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In this issue:
3-D Printer Puts Detector at Your Fingertips
Science Today: Watching Electrons with Lasers
First U.S. LHC Users' Meeting Focuses on Future

SLAC Today

Thursday - November 6, 2008

3-D Printer Puts Detector at Your Fingertips

Norman Graf (left) and Marco Oriunno with their model and CAD drawing (background). (Photo by Calla Cofield. Click for larger image.)

Blueprints decorate the desk top and design printouts cover the walls of Marco Oriunno's office. They all display plans for a potential particle detector for the International Linear Collider. But to show off the detector, Oriunno goes straight for a pile of colorful plastic. He and Norman Graf stack the pieces together like oversized Legos and voilĂ ! A 3-D version of the detector that can be displayed to scientists, engineers and other project members to help them better understand the massive detector they are trying to build.

Graf and Oriunno are planning the detector as members of the international Silicon Detector Design Collaboration. While design software allows Oriunni and Graf to map out the detector before it is built, Graf says the 3-D model reveals its physical structure in a way that can't be achieved with software images alone. "It's another learning tool. To have both the fully developed design in CAD [computer aided design] and the 3-D model makes a good convergence."  Read more...

(Daily Column - Science Today)

Watching Electrons with Lasers

A pulse of infrared laser light (red) is focused on a jet of nitrogen gas. In the jet, the laser's electric field interacts with the orbitals of nitrogen molecules to produce light in the extreme ultraviolet range (blue). Click image for an animation. (Image and animation courtesy of Markus Guehr.)

A team of researchers from the Stanford PULSE Institute for Ultrafast Energy Science at SLAC National Accelerator Laboratory has recently moved a step closer to visualizing the motions of electrons in molecules using a technique called high harmonic generation, or HHG.

Understanding these movements may help scientists better understand the early stages of chemical reactions. Electrons fuel chemical reactions. When chemicals react, electrons move between the molecules, building and breaking the connections, or bonds, that link atoms.

But in the world of quantum mechanics, electrons aren't easy to pin down. Physicists and chemists create mathematical descriptions called orbitals to illustrate the chance of finding an electron at a specific location of a molecule. Representations of these orbitals look like balloons attached to an atom's nucleus, the center of the atom.

"Orbitals are mathematical constructs," said SLAC researcher Markus Guehr, a member of the PULSE team. "They help us to understand how all of the processes work in there."

Guehr and the PULSE team used HHG to learn about the electron orbitals of nitrogen gas molecules. In an HHG experiment, the researchers use molecules as tiny accelerator light sources. A laser beam is focused onto a stream of cooled nitrogen gas. The electric field of the laser tears an electron from a nitrogen molecule. As the laser field oscillates, the electron is accelerated back into the molecule and recombines with its orbital. Once the electron returns to the molecule, its energy is converted into light in the extreme ultraviolet range.  Read more...

First U.S. LHC Users' Meeting Focuses on Future

(Photo - Jean Cottam)
Jean Cottam, assistant director for Physical Sciences and Engineering in the Office of Science and Technology Policy, speaks at the U.S. LHC Users' meeting on October 24. (Photo courtesy of Fermilab Today. Click for larger image.)

While technology has made communication easier, last month's U.S. Large Hadron Collider Users' meeting at Fermi National Laboratory was the first time that all U.S. LHC communities had come together.

The October 24 meeting brought together accelerator research and major experimental communities for the LHC. It was an opportunity for status updates about the LHC and its experiments, updates from the CERN users organization and a chance to focus on the future of the machine. Scientists at the meeting discussed a plan for the LHC, the machine's schedule and the LHC Accelerator Research Program. They heard from Alan Boyle, MSNBC science writer, who spoke on his perception of the LHC in popular culture.

Jean Cottam, assistant director for Physical Sciences and Engineering in the Office of Science and Technology Policy, talked about the future of the field and the role that her office plays in advising the president and the Office of Management and Budget. Cottam, a NASA astrophysicist, said she admires the fixability of LHC scientists' current problems.

"When we [NASA] build experiments, we launch them into space. If something goes wrong, it is all over. We have no chance to fix them," she said. "[With the LHC], you have an unfortunate situation on your hands, but a delay is just a delay."

She encouraged laboratory employees and users to keep OSTP informed of issues, challenges and valuable projects.

"What you're doing is exciting and important," Cottam said.

See the original article on Fermilab Today.


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