- Number 361 |
- April 23, 2012
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APEX: an electron gun for the next generation of light sources
APEX, the focus of the Advanced Photon Injector Experiment at DOE's Lawrence Berkeley National Laboratory, is an electron gun specifically designed for the front end of superconducting accelerators that will power the next generation of light sources based on free electron lasers, or FELs. FELs are undulators that wiggle electron bunches to produce pulses of coherent light. What makes APEX special is that it will continually produce well-shaped, ultrashort packages of electrons at rates of up to a million bunches per second.
FEL light sources are already online in Europe, Asia, and the U.S., chalking up research firsts by their unique combination of coherent light, broad tunability, and very high peak power. But compared to familiar synchrotron light sources they are tediously slow, with typical repetition rates in the hundreds or thousands of pulses per second. Some of the most interesting future science promised by FELs will explore how electrons move within molecules in close to real time, requiring very short x-ray pulses repeating hundreds of thousands or even a million times a second.
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Taming uncertainty in climate prediction
Uncertainty just became more certain, thanks to atmospheric and computational researchers at DOE’s Pacific Northwest National Laboratory using a scientific approach called "uncertainty quantification," or UQ, to assess and reduce uncertainties to better simulate precipitation. Their study is the first to apply a stochastic sampling method to select model inputs for precipitation models and improve atmospheric simulations within a regional weather research and forecasting model. Their approach marks a significant advance in representing precipitation, one of the most difficult climate components to simulate.
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Tracking advanced vehicle battery health
Drivers of traditional cars have a pretty good idea how far they can go on a tank of gas and how long their battery will last. Researchers at DOE's Idaho National Laboratory want to make advanced vehicle batteries just as predictable. One solution is the Impedance Measurement Box (IMB), which offers a quicker, cheaper battery monitor that could lead to more accurate lifetime predictions and doesn't drain the battery during testing, as other methods may.
IBM could contribute to a system that can track the health of hybrid and plug-in hybrid electric car batteries just as a gas gauge lets you know when you're about to run out of fuel. But measuring battery life isn't as simple as checking the gas gauge. Batteries slowly lose their capacity over time, delivering less and less energy with each charge. "It's like a gas tank, but the gas tank is shrinking," Christophersen says. -
Neutrons used to study a key protein in milk
Martha, a cow placidly grazing in a field in The Netherlands, became an important collaborator with researchers who successfully analyzed and characterized the internal protein structure and the composite particles of her milk using small-angle neutron scattering at DOE's Oak Ridge National Laboratory.
Casein micelles, a family of related phosphorus-containing proteins, make up 80 percent of the protein in cow milk. They are the building blocks of dairy products such as yogurt and cheese, supplying amino acids, calcium, and phosphorus to the body. More important, they are the principal vehicle for delivering calcium phosphate to rapidly growing newborns.