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In this issue:
First Gamma-ray-only Pulsar Observation Opens New Window on Stellar Evolution
A Special "Thank You" to Fred Kavli
LCLS/SSRL Users' Meeting Update
Lab Sign Gets a New Look
Word of the Week: Muon

SLAC Today

Friday - October 17, 2008

First Gamma-ray-only Pulsar Observation Opens New Window on Stellar Evolution

(Image - pulsar model)
Clouds of charged particles move along the pulsar's magnetic field lines (blue) and create a lighthouse-like beam of gamma rays (purple) in this illustration. (Image courtesy of NASA. Click for larger image.)

About three times a second, a 10,000-year-old stellar corpse sweeps a beam of gamma-rays toward Earth. This object, known as a pulsar, is the first one known to "blink" only in gamma rays, and was discovered by the Large Area Telescope onboard NASA's Fermi Gamma-ray Space Telescope, a collaboration with the U.S. Department of Energy and international partners.

"This is the first example of a new class of pulsars that will give us fundamental insights into how stars work," says Stanford University's Peter Michelson, principal investigator for the Large Area Telescope. The LAT data are processed by the SLAC National Accelerator Laboratory and analyzed by the International LAT Collaboration.

The gamma-ray-only pulsar lies within a supernova remnant known as CTA 1, about 4,600 light-years away in the constellation Cepheus. Its lighthouse-like beam sweeps Earth's way every 316.86 milliseconds and emits 1,000 times the energy of our sun. These results appear in the October 16 edition of Science Express.  Read the full news release....

A Special "Thank You" to Fred Kavli

Fred Kavli addresses invitees in the Kavli Building, while panelist and Stanford physics professor Andrei Linde looks on. (Photo by Calla Cofield. Click for larger version.)

Fred Kavli paid a visit to the lab on Wednesday for a "thank you" celebration held in his honor. The afternoon program featured a panel of particle physicists and astrophysicists, who spoke to invitees about the contrast between theory and experiment in those fields. Kavli himself and members of the Kavli Institute for Particle Astrophysics and Cosmology also made brief remarks.

In addition to the founding donation to create KIPAC, Fred Kavli and the Kavli Foundation made a generous donation earlier this spring that will create an endowment to fund two Kavli Fellows. (See "New Gift from Science Philanthropist to Benefit Students at KIPAC.") Those fellowship positions are set to begin in early 2009.

"Establishing these fellowships is a wonderful opportunity for us," said KIPAC Director Roger Blandford. "We're so thrilled to have the opportunity to say 'thank you' in person to Fred, for his special generosity and the generosity of the Kavli Foundation."

LCLS/SSRL Users' Meeting Update

The joint users' meeting of the lab's two key light sources is going strong this week. Science writer Brad Plummer discusses some of the highlights in his blog.

Lab Sign Gets a New Look

The previous sign. (Photo by Thanh Ly. Click for larger image.)

Facilities Department carpenters Mike Hughes (left), Ryan Kuhn and Ed Boise (right) put the finishing touches on the new temporary sign. (Photo by Calla Cofield. Click for larger image.)

In honor of the lab's new name, the sign at the lab's main entrance has a new look. Created by Facilities carpenters and painters, the wood-frame sign sports the new lab logo, and will mark the Sand Hill Road entry until a more permanent one is ready.

Word of the Week:

The muon shield inside the Front End Enclosure of the Linac Coherent Light Source. (Photo by Brad Plummer. Click for larger image.)

Muons are unstable, negatively charged elementary particles that form when cosmic rays strike the earth's atmosphere, or when accelerated electrons strike matter such as air molecules or components inside an accelerator. Similar to electrons, muons are classified as leptons. Because muons are more than 200 times as massive as electrons, they have intense penetrating power, and, unlike electrons, can easily pass through many materials. In the Linac Coherent Light Source, a special steel muon shielding wall was constructed near the electron beam dump to stop any unwanted muons that are generated as the electron beam is stopped.


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