By Neal Singer
On a stage empty of décor in Bldg. 962 in Tech Area 4, six youthful-appearing LDRD (Laboratory Directed Research and Development) presenters captured the attention of a small audience of about 40 with the intensity of their descriptions of their projects.
The noise level rose afterward when a rotating flux of some 50 Sandians inspected 36 posters describing other LDRD efforts.
“It’s about interacting, not just listening,” said LDRD manager Hank Westrich (1011) approvingly of the freewheeling discussions. The location was chosen because of the large room available for poster presentations.
The oral and poster sessions were preceded by a fact-filled opening talk by Sandia Div. 1000 VP Rick Stulen, who explained the evolving basis for winning the coveted three-year funding, which the Labs has used to develop promising new technologies.
In official terminology, these start-up funds are the “seed corn” of the Labs, which “nurture its core, support its missions, and drive its future,” said Rick.
The program’s history and results are indeed unusual.
According to Rick’s figures, early-stage LDRD grants have supported 60 percent of Sandia’s R&D 100 award winners since 1992. (R&D 100 award winners are determined yearly by independent judges selected by R&D Magazine from projects submitted to the competition from around the world. The projects must show enough development, in addition to original research, to make a difference in the world’s technologies.)
In addition, LDRD funds have supported five of Sandia’s 10 most highly cited publications from 2002-2006. (The number of citations a research paper receives in the papers of later researchers is thought to be a key indicator of its importance.)
“The impact of the [nearly $150 million] LDRD program far exceeds the 8 percent of Sandia’s budget it represents,” Rick said.
A deliberately slimmed-down reviewing process now allows PIs “to devote more time to research rather than paperwork,” he said. In addition, the formerly opaque process has been changed to provide “insightful comments back to PIs, which they seem to appreciate,” he said.
Perhaps surprisingly, Rick’s tables showed that the average start-up project size had increased into the $400,000 range, with a decline in projects in the less-than-$100,000 range. “Don’t hesitate to propose $500,000 to $700,000 programs that will make an impact, even in activities that may not see the light of day for five to 10 years,” he said.
“There’s a myth at the Labs that LDRDs [projects] are only occupied by folks in mid and late career who know how to work the system,” said Rick. Projecting a graph that showed a breakdown of participants by age, he said, “As you can see, almost 50 percent of funding recipients have been here less than five years. Twenty percent have been here five to ten years.”
By accident or design, the speakers seemed to embody the youthful appearance of the figures presented by Rick.
Dahv Kliner (8368) presented ongoing work in the Fiber Laser Grand Challenge, which is developing a new generation of compact, rugged, high-power lasers based on fiber optics. The group has achieved a peak power of more than 1 MW from a single fiber, a factor of 100 beyond the conventional “single-mode limit.” This performance was achieved using the patented coiling technique, first published by Sandia researchers in 2000, that has become the de facto worldwide standard for power scaling of fiber sources. The method has been licensed for industrial applications and was a recipient of this year’s R&D 100 Award.
Dahv pointed out that the peak in-fiber irradiance is beyond the damage threshold for fused silica reported in some studies. Further Grand Challenge research has shown that these earlier reports were incorrect, and the fundamentally new understanding of optical damage is “rewriting the textbooks,” with significant implications for high-power laser optics in general. The high-profile program is now entering its fourth and final year of LDRD support.
Shanalyn Kemme (1725) discussed her efforts to manage a body's thermal emission through use of a thin, textured coating. The coating enables an effect called plasmon/photon coupling. Plasmons are waves of electrons that move parallel to the surface of an object. Through optimum choice of coating material and surface texture parameters (such as grating period and depth), both the angular pattern and wavebands of thermal emission can be shaped.
The method works because a sub-wavelength grating provides phased coupling between the incoherent thermal mode and coherently radiated photons. Key to this mechanism is the subwavelength diffractive optic. Its parameters determine the efficiency of the coupling, angles of radiation, and wavelengths emitted. Small pieces of this coupling diffractive optic will be added to a binder and painted conformally onto an object, she said, so that it should appear almost invisible to heat-detecting instruments.
Hongyou Fan (1815) described his group’s success in reducing defects in the epitaxial growth of single-crystal semiconductor materials. The work contributed to winning an R&D 100 award this year, and was also selected for a 2007 LDRD Award for Excellence. Hongyou and his team developed photolithographically defined and self-assembled carbon nanostructures to provide the first hierarchical growth templates for defect reduction in wide bandgap semiconductor heteroepitaxy. The work, which he said may impact all forms of heteroepitaxy, is tightly aligned with Sandia’s solid-state lighting initiative and the next generation of RF electronics.
