Gamma ray / characteristic X ray coded aperture imaging with energy resolving hybrid pixel detector
Anton Tremsin, Research Physicist
Space Sciences Laboratory
Applications for Fall 2025 are closed for this project.
We want to continue to show feasibility (demonstrate in the lab) a sensing/imaging approach we hope to propose in the future on a low-cost, space-based platform (cubesat, small sat, rocket). This effort supports proof of concept using mostly what we have available in the lab.
Timepix/Medipix is a hybrid pixel detector (consist of the sensor and the ASIC).
A sensor (Si, CdTe, etc.) is bump bonded to the ASIC, a potential is applied, a particle interacts within the sensor volume, creates charge, and is sensed by the ASIC.
The ASIC measures an event time of arrival, the time over threshold (a proxy for charge/energy), and the associated pixel address of the event. This occurs for each and every pixel on the device.
A coded aperture mask has an array of redundant pinholes. The mask is opaque to photons (up to a certain energy), so each pinhole allows photons to pass freely. (Higher energy photons will create secondaries in the mask.)
The mask is placed in front of the detector, an isotope source (or characteristic xrays from a source) generate something to detect (and hopefully image).
The detector requires careful calibration. Data cubes are acquired and "normalized". Photon events can be centroided. Ultimately the corrected (and maybe centroided) data can then be reconstructed to form an image of the source.
Different computational reconstruction methods exist to explore as well.
Future improvements would include moving software routines to firmware/GPU/TPU and integrating the associated H/W, electronics, etc. and start to think more about power/bandwidth budgets, etc. for a mission concept.
Role: -Read appropriate literature
-Create plan for the semester
-Setup associated hardware (may need to design, build, etc. support hardware?)
-Data acquisition
-Analyze data
-Develop/tune S/W to prepare data (e.g. data calibration, cluster sorting, centroiding, energy conversion, etc.)
-Develop S/W to perform reconstructions and analyze/compare (inverse methods, different learning methods)
-If time allows, start to define bounds/limitations of approach (e.g. angular/spectral resolving limitations, etc.)
-Create project summary, lessons learned
Qualifications: -Interest in space H/W, detectors, computational methods, data processing, physics of whats involved.
-Likely someone studying (in no particular order): physics, EE/CS, other engineering- ME, AE, applied math, astro
-Comfortable utilizing python, or other language(s), and/or eager to learn
-Good at turning screws, bolts, etc.
-Ability to clearly communicate, ask questions, work respectfully with other student(s) and staff
-Ability to return for additional semesters are preferred
-Candidates need to have open "blocks" of time in their schedule they can commit for this URAP opportunity. As we are an offsite location, some time commitment is required for traveling to/from the lab. (An hour here-or-there does not work).
-Some of the S/W tasks can be worked on offsite (at home,etc.)
-Total hour commitment is negotiable, though 6-12 hours per week is likely ideal.
Day-to-day supervisor for this project: Travis Curtis, Staff Researcher
Hours: to be negotiated
Off-Campus Research Site: Space Science Laboratory 7 Gauss Way Berkeley, CA. 94720 (Easily accessible by taking the H-bus.)
Related website: https://www.ssl.berkeley.edu/
Engineering, Design & Technologies Mathematical and Physical Sciences