Germanium detector characterization and calibration for the COSI Gamma-ray Space Satellite
John Tomsick, Research Scientist
Space Sciences Laboratory
Applications for Fall 2025 are closed for this project.
The Compton Spectrometer and Imager (COSI) is a NASA-funded gamma-ray space telescope currently in the calibration and characterization phase at Space Sciences Laboratory (SSL). After launch (anticipated August 2027), COSI will survey the 0.2–5 MeV sky as the most sensitive telescope in history in the energy range of nuclear physics. Astronomy in the COSI energy range is the key to science including Galactic nucleosynthesis and the origin of positrons in our galaxy.
The novel COSI sensitivity is possible due to its high-purity germanium detectors, which have been developed in Berkeley over the past quarter century. The COSI detectors are capable of providing the <1% energy resolution and ~1 mm 3D position resolution needed to enable COSI science – assuming they have been properly characterized and calibrated!
Role: To that end, the COSI team at Space Sciences Lab has openings for new apprentices to assist with the calibration and characterization of our flight detectors. The germanium analysis team at SSL consists of detector enthusiasts including undergraduates, grad students, postdoctoral researchers, electrical engineers, and research scientists. Each URAP will be responsible for their own project under the supervision of a direct mentor. Students will analyze calibration data from germanium detectors operated in the lab at SSL. Depending on the project, students may also use simulation tools to model the detector response and compare it to data.
The concrete learning goals will depend on your interests and the details of your project. However, by the end of the year, you will be able to:
1. write code to perform low-level analysis of germanium detector calibration data in python and/or julia language;
2. develop cut-flow based pipelines to select data that are appropriate for a given analysis project;
3. produce plots to support communication of trends or features in data;
4. describe the physics of X-ray and gamma-ray interactions in matter and of signal generation in semiconductor devices to a non-expert in the field; and
5. make regular audience-appropriate research update presentations to peers and mentors during weekly small-group meetings.
Qualifications: Prerequisites and expectations for this position:
-interest in instrumentation for particle physics and/or astrophysics;
-regular weekly time blocks dedicated to in-person work at Space Sciences Laboratory (10 minute ride from campus on the H shuttle) during business hours, with at least 3 URAP units (9 hours / week);
-growth mindset, openness to constructive feedback, and enthusiasm for learning new skills;
-communication and reliability related to scheduling, even when the semester becomes busy;
-working on a highly collaborative team;
-1 year of introductory physics coursework or equivalent;
-prior programming experience in python, julia, and/or c++; and
In your response, please include the following:
-why you are interested in this position and what you are hoping to get out of it;
-a description of a past research experience, including the big-picture science and the overall goal of the project, and your personal contribution (talk about a class project if no prior research experience, and please include name or contact for your mentor or instructor if available);
-a description of a past coding project in python, julia, or c++, in which you explain the purpose of the project and the functionality of the code you wrote (include github links if available, and please be ready to share an example of your work if invited to interview for this position);
-a brief description of any prior experience with jupyter notebooks, object oriented programming, bash language or command-line tools, ssh and remote servers, git or other version control tools, and/or matplotlib/numpy/pandas python packages (none of this is required, but all of it is helpful for us to know);
-a tentative list of 3+-hour-long time blocks available for in-person research (we do understand that schedules will change as the semester starts up); and
Our group is committed to an inclusive learning and working environment and welcomes applications from all enthusiastic students who meet the prerequisites and are willing to commit to the expectations. We look forward to hearing from you!
Day-to-day supervisor for this project: Dr. Field Rogers, Post-Doc
Hours: 9-11 hrs
Off-Campus Research Site: Off-Campus Research Site at UC Berkeley's Space Sciences Laboratory (SSL). Please take the Hill shuttle from the Hearst mining circle to the top of the hill. SSL is the last stop (~10 min bus ride). Address: 7 Gauss Way, Berkeley, CA 94720.
Related website: https://cosi.ssl.berkeley.edu
Mathematical and Physical Sciences