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In this issue:
From the KIPAC Director: GLAST—Watcher of the Skies
Building the LCLS: Weekly Update
Word of the Week: Pump-Probe
Remembering Hobey DeStaebler
Friday - June 27, 2008 |
From the KIPAC Director: GLAST—Watcher of the SkiesRoughly 6,000 years ago, a 954-year-old neutron star about 10 miles in diameter spinning on its axis 30 times per second used its strong magnetic fields—in a sort of souped up LINAC—to create a gamma-ray photon. This photon escaped from a dense crowd of X-rays, electrons and positrons, all eager to make its acquaintance, into the vast reaches of interstellar space. It is now just outside of our solar system, hurtling towards Earth at the speed of light and sometime next week it will keep an appointment with a three-ton orbiting satellite: the Gamma-ray Large Area Space Telescope (GLAST). However, just as the gamma ray meets its demise inside the GLAST detector, it will give birth to an electron and a positron, which will continue along similar trajectories before spawning several generations of descendents whose genealogy will be reconstructed using a criss-cross pattern of nearly a million Silicon strips and who will hold a family reunion in a block of Cesium Iodide at the end of the detector where each particle will create a flash of light dependent upon the energy of the original gamma ray photon. All of this information about the arrival and fate of this gamma ray will be converted into a brief radio message, which will be transmitted to Earth via another satellite, before being logged in SLAC's Large Area Telescope (LAT) Instrument Science Operations Center (ISOC), located in Building 84. Read more... |
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