Validating the 3D Position Calibration of the COSI Germanium sensors
Jesse Hart (He/His/Him) (2028) | Physics BA
Jesse Hart is a SURF L&S scholarship recipient and a third-year Physics major. Working at the intersection of astrophysics and scientific instrumentation, Jesse is helping validate a calibration method for the germanium detectors aboard the NASA Compton Spectrometer and Imager (COSI), a satellite mission set to launch in 2027. By improving how the detectors determine the position of incoming gamma rays, his research will help ensure the mission collects reliable data to better understand some of the universe’s most energetic events, including short gamma-ray bursts associated with neutron star mergers.
What made you choose this research project? How did your interest in your research topic emerge?
I chose this topic because of its position at the intersection of instrumentation and astrophysics, my current primary interests. I’m especially drawn to how detector work enables real scientific discovery. In this case, the project focuses on validating a depth calibration method for a gamma-ray detector, which is a critical step in making sure the data we collect can actually be trusted and used for analysis.The gamma-ray detector is a part of a NASA Small Explorer Compton Spectrometer and Imager (COSI) satellite mission that will launch into low Earth orbit in 2027.
What is your project about (in simple terms)? How does it relate to issues or ideas you have been studying in your coursework?
In simple terms, my project is about making sure a detector can correctly determine where a gamma-ray interaction happens. This is important because accurate position information is necessary to reconstruct where the gamma rays originated. I’m working on validating an existing method that estimates this positional depth information using real experimental data collected in a controlled setup. If the method works well, it improves the overall performance of the detector.
The Compton Spectrometer and Imager (COSI) uses techniques such as Compton scattering inside Germanium detectors to reconstruct the gamma-ray interactions. I was first introduced to Compton scattering in my introductory physics courses before transferring to UC Berkeley, and that early exposure helped spark my interest in scientific instrumentation and detector physics. I have since deepened my understanding through coursework in computational physics, electromagnetism, and quantum mechanics. That progression led me to become interested in how physical interactions are translated into measurable signals and analyzed in practice, which directly connects to this project.
What are you most excited about this summer? Will your research entail travel, access to special collections, or experiments?
I’m most excited about working directly with real detector data and contributing to a project that has a clear connection to an active research effort. It is exciting to know that the work I’m doing could support future scientific observations.
My work will mainly involve data analysis and computational work rather than travel, but I’ll be working closely with researchers and gaining hands-on experience with special dataset collections and the types of tools and methods used in experimental physics. I’m also excited to follow the progress of the COSI mission and see it move toward launching.
What do you hope to learn from this experience? What would success look like for you?
I hope to deepen my understanding of how detectors actually work in practice, especially how raw signals are processed and turned into meaningful physical information. I also want to improve my skills in data analysis, statistical modeling, and communicating technical results clearly.
For me, success would mean being able to rigorously evaluate the calibration method as well as being able to clearly communicate the results both in a technical way and in a way that could be understood by the general public.
What challenges do you anticipate confronting?
One challenge I anticipate is working with real experimental data, which is often more complex than textbook examples or simulations. Understanding sources of uncertainty and distinguishing signals from noise can be challenging. Another challenge is making sure that I communicate my results clearly, especially when the work involves technical details. Learning how to present complex ideas in a clear and accurate manner is something that I am working on.
What do you hope comes out of this research? What impact do you hope your research will have?
I hope this research contributes to improving the reliability of COSI by validating the method used to determine interaction depth. Even small improvements in calibration can have a meaningful impact on the quality of the data and the conclusions drawn from it. I’m interested in being a part of the process that enables scientific discovery. Projects like this help ensure that when scientists analyze data from instruments, they can trust the results. Being able to contribute to that foundation is something I find very meaningful.