Academic Calendar

All future

Wednesday, November 29th 2017
7:00 pm:
Speaker: Philip Kim, Harvard University
Subject: Stacking atomic layers: quest for new materials and physics

Modern electronics has been heavily relied on the technology to confine electrons in the interface layers of semiconductors. In recent years, scientists discovered that various atomically thin materials including graphene, a single atomic carbon layer, can be isolated. In these atomically thin materials, quantum physics allows electrons to move only in an effective 2-dimensional (2D) space. By stacking these 2D quantum materials, one can also create atomic-scale heterostructures with a wide variety of electronic and optical properties. I will discuss the creation of new heterostructures based on atomically thin materials and emerging new physics with technological implications therein.

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

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