Technique to hunt dark matter could search for planets

An astrophysics technique used to search for "dark matter" may prove valuable in finding planets orbiting suns near the center of our galaxy. That is the view of Laboratory scientists David Bennett and Sun Hong Rhie in a paper for the Astrophysical Journal.
Bennett is part of an international team that is searching for dark matter: nonvisible astrophysical objects-such as black holes, white dwarfs, brown dwarfs, and neutron stars-that are estimated to account for 90% of gravitational mass in our galaxy. Rhie is an expert on theoretical aspects of gravitational lensing by double stars and planetary systems.
In hunting for dark matter, astrophysicists use a method known as microlensing, in which gravity from a large dark object passing in front of a distant star makes the light from that star appear brighter for a time. This change in brightness can be graphed in the form of a light curve, typically a bell shape.
If the same search technique is oriented toward the center "bulge" of our galaxy, Bennett and Rhie say, faint stars could be used to microlens more distant and brighter stars. A planet associated with the faint star could then be detected within the resulting light curve. The planet would appear as a brief modulation of the bell-shaped curve.
The work by Livermore astrophysicists shows that an ambitious microlensing program could detect planets ranging from Jupiter down to the mass of less than ten Earths. While there are several other techniques for finding planets, microlensing appears to be the only ground-based technique that is sensitive to small planets.
Contact: David Bennett (510) 423-0656 (bennett3@llnl.gov) or Sun Hong Rhie (510) 423-0660 (sunhong2igpp.llnl.gov).


Livermore provides spectrometer to Poland

Polish border guards are in a better position to do on-the-spot analysis of suspicious materials entering or leaving their country, thanks to a portable gamma-ray spectrometer the Laboratory has provided by way of the Department of Energy and Department of State.
Before delivery of the device in June, the only way Polish border guards could analyze suspicious materials was by sending them off to the Polish Central Lab. At an international forensics conference last fall, the director of the Polish Central Lab voiced the need for a portable system, noting more than 100 border incidents involving suspicious materials in 1995.
The surplus spectrometer was provided by the Laboratory's Emergency Preparedness and Response Division, a unit of the Nonproliferation, Arms Control, and International Security directorate. In addition to tracking and analyzing materials at Polish border crossings, the spectrometer will be used for radiological monitoring.
Contact: Tom Smith (510) 422-8252 (smith77@llnl.gov).

Portable treatment system promises cleanup savings

Automated, portable groundwater treatment facilities developed by Laboratory scientists promise to save time and millions of dollars in environmental cleanup costs. Spurring development of the portable treatment units is cleanup of groundwater beneath the Livermore site. Groundwater contamination is primarily volatile organic compounds largely left over from the time when the site was a naval air training station. There are five stationary treatment facilities currently in operation at the Livermore site, treating water pumped from 27 extraction wells.
Through geologic and geophysical analysis of subsurface conditions and the use of computer models, scientists can estimate the optimum locations for extraction wells that connect to surface treatment facilities. Because those locations change over the course of cleanup operations, the versatility of the new portable units will allow Livermore scientists to attack specific areas of contamination as the cleanup proceeds-at lower costs for the facility, piping, and manpower (for more information see S&TR Jan./Feb. 1996 and May 1996).
Laboratory remediation experts expect to save more than $10 million with the new portable facilities, which will substitute for previously planned stationary treatment facilities. The portable treatment approach is also expected to speed cleanup by allowing remediation experts to move the treatment systems easily to different locations to most efficiently remove the pollution.
Contact: Ed Folsom (510) 422-0389 (folsom1@llnl.gov).

Lab acheives chip production breakthroughs

Two breakthroughs by Laboratory researchers could help U.S. manufacturers produce computer chips with 1,000 times more memory than today's chips-and do so ten times faster than current technology.
The advances appear to largely overcome two critical hurdles that could have blocked the use of extreme ultraviolet (EUV) light to make computer chips in a process called EUV lithography. EUV lithography would allow 21st century computer chip makers to work with light wavelengths 20 times shorter than those of today's technology, reducing line widths or feature sizes on chips from 0.35 to 0.1 micrometer and smaller.
Lawrence Livermore's advances came in two key areas:
  • A critical 20- to 50-fold improvement in accuracy for measuring the surface shapes of optical components used in the lithography process.
  • A 300,000-fold reduction in the number of defects in the multilayer-coated reflective masks used to transfer circuit patterns onto silicon wafers, or chips. The reduction in mask defects springs from an ion beam sputter deposition system developed by the Laboratory and Veeco Instruments Inc, a Plainview, New York, semiconductor equipment company.
    Contact: Andrew Hawryluk (510) 422-5885 (hawryluk1@llnl.gov).

    Lab conducts test of airborne multisensor pod

    Researchers from the Laboratory's Nonproliferation, Arms Control, and International Security directorate conducted airborne tests earlier this year of a multisensor unit they developed to remotely detect small quantities of chemicals and radionuclides. Designed primarily for weapons treaty verification, the unit has potential applications in environmental monitoring or in the event of an industrial accident or natural disaster.
    The 5-m-long by 1-m-wide cylindrical unit, designed to attach to the underside of an aircraft wing, is called the Effluent Species Identification (ESI) pod. A miniature laboratory, the pod contains four effluent sensors: an ion mass spectrometer for identifying chemicals, a radionuclide analyzer to detect radioactivity, a krypton sampler, and an aerial atmosphere sampler. Sensor guidance is provided by a target tracking system located in a small revolving turret on the underside of the pod.
    Laboratory researchers developed one of the sensors and integrated it and the three others into the ESI pod, which they also developed. Collaborating with the Laboratory were Pacific Northwest National Laboratory and the Savannah River Technology Center. The pod is one of several being developed as part of the Department of Energy's Airborne Multisensor Pod System, a nonproliferation program involving several DOE laboratories, the U.S. Navy, and private industry.
    Contact: Joe Galkowski (510) 422-0602 (galkowski1@llnl.gov).

    Seeping gases can aid detection of nuclear tests

    Tiny amounts of radioactive rare gases that seep to the surface from underground nuclear explosions could foil nations secretly trying to evade a proposed ban on nuclear tests. This finding by Lawrence Livermore scientists offers international agencies another possible tool for monitoring a nuclear weapons test ban.
    In the August 8 issue of the British journal Nature, the scientists reported that gases produced by nuclear explosions and released along natural faults and cracks in the Earth can be used to detect clandestine nuclear tests.
    The finding is based on an experiment conducted in 1993 at the Department of Energy's Nevada Test Site. In the experiment, the Lawrence Livermore team mixed small amounts of two nonradioactive gases, helium-3 and sulfur hexafluoride, into chemical explosives in a non-nuclear test that simulated a deeply buried underground nuclear explosion.
    Says geophysicist Charles Carrigan, who led the Livermore team: "Our experiment shows that people who attempt to conduct a clandestine nuclear test will not have any guarantee they can hide it from detection during an on-site inspection."
    Contact: Charles Carrigan (510) 422-3941 (carrigan2@llnl.gov).