February 1, 2019

Sydney Andrews:The Life and Death of Masive Starts

Mankind has long observed the stars in the night sky. New stars are continually being born, living their lives, and dying; returning themselves to the cosmic circle of life. The lives the stars lead depend on how large they are. Our sun is a relatively average and low mass star. However, massive stars are less common and live more dramatic lives. This talk will follow the life of a massive star: from formation, through it's main phases of life, it's dramatic and explosive death as a core-collapse supernova, and what remains of the star in the cosmos.

Sydney Andrews is a Graduate Research Assistant at Stony Brook University. She has won the 2018 Department of Energy Computational Science Graduate Fellowship (DOE CSGF) for work in computational astrophysics and core-collapse supernovae. A Los Alamos native, she has also held student research appointments at Los Alamos National Laboratory (2014-2017).

February 22, 2019

Abhay Deshpande: In search for the (real) origin of mass of the visible universe and spin of the proton: a journey full of surprises and puzzles

Protons and neutrons have two fundamental properties: their mass and spin. We know what their values are since ~1930’s. Based on experiments performed at SLAC (Stanford Linear Accelerator Center) in the mid 1960’s we know that protons (and neutrons) are made up of other smaller, “invisible" particles called quarks. Quarks are bound inside the protons tightly by gluons. It is hence natural to expect that the quarks (and gluons) are responsible for imparting the mass and spin to the protons (and neutrons). However, we have learnt quite surprisingly that quarks themselves only contribute less than 0.1% of the mass of the proton and 20% of its spin. Gluons are massless, but contribute another 20% to the spin of the proton. Investigations over the past 50+ years have yet to solved this essential mystery of how all this fits in to the Standard Model of Physics: Essentially, we do not understand where the mass of the protons, neutrons and the nuclei (and hence the universe) comes from, neither do we understand where the spin of protons and neutrons comes from. In this talk we will go on a fast journey over the past four decades of our investigations and visit the puzzles, surprises, that we faced. Finally I will present a ray of hope and talk about what it will take to solve this persistent puzzle, a future collider we hope to build.

Abhay Deshpande is a professor of physics in the department of physics and astronomy at Stony Brook University. His research focuses on understanding the structure of the smallest particles found in nature: the protons and neutrons that make up the entire visible universe in the framework of Quantum Chromodynamics (QCD). To understand their structure Abhay has performed experiments at the European Nuclear and Particle Physics Laboratory (CERN) in Geneva, the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory, and the Thomas Jefferson Accelerator Facility (Jefferson Lab) located in Newport News, VA. He is the director of the Center for Frontiers in Nuclear Science (CFNS) recently setup jointly by Stony Brook University and Brookhaven to help realize the future US Electron Ion Collider (EIC). He has served as the founding chair of the international EIC Users Group interested in working at the future EIC. Abhay did his Ph.D. at Yale University in 1995, was a post doctoral fellow at CERN, a RIKEN Fellow at the RIKEN-BNL Research Center. He joined the department of physics and astronomy at Stony Brook University in 2004.

March 29, 2019

Thomas Weinacht: Light, color and vision: how we see and interpret the world around us

In this talk I will discuss the basic physics of how vision works, and how we perceive the world around us, including basic ideas about the nature of light, photography, depth perception, primary colors and moving images.

Thomas Weinacht is a professor in the department of physics and astronomy at Stony Brook University. His group’s research centers upon measuring and controlling dynamics in atomic and molecular systems using shaped ultrafast laser pulses. The group is working to develop new time resolved spectroscopies to follow the quantum dynamics of electrons and nuclei in molecular systems. Their approach is to work on experiments of varying complexity, and to understand our experimental results through both simple intuitive models and detailed calculations.

April 26, 2019

Jan C. Bernauer: The Proton Radis Puzzle

Protons are one of the basic building blocks of the matter around us. But 100 years after their discovery, we still don't understand some of their basic properties very well. The proton's root-mean-square charge radius, describing the extend of the proton's charge distribution --in other words, it's size-- is one of them. In 2010, two experiments presented new results for the radius, using fundamentally different techniques. One measured the energy levels of muonic hydrogen, and extracted the radius from the so called Lamb-shift. The other employed the MAMI electron accelerator to scatter electrons off a hydrogen target to measure the shape of the charge distribution. Their results are about 4% different, about 7 times the experimental uncertainty. Since then, this proton radius puzzle has been the focus of many experimental and theoretical work around the world, but it remains unresolved so far. In the talk, we will go over the history of the puzzle and the experimental methods to measure the radius. I will then discuss the current state, ongoing and future experiments and possible resolutions.

Jan C. Bernauer is an assistant professor of physics in the department of physics and astronomy at Stony Brook University in a joined position with the Riken BNL Research Center. He is mainly interested in precision measurements to study the properties of protons and neutrons, as well as to search for new physics beyond the Standard Model. He studied in Mainz and finished his Ph.D. in 2010, measuring the proton form factors and radius using the MAMI accelerator. He then joined MIT as a postdoc and later research scientist, working on the OLYMPUS experiments at DESY and the DarkLight experiment at Jefferson Lab. He joined the department in 2018.