Scientists reveal plans for largest dark matter detector in the world

While the idea of dark matter has long fascinated scientists and amateur astronomers alike, no one has ever come close to understanding it, much less detecting and containing it. However, an international physics collaboration has planned an experiment to change that.

The second generation Large Underground Xenon experiment, called the LUX-ZEPLIN (LZ), is being led by University of California, Santa Barbara physicists.

The team will construct the largest dark matter detector in the world at a site a below ground in the Black Hills of South Dakota.

Since it was first hypothesized in 1932, dark matter has eluded characterisation. It makes up most of the matter in the universe, is void of light and affects the gravity of galaxies, but beyond that little else is known.

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Scientists have theorized that dark matter is comprised of weakly interacting massive particles (WIMPS). To detect dark matter, scientists will focus on finding WIMPS.

The LZ detector will contain seven tonnes of active liquid xenon, a chemical element naturally occurring in small amounts in Earth’s atmosphere.

When WIMPS collide with xenon atoms, they produce photons (light) and electrons, and these signals are precisely mapped by measuring their brightness.

However, these WIMP collisions do not happen frequently. Scientists hope that with this new, highly sensitive technology they will be able to record up to five events in three years.

“Our dream would be after about a year’s worth of data that there would be a signal of dark matter,” said UC Santa Barbara physics professor Harry Nelson, the leader of the LZ collaboration. “That’s how rare a dark matter event is.”

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The assembly of the detector is no easy task, either. In addition to the liquid xenon, the outer part will contain 27 tonnes of scintillator liquid, a type of oil that becomes illuminated in the presence of neutrons and gamma rays. The detector will then be contained within a tank of water.

The experiment must be conducted deep underground to keep the detectors from exposure to cosmic rays, but radiation from the decay of elements in the detectors’ surroundings can still affect the accuracy of the results. The LZ detector will be equipped with extra layers of particle detection outside the liquid xenon to ensure reliability.

The LZ project will be funded by the Department of Energy and the National Science Foundation. Equipment building could begin in 2015, based on when the funding becomes available, with experiment operations beginning in 2018.

Perhaps by LZ’s conclusion, scientists will have shed some light on the seemingly unsolvable mystery of dark matter.


First body image courtesy of Matthew Kapust, Sanford Lab, second body image courtesy of the UC Santa Barbara Current.


Reusable spacecraft to make space travel more affordable and accessible

Today, space missions and satellite launches take years of planning and hundreds of millions of dollars in expenses. While we certainly benefit from these explorations, their time and cost slows progress.

To increase efficiency, the US Defense Advanced Research Projects Agency (DARPA) is beginning work on a reusable spacecraft that could change the way we think about space travel.

The vehicle, called the Experimental Spaceplane (XS-1), aims to make space exploration faster and more affordable, which will result in more frequent spaceflights.

DARPA has contracted three leading aircraft systems companies to design the spacecraft: The Boeing Company, Masten Space Systems and Northrop Grumman Corporation.

“We chose performers who could prudently integrate existing and up-and-coming technologies and operations, while making XS-1 as reliable, easy-to-use and cost-effective as possible,” explained DARPA program manager Jess Sponable.

“We’re eager to see how their initial designs envision making spaceflight commonplace—with all the potential military, civilian and commercial benefits that capability would provide.”

The XS-1 will fly unmanned at hypersonic speeds to execute its main purpose, deploying satellites into orbit. After releasing the satellites, the body of the spacecraft will return to earth and be readied for its next launch.

For now, goals of the XS-1 mission are more developmental. The program will attempt to fly 10 times in 10 days, reach hypersonic speeds and deploy a small payload into orbit, all while drastically reducing the cost.

To achieve these goals, DARPA will evaluate each company’s designs throughout the process, performing risk assessments and analysing how the technology can be pushed further.

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The companies are also expected to have alternative approaches for both technical aspects and affordability. These high expectations mean that the development of the XS-1 will not be easy, but its systems should be sound.

A final part of the development process is determining how the reusable spacecraft design can be used for military, civilian and commercial purposes.

Indeed, the prospect of this inexpensive vehicle stirs futuristic visions of space tourists exploring the galaxy recreationally, with space travel becoming as accessible as flying in an airplane.

While this use of DARPA’s reusable spacecraft is a ways off, more practical applications are within reach. The XS-1 will increase the number of missions that launch each year with its quick turnaround rate.

Subsequently, the amount of data collected by those missions will increase, giving us a more comprehensive, detailed understanding of space.


Images and video courtesy of DARPA.