“Defect-reduction strategies for group III nitride semiconductors are of immense technological importance,” he said. Use of combined lithographically and self-assembled templates offers freedom from conventional top-down etched-template approaches, he later explained, and hence new opportunities. More importantly, the porous carbon materials exhibit what he feels to be ideal structure and framework chemistry for water purification, nuclear waste treatment, sensors, catalysis matrices, energy conversion and storage.
Winning two awards, joining Sandia as a PMTS, and the Sept. 1 birth of an 8.5-pound daughter named Cindy have made this a pretty good year for Hongyou.
Mark Boslough’s (1433) gut-wrenching simulations of asteroids hitting Earth improved upon science fiction renditions of the same phenomenon by offering new information about the effects of such impacts. Formerly thought to be chiefly a downward thrust that dug out significant craters in earth, Mark’s use of Sandia’s CTH codes on the Red Storm supercomputer has demonstrated that small cratering events can actually involve large airbursts with incandescent fireballs in contact with a surface area of hundreds of square kilometers for tens of seconds.
Explosions may occur above the Earth, he said, when the exponentially increasing air resistance causes an exponentially increasing broadening of the incoming asteroid.
While Mark’s work did not involve creation of a new device, Sandia senior LDRD manager Wendy Cieslak (1010) pointed out that any possible assault on Earth that did not have an upper limit on the damage it could do — as asteroids do not — was clearly a province for exploration by a national security laboratory.
Tammy Kolda (8962) showed computer codes could use mathematical matrices to combine disparate data sources, such as email, telephone, open source, and cell phone data, into a single report that could be mined for particular information. The novel methods for mathematically analyzing graphs include automatically grouping and labeling hyperlinked web pages according to their importance and topic. The approach relies on tensor decomposition methods, which is a new approach to graph and data analysis.
Two new software packages were developed as part of this work: The Tensor Toolbox for Matlab for computations on tensors and TaMALE for graph visualization. The research breaks new ground in cyber security applications.
David Gill (2455) discussed his group’s creation of optimized, light-weight, high-strength structures for aerospace applications. His group used a new code for structural optimization based on Sandia’s extended finite-element method (X-FEM) code, and then partnered with University of Rhode Island to develop generalized 3-D structural optimizations.
In the past, he told the Lab News, such computer renditions weren’t helpful because the topologically optimized structures couldn’t be fabricated by ordinary manufacturing processes. These start with a block of material from which sections are cut or etched away. But using Sandia’s LENS® (Laser-Engineered Net Shaping™), a trademark additive manufacturing process which creates objects out of laser-heated powders, the structures were created. They combine high strength with the lowest possible weight. The project is called, mysteriously enough, “titanium-cholla” because titanium is one of the chief materials for aerospace applications and the structure of the dried cholla cactus is like an optimized torsional beam, which could be used to lighten an automobile driveshaft while maintaining strength comparable to current designs.
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Winners of the 2007 LDRD Award for Excellence are:
-- Neal Singer
By Patti Koning
Since 9/11, radiation detection has taken on a new immediacy as a means of preventing a nuclear weapon attack within the US. Gamma-ray and neutron detectors are being deployed at border crossings and ports, with the goal of enabling interdiction of a nuclear weapon or material before it enters the country.
A neutron scatter camera being developed at Sandia/California offers a new way to detect radiation. The instrument is able to count neutrons from a source of special nuclear material (SNM) and localize it — meaning it doesn’t just tell you there is radiation, but where it is emanating from and, under some circumstances, how much there is.
The results so far are encouraging, says principal investigator Nick Mascarenhas (8132). The neutron scatter camera potentially could detect SNM in quantities of interest in national and homeland security and from distances competitive with or beyond other capabilities. Nick says the goal is to reach much greater standoff detection ability.
Distance is a significant benchmark because it also means the neutron scatter camera can detect through heavy shielding, a concern at any border crossing or point of entry.
“This instrument can pinpoint a hot spot in another room through walls, something not typically possible with gamma-ray detectors,” he says. “It’s beating the older technologies, performance-wise, but we want to push the limits of what this instrument can do — to increase sensitivity and detection distance.”
