An improved elliptic guide concept for a homogeneous neutron beam without direct line of sight

Ballistic neutron guides are efficient for neutron transport over long distances, and in particular elliptically shaped guides have received much attention lately. However, elliptic neutron guides generally deliver an inhomogeneous divergence distribution when used with a small source, and do not allow kinks or curvature to avoid a direct view from source to sample. In this article, a kinked double-elliptic solution is found for neutron transport to a small sample from a small (virtual) source, as given e.g. for instruments using a pinhole beam extraction with a focusing feeder. A guide consisting of two elliptical parts connected by a linear kinked section is shown by VITESS simulations to deliver a high brilliance transfer as well as a homogeneous divergence distribution while avoiding direct line of sight to the source. It performs better than a recently proposed ellipse-parabola hybrid when used in a ballistic context with a kinked or curved central part. Another recently proposed solution, an analytically determined non-linear focusing guide shape, is applied here for the first time in a kinked and curved ballistic context. The latter is shown to yield comparable results for long wavelength neutrons as the guide design found here, with a larger inhomogeneity in the divergence but higher transmission of thermal neutrons. It needs however a larger (virtual) source and might be more difficult to build in a real instrument

Bi-spectral beam extraction in combination with a focusing feeder

Bi-spectral beam extraction combines neutrons from two different kind of moderators into one beamline, expanding the spectral range and thereby the utilization of an instrument. This idea can be realized by a mirror that reflects long wavelength neutrons from an off-axis colder moderator into a neutron guide aligned with another moderator emitting neutrons with shorter wavelengths which will be transmitted through the mirror. The mirror used in such systems is typically several meters long, which is a severe disadvantage because it reduces the possible length of a focusing device in design concepts requiring a narrow beam at a short distance from the source, as used in many instruments under development for the planned European Spallation Source (ESS). We propose a shortened extraction system consisting of several mirrors, and show that such an extraction system is better suited for combination with a feeder in an eye of the needle design, illustrated here in the context of a possible ESS imaging beamline.Comment: Published in Nuclear Instruments and Methods in Physics Research, Section

Final Report German Work package K7 Simulation Code Development, Help Desk ESS ID SD015DE

The work package K7 Simulationscode Entwicklung, Helpdesk comprised the further development of the Monte Carlo simulation package VITESS for the simulation of neutron scattering experiments, its use to study general questions related to ESS instrumentation in collaboration with the ESS Data Management and Software Center DMSC in Copenhagen and support for users. The package contains now a visualization of instrument and trajectories, the possibility for numerical optimization of instrument parameters and options for parallelization of the simulation for multi core PCs and for computer clusters. Among other improvements, modules to simulate lenses and true elliptical guides have been written, and the monochromator and the detector module have been improved significantly. The graphical user interface and the treatment of events are more user friendly now. For the ESS project, the performance of different guide geometries were compared, different options for extraction systems and guides without direct line of sight developed and optimized, and the effect of gravity and waviness investigated. The work was executed in collaboration with the DMSC. Most of the results have been published already. Apart from direct support for some users, user support was realized by completing and improving the documentation, updating the internet site, setting up a Facebook account and a new email lis

Are iSchools’ more adaptable than library schools?: Analysis of lis student engagement in programmatic changes and improvements

The iSchools organization and its 65 member schools frequently reference their roles and responsibilities as leaders in information education. With the iSchools’ commitment to advance the information field (iField) through collaborative academic and research endeavors, it would logically follow that individual iSchool constituents are engaged in promoting improvements to their own educational programs, thus strengthening the future of the iField. This poster examines how iSchools and non-iSchools engage their master’s student constituents in implementing programmatic changes and improvements to their library and information science (LIS) degree program(s). The results of a content analysis of 15 American Library Association (ALA) accreditation self-study documents were compared based on iSchool membership status to determine whether iSchools were more likely to implement programmatic changes and improvements based on student engagement than non-iSchools. Our results revealed little difference between how iSchools and non-iSchools use LIS student engagement to implement programmatic changes and improvements

Bioart et bioéthique. Compte-rendu de Bioart : transformations du vivant, sous la direction d’Ernestine Daubner et Louise Poissant

Compte-rendu / ReviewÀ travers des exemples d’œuvres bioartistiques et des réflexions sur celles-ci, l’ouvrage collectif Bioart : transformations du vivant met en exergue l’intérêt de cette approche artistique pour soulever les enjeux éthiques liés au vivant, aux sciences et à l’art en lui-même.Through examples of bioartistic works and reflections on these, the edited collection Bioart : transformations du vivant highlights the importance of this artistic approach to raising ethical issues related to life, science and the art in itself

The dependence of the gravity effect in elliptic neutron guides on the source size

Elliptic neutron guides are expected to be widely used for construction of long neutron beamlines at the future European Spallation Source and other facilities due to their superiour transmission properties compared to conventional straight guides. At the same time, neutrons traveling long distances are subject to the action of gravity that can significantly modify their flight paths. In this work, the influence of gravity on a neutron beam propagating through elliptic guides is studied for the first time in a systematic way with Monte Carlo simulations. It is shown that gravity leads to significant distortions of the phase space during propagation through long elliptic guides, but this effect can be recovered by a sufficiently large source size. The results of this analysis should be taken into account during design of long neutron instruments at the ESS and other facilities

Analysis of LIS student engagement in systematic program planning: preliminary results

Systematic program planning is an approach that facilitates continuous higher education improvements through evidence-based, data-driven decision-making that includes the program’s constituencies. Library and information science (LIS) education master’s degree programs are required by the American Library Association to demonstrate that their constituents are engaged throughout their ongoing, broad-based systematic planning processes. Minimal research exists on how programs engage their constituents in systematic planning and how responsive programs are to their constituents. This study examines how LIS programs engage an essential constituency, students. A content analysis of 15 accreditation self-study documents was conducted to understand what methods programs use to engage students, how frequently and consistently these methods are used, and what types of changes and improvements were implemented based on student engagement. This paper reports our preliminary findings, which will be useful to educational programs seeking to enhance their systematic planning processes and make their constituent engagement efforts more fruitful

La pedagogía hospitalaria frente a un niño con pronóstico fatal. Reflexiones en torno a la necesidad de una formación profesional específica

Este artículo se centra en la figura del pedagogo hospitalario frente al acompañamiento del niño en fase terminal. Su rol, como profesional de la educación, se canaliza dentro de un equipo multiprofesional en el apoyo que presta tanto al paciente pediátrico, como a su familia y al resto de los profesionales involucrados en su atención, con el objetivo de afrontar el impacto derivado de una enfermedad con pronóstico fatal. Para que este apoyo sea efectivo es necesario, a su vez, que el profesional de la educación cuente con una formación específica en este ámbito. Presentamos aquí algunas pautas de actuación y reflexiones en torno a este tema

Computer simulation tests of optimized neutron powder diffractometer configurations

Recent work has developed a new mathematical approach to optimally choose beam elements for constant wavelength neutron powder diffractometers. This article compares Monte Carlo computer simulations of existing instruments with simulations of instruments using configurations chosen using the new approach. The simulations show that large performance improvements over current best practice are possible. The tests here are performed on instruments optimized for samples with a cubic structure which differs from the optimization for triclinic structure samples. A novel primary spectrometer design is discussed and simulation tests show that it performs as expected and allows a single instrument to operate flexibly over a wide range of measurement resolutio