Provakar Datta, Department of Physics, University of Connecticut

Probing the Neutron’s Internal Structure via High-Q2 Electromagnetic Form Factor Measurements

The electromagnetic form factors (EMFFs) are among the most basic observables sensitive to the nucleon’s internal structure. Knowing their values with high precision in a wide range of squared four-momentum transfer (Q2) is essential for the advancement of QCD. The high Q ² precision data of the nucleon EMFFs are scarce due to the challenges associated with such measurements. However, the Super BigBite Spectrometer (SBS) collaboration is currently running multiple experiments in Jefferson Lab’s experimental Hall A to precisely measure the proton and neutron EMFFs with unprecedented Q ² reach, which will vastly improve the situation. In this talk, I will give an overview of the SBS high Q ² program with a focus on the SBS-GMn experiment. SBSGMn, the very first SBS experiment, was completed during Oct. 2021 - Feb. 2022 running period to measure the neutron magnetic form factor (GnM) up to Q ² = 13.6 (GeV/c) ² using “ratio” method. I will briefly discuss the underlying theory, measurement technique, associated technical challenges, and present our progress of physics analysis including preliminary data/MC comparisons. I will also show realistic projections of the final uncertainties on GnM, emphasizing the high-Q ² data points.

Dr. Heide Ibrahim, INRS, Canada

Filming ultrafast chemical reactions in real-time – from coherent motion to roaming dynamics

Upon photoexcitation, molecules can undergo different types of transformations such as simple vibrations or rotations, but also migrations, or dissociations. Due to the required combination of ultrafast time-scales and ultra-small length-scales involved, specific tools are required to follow such reactions in real-time. Here, we are using time-resolved Coulomb explosion imaging (CEI) as the ultrafast tool to image such dynamics. With CEI, we can not only image coherent molecular dynamics such as proton migration in acetylene; it also works for various dissociation pathways, even if they occur differently from one molecule to another.

In the formaldehyde molecule, we can see fragments following the direct, conventional dissociation path, as well as fragments deviating from this minimum energy path. So-called roaming fragments or “roamers” explore the potential energy landscape in a statistical manner and were directly captured in real-time, despite the signal’s statistical character. This is possible due to the single-molecule sensitivity of CEI. In addition to the first direct observation of roaming fragments undergoing dynamics, we could show that the onset of roaming occurs actually several orders of magnitude earlier than previously expected. We thus show that CEI provides the means to extract new, unexpected pathways, which would otherwise remain hidden underneath a strong background.

Abhishek Bannerjee, Harvard University

Title: TBA

Prof. Simone Colombo
University of Connecticut

Title: Quantum Metrology with Ultracold Atoms (and Optical Cavities)

Abstract:

In this colloquium, I will introduce the application of atomic, molecular, and optical (known as AMO) physics to the field of quantum metrology. I will show how atoms are used as probes of our universe and how to harness quantum effects to enhance their sensing capabilities.

I will then focus on a specific type of atomic sensor and one of my research interests: optical atomic clocks. State-of-the-art optical atomic clocks achieve mind-boggling stabilities and in many regimes are almost solely limited by quantum noise. Building upon recent results (mine and from other groups), I will illustrate how optical clocks’ performances can be pushed beyond current quantum noise limitations and how they can be/are deployed in the search for new physics and the testing of the fundaments of general relativity. Within this framework, I will finally overview the research activities I am developing at UConn.