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In this issue:
Reference Design Report Released for the ILC
Science Today: BaBar's Astonishing Decays
Scientists + Experiments = Big Fun at Tech Museum

SLAC Today

Thursday - February 8, 2007

Reference Design Report Released for the ILC

Members of the International Committee for Future Accelerators and the International Linear Collider Steering Group at Thursday's press conference in Beijing. (Image courtesy of Youhei Morita.)

The International Committee for Future Accelerators (ICFA) today announced the release of the Reference Design Report (RDR) for the International Linear Collider (ILC), a proposed future particle accelerator.

Hurling some 10 billion electrons and their anti-particles, positrons, toward each other at nearly the speed of light, beams in the ILC will collide 14,000 times every second at extremely high energies—500 billion-electronvolts (GeV). These spectacular collisions create an array of new particles that will answer some of the most fundamental questions about the nature of the universe, such as the origin of mass, dark matter, dark energy, extra dimensions and beyond. The current 31-kilometer design allows for an upgrade to a 50-kilometer, 1 trillion-electronvolt (TeV) machine during the second stage of the project. Organized by the Global Design Effort (GDE), a team of more than 60 scientists, the ILC is an international endeavor that brings together more than 1,000 scientists and engineers from more than 100 universities and laboratories in over two dozen countries.  Read more...

(Daily Column - Science Today)

BaBar's Astonishing Decays

In the year following the discovery at SLAC (and simultaneously at Brookhaven National Lab) of the J/ψ in November 1974, a whole family of particles, whimsically called charmonia, appeared in experiments here and at DESY, in Hamburg, Germany. Heavy members of the family decayed into lighter members of the family, emitting photons or pions, usually. Their predilection to remain within the family was explained by their being composed of a charmed quark and its antiquark. Until the quark and antiquark annihilated, a rare occurrence, they remained charmonia. A charmed quark and its antiquark, given sufficient energy could instead become two charmed particles, but below threshold, where there wasn't sufficient energy to make charmed particles, the quark-antiquark pair persisted a long time: up to 10-20 seconds!

The discovery of charmonium states made quarks tangible. No longer could you say quarks were just a mathematical construct. Moreover, you could calculate the properties of charmonium states using techniques developed fifty years earlier to describe simple atoms. There was plenty to measure and theorists had an easy life. These were the halcyon days of particle physics.

SLAC's PEP-II asymmetric B factory was built to study the next quark, the b quark and so the energy of the machine is much higher than the energy of SPEAR, where c the quark made its appearance. However, sometimes the colliding electron or positron emits an energetic photon just before colliding with its counterpart coming from the other direction. Indeed sometimes it emits enough energy so that then the electron-positron collision has just about the same energy as there was a SPEAR and it is possible to study the charmonium particles even with PEP-II.  Read more...

Big Fun at Tech Museum

(Photo - Science Museum)
The genetics exhibit at the San Jose Museum of Technology and Innovation is one of the museum's busiest spots. (Image courtesy of the Tech Museum.)

Sitting at a portable table surrounded by small tubes, black lights and other laboratory trappings, Leremy Colf called out to passing kids, "Do you guys want to try doing science?"

It didn't take long to recruit his first round of scientists-in-training. Four fifth-graders sat down in front of a row of tubes while chaperones looked on. This type of experience is exactly why schools bring classes to San Jose's Museum of Technology and Innovation.

What sets Colf's presentation apart from the other museum programs is its origin. Colf is one of the Stanford graduate students and postdoctoral scholars who trek down to the museum each quarter, engaging visitors in one of three hands-on genetics experiments. One goal of the demonstrations and of the main genetics exhibit, also designed with the aid of Stanford experts, is to show people how the field of genetics touches their lives each day.

In Colf's demonstration, the children learned how scientists make medicines, such as insulin, that are produced by bacteria. Colf started by asking what the kids knew about diabetes. "It's when people get overweight and can't eat a lot of junk food," one child replied. "There's insulin in your blood and people don't have enough so they have to take shots," his friend added. Another boy said that his uncle had diabetes.  Read more...

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