Metal-loaded organic scintillators for neutrino physics

Organic liquid scintillators are used in many neutrino physics experiments of the past and present. In particular for low energy neutrinos when realtime and energy information are required, liquid scintillators have several advantages compared to other technologies. In many cases the organic liquid needs to be loaded with metal to enhance the neutrino signal over background events. Several metal loaded scintillators of the past suffered from chemical and optical instabilities, limiting the performance of these neutrino detectors. Different ways of metal loading are described in the article with a focus on recent techniques providing metal loaded scintillators that can be used under stable conditions for many years even in ton scale experiments. Applications of metal loaded scintillators in neutrino experiments are reviewed and the performance as well as the prospects of different scintillator types are compared.Comment: 46 pages, 5 figure

Production and Properties of the Liquid Scintillators used in the Stereo Reactor Neutrino Experiment

The electron antineutrino spectrum in the Stereo reactor experiment (ILL Grenoble) is measured via the inverse beta decay signals in an organic liquid scintillator. The six target cells of the Stereo detector are filled with about 1800 litres of Gd-loaded liquid scintillator optimised for the requirements of the experiment. These target cells are surrounded by similar cells containing liquid scintillator without the Gd-loading. The development and characteristics of these scintillators are reported. In particular, the transparency, light production and pulse shape discrimination capabilities of the organic liquids are discussed.Comment: 10 pages, 4 figure

Eco-car: A perfect vehicle for technical design teaching?

Design methods and tools are generally best learned and developed experientially [1]. Finding appropriate vehicles for delivering these to students is becoming increasingly challenging, especially when considering only those that will enthuse, intrigue and inspire. This paper traces the development of different eco-car design and build projects which competed in the Shell Eco-Marathon. The cars provided opportunities for experiential learning through a formal learning cycle of CDIO (Conceive, Design, Implement, Operate) or the more traditional understand, explore, create, validate, with both teams developing a functional finished prototype. Lessons learned were applied through the design of a third and fourth eco-car using experimental techniques with bio-composites, combining the knowledge of fibre reinforced composite materials and adhesives with the plywood construction techniques of the two teams. The paper discusses the importance of applying materials and techniques to a real world problem. It will also explore how eco-car and comparing traditional materials and construction techniques with high tech composite materials is an ideal teaching, learning and assessment vehicle for technical design techniques

Novel Opaque Scintillator for Neutrino Detection

There is rising interest in organic scintillators with low scattering length for future neutrino detectors. Therefore, a new scintillator system was developed based on admixtures of paraffin wax in linear alkyl benzene. The transparency and viscosity of this gel-like material can be tuned by temperature adjustment. Whereas it is a colorless transparent liquid at temperatures around 40C it has a milky wax structure below 20C. The production and properties of such a scintillator as well as its advantages compared to transparent liquids are described.Comment: 11 pages, 6 figure

Continuum robot actuation by a single motor per antagonistic tendon pair: Workspace and repeatability analysis [Kontinuumsroboter-Aktuierung mittels eines Motors pro antagonistischen Kabelpaar. Arbeitsraum- und Wiederholgenauigkeitsanalyse]

Kontinuumroboter sind stark im Fokus aktueller medizinrobotischer Forschung. Da die meisten der in der Literatur vorgestellten Systeme jedoch komplexe und große Aktoreinheiten aufweisen, kann das Erstellen eines solchen Systems in aufwendigen, kostenintensiven und sperrigen Aufbauten resultieren, welche ungeeignet für die räumlichen Anforderungen des Einsatzes in medizinischen Szenarien sind. In dieser Arbeit wird ein einfaches, effizientes kontinuumrobotisches System vorgestellt, in welchem ein antagonistisches Paar von Kabelzügen durch einen Servomotor bewegt wird, anstatt jedes Kabel durch einen einzelnen Motor zu treiben. Auf diese Weise kann die Grundfläche der Aktoreinheit klein gehalten werden und die Methode resultiert in einem einfacheren Aufbau. Der resultierende 260 mm lange Roboter mit 9,9 mm Durchmesser erreicht eine Wiederholgenauigkeit von 1,8 % seiner Länge. In zukünftigen Arbeiten dient er als Basis für die Integration von verschiedener Sensormodalitäten in Kontinuumroboter und zur Evaluation von Steueralgorithmen

Development of metal loaded liquid scintillators for future detectors to investigate neutrino properties

Several future neutrino experiments call for metal loaded liquid scintillators for neutrino detection. The challenge in the development of such scintillators is how to dissolve large amounts of the metal in an organic liquid scintillator without degrading the optical properties. A promising new approach is the use of metal ß-diketonates. Different to earlier approaches which resulted in non-stable metal loaded scintillators, long term stability of optical and chemical properties is expected. A method to develop a highly In-loaded liquid scintillator for a future real-time experiment that measures the low energy solar neutrino spectrum via the charged current interaction is investigated. This research includes the synthesis and purification of pure In(acetylacetone)3, optical characterization of scintillator components, theoretical modeling, optimization of the scintillator composition and measurements in a prototype detector. The approach used is motivated by the expected stability and purity which are both basic requirements on such a metal loaded scintillator. The same method is used for the investigation of a Gd-loaded scintillator for a reactor neutrino experiment that aims to measure neutrino mixing parameters. Finally, a further application of this approach could be the fabrication of a Nd-loaded liquid scintillator for a future experiment searching for neutrinoless double ß-decay

Three-dimensional hindfoot alignment measurements based on biplanar radiographs: comparison with standard radiographic measurements

Objective: To establish a hindfoot alignment measurement technique based on low-dose biplanar radiographs and compare with hindfoot alignment measurements on long axial view radiographs, which is the current reference standard. Materials and methods: Long axial view radiographs and low-dose biplanar radiographs of a phantom consisting of a human foot skeleton embedded in acrylic glass (phantom A) and a plastic model of a human foot in three different hindfoot positions (phantoms B1-B3) were imaged in different foot positions (20° internal to 20° external rotation). Two independent readers measured hindfoot alignment on long axial view radiographs and performed 3D hindfoot alignment measurements based on biplanar radiographs on two different occasions. Time for three-dimensional (3D) measurements was determined. Intraclass correlation coefficients (ICC) were calculated. Results: Hindfoot alignment measurements on long axial view radiographs were characterized by a large positional variation, with a range of 14°/13° valgus to 22°/27° varus (reader 1/2 for phantom A), whereas the range of 3D hindfoot alignment measurements was 7.3°/6.0° to 9.0°/10.5° varus (reader 1/2 for phantom A), with a mean and standard deviation of 8.1° ± 0.6/8.7° ± 1.4 respectively. Interobserver agreement was high (ICC = 0.926 for phantom A, and ICC = 0.886 for phantoms B1-B3), and agreement between different readouts was high (ICC = 0.895-0.995 for reader 1, and ICC = 0.987-0.994 for reader 2) for 3D measurements. Mean duration of 3D measurements was 84 ± 15/113 ± 15s for reader 1/2. Conclusion: Three-dimensional hindfoot alignment measurements based on biplanar radiographs were independent of foot positioning during image acquisition and reader independent. In this phantom study, the 3D measurements were substantially more precise than the standard radiographic measurement