Academic Calendar

All future

Tuesday, December 19th 2017
11:00 am:
Thesis Defense in 110 PAN
Speaker: Gordon Stecklein, University of Minnesota
Subject: Generation and Absorption of Pure Spin Currents Using Graphene Nonlocal Spin Valves
This is the public portion of Mr. Stecklein's thesis defense. His advisor is Paul Crowell.

In this talk I will discuss the fabrication and measurement of nanoscale devices in which a spin-polarized electrical current is used to inject spins into graphene, which then diffuse. We demonstrate the electrical detection of spins in graphene devices with micron-scale spin diffusion lengths and analyze how the spin lifetime and spin diffusion lengths are affected by electrostatic gating. The spin current absorbed by an adjacent ferromagnet is calculated and demonstrated to increase as the electrical conductance of the graphene/ferromagnet interface is improved. Quantitative modeling, including a finite element model of the spatial distribution of spins and the effect of a thin metallic island, indicates that the absorbed spin current is nearing the regime necessary for future technological applications.

1:00 pm:
Thesis Defense in Tate 201-20
Speaker: Mark Mackey, University of Minnesota
Subject: End-Effects in Diblock Copolymer Melts
This is the the public portion of Mr. Mackey's MS Thesis defense.

Friday, December 29th 2017
2:00 pm:
Thesis Defense in M10 library
Speaker: Pamela Sooriyan, University of Minnesota
Subject: Dose enhancement in bone due to the 16O(γ,n)15O reaction
This is the public portion of Ms. Sooriyan's thesis defense. Her thesis advisor is John Broadhurst.

External beam radiation therapy is the most common option in the treatment of malignant tumors. It mainly uses Bremsstrahlung photons produced when highly accelerated electrons are incident on a target of high atomic number, gamma rays produced by radionuclides, and electrons beams. In the mega-voltage range of photon beams, the dose absorbed by the tumor is primarily by the incident photons losing their energy to the tissues of the tumor by Compton scattering and pair production. Enhancing photonuclear disintegrations offers the possibility of increasing the dose to the tumor (for the same delivered dose) by introducing secondary charged particles in the irradiated region.
The dose delivered by secondary charged particles from the 16O(γ,n)15O reaction in bone was measured in an attempt to explore the feasibility of local dose enhancement due to photo nuclear disintegrations.

For an externally delivered dose of 13 Gray, the additional dose due to positrons was measured to be 0.18 mGray in bone and 0.025 mGray in tissue, using a photon beam that had about 1.3% of photons of energy needed to initiate the 16O(γ,n)15O reaction.

Thursday, March 1st 2018
Speaker: Sara Seager, MIT

Wednesday, April 18th 2018
7:00 pm:
Kaufmanis Public Lecture in McNamara Alumni Center
Speaker: Victoria Kaspi, McGill University
Subject: To be announced.

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