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In this issue:
ATLAS Toroid Lowered into Cavern at CERN
Safety Today: Chemical Substitution Replaces Hexavalent Chromium Baths
SULI Students Arrive
Safety Seconds

SLAC Today

Tuesday - June 26, 2007

ATLAS Toroid Lowered into Cavern at CERN

The first Toroid End Cap magnet just before it was placed in the ATLAS cavern. (Click on image for larger version.)

What do you get when you cross a 260-ton magnet with an experienced and talented assembly team at CERN? The successful installation of the first Toroid End Cap magnet for the ATLAS detector, which was completed early last week.

This 12-meter tall component complements the barrel toroid magnet, one of the largest magnets ever built. The size is necessary to produce magnetic fields tens of meters across within the ATLAS detector. Such fields are critical in measuring muons, the longest lasting of the unstable elementary particles.

In addition to being very large, the toroid end-cap magnets are also very delicate, containing eight super conducting magnetic coils.

"It was one of the most difficult objects we have had to lower into the cavern," said ATLAS project engineer Mark Hatch.

Using a 280-ton overhead crane—not the most agile of machines—the team at CERN carefully lowered the End Cap 240 feet into the ATLAS cavern. They then fit it into place within the Barrel Toroid, the main piece of magnetic hardware, without damaging any of the experiment's many sensitive components.

Teams from SLAC have been involved with the ATLAS experiment for the past 11 months, working on the pixel detector, the trigger, and the commissioning of studies.  Click here to read a related SLAC Today story.

(Column - Safety Today)

Chemical Substitution Replaces Hexavalent Chromium Baths

A subcontractor removes chromic acid from a 900 gallon tank.

It's not the emptying of any old tank, but the end of use of a toxic chemical. Recently, the SLAC Plating Shop ended its use of hexavalent chromium cleaning and dying baths and began using less hazardous chemical substitutes. While no exceedances of permissible exposure levels of hexavalent chromium have ever been detected in Plating Shop operations, the elimination of this toxin in metal finishing operation reduces the risk of employee exposure. In addition, this decreases environmental concerns associated with hexavalent chromium in hazardous waste generation, wastewater discharges, and ambient air emissions.

With an eye toward avoiding the costs and potential long-term efforts of conducting an OSHA-required monitoring program for hexavalent chromium, Plating Shop Manager Ali Farvid committed to identifying, testing, and implementing the use of substitutes for these two baths. One bath to be replaced is a 900-gallon mixture of chromic and nitric acids used to clean long copper parts and the other is a dye containing 300 gallons of Alodine used to produce a protective coating on aluminum. Both baths are replaceable with safer alternatives. The chromic acid will be replaced with the same phosphoric acid-nitric acid mixture presently being used for cleaning and etching small copper parts. The Alodine bath is currently being run in parallel with its replacement, a non-chromic dip solution, which will still provides the same military specification surface finishing standards offered by the Alodine bath.

This successful project was a joint effort between the Chemical and General Safety Department (CGS), Waste Management (WM), and Mechanical Fabrication Department (MFD). MFD provided the expertise to identify the suitability of bath replacements and the labor to install the new baths; CGS funded the cost of the new chemicals to help kick-start this effort; and WM funded the disposal of the chromic bath. WM will also fund the disposal of the Alodine bath when it is fully removed from service. This team effort has resulted in improved worker and environmental safety.

SULI Students Arrive

(Photo - SULI students)
The 2007 SULI students.
Click on image for larger version.

This week, SLAC welcomes to its various experiments 23 of the best and brightest undergraduate students North America has to offer. Handpicked from over 100 applicants, this year's Science Undergraduate Laboratory Internship (SULI) students have arrived.

"The SULI program gives many students their first taste of forefront research," said SULI Program Manager Mike Woods. "Some tasks and equipment can be intimidating the first time, but working in a team environment helps the learning process."

After a week of lab and safety orientation, the students will join experiments throughout SLAC. There, interns are expected to complete an extensive project culminating in a presentation at the end of the nine week internship. Last year's projects included research on protein crystallization, robots, gamma ray bursts and photovoltaic electrochemical cells.

Although they are scattered throughout SLAC, the interns will be encouraged to form a bonded community during their stay by living, cleaning, and cooking together in Stanford campus' Hammerskjold House.

"We really try to encourage a team atmosphere," said Woods. "That mentality, along with the guidance of their mentors, really helps put their projects into the context of the 'bigger picture' of science research."

Safety Seconds

Unfortunately as many of you recall, yesterday's test was not an academic exercise but a true story that played out last year. The driver involved passed away when he finally left to find help, and was called a hero by the media for losing his life. Would you call it the same way?

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