Paving the way for LZ

In March, the conceptual design for the LUX ZEPLIN (LZ) experiment was reviewed and approved by the Department of Energy. Today, researchers and engineers are working on advancing the design, bringing them one step closer to construction. 

"We've gone through the first big hurdle and got approval to move forward," said Gil Gilchriese, referring to the Critical Design-1/3a review held in March. The next big hurdle is the CD-2/3b review in Spring 2016. "We're on track and feel pretty good about where we are." Gilchriese is the LZ Project Scientist from Lawrence Berkeley National Laboratory. 

LZ will replace the Large Underground Xenon experiment, the world's most sensitive dark matter detector. Weakly Interacting Massive Particles, or WIMPs, are the leading theoretical candidates for dark matter. LZ, which will hold 10 metric tons of liquid xenon, compared to the nearly 400 kilograms of xenon in LUX, promises to be hundreds of times more sensitive. 

The sheer size of the LZ detector requires advance planning, which started long before LUX was installed. The water tank that holds the LUX detector was designed to accommodate LZ. The big question, however, was whether it could fit down the shaft.   

Like LUX, LZ's detector will be built in a lab at the surface. From there it will travel the same route to the head frame where it will be slung under the cage for a slow descent to the 4850. The project turned to Mechanical Engineer Mike Johnson to design a fixture that would transport the detector, including the protective shield that will surround the actual detector during its descent. The protective shield is the largest dimension so that was what was checked during the test. 

"The important thing with this test was to make sure it would fit in the shaft," Experiment Review Engineer David Taylor said. "It lowered nicely and came back up nicely." A test using a device that will mimic the full-scale weight and size will be done later (the actual detector will weigh about 2.5 tons), Taylor added. 

"We had to show that we would be able to get the detector down the shaft. When you work with our guys, the amount of cooperation is just amazing. They always have the attitude, 'we can do that.' What they did paves the way for the fabrication of the detector."