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In this issue:
Groovy Beam Pipe Update
Food Drive: SLAC Goes Home with a Silver
Around SLAC: The Mark II Detector

SLAC Today

Tuesday - January 27, 2009

Groovy Beam Pipe Update

This insert, manufactured by SLAC and the company EMEGA, was placed inside the KEK-B accelerator beam pipe to trap stray electrons with its triangular grooves. (Photo by Mauro Pivi. Click for larger image.)

Something unwanted lurks within accelerator beam pipes around the world: stray electrons. This haze of electrons interacts with positron and proton beams, often causing distortion. Previous tests showed that an insert designed by SLAC researchers works well to capture stray electrons in an environment with no magnetic field. Now, recent tests carried out at the Japanese accelerator facility KEK confirm that a new insert can reduce this electron cloud effect in a magnetic field.

The tests show that triangular grooves on the beam pipe's interior surface trap stray electrons spiraling through the magnetic field, reducing the number of electrons in the cloud by up to a factor of 10. (Read more about the design in "Don't Rain on My Parade.") The results indicate a significant overall decrease in the number of electrons in the KEK beam pipe. Better yet, the number of electrons detected continued to decrease over the duration of each test, suggesting that the electron cloud will continue to shrink over even longer periods of time.  Read more...

Food Drive: SLAC Goes Home with a Silver

Thank you to everyone who participated in the Second Harvest Food Bank program in December 2008. Because of your generosity, Second Harvest awarded SLAC a Silver Medal. The lab collected in total 1,088 pounds of non-perishable foods, and virtual donations of $1,188 dollars.

Thanks to all for your commitment to helping others.

(Photo - The Mark II detector)
The Mark II detector. (Photo by Brad Plummer. Click for larger image.)

Around SLAC:
The Mark II Detector

First installed to explore the behaviors of subatomic particles in the SPEAR storage ring in 1977, the 1800-ton Mark II detector was updated to examine tau lepton decays in the PEP collider during the early 1980s. Later that decade the Mark II became the primary detector for the Stanford Linear Collider. It was retired in the fall of 1990, and partially dismantled starting in 2004. (See "The Many Lives of Mark II.") Its massive structure still stands in the SLAC Collider Hall (right). For a timeline and historical photos, see the SLAC Archives and History Office's Mark accelerators and detectors Web page.

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