In 1933, Fritz Zwicky realized that most of the matter in the Coma galaxy cluster was invisible. This finding launched a decades-long search for dark matter. Observation after observation has confirmed that this mysterious matter must exist and in fact makes up about a quarter of our universe. But we have yet to identify its specific nature.
The search for WIMPs
A leading hypothesis is that dark matter is composed of Weakly Interacting Massive Particles, or WIMPs. LUX-ZEPLIN (LZ) scientists will look for these particles by searching for evidence of WIMPs colliding with xenon nuclei inside the LZ detector, installed 4850 feet underground in South Dakota's Sanford Underground Research Facility (SURF). The detector is designed to hold 10 metric tonnes of liquid xenon, providing plenty of target atoms for WIMPs to bump into.
From design and fabrication to commissioning and data analysis
The LZ group at SLAC, which includes several KIPAC members, has played a major role in the design and fabrication of the experiment, including developing a unique test platform at SLAC used to prototype and enhance the performance of the LZ detector. The platform will continue to serve as a research and development tool for LZ upgrades and future xenon-based experiments. The SLAC LZ group is also responsible for separating radioactive krypton from the xenon for the detector, since radio-pure xenon is needed in concert with adequate shielding to ensure that the experiment can see the very faint signal of a dark matter particle among the noise from natural radiation sources.
The experiment will start operations in 2020, and the SLAC LZ group is transitioning to commissioning and data analysis, with first physics results expected some time in 2021.
For more information about LZ and KIPAC's role in the experiment, see SLAC's Lux-Zeplin page.