LLNL scientists assist in building detector to search for elusive dark matter material

Nov 15, 2012 by Anne M Stark
Shown is a side view of the Lawrence Livermore National Laboratory-designed and built copper photomultiplier tube mounting structure, which is a key component of the Large Underground Xenon (LUX) detector, located at the Sanford Underground Research Facility in Lead, S.D.

(Phys.org)—Lawrence Livermore National Laboratory researchers are making key contributions to a physics experiment that will look for one of nature's most elusive particles, "dark matter," using a tank nearly a mile underground beneath the Black Hills of South Dakota.

The Large Underground Xenon (LUX) experiment located at the Sanford Underground Research Facility in Lead, S.D. is the most of its kind to look for dark matter. Thought to comprise more than 80 percent of the mass of the universe, scientists believe dark matter could hold the key to answering some of the most challenging questions facing physicists in the 21st century. So far, however, dark matter has eluded direct detection.

LLNL researchers have been involved in the LUX experiment since 2008.

"We at LLNL initially got involved in LUX because of the natural technological overlap with our own nonproliferation development programs," said Adam Bernstein, who leads the Advanced Detectors Group in LLNL's Physics Division.

"It's very exciting to reflect that as a result, we are now part of a world-class team that stands an excellent chance of being the first to directly and unambiguously measure cosmological dark matter in an earthly detector."

The cutting-edge science and technology of rare event detection represented by LUX is of direct interest for LLNL and U.S. nonproliferation, arms control and nuclear security missions, Bernstein noted.

Shown is a top-down view of the Lawrence Livermore National Laboratory-designed and built copper photomultiplier tube mounting structure, which is a key component of the LUX detector.

In particular, cryogenic noble liquid detectors of this kind may allow for improved, smaller footprint reactor antineutrino monitoring systems, with application to the reactor safeguards regime.

Xenon and argon detectors of very similar design also have excellent neutron and gamma ray detection and discrimination properties, and may assist with missions related to the timely discovery and characterization of fissile materials in arms control and search contexts.

LLNL scientists and technicians have made important contributions to LUX.

Lab staff physicist Peter Sorensen has directed the LUX Analysis Working Group, spent months at the site helping to install the detector, and has written numerous peer-reviewed articles on how to perform searches for a range of dark matter candidates using LUX and related detectors.

Fellow LLNL staff physicist Kareem Kazkaz is the author of the LUX detector simulation package, known as LUXSIM, and has directed the Simulations Working Group for the project. The simulation software embodied in LUXSIM is uniquely well suited for low background detectors of this kind, and has been picked up by other users in the dark matter and nonproliferation communities.

LLNL technicians John Bower and Dennis Carr (who is now retired) both played key roles in the manufacture and installation of elements of the LUX detector, including building the precision-machined copper photo multiplier tube mounting apparatus. Lab safety engineer Gerry Mok performed detailed calculations demonstrating the safety of the LUX pressurized and cryogenic systems under a range of possible accident scenarios. His work was important to the successful safety review of the LUX detector.

The Sanford Underground Research Facility (Sanford Lab), located in the former Homestake gold mine, is owned and operated by the South Dakota Science and Technology Authority, with support from the Department of Energy and the DOE's Lawrence Berkeley National Laboratory. The LUX scientific collaboration includes dozens of scientists at 17 research universities and national laboratories in the United States and Europe.

The LUX detector took more than three years to build in a surface facility at the Sanford Lab. In July, a team of researchers, engineers and technicians installed the detector in an excavated cavern 4,850 feet underground. Nearly a mile of solid rock will protect the sensitive experiment from the shower of cosmic radiation that constantly bombards the surface of the earth. Cosmic radiation would drown out faint signals if the detector were on the surface.

LUX also must be protected from the small amounts of natural radiation from the surrounding rock. That's why the detector, which would just fit inside a telephone booth, was lowered into a very large stainless steel tank—20 feet tall by 24 feet in diameter. That tank has now been filled with more than 70,000 gallons of ultra-pure de-ionized water that will shield the detector from gamma radiation and stray neutrons.

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Nanowill
1 / 5 (2) Nov 15, 2012
Waste of effort. A simple proof shows there is no CDM.
Cosmological Holographic Principle shows Universe is almost entirely composed of normal matter. I'll send you a one page overview if requested. Willoakley@earthlink.net
vacuum-mechanics
1 / 5 (2) Nov 15, 2012
The Large Underground Xenon (LUX) experiment located at the Sanford Underground Research Facility in Lead, S.D. is the most sensitive detector of its kind to look for dark matter. Thought to comprise more than 80 percent of the mass of the universe, scientists believe dark matter could hold the key to answering some of the most challenging questions facing physicists in the 21st century. So far, however, dark matter has eluded direct detection.

The problem that dark matter is so difficult to find may be because the wrong misinterpretation that vacuum is empty space! Indeed we can to make a simple scientific indirect prove that vacuum space is not empty, in the same way like neutrino proving. Then it is easy to prove and understand that dark matter is just the manifest of vacuum medium property ….
http://www.vacuum...14〈=en
theon
1 / 5 (2) Nov 16, 2012
Quare fremuerunt gentes et populi meditati sunt inania?
Why do the heathen rage, and the people imagine a vain thing?

We have to get to terms with the fact that CDM works badly at the galactic level, and worse in the Galaxy. It is not needed either, there are enough Herschel cold clouds to account for the full dynamical Galactic matter and missing baryons.
Being bottom-up, how can CDM explain the now confirmed galaxies at redshift z=10?
And SuSy does not appear to work, hence not to deliver a WIMP.

This LUX search will go like all the previous ones; it will move the goalposts.
Nanowill
1 / 5 (1) Nov 17, 2012
NO CDM, Proof: WMAP gives a Universe mass density ρ ~ 9.9 x 10^-27kg/m3. A radius R = 1.301x10^26m, and observable volume V = (4/3)πR^3 = 9.224x10^78m^3 give a Universe mass of 9.132x10^52kg. If mostly due to electrons and protons at 1.673x10^-27kg, there are 5.46 x 10^79 of both electrons and protons in the Universe, matter being electrically neutral. The electron rest mass 0.511MeV is rotationally relativistic by alpha ~1/137, so the effective mass in the rotating frame is 70.02MeV, and of wavelength 1.77x10^-14m. The number of electron wavelengths that just fit into the Universe radius is 1.301x10^26/1.77x10^-14 = 7.35x10^39. The square of this number is 5.40x10^79, which is the number of electrons in the Universe as calculated above, within WMAP error. (9.8 x 10^-27kg/m3 is a closer fit). Hence the Universe is a quantum construct.
Unless this is an incredible coincidence, essentially the entire Universe mass is due to electrons and protons, i.e. there are no CDM particles.
Job001
1 / 5 (1) Nov 19, 2012
NO CDM, Proof: Nice calculation, yet neglecting the accumulated relativistic energy of light and simple particles since the big bang of which a negligible amount can be observed. Relativistic energy has to be less negligible than typically assumed. A better assumption is physicists have either made the wrong assumptions or haven't done the integral radiation calculation.
After all, a particle moving near the speed of light can be a hundred times more massive and yet it's just a simple particle like an electron. Relativistic photons and particles move away unobserved. Are you partially correct yet neglecting the relativistic energy hidden in simple particles and photons themselves containing more mass than calculated with standard simple mass calculations?

A simple observation: More relativistic accelerators like black hole jets and stars with photons and relativistic particles exists than imagined before a few years ago and surely this radiation mass has not been reconciled.