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In this issue:
Mixing Electricity and Water
Science Today: A Historic Magnet Finds New Life in ESA
ASTM Standards Now Online

SLAC Today

Thursday - August 9, 2007

SLAC physicist Andrew Fisher holds a section of heavy copper winding used as a conductor in electromagnets, hollowed out to carry low conductivity cooling water.

Mixing Electricity and Water

Every hair dryer in America is tagged with a large warning label not to use it near water for one obvious reason: mixing the two could result in electrocution and even death. But did you know that it is not actually the water that presents the threat? Water in its purest form is not conductive. Instead, it is the impurities in the water—salts, dust, and so on—that enables it to conduct electricity. In fact, low conductivity water (LCW)—which is purified and deionized—has been used for decades to cool high-voltage equipment such as magnets and klystrons.

LCW commonly flows through accelerator magnets to cool them. These rectangular, copper or aluminum wires measure up to two inches per side and are coiled in various arrangements to produce magnetic fields of different shapes and strengths. A hole in these copper wires carries LCW to remove heat generated by the electric currents.

"SLAC makes a lot of hot water," said SLAC electrical engineer Martin Berndt, who has designed magnets and power supplies that use LCW at SLAC for over 30 years. "It is a great way of removing heat from high-power electrical devices."

The PEP ring, the SSRL ring and various beam transport lines contain many magnets that use LCW. Unlike hair dryers, the concern with mixing water and electricity in the magnets is not electrocution, but corrosion. Lowering the water's conductivity effectively minimizes this corrosiveness. Without LCW, the magnets would slowly be eaten away from the inside out and engineers would have to find another way to dissipate as much as 30 megawatts—16,000 hair dryers worth—of power every day.

(Daily Column - Science Today)

A Historic Magnet Finds New Life in ESA

The wiggler magnet that, after operating in the SPEAR storage ring for over 20 years, has found a new life producing hard synchrotron radiation for the T-475 test beam. (Click on image for larger version.)

Old magnets often get reused in new applications, and the latest example of this comes from the End Station A (ESA) test beam program. An eight-pole wiggler magnet, originally operated in the SPEAR storage ring for over 20 years, has found a new life producing hard synchrotron radiation for the T-475 test beam. Part of the ILC energy spectrometer R&D program, T-475 is testing a synchrotron radiation detector based on quartz fibers, an idea largely inspired by the original Stanford Linear Collider WIre Synchrotron Radiation Detector (SLC WISRD) spectrometer. To get a reasonable signal rate, however, synchrotron photons in excess of 1 MeV are needed.

The SPEAR wiggler was originally installed in 1981 to both increase luminosity for the colliding High Energy Physics program, and to provide intense photons to three experimental stations for SSRL. This wiggler was a perfect match for the T-475 needs aside from one small detail. For the ESA installation, the wiggler needed to be mounted vertically rather than the horizontal orientation used in SPEAR. This Spring, a team lead by Ray Arnold, Carsten Hast and Dieter Walz prepared this historic magnet for installation in ESA. After a thorough cleaning and new paint job, the wiggler was fitted with new field plates and mounted vertically on a custom support stand. The magnet was installed on the ESA beamline at the end of May, and performed well during the three week ESA run which ended July 25th.

ASTM Standards
Now Online

In conjunction with the Stanford University Libraries, the SLAC Research Library recently purchased the complete online collection of American Society for Testing and Materials (ASTM) MyStandards. The standards collection is fully searchable by specific standard number or subject. It is also possible to browse by interest areas such as copper, industrial hygiene and safety, fasteners and so on. The standards are full text PDF files that may be saved to the user's computer.

In addition, SLAC now has access to the ASTM MyDigitalLibrary, a vast repository of technical content including over 40,000 papers from thousands of technical experts around the world who participate in ASTM International. All of the following are available full text:

• Entire 950+ Special Technical Publication peer-reviewed papers, usually presented at symposia sponsored by ASTM's 140 technical committees.

• Entire 50+ Manuals and Monographs

• Entire 13,000+ Journal articles from the Journal of ASTM International; the Journal of Testing and Evaluation; Geotechnical Testing Journal; Journal of Forensic Sciences; Cement, Concrete and Aggregates; Journal of Composites Technology and Research

The SLAC Research Library staff is ready to help you locate any materials you need, and to perform in-depth literature searching on any subject. Give them a call at x2411 or email them at

Make sure you also check out our ASME Standards, CyberRegs, NFPA Codes Online, ASM Handbook & Alloy Center, ASME BPVC, FMGlobal, and International Code Council including 1997 UBC.

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