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In this issue:
ANITA is Back in Business
Science Today: In Too DEEP: Tracking the Changes in Galaxy Clusters
2007 SERT Members Awarded Certificates
Gamma Ray Conference Begins Today at KIPAC
Blood Drive Today

SLAC Today

Thursday - November 8, 2007

ANITA is Back in Business

The ANITA probe visited SLAC in June 2006 for calibration tests using the accelerator beam and a block of ice.

The Antarctic Impulsive Transient Array (ANITA)—that plucky probe that visited SLAC last year before taking to the skies of Antarctica—is back in action. Last month, a schematic of ANITA and the ice target used to calibrate its antennae made the cover of the October 26 edition of Physical Review Letters, and next year NASA plans to send her back for round two over the south pole.

According to SLAC physicist Pisin Chen, one of the investigators working with the ANITA team, the success of the original calibration experiments at SLAC in June of 2006 is proving how valuable particle accelerators can be in the field of astrophysics.

"This is something SLAC should be proud of," Chen said. "Using a particle accelerator to study astrophysics is unique. The high-energy beam from SLAC's linac has such wonderful quality—it can be of great use to the astrophysics community."

ANITA was designed to circle Antarctica tethered to a high-altitude balloon at more than 100,000 feet searching for evidence of ultra-high energy cosmic neutrinos, which generate radio waves when they strike the ice. ANITA researchers brought the detector array to SLAC for calibration tests involving the linac and 10 tons of ice to simulate the Antarctic signals.

(Daily Column - Science Today)

In Too DEEP:
Tracking the Changes
in Galaxy Clusters

A Hubble telescope image of a galaxy cluster in DEEP2.

Made up of hundreds or thousands of individual galaxies each, clusters of galaxies are the most massive objects in the present-day universe. The history of their formation—a procession of smaller groups falling together under the influence of gravity—can provide powerful information about the cosmos and especially about the mysterious dark energy that is accelerating the universe's expansion.

The light from very distant galaxies takes several billion years to reach us, so studying faraway galaxies gives us a window into cosmic history. The DEEP2 Galaxy Redshift Survey has observed tens of thousands of galaxies at a distance of seven billion light-years, covering more than half of the total age of the universe. My recent research has focused on detecting and studying galaxy clusters in DEEP2. By comparing DEEP2 clusters to nearby ones, it should be possible to trace the history of cluster formation and extract cosmological information.

All this would be straightforward if it weren't for those pesky galaxies. They didn't look the same then as they do now. Present-day clusters contain mostly so-called red-and-dead galaxies—old systems that have stopped forming any new stars. DEEP2 clusters are very different, with many more young galaxies forming stars at a furious pace. These evolutionary differences make it a complicated endeavor to compare distant clusters to nearby ones.

At the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), I am working with Professor Risa Wechsler and Postdoc Michael Busha to apply the lessons of DEEP2 to future cluster surveys that will observe millions of galaxies in the distant universe. By combining galaxy evolution models with detailed simulations of cluster formation, we can determine the best methods to use in projects like the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope (LSST) survey, both of which have connections to SLAC.

2007 SERT Members Awarded Certificates

(Group Photo)
The 2007 SERT graduates.
(Click on image for larger version.)

Graduates of SLAC's newly refashioned Post-Earthquake Emergency Response Team (SERT) met for a certification ceremony on Tuesday morning. The course is sponsored by the SLAC Environment, Safety and Health (ES&H) Fire and Emergency Management Group and is led by Barbara Cimino, Emergency Manager for the City of Palo Alto. The SERT self-activates in the event of an earthquake and is trained to engage in light search and rescue, triage and treatment, and related duties related to securing life safety following a severe earthquake. A new SERT class to further expand the team membership will start early in 2008.

Gamma Ray Conference Begins Today at KIPAC

(Conference logo)
An international team of scientists gathers at SLAC this week to discuss the future of gamma-ray astronomy. After years spent focusing on the Gamma-ray Large Area Space Telescope (GLAST), which is set to launch early next year, the collaborators are now looking farther into the future.

"With our strong involvement in gamma-ray astronomy, we now have to start thinking about future instruments," says Stefan Funk, SLAC researcher and organizer of the workshop, which is expected to include around 75 scientists. Hiroyasu Tajima and Roger Romani also helped to organize the workshop.

GLAST's anticipated lifetime will be 5 to 10 years. After that, Funk says, its scientific discovery potential is expected to decrease.

A space telescope more advanced than GLAST would be expensive and extremely difficult to build, so Funk and many other astronomers are now considering a ground-based instrument.

Currently there are three major ground-based gamma-ray instruments, which are capable of detecting gamma rays greater than 100 Terra-electron volts. Funk hopes that a future ground-based instrument would improve by an order of magnitude in sensitivity and also decrease the energy threshold to as low as 20 Giga-electron volts, an energy level currently not deeply studied. "There is a large number of theoretical predictions of what we could see there, we just don't know, but we will know better once GLAST is in orbit," Funk says.

Of the meeting, Funk says, "It's meant to discuss, think about and describe the options we have for the future gamma ray instrument." By the end of the week, the scientists will have a better idea of instrument parameters such as the size and number of telescopes, the altitude at which to put it at, and how to build the Next Big Thing in gamma-ray astronomy.

Blood Drive Today

(Logo)SLAC will host a blood drive in the Panofsky Auditorium Lobby today from 8:00 a.m. until 3:00 p.m. This drive is open to all members of the SLAC community and the general public.

To donate blood, you must:
- Be at least 17 years of age
- Weigh at least 110 pounds
- Be feeling healthy
- Be well hydrated
- Eat before donation

To schedule an appointment online, log onto the Stanford Blood Center website and click on "Find a Blood Drive." Then click on "Mobile Drive Scheduler" and enter SLA5323 in the "Sponsor Code" box. Click on the date of the drive and then follow the prompts to schedule your appointment.

Appointments will be given priority, but walk-ins are always welcome!

Please contact Lauren Barbieri with questions.

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