CDF's "siliconers" are first line of detector defense

Clockwise: Satyajit Behari, Mark Mathis, Oscar Gonzalez-Lopez, Thomas Junk, Miguel Mondragon, Ricardo Eusebi, Alexander Sukhanov, John Freeman and Sergo Jindariani.

Every Monday morning at 10:30 a.m. in CDF, like the Olympic torch hand off, one silicon detector group member passes the shift pager to another.

"Silicon detector experts are the first line of defense when problems arise," said Sergo Jindariani, co-leader of the silicon detector group.

The silicon detector, which was installed in 2001 for CDF's Run II, is the prototype CMS and ATLAS were modeled after. This makes the information the CDF detector takes crucial for the LHC. The detector precisely measures a particle's trajectory or path.

"Silicon detectors give us access to physics that we could not do otherwise. Their level of precision has changed the paradigm in hadron collider physics," said Rob Roser, CDF co-spokesperson.

In order to get such precise measurements, the silicon detector is located next to the beampipe, a very harsh environment for its delicate sensors.

To keep the detector running well, a team of 13 silicon detector specialists take turns in week-long, 24/7 shifts watching over and responding to any problems with the detector seen by the shift crew in the CDF Main Control Room. Each expert on shift cannot be more than 20 minutes away from CDF and must be near a computer that has the software necessary to fix the problem. During major detector access, silicon detector group members, or siliconers, must be present in the CDF main control room.

"You have to be vigilant and very alert all the time," said Satyajit Behari, co-leader of the CDF silicon detector group.

Although the lifestyle of a siliconer can be hectic at times, the dedicated members of the group know their work is important to new physics discoveries. Because of their diligence, more than 90 percent of the detector's channels are operational eight years later, and there have been no major detector failure incidents in the past three years.

The experts are trained to address operational issues in data taking. Each one must take eight to 10 shifts a year, although there are times, like an electronics board failure, when additional experts may need to come in. Sometimes former members of the group are called in to help, which they do without hesitation.

"Once a siliconer, always a siliconer," both Behari and Jindariani said in unison.

-- Tia Jones

Fermilab's daycare students give to children of Gran Sasso

The area near Gran Sasso laboratory in Italy was hard hit by the April 5 earthquake near L’Aquila. To help employee's children stay close to their parents during this difficult time, Gran Sasso began a childcare program. The children of Fermilab's daycare, The Children's Center, wrote a letter, drew pictures and a banner and collected art supplies for the children of Gran Sasso.

Students from Fermilab's daycare made paintings, such as the one above, for the children of Gran Sasso.

Fermilab's daycare students made a banner to greet the children of Gran Sasso.

Read the letter (pdf) from children at Fermilab's daycare to the children of Gran Sasso.

If you would like to donate art supplies for the children of Gran Sasso, you can bring them to the Office of Communication on the eastside atrium level of Wilson Hall.

Eight ways scientists look at-but don't yet see-dark matter

From Discover magazine, June 22, 2009

Scientists hunt for the unseen matter that glues together the cosmos. But some wonder whether it even exists.

The Galactic Cushion
The Hubble Space Telescope recently beamed back pictures of 29 dwarf galaxies in the Perseus Cluster that, by all appearances, should have been torn to shreds by the gravitational tidal forces of their giant neighbors. Instead, like islands of calm in a stormy sea, the little galaxies remain stable and intact. A team of European astronomers says the secret to their cohesion is a cushion of dark matter that protects them from the gravitational tug-of-war outside. Dark matter, believed to be particularly abundant in dwarf galaxies like these, counteracts the pull of the nearby giants, leaving the smaller galaxies in peace.

Hubble's findings mark the next step in a major research effort aimed at understanding some of the strangest stuff in the cosmos. Dark matter neither emits nor reflects light and cannot be observed directly, posing a challenge for scientists. Although dark matter is thought to be five times as abundant as "normal" matter, finding enough to study has proven difficult.

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