ArgoNeuT sees first events

Flavio Cavanna points at an image of the first ArgoNeuT tracks, taped to the detector. Click on the image to see a close-up of the first raw data, which show a cosmic-ray event.

The liquid-argon program at Fermilab is moving ahead. Less than a week after the liquid-argon electronics test station recorded its first cosmic-ray events (see Fermilab Today, Aug. 13, 2008), the Argon Neutrino Test collaboration reported the observation of its first events at Fermilab.

"We started filling the detector with liquid argon on Monday, and by Saturday [Aug. 9] we had the first events," said ArgoNeuT spokesperson Bonnie Fleming, Yale University. "It's gone very well. So far, all systems look quite good."

Flavio Cavanna, of the University of L'Aquila, Italy, Ornella Palamara and Maddalena Antonello, from Gran Sasso National Laboratory, were the people working on the ArgoNeuT detector when it revealed the first cosmic-ray interactions. This team, which also works on the ICARUS experiment in Italy, came to Fermilab at the end of July to share its experience in starting up liquid-argon detectors.

"People were thinking this technology is black magic. But it's more like learning to drive a new car. You need to adjust the seat, point the mirrors in the right direction," said Cavanna, who worked with Fermilab's Andy Lathrop on starting up the cryogenics system. "The liquid-argon technology is more than reliable."

The ArgoNeuT detector relies on a time projection chamber filled with liquid argon to detect the tracks of charged particles. The chamber is about 3 feet long and 1.5 feet wide and high. Collaboration members at Michigan State University developed its electronics.

Later this year, the collaboration will move the detector into the NuMI/MINOS tunnel at Fermilab to measure the interaction of muon neutrinos with argon. The result will add to the analysis of neutrino data collected by ICARUS as well as future liquid-argon detectors.

"It's a big step for the technology of liquid-argon detectors in the U.S.," said Mitch Soderberg, who worked on setting up the detector in the Proton Assembly Building. "We're gaining the experience and knowledge necessary to build bigger detectors that can help answer some of the open questions about neutrinos."

To learn more about the ArgoNeuT experiment, read this article in the August issue of symmetry.

-- Kurt Riesselmann

Members of the ArgoNeuT team gather in front of their detector in the Proton Assembly Building. Later this year, the collaboration will move its detector into the NuMI/MINOS tunnel to record neutrinos.

A giant astronomical survey completes its mission: A new mission begins

From Sloan Digital Sky Survey,
Aug. 15, 2008

CHICAGO -- After a decade of construction and eight years of operation (SDSS-I, 2000-2005; SDSS-II, 2005-2008), the Sloan Digital Sky Survey (SDSS) completed its observations in mid-July and will release its final data set to the public in October. SDSS-III, a six-year program composed of four new surveys, has now begun, using the same telescope.

"I'm glad we didn't know at the beginning how hard it would be and how long it would take," said SDSS Project Scientist Jim Gunn, the Princeton astronomer who has guided the project since its inception. "But now that we've finally accomplished what we set out to do, and much more besides, it seems worth all the effort and all the headaches along the way."

Using a dedicated 2.5-meter diameter telescope equipped with two specialized instruments -- a 125-Megapixel digital camera and spectrographs that observe 640 stars and galaxies at a time -- SDSS has completed its original goals by making deep, multi-color images covering more than one-quarter of the sky and measuring the distances to nearly one million galaxies and over 100,000 quasars, thus creating the largest ever 3-dimensional maps of cosmic structure.

"What amazes me is the huge range of the discoveries that have come from SDSS data," said SDSS-II Director Richard Kron, an astronomer at the University of Chicago and Fermilab. "We designed it primarily as a survey to map the distribution of galaxies and quasars, but it's also had a huge impact on the study of stars, the structure of our own Galaxy, and even solar system objects."

Those achievements are being celebrated this weekend at an international symposium titled "The Sloan Digital Sky Survey: Asteroids to Cosmology," hosted by the Kavli Institute for Cosmological Physics at the University of Chicago. In more than 80 presentations, astronomers from around the globe will describe new discoveries about stars, galaxies, and the cosmos, from the SDSS and from some of the other ambitious surveys that it helped inspire.

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