Jim Lund, manager of Rad/Nuc Detection Systems Dept. 8132, thinks the neutron scatter camera might be the best answer to the problem of seeking out smuggled SNM.
“It’s more penetrating and can detect unambiguously at a greater distance and through more shielding,” he says.
The project is supported by NNSA’s Office of Nonproliferation R&D (NA-22). After successful initial development, the technology is being transitioned to both the Defense Threat Reduction Agency (DTRA) and Domestic Nuclear Detection Office (DNDO) to support specific applications.
DNDO impressed by device
Recently, representatives from DNDO sat in on a presentation by Nick to NNSA. They were so impressed that they asked him how quickly he could have it ready to ship to Hawaii as part of George Lasche’s (6418) in-transit radiation characterization project (Lab News, Aug. 17, 2007).
The neutron scatter camera will make three round-trips to Hawaii — the first departed from the Port of Oakland in early September. George says the camera has the potential to reduce false alarm rates — a critical issue for in-transit radiation detection.
“Our other instruments have told us a lot about the nature of nuclear radiation at sea, but not where it is coming from. The neutron scatter camera can tell us where the radiation is coming from and the size of the object. This information is very helpful in deciding if we have a serious threat on our hands and can lead to fewer false alarms and a better chance of not missing the real thing,” he says.
DTRA is funding a separate project to use the neutron scatter camera to measure and characterize background neutrons at Sandia/California, Sandia/New Mexico, and in Alameda, Calif.
“There are neutrons all over the place from cosmic radiation, even when you are sitting indoors,” says Nick. “Our instrument can measure the energies, rates, and angular variation. This is important in understanding standard operating conditions. You can’t really detect anomalies until you understand what’s normal. This data can also be used to improve instruments to better suppress the standard operating conditions.”
The neutron scatter camera has an advantage over traditional neutron detection because it can differentiate low-energy neutrons from high-energy neutrons.
Device only sees high-energy neutrons
“It doesn’t have to worry about the low-energy nuisance neutrons that are always all around us because it can only see high-energy neutrons, and the high-energy neutrons carry almost all of the imaging information,” says George.
Another advantage is shielding. While gamma rays can be blocked from detectors quite easily, neutrons are much more difficult to conceal. In a lab test, the camera easily detected and imaged a source placed across the hallway, through several walls and cabinets.
Jim notes that the neutron scatter camera is limited in terms of size and time, compared with gamma-ray detectors.
“Ideally, we’d use both systems,” he says. “The neutron scatter camera isn’t practical as a handheld detector with immediate feedback.”
Nick and his team — Kevin Krenz, Peter Marleau, Stan Mrowka (all 8132), and Jim Brennan (8321) — took a slow, careful approach to developing the neutron scatter camera, which has paid off. They started with just two elements and worked to understand everything about how the instrument worked on a simpler scale before moving on. The result is a scalable instrument.
The camera consists of elements containing proton-rich liquid
scintillators in two planes. As neutrons travel through the scintillator, they bounce off protons like billiard balls. This is where “scatter” comes into play — with interactions in each plane of detector elements, the instrument can determine the direction of the radioactive source from which the neutron came.
The neutron eventually flies off, but not before energizing the protons with which it has interacted. The proton will lose its energy in the scintillator. As that energy is lost, it is converted into light. Photomultiplier tubes coupled to the scintillator detect the light.
Computers record data from the neutron scatter camera, and using kinematics, determine the energy of the incoming neutron and its direction. Pulse shape discrimination is employed to distinguish between neutrons and gamma rays.
The biggest obstacle to the camera becoming widely adopted is the liquid scintillator, which is flammable, hazardous, and requires special handling. According to Nick, materials exist that could be used as a solid scintillator, but they need to be mass-produced and made readily available in the US for this purpose. Solid scintillator material, he says, is not in the scope of the current project but is a logical next step.
The current version of the neutron scatter camera has four elements on one side and seven on the other. To improve sensitivity and direction, all that is required is to add more elements.
Nick describes scaling up as an engineering challenge rather than a scientific limit. Bigger means more places where things can break down, but this isn’t a physics issue, he says.“We are not concerned with size at this point — our mission is to understand everything about the performance of this instrument and make it the best it can be,” he says. “Making it portable or compact might be the next steps, but that’s something I’m confident that Sandia, as an engineering laboratory, can solve.” -- Patti Koning