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In this issue:
Persis S. Drell Named Fourth Director of SLAC
Science Today: Using PEP-II as a Low-energy Machine: An Unexpected Use of BaBar Data
Cyber Shopping Could Cost You A Bundle
GLAST Arrives at Naval Research Laboratory For Final Testing

SLAC Today

Thursday - December 6, 2007

Persis S. Drell Named Fourth Director of SLAC

Persis Drell met with Secretary of Energy Samuel W. Bodman (left) and Under Secretary for Science Raymond L. Orbach last Tuesday in Washington, D.C.

Persis S. Drell has been named Director of the Stanford Linear Accelerator Center (SLAC), effective immediately, Stanford University president John Hennessy announced today. Drell, a professor of physics at SLAC, has held a series of senior positions at the laboratory since 2002 and has served as acting director since September. Stanford University operates SLAC on behalf of the Department of Energy's Office of Science.

Supportive of Drell's appointment, U.S. Secretary of Energy Samuel W. Bodman said he was pleased to have such a qualified individual leading SLAC, furthering departmental support for breakthroughs in science and technology so the nation remains at the forefront of innovation and continues to lead the world in basic energy sciences.

Drell's appointment as director follows an international search and interview process conducted by a committee appointed by President Hennessy. The committee began its work in March 2007, when former director Jonathan Dorfan announced his intention to step down.  Read the full press release...

(Daily Column - Science Today)

Using PEP-II as a Low-energy Machine: An Unexpected Use of BaBar Data

The BaBar experiment has been designed for studying charge parity (CP) violation in B meson decays, which requires an available energy slightly above 10 GeV in the electron-positron center-of-mass. Thanks to the performance of PEP-II, very large amounts of data have been recorded in this way. While most BaBar physicists are busy doing analyses with B mesons, a few of them have found an unusual way to dig for interesting physics. They use the so-called "initial state radiation," where a high-energy photon is emitted by either the electron or the positron before they annihilate. Depending on the radiated photon energy, the annihilation final state can have any mass from threshold to 10 GeV, thus allowing in one go a study of low-energy electron-positron annihilation to be made for free from the BaBar data. Traditionally, experiments at older machines have covered this energy range piece-wise from the pioneering times in Novosibirsk, Orsay, Frascati, SLAC, DESY and more recently again in Novosibirsk, Beijing, Frascati and Cornell. 

BaBar results for initial state radiation are underway. Several papers have already been published for most of the hadronic final states: the results exceed all the previous data in precision and energy coverage. A very special analysis concerns the production of a pair of charged pions which has the largest cross section at low energy: the final state is simple, but since a precision better than 1% is needed, this analysis requires a new level of understanding of the BaBar performance. In fact, each detector efficiency has to be controlled at the level of a few parts in a thousand. Results are expected soon.

Why invest so much effort into a seemingly old-hat physics? The reason is that the electron-positron annihilation cross section into hadrons is one of the most fundamental observables in particle physics. In particular, it is the much-needed ingredient to compute what is called "vacuum polarization," a quantum effect originating from the fluctuation of a propagating photon into pairs of charged particles and their antiparticles, including electrons and positrons, but also quarks and antiquarks. This polarization of the vacuum is named by analogy with the more familiar polarization of an insulator when its molecules acquire electric dipoles under the effect of an external electric field. Vacuum polarization is present in a variety of physical situations because it leads to a modification of the electric charge as measured in charged particle interactions. For example, an increase of about 3% occurs between the textbook value of the elementary electric charge and its effective value at the energy scale of the Z0 boson mass. Precision tests of the electroweak Standard Model with CERN's Large Electron Positron collider (LEP) and the Stanford Linear Collider (SLC), and the indirect determinations of the Higgs boson mass would have been meaningless without taking this effect into account. Another important application of vacuum polarization is a modification of the magnetic moment of the leptons from their purely electromagnetic origin. It is probably here that the BaBar results are most eagerly awaited: they will help establish or not the tantalizing discrepancy that seems to exist between the precise direct measurement of the muon magnetic moment performed at Brookhaven National Laboratory and the Standard-Model prediction which relies heavily on the vacuum-polarization calculation. Future investigations with the muon and forthcoming electroweak tests with the Large Hadron Collider (LHC) at CERN and later the International Linear Collider (ILC) will require even better accuracy for the electron-positron cross section, justifying the effort made with BaBar.

Cyber Shopping Could Cost You A Bundle

There has been an alarming upward trend in infections on SLAC computers in the past several days. We suspect this is related to holiday "cyber shopping" on SLAC computers.

Attackers have set traps for the holiday cyber shoppers. You don't want to get caught in these traps! Your computer could become infected and your personal information stolen. Please keep the following in mind year round, and especially during the holiday season.

• Always keep your operating system fully patched. (Patch Windows operating systems here.)
• Keep your antivirus software up to date. (Symantec definitions can be found here.) Run a weekly full antivirus scan as well. The full scan is to find viruses that might have infected the system before the definitions were updated to detect them.
• Get your firewall up. A firewall helps make you invisible on the internet and blocks all communication from unauthorized sources. It's especially important to run a firewall if you have a broadband connection.
• Beware of e-cards as they can contain viruses and other malware. Reading all your e-mail in plain text can help here too!
• Do not shop from someone else's computer, including public systems.
• Do not shop via public WiFi hotspots. Attackers set up their own hotspots in public areas (including airports) that look like the real ones.
• Beware of spoofed sites, and look for the lock symbol to ensure the site uses encryption.

The Federal Trade Commission's Tips for Smart Holiday Shopping Online offer additional tools.

These two Cyber Security Awareness Month articles are also applicable to cyber shopping: Tools, Training, Useful Websites and Using Browsers, SSL and Domain Names

GLAST Arrives at Naval Research Laboratory For Final Testing

(Photo - GLAST arrives at NRL)
GLAST arrived at the Naval Research Lab in an environmentally-controlled container. Workers are handling purge gas lines intended to protect GLAST from contamination or excessive humidity. (Image courtesy of NRL.)

The Gamma-ray Large Area Space Telescope (GLAST) has arrived at the Naval Research Laboratory (NRL) in Washington, for its final round of testing.

The GLAST spacecraft has successfully completed two of its three environmental tests at the prime contractor, General Dynamics Advanced Information Systems in Gilbert, Arizona. These tests included exposure to extreme vibrations and electromagnetic fields. "We've completed two of the big three tests, and now we're going to the NRL to perform the third," said GLAST project manager Kevin Grady of NASA's Goddard Space Flight Center in Greenbelt, Maryland.

On November 26, the spacecraft began its drive across the country in a specially modified truck and arrived at NRL on November 28. At NRL, the spacecraft will undergo thermal and vacuum testing to ensure that it can survive the 90-degree Fahrenheit (50-degree Celsius) temperature swings it will experience in Earth orbit.

"Although gamma rays can travel billions of light-years across the universe, they can't penetrate Earth's atmosphere, so we must launch our instruments into space. We need to ensure the observatory can function in the space environment, and that is the main goal of the testing about to take place," says GLAST project scientist Steve Ritz of NASA Goddard.  Read more...


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