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In this issue:
Shedding Light on a Cosmic Mystery
Science Today: GLAST's Dance Card Begins to Fill
Panofsky on Physics, Politics and Peace--Pief Remembers Released Today
Mark Your Calendars: October 11th All-Hands Briefing

SLAC Today

Thursday - October 4, 2007

SLAC's Takaaki Tanaka has found direct evidence that supernova remnant RX J1713.7-3946 (here imaged with Suzaku X-ray telescope) can accelerate cosmic rays up to 1015 eV. (Click image for larger version.)

Shedding Light on a Cosmic Mystery

A SLAC astrophysicist and his collaborators may have finally solved the long-standing conundrum about the origin of cosmic rays. These streams of subatomic particles—mostly protons—continuously careen through our galaxy, bombarding Earth's atmosphere with tremendous energies. Since their discovery in 1912, researchers have marveled at how ordinary particles could attain such extraordinary energies, but despite intense experimental and theoretical efforts, these questions have eluded definitive answers.

The predominant theory has posited that cosmic rays are accelerated in the supersonic shocks surrounding supernova remnants. According to this hypothesis, turbulent magnetic fields force the particles to ricochet wildly across the shockfront, gaining energy with every crossing until eventually releasing into the cosmos at relativistic speeds. Until now, however, most evidence for this conjecture was circumstantial, relying on theory and logic rather than direct observation.

Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) post-doc Takaaki Tanaka and colleagues have found definitive evidence that supernova remnants are accelerators of cosmic rays, reporting their results in the October 4 issue of Nature. Read more...

(Daily Column - Science Today)

GLAST's Dance Card Begins to Fill


The Hobby-Eberly Telescope at McDonald Observatory in west Texas. (Photo credit McDonald Observatory. Click image for larger version.)

The Gamma-ray Large Area Space Telescope (GLAST) is scheduled for launch early next year, and although it will observe a great variety of interesting high-energy sources, one type of object in particular is expected to dominate the gamma-ray sky: a special class of active galactic nuclei known as "blazars." GLAST will detect thousands of blazars, and in anticipation of this volume of new data, Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) astronomers, in collaboration with their colleagues at Caltech, at Oxford, and in Europe, have assembled the Candidate Gamma-Ray Blazar Survey, or CGRaBS.

The goal of the CGRaBS project is to select, in advance of the launch of GLAST, the best and brightest sources that GLAST will see. CGRaBS has identified the 1,625 objects that have radio and X-ray properties that are the most "blazar-like." The CGRaBS team attempts to gather optical data on each source to determine its precise classification and its redshift, which is a measure of its distance from us. Most of the CGRaBS optical campaign has been conducted on the Hobby-Eberly Telescope at McDonald Observatory in west Texas. Additional observations have been conducted at other large telescopes throughout the world, including at Palomar Observatory in southern California, at the Very Large Telescope in Chile, and at the 10-meter Keck telescope at the summit of Mauna Kea.

By learning about as many objects as possible before GLAST launches, the CGRaBS team can pick out the most interesting or unusual sources in advance, allowing them to identify which sources will warrant more careful study in the GLAST era. In essence, by "doing their homework" on these objects before GLAST detects them, the team can avoid constantly having to "play catch-up" after GLAST detects them. With the CGRaBS list as a guide, and the unprecedented quality of the gamma-ray data from GLAST, the coming years will be a very exciting time for blazar science.

Panofsky on Physics, Politics and Peace—Pief Remembers
Released Today


Pief Panofsky's book, Panofsky on Physics, Politics and Peace—Pief Remembers, is now available in bookstores and online.

Not only is the book an autobiography of this extraordinary man, but a discussion and analysis of issues critical to the relationship between independent academic inquiry and government funding of basic science. The major interests and activities of Pief's life are discussed in turn, from his early research at the beginning of World War II, to his work at SLAC, to his life-long efforts toward arms control and the nonproliferation of nuclear weapons. The book gives detailed descriptions of each phase of Pief's career, informing readers about the issues surrounding his work.

In compiling these memoirs, many people from SLAC made significant contributions. Ellie Lwin managed the production of the book, and Pief worked closely with the Archives and History Office staff, which provided information from his collected papers to fill in occasional gaps in his still-prodigious memory. The Archives Office also assembled photos and captions and obtained publication permissions. The SLAC InfoMedia Solutions staff formatted the photos and figures and consulted on the nuances of pdf manuscript submission.

Mark Your Calendars: October 11th
All-Hands Briefing

Next Thursday, October 11, everyone is requested to attend one of four scheduled 75-minute sessions (8:30 a.m., 10:30 a.m., 1:30 p.m. or 3:30 p.m.) of the 2007 "Safety and Security Briefing & Expo" in the Panofsky Auditorium. Acting Director Persis Drell will give the opening talk, followed by several speakers who will discuss various aspects of safety and security, including DOE Counterintelligence efforts.

Stay tuned to SLAC Today on Monday for more detailed information on these sessions.


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