Public defense of the doctoral dissertation will be held on June 9th 2007 at 12 o'clock in auditorium D101 of the Department of Physical Sciences of the University of Helsinki, Finland.
VTT's MultiTrans programme enables modelling of radiation transport in arbitrary 3D geometry. The computational geometry is generated directly from a CAD-model, which makes it possible to use modern design tools. The computational grid is tree-structured and self-adaptive at the material boundaries, where the mesh automatically becomes the finest. With this method, even a complicated geometry can be represented in fine detail without an excessive number of grid points compared to equidistant mesh.
The tree-structure makes it possible to always find a coarser representation for the problem. This enables the use of multigrid method in iterative solution of the transport equation: the problem can be quickly solved on a much coarser grid, and this solution can then be used as an initial guess for the solution on finer grids. Multigrid method accelerates the iterative solution significantly. In addition, the tree structure leads to a smaller number of grid points, which also makes the iterative solution faster. To VTT's knowledge, this is the first application of the tree-multigrid technique to the radiation transport modelling.
The MultiTrans programme has been tested for different radiotherapy, such as boron neutron capture therapy (BNCT) given at VTT's nuclear research reactor, and for reactor physics applications. So far, the MultiTrans programme has been in use only at VTT.
When high accuracy is required, the simplified spherical harmonics approximation of the radiation transport used in MultiTrans has, in some cases, turned out to be problematic. More accurate methods will be studied further.
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University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
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