For decades, the LBNL Semiconductor Detector Lab (SDL) has been at the forefront of advancements in gamma-ray detector technology. Amongst the technologies pioneered at the SDL are double-sided high-purity germanium (HPGe) strip detectors with amorphous germanium (a-Ge) contacts  (Fig. 1). These devices find application in a range of areas including basic science, nuclear security, medical imaging, and gamma-ray astronomy. Using this technology, SDL researchers have designed, developed, and built detectors for multiple instruments for astrophysics projects led by the Space Sciences Laboratory at UC Berkeley . These include the Compton Spectrometer and Imager (COSI) [3-6] and the Gamma-Ray Imager/ Polarimeter for Solar Flares (GRIPS) [7-9], which were successfully flown on balloon missions for NASA.
Currently, the SDL is abuzz with activity as researchers work on the next iteration of the COSI instrument . Fig. 2 shows a diagram of this instrument. This gamma-ray telescope is scheduled for launch in 2025 and will be flown on a spacecraft in low Earth orbit for at least two years. An artist’s rendering of the spacecraft is shown in Fig. 3. The primary objective of the COSI instrument is to explore where the production of heavy elements in the Milky Way occurs. It will also map the distribution of positron-electron annihilations, providing valuable insights into the distribution of antimatter. At the heart of this exciting mission to improve our understanding of our galaxy, and at the heart of the instrument, lie SDL detectors.
NSD’s Joanna Szornel and Mark Amman have recently fabricated the first set of detectors, which are intended for the device prototype. One of these devices is shown in Fig. 1. Soon, they will begin the production of flight detectors for the final instrument.
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