SLAC Today is online at:
http://today.slac.stanford.edu

In this issue:
PetaCache: Use That Memory
SSRL Result: First Look at Key Enzyme’s Assembly
DC2 Seeks the Secrets of the Gamma-ray Sky
SLAC Today

Thursday – March 2, 2006
(Photo of SLAC Computing Center)
Image by Peter Ginter

PetaCache: Use That Memory

by Kelen Tuttle

For decades, high energy experimental physicists have struggled with a fundamental problem: they simply have too much data to analyze quickly and in its entirety. BaBar researchers routinely wait nine months for computers to sift through large datasets, searching for interesting events and setting these aside for later analysis. This “data skimming” alone constantly uses about 50 percent of BaBar's computing power. And that’s before a researcher can even start analyzing his or her data. Preparing data from CERN's Large Hadron Collider (LHC) will only take longer.

Recognizing this widespread limitation, a team at SLAC is developing the PetaCache project, a new way of thinking about data access and storage. With new computer software and more efficient types of memory, PetaCache may significantly increase the speed of data analysis.

“PetaCache may help scientists change the way they think about exploring new ideas,” said PetaCache project manager Randal Melen. “It will allow a physicist with a sudden new idea, an ‘I wonder if…’ moment, to quickly begin exploring that new idea.”  Read more...
(Weekly Column - Science Today)

SSRL Result:
First Look at Key Enzyme’s Assembly

by Heather Rock Woods

SSRL and Stanford scientists, in collaboration with a team from UC Irvine, have gotten the first look into how the metal active center of an the enzyme largely responsible for fertilizing plants is assembled.

Certain bacteria employ this enzyme, called nitrogenase, to turn nitrogen from the air into a form that plants can use for healthy growth. In contrast to the enzymatic reaction, chemically manufacturing nitrogen fertilizer chemically requires extreme pressures and temperatures and thus huge amounts of energy. Read more...

(Image - nitrogenase model)

A model of the enzyme nitrogenase shows the metal core (circled in black), called FeMoco, where chemical reactions take place.


Weekly SSRL Update

The past week at SPEAR included 24 hours of beam for accelerator physics studies and 142 hours of beam delivered to users. SPEAR delivered beam in 98.6 percent of all hours scheduled, compared to a 2006 average of 96.3 percent. Specifics on the SPEAR status and the various beam lines currently operating can be found online.

DC2 Seeks the Secrets of the Gamma-ray Sky

by David Harris

(Image - GLAST)

Gamma rays will reveal many secrets of the universe—but not until we know how to read their signals. Launching this week at SLAC is the GLAST Data Challenge 2 (DC2), a months-long “roleplay” of how physicists will analyze data coming from the Gamma-ray Large Area Space Telescope when it goes into orbit in 2007. DC2 follows an earlier, more rudimentary version of the challenge held from December 2003 to February 2004.

For the challenge, the organizing team members have secretly hidden a variety of astronomical objects in a computer-simulated mock universe, very similar to our own. They then calculated what that galactic center would look like to GLAST’s telescopes and created large data files to simulate the observations that will be beamed back to Earth from the satellite.

DC2 members take the enormous quantity of simulated data, representing 55 days’ worth of observation, and try to determine as much as possible about the mock universe. They will use the exercise to refine their analysis tools and techniques.  Read more...

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