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Public Lecture: A Comet on Earth - Results from the Stardust Mission
Cloud Chamber Views the Invisible
SLAC's Emergency Response Team Seeks Volunteers

SLAC Today

Friday - August 25, 2006

(Image - public lecture poster)

Public Lecture: A Comet on Earth -
Results from the Stardust Mission

The Stardust spacecraft returned from a 6-year voyage in January of 2006. During the mission, it swept through the tail of comet Wild 2 (pronounced Vilt), collecting microscopic particles. The payload re-entered the atmosphere two years later and gently landed in the Utah desert. Since January, researchers have been extracting the particles and using an extensive array of techniques to measure such things as elemental and isotopic abundance, mineralogy and petrology. Researchers at SLAC have been using an x-ray microprobe at the Stanford Synchrotron Radiation Laboratory (SSRL) to determine the amount of different elements present in these particles. Please join SLAC researcher Sean Brennan on Tuesday, August 29 at 7:30 p.m. for a preliminary look at the results from the Stardust mission.  More information...

Cloud Chamber
Views the Invisible

(photo - cloud chamber)
SLAC's cloud chamber was on display for visitors earlier this month. 

BaBar collaborator and SLAC tour guide Luke Corwin used a classic technology to pique new interest on a recent tour for high school students. Using a resident cloud chamber, Corwin revealed the invisible: cosmic rays.

The cloud chamber uses simple supplies in an ingenious way. Its terrarium-sized plexiglass box has a felt rim and a glass top. The felt is soaked with liquid ethanol, which also forms a pool a centimeter or two deep at the bottom of the box. The chamber quickly fills with ethanol vapors. Beneath the box, blocks of dry ice super-cool the ethanol to below its condensation point, so a layer of supersaturated ethanol forms above the liquid. But vapor cannot condense in a pure medium; it needs an imperfection onto which it can cling and condense.

As a charged particle shoots through the chamber, it knocks electrons off neutral oxygen and nitrogen atoms in the air, turning them into positive ions that act as imperfections. Ethanol vapors condense on the ions left by the ray. A light shone from one side illuminates the fine, fleeting trails of mist.

At Corwin's talk, some 15 young adults in a summer program with Bayshore Christian Ministries of East Palo Alto crowded around the chamber, watching for evidence of muons, pions or electrons. The occasional proton left a trail as thick as a pinkie finger.

That a pico-sized particle can generate such a big trail "gives you some idea of the energy it has," said Corwin. "By making the invisible visible, it's a starting point to talk about things around us we can’t see."

Students called out to each other as they saw trails materialize. "They were interested in what they were seeing," says Corwin. "I hope some of them will pursue an education that will allow them to fully understand the mysteries they saw in the cloud chamber."

Emergency Response Team Seeks Volunteers

Geologists predict a greater than 20% chance of a major earthquake on the San Francisco Bay Area segment of the San Andreas fault in the next 30 years. This fault runs only 1/4 mile from the western end of SLAC property and could cause severe shaking throughout the SLAC site. Other Bay Area faults also have the potential to cause varying degrees of damage at SLAC. The chance of a major earthquake somewhere in the greater San Francisco Bay Area during the next 30 years is pegged at an amazing 70%. If you knew there was a 70% chance of rain tomorrow, you would be wise to grab an umbrella. Local communities, including SLAC, are doing the equivalent.

Following a major earthquake, local peninsula communities could be isolated from emergency services and outside assistance for several days or more. In case this happens, communities are training volunteer Emergency Response Teams to assist emergency responders. Menlo Park, for example, has trained 300 volunteers to provide first aid and light search and rescue capabilities.

SLAC is a community with its own Emergency Response Team. The SLAC Emergency Response Team (SERT) trains and drills in first aid, triage, light search and rescue, and other emergency tasks that will be essential following a severe earthquake on the peninsula. The team has been in operation since the 1990's. Due to changes in management, SERT had a quiet year in 2005, but activity is now picking up again with quarterly meetings and a new training program.

Under Fire Marshal Robert Reek and Assistant Fire Marshal Ralph Kerwin, the SERT membership list is being expanded and updated and the team is actively recruiting new members, with an initial goal of achieving a 30-person team.

Members will be educated in the latest emergency assistance techniques through a new certificate program. Beginning in September, on-site classes will be based on the City of Palo Alto's successful PANDA (Palo Alto Neighborhood Disaster Activity) training program, customized for SLAC conditions. This training program will be taught by the City of Palo Alto's Office of Emergency Services and will consist of six half-day classes covering a variety of topics including Introduction to Disasters, Disaster Medical Operations and Disaster Psychology. The classes will be offered on a bi-monthly basis over the course of a year. Due to resource limitations, they will be available only to SERT volunteers. Read more...

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