Art McDonald
Gordon and Patricia Gray Chair Emeritus
2015 Nobel Physics Laureate
Department of Physics, Engineering Physics and Astronomy, Queen’s University

Abstract

Liquid argon has excellent properties for the detection of Weakly Interacting Massive Particles (WIMPS) as candidates for Dark Matter. Gravitational effects of Dark Matter in our galaxy imply a significant density of WIMP particles if they form a significant fraction of the Dark Matter. It is possible to search for such particles causing nuclear recoils in large underground liquid argon detectors as we move through the galaxy. Interactions from gamma and beta rays can be strongly suppressed due to very different duration of the light emission from such background. A progression of detectors from DEAP to Darkside to ARGO will be discussed that will push the sensitivity for WIMPS by several orders of magnitude, to the point where the sensitivity is limited by background from atmospheric neutrino interactions.

Timbits, coffee, tea will be served in STI A before the colloquium.

Luv-A-K9

Decompress by petting a volunteer therapy dog. Please be sure to thank our guests and volunteers from LUV-A-K9.

Hosts: Departments of Physics and Chemistry

Contact: PhysicsPlus@queensu.ca

Ré Mansbach
Assistant Professor of Physics
Concordia University, Montreal, Quebec, CA

pronouns: they/them/iel ou il

Abstract

Physicists enjoy simplicity; there is a reason that the spherical cow in a vacuum is a running joke. And simplicity can be very important in making progress on complex problems. If there is some way to reduce the number of considerations in a problem from thousands even to hundreds, it is often a much easier problem to solve. But how do you know what's important? There is no one single, straight answer. I will talk today about some of the tactics I take towards problems—in my science, in my career, and in my mental health. I will introduce you to techniques such as multi-scale molecular dynamics simulations, deep learning, and dimensionality reduction, in the context of one of my lab's major areas: the design of small proteins (antimicrobial peptides or AMPs) that can destroy bacteria. I will also describe some of our early results in probing and describing search spaces for AMPs and assessing the molecular properties of an unusual beta-sheet-forming AMP. Along the way, I will describe my own career trajectory and some advice I have for younger scientists from all backgrounds (but spoilers! my favorite piece of advice is to ignore any advice that isn't right for you.)

Timbits, coffee, tea will be served in STI A before the colloquium

Marianne Moore
MIT

Abstract:

The sexaquark, a hypothetical stable and neutral six-quark state, has been recently proposed as a dark matter candidate. Here, I argue it is very unlikely sexaquarks could consistently compose more than a billionth of the dark matter abundance for a wide range of scattering cross sections and annihilation rates. To draw these conclusions, I will connect several topics, including the sexaquark freeze-out abundance, dark matter direct detection constraints, neutrino experiments, and accumulation mechanisms for sexaquarks in the Earth. I will show how the sexaquark cosmology enforces that a large contribution to dark matter is only possible with a similarly large antisexaquark population. This population, however, would leave a stark annihilation signal in a detector such as Super-Kamiokande. I will summarize with how sexaquarks as a large component of the dark matter is incompatible with current observational data.

McDonald Institute seminars bring together experimental and theoretical astroparticle physicists and astronomers. They are held approximately fortnightly, September to November and January to March, and on an ad hoc basis outside of term. They currently take place on Mondays at 2:30 PM in STI 501 and/or on Zoom. Contact Aaron Vincent if you would like to attend through zoom.

Art McDonald
Queen's University

Join us for a free event with our own Dr. Art McDonald. Starting at 7:00pm, Dr. McDonald will give an exciting talk about how we come to learn about the history of the Universe by going deep underground, and how this history comes to rely on various mysterious things like dark matter and neutrinos.

Dr. Art McDonald is the Gordon and Patricia Gray Chair in Particle Astrophysics, emeritus, at Queen's University. He is also a co-recipient of the 2015 Nobel Prize in Physics and the 2016 Breakthrough Prize in Physics for the discovery that neutrinos have mass. 

Event is now closed.

George & Maureen Ewan Lecture Series

This talk is part of the George & Maureen Ewan Lecture Series. Dr. Ewan focused on nuclear physics and sub-atomic research, particularly the solar neutrino problem as a co-founder of the Nobel Prize-winning Sudbury Neutrino Observatory (SNO) experiment. With his work recognized at the highest level, Dr. Ewan pushed ahead with a goal of influencing the next generation of scientists here at Queen’s, remarking that “it is vital that we scientists make our work accessible to the general public.” His wife, Maureen, agreed, saying “his work is so remote from what most people would find comprehensible.” Effective communication skills are vital to successful research. As he put it, scientists have so much of value to share with the world. “As a rule, scientists don’t inform the educated public, there are people who work on exciting experiments who could give very good talks. My dream is to have them come to Queen’s to give lectures on the state of their experiments and especially about their results, and to do it in a way that people without PhDs can understand.”

This is why Dr. Ewan and his wife decided to donate $100,000 to Queen’s to create the George & Maureen Ewan Lecture Series, which will support seminar and lecture programs designed to increase scientific discourse and culture within the Particle Astrophysics community at Queen’s University.

Dr. Ewan’s gift gives the department access to $10,000 a year until the fund is depleted. A $10,000 annual budget will make it possible for the department to look farther afield for guest lecturers and host them for a longer stay. “The idea is to have the guest lecturers stay for a while and spend some quality time with the students, interacting with them and working with them in the labs,” says Dr. Tony Noble, former SNOLAB director and the current Scientific Director of the Arthur B. McDonald Canadian Astroparticle Physics Research Institute.

The McDonald Institute and Queen’s University are very excited about the opportunities offered by The Ewans’ generous endowment, and look forward to organizing public lectures that will benefit researchers in the Physics department, and the wider Queen’s and Kingston communities!

John Schreuders
M Eng, P.Eng

Abstract

We will begin by explaining the design, implementation and testing of the Operational Control Software (OCS) used to control the Space Station Remote Manipulator System (SSRMS) currently deployed on the International Space Station. The talk will cover how requirements were developed along with the underlying architecture for the OCS on the SSRMS and beyond with the Special Purpose Dextrous Manipulator (SPDM or Dexter). Additionally, the talk will walk the audience through how the OCS was tested and ultimately delivered to NASA for launch with the robotic hardware. From there, the talk will briefly expand on the career of John over the years and lead into lessons learned during that time. Specifically, the talk will examine the importance of capturing requirements and strategies to accomplish this. Then, the talk will focus on the need for testing at all levels, from software with a simulated reality to flight hardware testing. Then, the talk will delve into the crucial need for engineers to hone their communication skills throughout their careers.

This speech aims to give the listener a perspective on the career of a professional engineer whose first significant project was sensational: placing a robotic arm on a space station and making it work. From there, the talk will give the audience a quick walk-through of John’s career and his lessons along the way.

Timbits, coffee, tea will be served in STI A before the colloquium.