Seminar Thursday July 28 – William Davis

Speaker: William Davis
Location: Physics 175
Time: 3:30, July 28, 2015

Characterization and Study of a Medical Linear Accelerator Mounted Mini-Beam Collimator

Abstract: Conventional external beam radiotherapy makes use of uniform beams to deliver a dose of radiation.  This method has proven effective in the treatment of many cancers, but unavoidably deposits dose in healthy tissue as well.  Spatial fractionation techniques seek to minimize the damage to healthy tissue caused by the radiation beam.  Mini-beam radiotherapy is a method of spatial fractionation which makes use of an array of parallel planar beams.  A group at the Saskatchewan Cancer Agency have developed a mini-beam collimator for use with a medical linear accelerator operated at a nominal energy of 6MV.
Various attributes of the mini-beam collimated beam are under study at the Saskatoon Cancer Centre.   The dose distribution and its consistency across a set of medical linear accelerators have been measured and simulated.  Variations in dose due to accelerator settings are being characterized.  The effect of mini-beam irradiation on cells is currently being examined.

Seminar Tuesday July 21 – Reza Behbahani

Speaker: Reza Behbahani
Location: Physics 175
Time: 14 July, 2015, 3:30

Energetic ion beam emission enhancement for short lived radio isotopes (SLRs) production by using a low energy dense plasma focus device.

Abstract: ​Short lived radioisotopes (SLR) such as 13N, 17F, 18F, 15O, and 11C have been produced through either external solid (exogenous method) or high atomic number gas (endogenous method) targets. These radioisotopes are positron emitter used for positron emission tomography (PET) imaging. Positron emission tomography is an imaging technique that shows the distribution of positron-emitting nuclides in a patient’s body. SLRs (10 min. to 100 min. half lifetime) must be produced in proximity of treatment or diagnostic facilities .Cyclotron is often used for this purpose. A new Dense Plasma Focus machine ( DPF) is being develop at University of Saskatchewan to produce Nitrogen-13 radioisotope. Nitrogen-13 is used to tag ammonia molecules for PET myocardial perfusion imaging. Dense Plasma Focus machine ( DPF) can generate high energetic ion with suitable flux to produce Nitrogen-13 through the 12C(d, n)13N nuclear reaction. In this presentation I am going to introduce DPF machine, progress of the project and the future approach.

Seminar Tuesday July 14 – Niloofar Zarifi

Speaker: Niloofar Zarifi
Location: Physics 175
Time: 14 July, 2015, 3:30

Computational approaches and structural prediction of high pressure molecular solids

Abstract: ​My talk is divided into two main sections. The first part is to examine the performance and reliability of several current density functionals in the description of the electronic structures of small band gap materials and strongly correlated systems. To accomplish the first goal, we employed density functional theory (DFT) and several correlation corrected functionals to investigate the properties of solid AlH3 and EuO at high pressure. The second objective of this investigation is to predict energetically stable crystalline structures at high pressure. The reliability and relative efficiency of two recently proposed structure prediction methods, viz, Particle Swarm Optimization (PSO) and the Genetic Algorithm (GA) were critically examined. We applied the techniques to two separate systems. The first system is solid CS2 which was recently found to be a superconductor with a critical temperature of 6 K from 60 – 120 GPa and second system is prediction of plausible crystalline structures of Xe-halides at high pressure.

Seminar Tuesday July 7 – Greg Tomney

Speaker: Greg Tomney
Location: Physics 175
Time: 7 July, 2015, 3:30

Magnetic Saturation of the Iron Core in the STOR-M Tokamak

Abstract: In the field of controlled nuclear fusion, the tokamak (a toroidal vacuum chamber which uses magnets to confine and heat plasma to fusion temperatures/ pressures) is one of the most promising candidates for a fusion reactor. The spherical tokamak (ST) has been a good candidate for tokamak reactor designs since its inception in the 1980s. The design boasts economic benefits that are especially important for labs looking to build tokamaks for research as the ST cuts down on the cost of the large magnets needed to establish the strong magnetic fields in a tokamak. One of the problems with the ST design is less space for a centre solenoid which can be used to induce plasma current. Using the iron-core tokamak STOR-M we are able to study plasma performance as the core becomes increasingly magnetized. This effect is of some concern to the tokamak community as it becomes more pronounced as the size of the tokamak core region (the hole in the tokamak torus) decreases.