November 21, 2003  


GLAST Milestone: Integration and Testing of Engineering Models

By Larry Wai and Anna Gosline

The Large Area Telescope (LAT) project, a key component of GLAST, recently sailed through its first phase of testing with great success. Conducted at SLAC in conjunction with NASA, this milestone brings physicists one step closer to uncovering the mysteries of the gamma ray sky. The project is an exciting new horizon for particle physics that could lead to discoveries of cosmic proportions.

Clean room where the LAT team tested the integrated detector with cosmic ray muons as well as gamma rays. (Photo by Peter Ginter)

"The LAT detector will be the world’s most sensitive and massive space-based gamma ray telescope when it is launched in 2006," said LAT principal investigator Peter Michelson (Stanford University).

The energy range of the LAT will be unparalleled—from 10 MeV to over 100 GeV—and much more sensitive at detecting and deciphering high energy gamma rays than any other instrument in space. This superior range and sensitivity will allow scientists to answer previously unimaginable questions.

"GLAST science topics include study of the most powerful accelerators in the universe, active galactic nuclei, as well as the potential discovery of the elusive nature of Dark Matter," said Steven Kahn (KIPAC).

Before it can take to the sky, SLAC researchers have to prove that it will work seamlessly in the laboratory.

Testing Detector Prototype

"Early identification of problems is crucial in the overall process of putting a working instrument into space," said Tune Kamae (AG). "Unlike traditional accelerator based experiments, GLAST will be totally inaccessible for repair after launch. This imposes extremely rigorous standards for the integration and test phase for the detector."

Under the management of Elliott Bloom (EK), the LAT Integration and Test (I&T) Subsystem team successfully assembled and tested a small prototype of the LAT detector. According to Elliott, "The testing went beautifully and we are excited by the results. The whole team worked really well together and achieved a great deal."

These hardware tests focused on two components of the LAT detector: the silicon strip tracker and the cesium iodide calorimeter. The tracker, from Instituto Nazionale di Fisica Nucleare (INFN, Italy), measures the trajectory and ultimately the source of celestial gamma-rays. The calorimeter, from the Naval Research Laboratory in Washington, D.C., measures the energy of gamma rays. These two components were combined to create an integrated detector, working together to decipher fingerprints of gamma rays.

Tucked away in a 6,000 square foot clean room, the LAT team tested the integrated detector with cosmic ray muons as well as gamma rays generated by a Van De Graaf accelerator, originally used to test the Crystal Ball Detector in 1978. Huge samples of data were collected in shifts around the clock and on weekends.

Technicians Reggie Rogers and Jeff Tice (both REG) got their first taste of the rigors of space hardware manufacturing as they worked elbow-to-elbow with fellow aerospace veteran Mark Molini (REG). Rogers commented, "The manufacturing process for flight hardware is really impressive in the level of care and detail in documentation of the process. We’ve really got our work cut out for us for the next couple of years."

Accelerated Pace

Despite the recent frenzy of the I&T Subsystem, LAT Project Manager Lowell Klaisner (GLAST) expects the pace will accelerate as the research continues and more components of the LAT are integrated into the full detector. "The entire facility will be a beehive of activity when integration of the LAT is in full swing starting in the summer of 2004," Klaisner said.

Positive results at this early stage in development are promising for the overall success of the completed LAT. The testing of the integrated engineering models is a crucial first step towards manufacturing the entire LAT detector, which will be two orders of magnitude more complex. The hard work and dedication of the LAT team gives every indication that SLAC will rise to the challenge of space.


The Stanford Linear Accelerator Center is managed by Stanford University for the US Department of Energy

Last update Wednesday November 19, 2003 by Kathy B